[v3,1/3] riscv: Move kernel mapping to vmalloc zone

Message ID	20200524085259.24784-2-alex@ghiti.fr (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=l142=7G=lists.infradead.org=linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@kernel.org> DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D71620787 sender: alex@ghiti.fr) by relay10.mail.gandi.net (Postfix) with ESMTPSA id 88A61240003; Sun, 24 May 2020 08:54:19 +0000 (UTC) From: Alexandre Ghiti <alex@ghiti.fr> To: Michael Ellerman <mpe@ellerman.id.au>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, Anup Patel <Anup.Patel@wdc.com>, Atish Patra <Atish.Patra@wdc.com>, Zong Li <zong.li@sifive.com>, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org Subject: [PATCH v3 1/3] riscv: Move kernel mapping to vmalloc zone Date: Sun, 24 May 2020 04:52:57 -0400 Message-Id: <20200524085259.24784-2-alex@ghiti.fr> In-Reply-To: <20200524085259.24784-1-alex@ghiti.fr> References: <20200524085259.24784-1-alex@ghiti.fr> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit summary: Content analysis details: (-0.7 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at https://www.dnswl.org/, low trust [217.70.178.230 listed in list.dnswl.org] 0.0 SPF_NONE SPF: sender does not publish an SPF Record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record Precedence: list Cc: Alexandre Ghiti <alex@ghiti.fr> Sender: "linux-riscv" <linux-riscv-bounces@lists.infradead.org> Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org
Series	vmalloc kernel mapping and relocatable kernel \| expand [v3,0/3] vmalloc kernel mapping and relocatable kernel [v3,1/3] riscv: Move kernel mapping to vmalloc zone [v3,2/3] riscv: Introduce CONFIG_RELOCATABLE [v3,3/3] arch, scripts: Add script to check relocations at compile time

Alexandre Ghiti May 24, 2020, 8:52 a.m. UTC

This is a preparatory patch for relocatable kernel.

The kernel used to be linked at PAGE_OFFSET address and used to be loaded
physically at the beginning of the main memory. Therefore, we could use
the linear mapping for the kernel mapping.

But the relocated kernel base address will be different from PAGE_OFFSET
and since in the linear mapping, two different virtual addresses cannot
point to the same physical address, the kernel mapping needs to lie outside
the linear mapping.

In addition, because modules and BPF must be close to the kernel (inside
+-2GB window), the kernel is placed at the end of the vmalloc zone minus
2GB, which leaves room for modules and BPF. The kernel could not be
placed at the beginning of the vmalloc zone since other vmalloc
allocations from the kernel could get all the +-2GB window around the
kernel which would prevent new modules and BPF programs to be loaded.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/riscv/boot/loader.lds.S     |  3 +-
 arch/riscv/include/asm/page.h    | 10 +++++-
 arch/riscv/include/asm/pgtable.h | 37 +++++++++++++-------
 arch/riscv/kernel/head.S         |  3 +-
 arch/riscv/kernel/module.c       |  4 +--
 arch/riscv/kernel/vmlinux.lds.S  |  3 +-
 arch/riscv/mm/init.c             | 58 +++++++++++++++++++++++++-------
 arch/riscv/mm/physaddr.c         |  2 +-
 8 files changed, 87 insertions(+), 33 deletions(-)

Zong Li May 26, 2020, 9:43 a.m. UTC | #1

On Sun, May 24, 2020 at 4:54 PM Alexandre Ghiti <alex@ghiti.fr> wrote:
>
> This is a preparatory patch for relocatable kernel.
>
> The kernel used to be linked at PAGE_OFFSET address and used to be loaded
> physically at the beginning of the main memory. Therefore, we could use
> the linear mapping for the kernel mapping.
>
> But the relocated kernel base address will be different from PAGE_OFFSET
> and since in the linear mapping, two different virtual addresses cannot
> point to the same physical address, the kernel mapping needs to lie outside
> the linear mapping.
>
> In addition, because modules and BPF must be close to the kernel (inside
> +-2GB window), the kernel is placed at the end of the vmalloc zone minus
> 2GB, which leaves room for modules and BPF. The kernel could not be
> placed at the beginning of the vmalloc zone since other vmalloc
> allocations from the kernel could get all the +-2GB window around the
> kernel which would prevent new modules and BPF programs to be loaded.
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> ---
>  arch/riscv/boot/loader.lds.S     |  3 +-
>  arch/riscv/include/asm/page.h    | 10 +++++-
>  arch/riscv/include/asm/pgtable.h | 37 +++++++++++++-------
>  arch/riscv/kernel/head.S         |  3 +-
>  arch/riscv/kernel/module.c       |  4 +--
>  arch/riscv/kernel/vmlinux.lds.S  |  3 +-
>  arch/riscv/mm/init.c             | 58 +++++++++++++++++++++++++-------
>  arch/riscv/mm/physaddr.c         |  2 +-
>  8 files changed, 87 insertions(+), 33 deletions(-)
>
> diff --git a/arch/riscv/boot/loader.lds.S b/arch/riscv/boot/loader.lds.S
> index 47a5003c2e28..62d94696a19c 100644
> --- a/arch/riscv/boot/loader.lds.S
> +++ b/arch/riscv/boot/loader.lds.S
> @@ -1,13 +1,14 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
>
>  #include <asm/page.h>
> +#include <asm/pgtable.h>
>
>  OUTPUT_ARCH(riscv)
>  ENTRY(_start)
>
>  SECTIONS
>  {
> -       . = PAGE_OFFSET;
> +       . = KERNEL_LINK_ADDR;
>
>         .payload : {
>                 *(.payload)
> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
> index 2d50f76efe48..48bb09b6a9b7 100644
> --- a/arch/riscv/include/asm/page.h
> +++ b/arch/riscv/include/asm/page.h
> @@ -90,18 +90,26 @@ typedef struct page *pgtable_t;
>
>  #ifdef CONFIG_MMU
>  extern unsigned long va_pa_offset;
> +extern unsigned long va_kernel_pa_offset;
>  extern unsigned long pfn_base;
>  #define ARCH_PFN_OFFSET                (pfn_base)
>  #else
>  #define va_pa_offset           0
> +#define va_kernel_pa_offset    0
>  #define ARCH_PFN_OFFSET                (PAGE_OFFSET >> PAGE_SHIFT)
>  #endif /* CONFIG_MMU */
>
>  extern unsigned long max_low_pfn;
>  extern unsigned long min_low_pfn;
> +extern unsigned long kernel_virt_addr;
>
>  #define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + va_pa_offset))
> -#define __va_to_pa_nodebug(x)  ((unsigned long)(x) - va_pa_offset)
> +#define linear_mapping_va_to_pa(x)     ((unsigned long)(x) - va_pa_offset)
> +#define kernel_mapping_va_to_pa(x)     \
> +       ((unsigned long)(x) - va_kernel_pa_offset)
> +#define __va_to_pa_nodebug(x)          \
> +       (((x) >= PAGE_OFFSET) ?         \
> +               linear_mapping_va_to_pa(x) : kernel_mapping_va_to_pa(x))
>
>  #ifdef CONFIG_DEBUG_VIRTUAL
>  extern phys_addr_t __virt_to_phys(unsigned long x);
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 35b60035b6b0..25213cfaf680 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -11,23 +11,29 @@
>
>  #include <asm/pgtable-bits.h>
>
> -#ifndef __ASSEMBLY__
> -
> -/* Page Upper Directory not used in RISC-V */
> -#include <asm-generic/pgtable-nopud.h>
> -#include <asm/page.h>
> -#include <asm/tlbflush.h>
> -#include <linux/mm_types.h>
> -
> -#ifdef CONFIG_MMU
> +#ifndef CONFIG_MMU
> +#define KERNEL_VIRT_ADDR       PAGE_OFFSET
> +#define KERNEL_LINK_ADDR       PAGE_OFFSET
> +#else
> +/*
> + * Leave 2GB for modules and BPF that must lie within a 2GB range around
> + * the kernel.
> + */
> +#define KERNEL_VIRT_ADDR       (VMALLOC_END - SZ_2G + 1)
> +#define KERNEL_LINK_ADDR       KERNEL_VIRT_ADDR
>
>  #define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
>  #define VMALLOC_END      (PAGE_OFFSET - 1)
>  #define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
>
>  #define BPF_JIT_REGION_SIZE    (SZ_128M)
> -#define BPF_JIT_REGION_START   (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
> -#define BPF_JIT_REGION_END     (VMALLOC_END)
> +#define BPF_JIT_REGION_START   (kernel_virt_addr)
> +#define BPF_JIT_REGION_END     (kernel_virt_addr + BPF_JIT_REGION_SIZE)

It seems to have a potential risk here, the region of bpf is
overlapping with kernel mapping, so if kernel size is bigger than
128MB, bpf region would be occupied and run out by kernel mapping.

> +
> +#ifdef CONFIG_64BIT
> +#define VMALLOC_MODULE_START   BPF_JIT_REGION_END
> +#define VMALLOC_MODULE_END     VMALLOC_END
> +#endif
>

Although kernel_virt_addr is a fixed address now, I think it could be
changed for the purpose of relocatable or KASLR, so if
kernel_virt_addr is moved to far from VMALLOC_END than 2G, the region
of module would be too big. In addition, the region of module could be
+-2G around the kernel, so we don't be limited in one direction as
before. It seems to me that the region of the module could be decided
at runtime, for example, VMALLOC_MODULE_START is "&_end - 2G" and
VMLLOC_MODULE_END is "&_start + 2G". I'm not sure whether the size of
region of bpf has to be 128MB for some particular reason, if not,
maybe the region of bpf could be the same with module to avoid being
run out by module.

>  /*
>   * Roughly size the vmemmap space to be large enough to fit enough
> @@ -57,9 +63,16 @@
>  #define FIXADDR_SIZE     PGDIR_SIZE
>  #endif
>  #define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
> -
>  #endif
>
> +#ifndef __ASSEMBLY__
> +
> +/* Page Upper Directory not used in RISC-V */
> +#include <asm-generic/pgtable-nopud.h>
> +#include <asm/page.h>
> +#include <asm/tlbflush.h>
> +#include <linux/mm_types.h>
> +
>  #ifdef CONFIG_64BIT
>  #include <asm/pgtable-64.h>
>  #else
> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> index 98a406474e7d..8f5bb7731327 100644
> --- a/arch/riscv/kernel/head.S
> +++ b/arch/riscv/kernel/head.S
> @@ -49,7 +49,8 @@ ENTRY(_start)
>  #ifdef CONFIG_MMU
>  relocate:
>         /* Relocate return address */
> -       li a1, PAGE_OFFSET
> +       la a1, kernel_virt_addr
> +       REG_L a1, 0(a1)
>         la a2, _start
>         sub a1, a1, a2
>         add ra, ra, a1
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 8bbe5dbe1341..1a8fbe05accf 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -392,12 +392,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>  }
>
>  #if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
> -#define VMALLOC_MODULE_START \
> -        max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START)
>  void *module_alloc(unsigned long size)
>  {
>         return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START,
> -                                   VMALLOC_END, GFP_KERNEL,
> +                                   VMALLOC_MODULE_END, GFP_KERNEL,
>                                     PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
>                                     __builtin_return_address(0));
>  }
> diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
> index 0339b6bbe11a..a9abde62909f 100644
> --- a/arch/riscv/kernel/vmlinux.lds.S
> +++ b/arch/riscv/kernel/vmlinux.lds.S
> @@ -4,7 +4,8 @@
>   * Copyright (C) 2017 SiFive
>   */
>
> -#define LOAD_OFFSET PAGE_OFFSET
> +#include <asm/pgtable.h>
> +#define LOAD_OFFSET KERNEL_LINK_ADDR
>  #include <asm/vmlinux.lds.h>
>  #include <asm/page.h>
>  #include <asm/cache.h>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 27a334106708..17f108baec4f 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -22,6 +22,9 @@
>
>  #include "../kernel/head.h"
>
> +unsigned long kernel_virt_addr = KERNEL_VIRT_ADDR;
> +EXPORT_SYMBOL(kernel_virt_addr);
> +
>  unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
>                                                         __page_aligned_bss;
>  EXPORT_SYMBOL(empty_zero_page);
> @@ -178,8 +181,12 @@ void __init setup_bootmem(void)
>  }
>
>  #ifdef CONFIG_MMU
> +/* Offset between linear mapping virtual address and kernel load address */
>  unsigned long va_pa_offset;
>  EXPORT_SYMBOL(va_pa_offset);
> +/* Offset between kernel mapping virtual address and kernel load address */
> +unsigned long va_kernel_pa_offset;
> +EXPORT_SYMBOL(va_kernel_pa_offset);
>  unsigned long pfn_base;
>  EXPORT_SYMBOL(pfn_base);
>
> @@ -271,7 +278,7 @@ static phys_addr_t __init alloc_pmd(uintptr_t va)
>         if (mmu_enabled)
>                 return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>
> -       pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
> +       pmd_num = (va - kernel_virt_addr) >> PGDIR_SHIFT;
>         BUG_ON(pmd_num >= NUM_EARLY_PMDS);
>         return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
>  }
> @@ -372,14 +379,30 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
>  #error "setup_vm() is called from head.S before relocate so it should not use absolute addressing."
>  #endif
>
> +static uintptr_t load_pa, load_sz;
> +
> +void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
> +{
> +       uintptr_t va, end_va;
> +
> +       end_va = kernel_virt_addr + load_sz;
> +       for (va = kernel_virt_addr; va < end_va; va += map_size)
> +               create_pgd_mapping(pgdir, va,
> +                                  load_pa + (va - kernel_virt_addr),
> +                                  map_size, PAGE_KERNEL_EXEC);
> +}
> +
>  asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>  {
>         uintptr_t va, end_va;
> -       uintptr_t load_pa = (uintptr_t)(&_start);
> -       uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
>         uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE);
>
> +       load_pa = (uintptr_t)(&_start);
> +       load_sz = (uintptr_t)(&_end) - load_pa;
> +
>         va_pa_offset = PAGE_OFFSET - load_pa;
> +       va_kernel_pa_offset = kernel_virt_addr - load_pa;
> +
>         pfn_base = PFN_DOWN(load_pa);
>
>         /*
> @@ -402,26 +425,22 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>         create_pmd_mapping(fixmap_pmd, FIXADDR_START,
>                            (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE);
>         /* Setup trampoline PGD and PMD */
> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>                            (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);
> -       create_pmd_mapping(trampoline_pmd, PAGE_OFFSET,
> +       create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
>                            load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);
>  #else
>         /* Setup trampoline PGD */
> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>                            load_pa, PGDIR_SIZE, PAGE_KERNEL_EXEC);
>  #endif
>
>         /*
> -        * Setup early PGD covering entire kernel which will allows
> +        * Setup early PGD covering entire kernel which will allow
>          * us to reach paging_init(). We map all memory banks later
>          * in setup_vm_final() below.
>          */
> -       end_va = PAGE_OFFSET + load_sz;
> -       for (va = PAGE_OFFSET; va < end_va; va += map_size)
> -               create_pgd_mapping(early_pg_dir, va,
> -                                  load_pa + (va - PAGE_OFFSET),
> -                                  map_size, PAGE_KERNEL_EXEC);
> +       create_kernel_page_table(early_pg_dir, map_size);
>
>         /* Create fixed mapping for early FDT parsing */
>         end_va = __fix_to_virt(FIX_FDT) + FIX_FDT_SIZE;
> @@ -441,6 +460,7 @@ static void __init setup_vm_final(void)
>         uintptr_t va, map_size;
>         phys_addr_t pa, start, end;
>         struct memblock_region *reg;
> +       static struct vm_struct vm_kernel = { 0 };
>
>         /* Set mmu_enabled flag */
>         mmu_enabled = true;
> @@ -467,10 +487,22 @@ static void __init setup_vm_final(void)
>                 for (pa = start; pa < end; pa += map_size) {
>                         va = (uintptr_t)__va(pa);
>                         create_pgd_mapping(swapper_pg_dir, va, pa,
> -                                          map_size, PAGE_KERNEL_EXEC);
> +                                          map_size, PAGE_KERNEL);
>                 }
>         }
>
> +       /* Map the kernel */
> +       create_kernel_page_table(swapper_pg_dir, PMD_SIZE);
> +
> +       /* Reserve the vmalloc area occupied by the kernel */
> +       vm_kernel.addr = (void *)kernel_virt_addr;
> +       vm_kernel.phys_addr = load_pa;
> +       vm_kernel.size = (load_sz + PMD_SIZE) & ~(PMD_SIZE - 1);
> +       vm_kernel.flags = VM_MAP | VM_NO_GUARD;
> +       vm_kernel.caller = __builtin_return_address(0);
> +
> +       vm_area_add_early(&vm_kernel);
> +
>         /* Clear fixmap PTE and PMD mappings */
>         clear_fixmap(FIX_PTE);
>         clear_fixmap(FIX_PMD);
> diff --git a/arch/riscv/mm/physaddr.c b/arch/riscv/mm/physaddr.c
> index e8e4dcd39fed..35703d5ef5fd 100644
> --- a/arch/riscv/mm/physaddr.c
> +++ b/arch/riscv/mm/physaddr.c
> @@ -23,7 +23,7 @@ EXPORT_SYMBOL(__virt_to_phys);
>
>  phys_addr_t __phys_addr_symbol(unsigned long x)
>  {
> -       unsigned long kernel_start = (unsigned long)PAGE_OFFSET;
> +       unsigned long kernel_start = (unsigned long)kernel_virt_addr;
>         unsigned long kernel_end = (unsigned long)_end;
>
>         /*
> --
> 2.20.1
>

Alexandre Ghiti May 26, 2020, 5:06 p.m. UTC | #2

Hi Zong,

Le 5/26/20 à 5:43 AM, Zong Li a écrit :
> On Sun, May 24, 2020 at 4:54 PM Alexandre Ghiti <alex@ghiti.fr> wrote:
>> This is a preparatory patch for relocatable kernel.
>>
>> The kernel used to be linked at PAGE_OFFSET address and used to be loaded
>> physically at the beginning of the main memory. Therefore, we could use
>> the linear mapping for the kernel mapping.
>>
>> But the relocated kernel base address will be different from PAGE_OFFSET
>> and since in the linear mapping, two different virtual addresses cannot
>> point to the same physical address, the kernel mapping needs to lie outside
>> the linear mapping.
>>
>> In addition, because modules and BPF must be close to the kernel (inside
>> +-2GB window), the kernel is placed at the end of the vmalloc zone minus
>> 2GB, which leaves room for modules and BPF. The kernel could not be
>> placed at the beginning of the vmalloc zone since other vmalloc
>> allocations from the kernel could get all the +-2GB window around the
>> kernel which would prevent new modules and BPF programs to be loaded.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>> ---
>>   arch/riscv/boot/loader.lds.S     |  3 +-
>>   arch/riscv/include/asm/page.h    | 10 +++++-
>>   arch/riscv/include/asm/pgtable.h | 37 +++++++++++++-------
>>   arch/riscv/kernel/head.S         |  3 +-
>>   arch/riscv/kernel/module.c       |  4 +--
>>   arch/riscv/kernel/vmlinux.lds.S  |  3 +-
>>   arch/riscv/mm/init.c             | 58 +++++++++++++++++++++++++-------
>>   arch/riscv/mm/physaddr.c         |  2 +-
>>   8 files changed, 87 insertions(+), 33 deletions(-)
>>
>> diff --git a/arch/riscv/boot/loader.lds.S b/arch/riscv/boot/loader.lds.S
>> index 47a5003c2e28..62d94696a19c 100644
>> --- a/arch/riscv/boot/loader.lds.S
>> +++ b/arch/riscv/boot/loader.lds.S
>> @@ -1,13 +1,14 @@
>>   /* SPDX-License-Identifier: GPL-2.0 */
>>
>>   #include <asm/page.h>
>> +#include <asm/pgtable.h>
>>
>>   OUTPUT_ARCH(riscv)
>>   ENTRY(_start)
>>
>>   SECTIONS
>>   {
>> -       . = PAGE_OFFSET;
>> +       . = KERNEL_LINK_ADDR;
>>
>>          .payload : {
>>                  *(.payload)
>> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
>> index 2d50f76efe48..48bb09b6a9b7 100644
>> --- a/arch/riscv/include/asm/page.h
>> +++ b/arch/riscv/include/asm/page.h
>> @@ -90,18 +90,26 @@ typedef struct page *pgtable_t;
>>
>>   #ifdef CONFIG_MMU
>>   extern unsigned long va_pa_offset;
>> +extern unsigned long va_kernel_pa_offset;
>>   extern unsigned long pfn_base;
>>   #define ARCH_PFN_OFFSET                (pfn_base)
>>   #else
>>   #define va_pa_offset           0
>> +#define va_kernel_pa_offset    0
>>   #define ARCH_PFN_OFFSET                (PAGE_OFFSET >> PAGE_SHIFT)
>>   #endif /* CONFIG_MMU */
>>
>>   extern unsigned long max_low_pfn;
>>   extern unsigned long min_low_pfn;
>> +extern unsigned long kernel_virt_addr;
>>
>>   #define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + va_pa_offset))
>> -#define __va_to_pa_nodebug(x)  ((unsigned long)(x) - va_pa_offset)
>> +#define linear_mapping_va_to_pa(x)     ((unsigned long)(x) - va_pa_offset)
>> +#define kernel_mapping_va_to_pa(x)     \
>> +       ((unsigned long)(x) - va_kernel_pa_offset)
>> +#define __va_to_pa_nodebug(x)          \
>> +       (((x) >= PAGE_OFFSET) ?         \
>> +               linear_mapping_va_to_pa(x) : kernel_mapping_va_to_pa(x))
>>
>>   #ifdef CONFIG_DEBUG_VIRTUAL
>>   extern phys_addr_t __virt_to_phys(unsigned long x);
>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> index 35b60035b6b0..25213cfaf680 100644
>> --- a/arch/riscv/include/asm/pgtable.h
>> +++ b/arch/riscv/include/asm/pgtable.h
>> @@ -11,23 +11,29 @@
>>
>>   #include <asm/pgtable-bits.h>
>>
>> -#ifndef __ASSEMBLY__
>> -
>> -/* Page Upper Directory not used in RISC-V */
>> -#include <asm-generic/pgtable-nopud.h>
>> -#include <asm/page.h>
>> -#include <asm/tlbflush.h>
>> -#include <linux/mm_types.h>
>> -
>> -#ifdef CONFIG_MMU
>> +#ifndef CONFIG_MMU
>> +#define KERNEL_VIRT_ADDR       PAGE_OFFSET
>> +#define KERNEL_LINK_ADDR       PAGE_OFFSET
>> +#else
>> +/*
>> + * Leave 2GB for modules and BPF that must lie within a 2GB range around
>> + * the kernel.
>> + */
>> +#define KERNEL_VIRT_ADDR       (VMALLOC_END - SZ_2G + 1)
>> +#define KERNEL_LINK_ADDR       KERNEL_VIRT_ADDR
>>
>>   #define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
>>   #define VMALLOC_END      (PAGE_OFFSET - 1)
>>   #define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
>>
>>   #define BPF_JIT_REGION_SIZE    (SZ_128M)
>> -#define BPF_JIT_REGION_START   (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
>> -#define BPF_JIT_REGION_END     (VMALLOC_END)
>> +#define BPF_JIT_REGION_START   (kernel_virt_addr)
>> +#define BPF_JIT_REGION_END     (kernel_virt_addr + BPF_JIT_REGION_SIZE)
> It seems to have a potential risk here, the region of bpf is
> overlapping with kernel mapping, so if kernel size is bigger than
> 128MB, bpf region would be occupied and run out by kernel mapping.
>
>> +
>> +#ifdef CONFIG_64BIT
>> +#define VMALLOC_MODULE_START   BPF_JIT_REGION_END
>> +#define VMALLOC_MODULE_END     VMALLOC_END
>> +#endif
>>
> Although kernel_virt_addr is a fixed address now, I think it could be
> changed for the purpose of relocatable or KASLR, so if
> kernel_virt_addr is moved to far from VMALLOC_END than 2G, the region
> of module would be too big.


Yes you're right, that's wrong to allow modules to lie outside
the 2G window, thanks for noticing.


> In addition, the region of module could be
> +-2G around the kernel, so we don't be limited in one direction as
> before. It seems to me that the region of the module could be decided
> at runtime, for example, VMALLOC_MODULE_START is "&_end - 2G" and
> VMLLOC_MODULE_END is "&_start + 2G".


I had tried that, but as we need to make sure BPF region is different 
from the module's
that makes the macro definitions really cumbersome. I'll give a try 
again anyway. And
I tried to use _end and _start here but it failed, I have to debug this.


>   I'm not sure whether the size of
> region of bpf has to be 128MB for some particular reason, if not,
> maybe the region of bpf could be the same with module to avoid being
> run out by module.


On the contrary, BPF region must not be the same as module's since in 
that case,
modules could take all the space and make BPF fail.


Thanks for your review Zong,


Alex


>
>>   /*
>>    * Roughly size the vmemmap space to be large enough to fit enough
>> @@ -57,9 +63,16 @@
>>   #define FIXADDR_SIZE     PGDIR_SIZE
>>   #endif
>>   #define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
>> -
>>   #endif
>>
>> +#ifndef __ASSEMBLY__
>> +
>> +/* Page Upper Directory not used in RISC-V */
>> +#include <asm-generic/pgtable-nopud.h>
>> +#include <asm/page.h>
>> +#include <asm/tlbflush.h>
>> +#include <linux/mm_types.h>
>> +
>>   #ifdef CONFIG_64BIT
>>   #include <asm/pgtable-64.h>
>>   #else
>> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
>> index 98a406474e7d..8f5bb7731327 100644
>> --- a/arch/riscv/kernel/head.S
>> +++ b/arch/riscv/kernel/head.S
>> @@ -49,7 +49,8 @@ ENTRY(_start)
>>   #ifdef CONFIG_MMU
>>   relocate:
>>          /* Relocate return address */
>> -       li a1, PAGE_OFFSET
>> +       la a1, kernel_virt_addr
>> +       REG_L a1, 0(a1)
>>          la a2, _start
>>          sub a1, a1, a2
>>          add ra, ra, a1
>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
>> index 8bbe5dbe1341..1a8fbe05accf 100644
>> --- a/arch/riscv/kernel/module.c
>> +++ b/arch/riscv/kernel/module.c
>> @@ -392,12 +392,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>>   }
>>
>>   #if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
>> -#define VMALLOC_MODULE_START \
>> -        max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START)
>>   void *module_alloc(unsigned long size)
>>   {
>>          return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START,
>> -                                   VMALLOC_END, GFP_KERNEL,
>> +                                   VMALLOC_MODULE_END, GFP_KERNEL,
>>                                      PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
>>                                      __builtin_return_address(0));
>>   }
>> diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
>> index 0339b6bbe11a..a9abde62909f 100644
>> --- a/arch/riscv/kernel/vmlinux.lds.S
>> +++ b/arch/riscv/kernel/vmlinux.lds.S
>> @@ -4,7 +4,8 @@
>>    * Copyright (C) 2017 SiFive
>>    */
>>
>> -#define LOAD_OFFSET PAGE_OFFSET
>> +#include <asm/pgtable.h>
>> +#define LOAD_OFFSET KERNEL_LINK_ADDR
>>   #include <asm/vmlinux.lds.h>
>>   #include <asm/page.h>
>>   #include <asm/cache.h>
>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>> index 27a334106708..17f108baec4f 100644
>> --- a/arch/riscv/mm/init.c
>> +++ b/arch/riscv/mm/init.c
>> @@ -22,6 +22,9 @@
>>
>>   #include "../kernel/head.h"
>>
>> +unsigned long kernel_virt_addr = KERNEL_VIRT_ADDR;
>> +EXPORT_SYMBOL(kernel_virt_addr);
>> +
>>   unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
>>                                                          __page_aligned_bss;
>>   EXPORT_SYMBOL(empty_zero_page);
>> @@ -178,8 +181,12 @@ void __init setup_bootmem(void)
>>   }
>>
>>   #ifdef CONFIG_MMU
>> +/* Offset between linear mapping virtual address and kernel load address */
>>   unsigned long va_pa_offset;
>>   EXPORT_SYMBOL(va_pa_offset);
>> +/* Offset between kernel mapping virtual address and kernel load address */
>> +unsigned long va_kernel_pa_offset;
>> +EXPORT_SYMBOL(va_kernel_pa_offset);
>>   unsigned long pfn_base;
>>   EXPORT_SYMBOL(pfn_base);
>>
>> @@ -271,7 +278,7 @@ static phys_addr_t __init alloc_pmd(uintptr_t va)
>>          if (mmu_enabled)
>>                  return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>>
>> -       pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
>> +       pmd_num = (va - kernel_virt_addr) >> PGDIR_SHIFT;
>>          BUG_ON(pmd_num >= NUM_EARLY_PMDS);
>>          return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
>>   }
>> @@ -372,14 +379,30 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
>>   #error "setup_vm() is called from head.S before relocate so it should not use absolute addressing."
>>   #endif
>>
>> +static uintptr_t load_pa, load_sz;
>> +
>> +void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
>> +{
>> +       uintptr_t va, end_va;
>> +
>> +       end_va = kernel_virt_addr + load_sz;
>> +       for (va = kernel_virt_addr; va < end_va; va += map_size)
>> +               create_pgd_mapping(pgdir, va,
>> +                                  load_pa + (va - kernel_virt_addr),
>> +                                  map_size, PAGE_KERNEL_EXEC);
>> +}
>> +
>>   asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>   {
>>          uintptr_t va, end_va;
>> -       uintptr_t load_pa = (uintptr_t)(&_start);
>> -       uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
>>          uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE);
>>
>> +       load_pa = (uintptr_t)(&_start);
>> +       load_sz = (uintptr_t)(&_end) - load_pa;
>> +
>>          va_pa_offset = PAGE_OFFSET - load_pa;
>> +       va_kernel_pa_offset = kernel_virt_addr - load_pa;
>> +
>>          pfn_base = PFN_DOWN(load_pa);
>>
>>          /*
>> @@ -402,26 +425,22 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>          create_pmd_mapping(fixmap_pmd, FIXADDR_START,
>>                             (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE);
>>          /* Setup trampoline PGD and PMD */
>> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
>> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>>                             (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);
>> -       create_pmd_mapping(trampoline_pmd, PAGE_OFFSET,
>> +       create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
>>                             load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);
>>   #else
>>          /* Setup trampoline PGD */
>> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
>> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>>                             load_pa, PGDIR_SIZE, PAGE_KERNEL_EXEC);
>>   #endif
>>
>>          /*
>> -        * Setup early PGD covering entire kernel which will allows
>> +        * Setup early PGD covering entire kernel which will allow
>>           * us to reach paging_init(). We map all memory banks later
>>           * in setup_vm_final() below.
>>           */
>> -       end_va = PAGE_OFFSET + load_sz;
>> -       for (va = PAGE_OFFSET; va < end_va; va += map_size)
>> -               create_pgd_mapping(early_pg_dir, va,
>> -                                  load_pa + (va - PAGE_OFFSET),
>> -                                  map_size, PAGE_KERNEL_EXEC);
>> +       create_kernel_page_table(early_pg_dir, map_size);
>>
>>          /* Create fixed mapping for early FDT parsing */
>>          end_va = __fix_to_virt(FIX_FDT) + FIX_FDT_SIZE;
>> @@ -441,6 +460,7 @@ static void __init setup_vm_final(void)
>>          uintptr_t va, map_size;
>>          phys_addr_t pa, start, end;
>>          struct memblock_region *reg;
>> +       static struct vm_struct vm_kernel = { 0 };
>>
>>          /* Set mmu_enabled flag */
>>          mmu_enabled = true;
>> @@ -467,10 +487,22 @@ static void __init setup_vm_final(void)
>>                  for (pa = start; pa < end; pa += map_size) {
>>                          va = (uintptr_t)__va(pa);
>>                          create_pgd_mapping(swapper_pg_dir, va, pa,
>> -                                          map_size, PAGE_KERNEL_EXEC);
>> +                                          map_size, PAGE_KERNEL);
>>                  }
>>          }
>>
>> +       /* Map the kernel */
>> +       create_kernel_page_table(swapper_pg_dir, PMD_SIZE);
>> +
>> +       /* Reserve the vmalloc area occupied by the kernel */
>> +       vm_kernel.addr = (void *)kernel_virt_addr;
>> +       vm_kernel.phys_addr = load_pa;
>> +       vm_kernel.size = (load_sz + PMD_SIZE) & ~(PMD_SIZE - 1);
>> +       vm_kernel.flags = VM_MAP | VM_NO_GUARD;
>> +       vm_kernel.caller = __builtin_return_address(0);
>> +
>> +       vm_area_add_early(&vm_kernel);
>> +
>>          /* Clear fixmap PTE and PMD mappings */
>>          clear_fixmap(FIX_PTE);
>>          clear_fixmap(FIX_PMD);
>> diff --git a/arch/riscv/mm/physaddr.c b/arch/riscv/mm/physaddr.c
>> index e8e4dcd39fed..35703d5ef5fd 100644
>> --- a/arch/riscv/mm/physaddr.c
>> +++ b/arch/riscv/mm/physaddr.c
>> @@ -23,7 +23,7 @@ EXPORT_SYMBOL(__virt_to_phys);
>>
>>   phys_addr_t __phys_addr_symbol(unsigned long x)
>>   {
>> -       unsigned long kernel_start = (unsigned long)PAGE_OFFSET;
>> +       unsigned long kernel_start = (unsigned long)kernel_virt_addr;
>>          unsigned long kernel_end = (unsigned long)_end;
>>
>>          /*
>> --
>> 2.20.1
>>

Zong Li May 27, 2020, 6:05 a.m. UTC | #3

On Wed, May 27, 2020 at 1:06 AM Alex Ghiti <alex@ghiti.fr> wrote:
>
> Hi Zong,
>
> Le 5/26/20 à 5:43 AM, Zong Li a écrit :
> > On Sun, May 24, 2020 at 4:54 PM Alexandre Ghiti <alex@ghiti.fr> wrote:
> >> This is a preparatory patch for relocatable kernel.
> >>
> >> The kernel used to be linked at PAGE_OFFSET address and used to be loaded
> >> physically at the beginning of the main memory. Therefore, we could use
> >> the linear mapping for the kernel mapping.
> >>
> >> But the relocated kernel base address will be different from PAGE_OFFSET
> >> and since in the linear mapping, two different virtual addresses cannot
> >> point to the same physical address, the kernel mapping needs to lie outside
> >> the linear mapping.
> >>
> >> In addition, because modules and BPF must be close to the kernel (inside
> >> +-2GB window), the kernel is placed at the end of the vmalloc zone minus
> >> 2GB, which leaves room for modules and BPF. The kernel could not be
> >> placed at the beginning of the vmalloc zone since other vmalloc
> >> allocations from the kernel could get all the +-2GB window around the
> >> kernel which would prevent new modules and BPF programs to be loaded.
> >>
> >> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> >> ---
> >>   arch/riscv/boot/loader.lds.S     |  3 +-
> >>   arch/riscv/include/asm/page.h    | 10 +++++-
> >>   arch/riscv/include/asm/pgtable.h | 37 +++++++++++++-------
> >>   arch/riscv/kernel/head.S         |  3 +-
> >>   arch/riscv/kernel/module.c       |  4 +--
> >>   arch/riscv/kernel/vmlinux.lds.S  |  3 +-
> >>   arch/riscv/mm/init.c             | 58 +++++++++++++++++++++++++-------
> >>   arch/riscv/mm/physaddr.c         |  2 +-
> >>   8 files changed, 87 insertions(+), 33 deletions(-)
> >>
> >> diff --git a/arch/riscv/boot/loader.lds.S b/arch/riscv/boot/loader.lds.S
> >> index 47a5003c2e28..62d94696a19c 100644
> >> --- a/arch/riscv/boot/loader.lds.S
> >> +++ b/arch/riscv/boot/loader.lds.S
> >> @@ -1,13 +1,14 @@
> >>   /* SPDX-License-Identifier: GPL-2.0 */
> >>
> >>   #include <asm/page.h>
> >> +#include <asm/pgtable.h>
> >>
> >>   OUTPUT_ARCH(riscv)
> >>   ENTRY(_start)
> >>
> >>   SECTIONS
> >>   {
> >> -       . = PAGE_OFFSET;
> >> +       . = KERNEL_LINK_ADDR;
> >>
> >>          .payload : {
> >>                  *(.payload)
> >> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
> >> index 2d50f76efe48..48bb09b6a9b7 100644
> >> --- a/arch/riscv/include/asm/page.h
> >> +++ b/arch/riscv/include/asm/page.h
> >> @@ -90,18 +90,26 @@ typedef struct page *pgtable_t;
> >>
> >>   #ifdef CONFIG_MMU
> >>   extern unsigned long va_pa_offset;
> >> +extern unsigned long va_kernel_pa_offset;
> >>   extern unsigned long pfn_base;
> >>   #define ARCH_PFN_OFFSET                (pfn_base)
> >>   #else
> >>   #define va_pa_offset           0
> >> +#define va_kernel_pa_offset    0
> >>   #define ARCH_PFN_OFFSET                (PAGE_OFFSET >> PAGE_SHIFT)
> >>   #endif /* CONFIG_MMU */
> >>
> >>   extern unsigned long max_low_pfn;
> >>   extern unsigned long min_low_pfn;
> >> +extern unsigned long kernel_virt_addr;
> >>
> >>   #define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + va_pa_offset))
> >> -#define __va_to_pa_nodebug(x)  ((unsigned long)(x) - va_pa_offset)
> >> +#define linear_mapping_va_to_pa(x)     ((unsigned long)(x) - va_pa_offset)
> >> +#define kernel_mapping_va_to_pa(x)     \
> >> +       ((unsigned long)(x) - va_kernel_pa_offset)
> >> +#define __va_to_pa_nodebug(x)          \
> >> +       (((x) >= PAGE_OFFSET) ?         \
> >> +               linear_mapping_va_to_pa(x) : kernel_mapping_va_to_pa(x))
> >>
> >>   #ifdef CONFIG_DEBUG_VIRTUAL
> >>   extern phys_addr_t __virt_to_phys(unsigned long x);
> >> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> >> index 35b60035b6b0..25213cfaf680 100644
> >> --- a/arch/riscv/include/asm/pgtable.h
> >> +++ b/arch/riscv/include/asm/pgtable.h
> >> @@ -11,23 +11,29 @@
> >>
> >>   #include <asm/pgtable-bits.h>
> >>
> >> -#ifndef __ASSEMBLY__
> >> -
> >> -/* Page Upper Directory not used in RISC-V */
> >> -#include <asm-generic/pgtable-nopud.h>
> >> -#include <asm/page.h>
> >> -#include <asm/tlbflush.h>
> >> -#include <linux/mm_types.h>
> >> -
> >> -#ifdef CONFIG_MMU
> >> +#ifndef CONFIG_MMU
> >> +#define KERNEL_VIRT_ADDR       PAGE_OFFSET
> >> +#define KERNEL_LINK_ADDR       PAGE_OFFSET
> >> +#else
> >> +/*
> >> + * Leave 2GB for modules and BPF that must lie within a 2GB range around
> >> + * the kernel.
> >> + */
> >> +#define KERNEL_VIRT_ADDR       (VMALLOC_END - SZ_2G + 1)
> >> +#define KERNEL_LINK_ADDR       KERNEL_VIRT_ADDR
> >>
> >>   #define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
> >>   #define VMALLOC_END      (PAGE_OFFSET - 1)
> >>   #define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
> >>
> >>   #define BPF_JIT_REGION_SIZE    (SZ_128M)
> >> -#define BPF_JIT_REGION_START   (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
> >> -#define BPF_JIT_REGION_END     (VMALLOC_END)
> >> +#define BPF_JIT_REGION_START   (kernel_virt_addr)
> >> +#define BPF_JIT_REGION_END     (kernel_virt_addr + BPF_JIT_REGION_SIZE)
> > It seems to have a potential risk here, the region of bpf is
> > overlapping with kernel mapping, so if kernel size is bigger than
> > 128MB, bpf region would be occupied and run out by kernel mapping.

Is there the risk as I mentioned?

> >
> >> +
> >> +#ifdef CONFIG_64BIT
> >> +#define VMALLOC_MODULE_START   BPF_JIT_REGION_END
> >> +#define VMALLOC_MODULE_END     VMALLOC_END
> >> +#endif
> >>
> > Although kernel_virt_addr is a fixed address now, I think it could be
> > changed for the purpose of relocatable or KASLR, so if
> > kernel_virt_addr is moved to far from VMALLOC_END than 2G, the region
> > of module would be too big.
>
>
> Yes you're right, that's wrong to allow modules to lie outside
> the 2G window, thanks for noticing.
>
>
> > In addition, the region of module could be
> > +-2G around the kernel, so we don't be limited in one direction as
> > before. It seems to me that the region of the module could be decided
> > at runtime, for example, VMALLOC_MODULE_START is "&_end - 2G" and
> > VMLLOC_MODULE_END is "&_start + 2G".
>
>
> I had tried that, but as we need to make sure BPF region is different
> from the module's
> that makes the macro definitions really cumbersome. I'll give a try
> again anyway. And
> I tried to use _end and _start here but it failed, I have to debug this.
>
>
> >   I'm not sure whether the size of
> > region of bpf has to be 128MB for some particular reason, if not,
> > maybe the region of bpf could be the same with module to avoid being
> > run out by module.
>
>
> On the contrary, BPF region must not be the same as module's since in
> that case,
> modules could take all the space and make BPF fail.

ok, I got it. Thanks for the explaining.


>
>
> Thanks for your review Zong,
>
>
> Alex
>
>
> >
> >>   /*
> >>    * Roughly size the vmemmap space to be large enough to fit enough
> >> @@ -57,9 +63,16 @@
> >>   #define FIXADDR_SIZE     PGDIR_SIZE
> >>   #endif
> >>   #define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
> >> -
> >>   #endif
> >>
> >> +#ifndef __ASSEMBLY__
> >> +
> >> +/* Page Upper Directory not used in RISC-V */
> >> +#include <asm-generic/pgtable-nopud.h>
> >> +#include <asm/page.h>
> >> +#include <asm/tlbflush.h>
> >> +#include <linux/mm_types.h>
> >> +
> >>   #ifdef CONFIG_64BIT
> >>   #include <asm/pgtable-64.h>
> >>   #else
> >> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> >> index 98a406474e7d..8f5bb7731327 100644
> >> --- a/arch/riscv/kernel/head.S
> >> +++ b/arch/riscv/kernel/head.S
> >> @@ -49,7 +49,8 @@ ENTRY(_start)
> >>   #ifdef CONFIG_MMU
> >>   relocate:
> >>          /* Relocate return address */
> >> -       li a1, PAGE_OFFSET
> >> +       la a1, kernel_virt_addr
> >> +       REG_L a1, 0(a1)
> >>          la a2, _start
> >>          sub a1, a1, a2
> >>          add ra, ra, a1
> >> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> >> index 8bbe5dbe1341..1a8fbe05accf 100644
> >> --- a/arch/riscv/kernel/module.c
> >> +++ b/arch/riscv/kernel/module.c
> >> @@ -392,12 +392,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
> >>   }
> >>
> >>   #if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
> >> -#define VMALLOC_MODULE_START \
> >> -        max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START)
> >>   void *module_alloc(unsigned long size)
> >>   {
> >>          return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START,
> >> -                                   VMALLOC_END, GFP_KERNEL,
> >> +                                   VMALLOC_MODULE_END, GFP_KERNEL,
> >>                                      PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
> >>                                      __builtin_return_address(0));
> >>   }
> >> diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
> >> index 0339b6bbe11a..a9abde62909f 100644
> >> --- a/arch/riscv/kernel/vmlinux.lds.S
> >> +++ b/arch/riscv/kernel/vmlinux.lds.S
> >> @@ -4,7 +4,8 @@
> >>    * Copyright (C) 2017 SiFive
> >>    */
> >>
> >> -#define LOAD_OFFSET PAGE_OFFSET
> >> +#include <asm/pgtable.h>
> >> +#define LOAD_OFFSET KERNEL_LINK_ADDR
> >>   #include <asm/vmlinux.lds.h>
> >>   #include <asm/page.h>
> >>   #include <asm/cache.h>
> >> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> >> index 27a334106708..17f108baec4f 100644
> >> --- a/arch/riscv/mm/init.c
> >> +++ b/arch/riscv/mm/init.c
> >> @@ -22,6 +22,9 @@
> >>
> >>   #include "../kernel/head.h"
> >>
> >> +unsigned long kernel_virt_addr = KERNEL_VIRT_ADDR;
> >> +EXPORT_SYMBOL(kernel_virt_addr);
> >> +
> >>   unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
> >>                                                          __page_aligned_bss;
> >>   EXPORT_SYMBOL(empty_zero_page);
> >> @@ -178,8 +181,12 @@ void __init setup_bootmem(void)
> >>   }
> >>
> >>   #ifdef CONFIG_MMU
> >> +/* Offset between linear mapping virtual address and kernel load address */
> >>   unsigned long va_pa_offset;
> >>   EXPORT_SYMBOL(va_pa_offset);
> >> +/* Offset between kernel mapping virtual address and kernel load address */
> >> +unsigned long va_kernel_pa_offset;
> >> +EXPORT_SYMBOL(va_kernel_pa_offset);
> >>   unsigned long pfn_base;
> >>   EXPORT_SYMBOL(pfn_base);
> >>
> >> @@ -271,7 +278,7 @@ static phys_addr_t __init alloc_pmd(uintptr_t va)
> >>          if (mmu_enabled)
> >>                  return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
> >>
> >> -       pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
> >> +       pmd_num = (va - kernel_virt_addr) >> PGDIR_SHIFT;
> >>          BUG_ON(pmd_num >= NUM_EARLY_PMDS);
> >>          return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
> >>   }
> >> @@ -372,14 +379,30 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
> >>   #error "setup_vm() is called from head.S before relocate so it should not use absolute addressing."
> >>   #endif
> >>
> >> +static uintptr_t load_pa, load_sz;
> >> +
> >> +void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
> >> +{
> >> +       uintptr_t va, end_va;
> >> +
> >> +       end_va = kernel_virt_addr + load_sz;
> >> +       for (va = kernel_virt_addr; va < end_va; va += map_size)
> >> +               create_pgd_mapping(pgdir, va,
> >> +                                  load_pa + (va - kernel_virt_addr),
> >> +                                  map_size, PAGE_KERNEL_EXEC);
> >> +}
> >> +
> >>   asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> >>   {
> >>          uintptr_t va, end_va;
> >> -       uintptr_t load_pa = (uintptr_t)(&_start);
> >> -       uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
> >>          uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE);
> >>
> >> +       load_pa = (uintptr_t)(&_start);
> >> +       load_sz = (uintptr_t)(&_end) - load_pa;
> >> +
> >>          va_pa_offset = PAGE_OFFSET - load_pa;
> >> +       va_kernel_pa_offset = kernel_virt_addr - load_pa;
> >> +
> >>          pfn_base = PFN_DOWN(load_pa);
> >>
> >>          /*
> >> @@ -402,26 +425,22 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> >>          create_pmd_mapping(fixmap_pmd, FIXADDR_START,
> >>                             (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE);
> >>          /* Setup trampoline PGD and PMD */
> >> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
> >> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
> >>                             (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);
> >> -       create_pmd_mapping(trampoline_pmd, PAGE_OFFSET,
> >> +       create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
> >>                             load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);
> >>   #else
> >>          /* Setup trampoline PGD */
> >> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
> >> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
> >>                             load_pa, PGDIR_SIZE, PAGE_KERNEL_EXEC);
> >>   #endif
> >>
> >>          /*
> >> -        * Setup early PGD covering entire kernel which will allows
> >> +        * Setup early PGD covering entire kernel which will allow
> >>           * us to reach paging_init(). We map all memory banks later
> >>           * in setup_vm_final() below.
> >>           */
> >> -       end_va = PAGE_OFFSET + load_sz;
> >> -       for (va = PAGE_OFFSET; va < end_va; va += map_size)
> >> -               create_pgd_mapping(early_pg_dir, va,
> >> -                                  load_pa + (va - PAGE_OFFSET),
> >> -                                  map_size, PAGE_KERNEL_EXEC);
> >> +       create_kernel_page_table(early_pg_dir, map_size);
> >>
> >>          /* Create fixed mapping for early FDT parsing */
> >>          end_va = __fix_to_virt(FIX_FDT) + FIX_FDT_SIZE;
> >> @@ -441,6 +460,7 @@ static void __init setup_vm_final(void)
> >>          uintptr_t va, map_size;
> >>          phys_addr_t pa, start, end;
> >>          struct memblock_region *reg;
> >> +       static struct vm_struct vm_kernel = { 0 };
> >>
> >>          /* Set mmu_enabled flag */
> >>          mmu_enabled = true;
> >> @@ -467,10 +487,22 @@ static void __init setup_vm_final(void)
> >>                  for (pa = start; pa < end; pa += map_size) {
> >>                          va = (uintptr_t)__va(pa);
> >>                          create_pgd_mapping(swapper_pg_dir, va, pa,
> >> -                                          map_size, PAGE_KERNEL_EXEC);
> >> +                                          map_size, PAGE_KERNEL);
> >>                  }
> >>          }
> >>
> >> +       /* Map the kernel */
> >> +       create_kernel_page_table(swapper_pg_dir, PMD_SIZE);
> >> +
> >> +       /* Reserve the vmalloc area occupied by the kernel */
> >> +       vm_kernel.addr = (void *)kernel_virt_addr;
> >> +       vm_kernel.phys_addr = load_pa;
> >> +       vm_kernel.size = (load_sz + PMD_SIZE) & ~(PMD_SIZE - 1);
> >> +       vm_kernel.flags = VM_MAP | VM_NO_GUARD;
> >> +       vm_kernel.caller = __builtin_return_address(0);
> >> +
> >> +       vm_area_add_early(&vm_kernel);
> >> +
> >>          /* Clear fixmap PTE and PMD mappings */
> >>          clear_fixmap(FIX_PTE);
> >>          clear_fixmap(FIX_PMD);
> >> diff --git a/arch/riscv/mm/physaddr.c b/arch/riscv/mm/physaddr.c
> >> index e8e4dcd39fed..35703d5ef5fd 100644
> >> --- a/arch/riscv/mm/physaddr.c
> >> +++ b/arch/riscv/mm/physaddr.c
> >> @@ -23,7 +23,7 @@ EXPORT_SYMBOL(__virt_to_phys);
> >>
> >>   phys_addr_t __phys_addr_symbol(unsigned long x)
> >>   {
> >> -       unsigned long kernel_start = (unsigned long)PAGE_OFFSET;
> >> +       unsigned long kernel_start = (unsigned long)kernel_virt_addr;
> >>          unsigned long kernel_end = (unsigned long)_end;
> >>
> >>          /*
> >> --
> >> 2.20.1
> >>

Alexandre Ghiti May 27, 2020, 7:29 a.m. UTC | #4

Le 5/27/20 à 2:05 AM, Zong Li a écrit :
> On Wed, May 27, 2020 at 1:06 AM Alex Ghiti <alex@ghiti.fr> wrote:
>> Hi Zong,
>>
>> Le 5/26/20 à 5:43 AM, Zong Li a écrit :
>>> On Sun, May 24, 2020 at 4:54 PM Alexandre Ghiti <alex@ghiti.fr> wrote:
>>>> This is a preparatory patch for relocatable kernel.
>>>>
>>>> The kernel used to be linked at PAGE_OFFSET address and used to be loaded
>>>> physically at the beginning of the main memory. Therefore, we could use
>>>> the linear mapping for the kernel mapping.
>>>>
>>>> But the relocated kernel base address will be different from PAGE_OFFSET
>>>> and since in the linear mapping, two different virtual addresses cannot
>>>> point to the same physical address, the kernel mapping needs to lie outside
>>>> the linear mapping.
>>>>
>>>> In addition, because modules and BPF must be close to the kernel (inside
>>>> +-2GB window), the kernel is placed at the end of the vmalloc zone minus
>>>> 2GB, which leaves room for modules and BPF. The kernel could not be
>>>> placed at the beginning of the vmalloc zone since other vmalloc
>>>> allocations from the kernel could get all the +-2GB window around the
>>>> kernel which would prevent new modules and BPF programs to be loaded.
>>>>
>>>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>>>> ---
>>>>    arch/riscv/boot/loader.lds.S     |  3 +-
>>>>    arch/riscv/include/asm/page.h    | 10 +++++-
>>>>    arch/riscv/include/asm/pgtable.h | 37 +++++++++++++-------
>>>>    arch/riscv/kernel/head.S         |  3 +-
>>>>    arch/riscv/kernel/module.c       |  4 +--
>>>>    arch/riscv/kernel/vmlinux.lds.S  |  3 +-
>>>>    arch/riscv/mm/init.c             | 58 +++++++++++++++++++++++++-------
>>>>    arch/riscv/mm/physaddr.c         |  2 +-
>>>>    8 files changed, 87 insertions(+), 33 deletions(-)
>>>>
>>>> diff --git a/arch/riscv/boot/loader.lds.S b/arch/riscv/boot/loader.lds.S
>>>> index 47a5003c2e28..62d94696a19c 100644
>>>> --- a/arch/riscv/boot/loader.lds.S
>>>> +++ b/arch/riscv/boot/loader.lds.S
>>>> @@ -1,13 +1,14 @@
>>>>    /* SPDX-License-Identifier: GPL-2.0 */
>>>>
>>>>    #include <asm/page.h>
>>>> +#include <asm/pgtable.h>
>>>>
>>>>    OUTPUT_ARCH(riscv)
>>>>    ENTRY(_start)
>>>>
>>>>    SECTIONS
>>>>    {
>>>> -       . = PAGE_OFFSET;
>>>> +       . = KERNEL_LINK_ADDR;
>>>>
>>>>           .payload : {
>>>>                   *(.payload)
>>>> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
>>>> index 2d50f76efe48..48bb09b6a9b7 100644
>>>> --- a/arch/riscv/include/asm/page.h
>>>> +++ b/arch/riscv/include/asm/page.h
>>>> @@ -90,18 +90,26 @@ typedef struct page *pgtable_t;
>>>>
>>>>    #ifdef CONFIG_MMU
>>>>    extern unsigned long va_pa_offset;
>>>> +extern unsigned long va_kernel_pa_offset;
>>>>    extern unsigned long pfn_base;
>>>>    #define ARCH_PFN_OFFSET                (pfn_base)
>>>>    #else
>>>>    #define va_pa_offset           0
>>>> +#define va_kernel_pa_offset    0
>>>>    #define ARCH_PFN_OFFSET                (PAGE_OFFSET >> PAGE_SHIFT)
>>>>    #endif /* CONFIG_MMU */
>>>>
>>>>    extern unsigned long max_low_pfn;
>>>>    extern unsigned long min_low_pfn;
>>>> +extern unsigned long kernel_virt_addr;
>>>>
>>>>    #define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + va_pa_offset))
>>>> -#define __va_to_pa_nodebug(x)  ((unsigned long)(x) - va_pa_offset)
>>>> +#define linear_mapping_va_to_pa(x)     ((unsigned long)(x) - va_pa_offset)
>>>> +#define kernel_mapping_va_to_pa(x)     \
>>>> +       ((unsigned long)(x) - va_kernel_pa_offset)
>>>> +#define __va_to_pa_nodebug(x)          \
>>>> +       (((x) >= PAGE_OFFSET) ?         \
>>>> +               linear_mapping_va_to_pa(x) : kernel_mapping_va_to_pa(x))
>>>>
>>>>    #ifdef CONFIG_DEBUG_VIRTUAL
>>>>    extern phys_addr_t __virt_to_phys(unsigned long x);
>>>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>>>> index 35b60035b6b0..25213cfaf680 100644
>>>> --- a/arch/riscv/include/asm/pgtable.h
>>>> +++ b/arch/riscv/include/asm/pgtable.h
>>>> @@ -11,23 +11,29 @@
>>>>
>>>>    #include <asm/pgtable-bits.h>
>>>>
>>>> -#ifndef __ASSEMBLY__
>>>> -
>>>> -/* Page Upper Directory not used in RISC-V */
>>>> -#include <asm-generic/pgtable-nopud.h>
>>>> -#include <asm/page.h>
>>>> -#include <asm/tlbflush.h>
>>>> -#include <linux/mm_types.h>
>>>> -
>>>> -#ifdef CONFIG_MMU
>>>> +#ifndef CONFIG_MMU
>>>> +#define KERNEL_VIRT_ADDR       PAGE_OFFSET
>>>> +#define KERNEL_LINK_ADDR       PAGE_OFFSET
>>>> +#else
>>>> +/*
>>>> + * Leave 2GB for modules and BPF that must lie within a 2GB range around
>>>> + * the kernel.
>>>> + */
>>>> +#define KERNEL_VIRT_ADDR       (VMALLOC_END - SZ_2G + 1)
>>>> +#define KERNEL_LINK_ADDR       KERNEL_VIRT_ADDR
>>>>
>>>>    #define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
>>>>    #define VMALLOC_END      (PAGE_OFFSET - 1)
>>>>    #define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
>>>>
>>>>    #define BPF_JIT_REGION_SIZE    (SZ_128M)
>>>> -#define BPF_JIT_REGION_START   (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
>>>> -#define BPF_JIT_REGION_END     (VMALLOC_END)
>>>> +#define BPF_JIT_REGION_START   (kernel_virt_addr)
>>>> +#define BPF_JIT_REGION_END     (kernel_virt_addr + BPF_JIT_REGION_SIZE)
>>> It seems to have a potential risk here, the region of bpf is
>>> overlapping with kernel mapping, so if kernel size is bigger than
>>> 128MB, bpf region would be occupied and run out by kernel mapping.
> Is there the risk as I mentioned?


Sorry I forgot to answer this one: I was confident that 128MB was large 
enough for kernel
and BPF. But I see no reason to leave this risk so I'll change 
kernel_virt_addr for _end so
BPF will have its 128MB reserved.

Thanks !

Alex


>
>>>> +
>>>> +#ifdef CONFIG_64BIT
>>>> +#define VMALLOC_MODULE_START   BPF_JIT_REGION_END
>>>> +#define VMALLOC_MODULE_END     VMALLOC_END
>>>> +#endif
>>>>
>>> Although kernel_virt_addr is a fixed address now, I think it could be
>>> changed for the purpose of relocatable or KASLR, so if
>>> kernel_virt_addr is moved to far from VMALLOC_END than 2G, the region
>>> of module would be too big.
>>
>> Yes you're right, that's wrong to allow modules to lie outside
>> the 2G window, thanks for noticing.
>>
>>
>>> In addition, the region of module could be
>>> +-2G around the kernel, so we don't be limited in one direction as
>>> before. It seems to me that the region of the module could be decided
>>> at runtime, for example, VMALLOC_MODULE_START is "&_end - 2G" and
>>> VMLLOC_MODULE_END is "&_start + 2G".
>>
>> I had tried that, but as we need to make sure BPF region is different
>> from the module's
>> that makes the macro definitions really cumbersome. I'll give a try
>> again anyway. And
>> I tried to use _end and _start here but it failed, I have to debug this.
>>
>>
>>>    I'm not sure whether the size of
>>> region of bpf has to be 128MB for some particular reason, if not,
>>> maybe the region of bpf could be the same with module to avoid being
>>> run out by module.
>>
>> On the contrary, BPF region must not be the same as module's since in
>> that case,
>> modules could take all the space and make BPF fail.
> ok, I got it. Thanks for the explaining.
>
>
>>
>> Thanks for your review Zong,
>>
>>
>> Alex
>>
>>
>>>>    /*
>>>>     * Roughly size the vmemmap space to be large enough to fit enough
>>>> @@ -57,9 +63,16 @@
>>>>    #define FIXADDR_SIZE     PGDIR_SIZE
>>>>    #endif
>>>>    #define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
>>>> -
>>>>    #endif
>>>>
>>>> +#ifndef __ASSEMBLY__
>>>> +
>>>> +/* Page Upper Directory not used in RISC-V */
>>>> +#include <asm-generic/pgtable-nopud.h>
>>>> +#include <asm/page.h>
>>>> +#include <asm/tlbflush.h>
>>>> +#include <linux/mm_types.h>
>>>> +
>>>>    #ifdef CONFIG_64BIT
>>>>    #include <asm/pgtable-64.h>
>>>>    #else
>>>> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
>>>> index 98a406474e7d..8f5bb7731327 100644
>>>> --- a/arch/riscv/kernel/head.S
>>>> +++ b/arch/riscv/kernel/head.S
>>>> @@ -49,7 +49,8 @@ ENTRY(_start)
>>>>    #ifdef CONFIG_MMU
>>>>    relocate:
>>>>           /* Relocate return address */
>>>> -       li a1, PAGE_OFFSET
>>>> +       la a1, kernel_virt_addr
>>>> +       REG_L a1, 0(a1)
>>>>           la a2, _start
>>>>           sub a1, a1, a2
>>>>           add ra, ra, a1
>>>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
>>>> index 8bbe5dbe1341..1a8fbe05accf 100644
>>>> --- a/arch/riscv/kernel/module.c
>>>> +++ b/arch/riscv/kernel/module.c
>>>> @@ -392,12 +392,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>>>>    }
>>>>
>>>>    #if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
>>>> -#define VMALLOC_MODULE_START \
>>>> -        max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START)
>>>>    void *module_alloc(unsigned long size)
>>>>    {
>>>>           return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START,
>>>> -                                   VMALLOC_END, GFP_KERNEL,
>>>> +                                   VMALLOC_MODULE_END, GFP_KERNEL,
>>>>                                       PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
>>>>                                       __builtin_return_address(0));
>>>>    }
>>>> diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
>>>> index 0339b6bbe11a..a9abde62909f 100644
>>>> --- a/arch/riscv/kernel/vmlinux.lds.S
>>>> +++ b/arch/riscv/kernel/vmlinux.lds.S
>>>> @@ -4,7 +4,8 @@
>>>>     * Copyright (C) 2017 SiFive
>>>>     */
>>>>
>>>> -#define LOAD_OFFSET PAGE_OFFSET
>>>> +#include <asm/pgtable.h>
>>>> +#define LOAD_OFFSET KERNEL_LINK_ADDR
>>>>    #include <asm/vmlinux.lds.h>
>>>>    #include <asm/page.h>
>>>>    #include <asm/cache.h>
>>>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>>>> index 27a334106708..17f108baec4f 100644
>>>> --- a/arch/riscv/mm/init.c
>>>> +++ b/arch/riscv/mm/init.c
>>>> @@ -22,6 +22,9 @@
>>>>
>>>>    #include "../kernel/head.h"
>>>>
>>>> +unsigned long kernel_virt_addr = KERNEL_VIRT_ADDR;
>>>> +EXPORT_SYMBOL(kernel_virt_addr);
>>>> +
>>>>    unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
>>>>                                                           __page_aligned_bss;
>>>>    EXPORT_SYMBOL(empty_zero_page);
>>>> @@ -178,8 +181,12 @@ void __init setup_bootmem(void)
>>>>    }
>>>>
>>>>    #ifdef CONFIG_MMU
>>>> +/* Offset between linear mapping virtual address and kernel load address */
>>>>    unsigned long va_pa_offset;
>>>>    EXPORT_SYMBOL(va_pa_offset);
>>>> +/* Offset between kernel mapping virtual address and kernel load address */
>>>> +unsigned long va_kernel_pa_offset;
>>>> +EXPORT_SYMBOL(va_kernel_pa_offset);
>>>>    unsigned long pfn_base;
>>>>    EXPORT_SYMBOL(pfn_base);
>>>>
>>>> @@ -271,7 +278,7 @@ static phys_addr_t __init alloc_pmd(uintptr_t va)
>>>>           if (mmu_enabled)
>>>>                   return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>>>>
>>>> -       pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
>>>> +       pmd_num = (va - kernel_virt_addr) >> PGDIR_SHIFT;
>>>>           BUG_ON(pmd_num >= NUM_EARLY_PMDS);
>>>>           return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
>>>>    }
>>>> @@ -372,14 +379,30 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
>>>>    #error "setup_vm() is called from head.S before relocate so it should not use absolute addressing."
>>>>    #endif
>>>>
>>>> +static uintptr_t load_pa, load_sz;
>>>> +
>>>> +void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
>>>> +{
>>>> +       uintptr_t va, end_va;
>>>> +
>>>> +       end_va = kernel_virt_addr + load_sz;
>>>> +       for (va = kernel_virt_addr; va < end_va; va += map_size)
>>>> +               create_pgd_mapping(pgdir, va,
>>>> +                                  load_pa + (va - kernel_virt_addr),
>>>> +                                  map_size, PAGE_KERNEL_EXEC);
>>>> +}
>>>> +
>>>>    asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>>>    {
>>>>           uintptr_t va, end_va;
>>>> -       uintptr_t load_pa = (uintptr_t)(&_start);
>>>> -       uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
>>>>           uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE);
>>>>
>>>> +       load_pa = (uintptr_t)(&_start);
>>>> +       load_sz = (uintptr_t)(&_end) - load_pa;
>>>> +
>>>>           va_pa_offset = PAGE_OFFSET - load_pa;
>>>> +       va_kernel_pa_offset = kernel_virt_addr - load_pa;
>>>> +
>>>>           pfn_base = PFN_DOWN(load_pa);
>>>>
>>>>           /*
>>>> @@ -402,26 +425,22 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>>>           create_pmd_mapping(fixmap_pmd, FIXADDR_START,
>>>>                              (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE);
>>>>           /* Setup trampoline PGD and PMD */
>>>> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
>>>> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>>>>                              (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);
>>>> -       create_pmd_mapping(trampoline_pmd, PAGE_OFFSET,
>>>> +       create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
>>>>                              load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);
>>>>    #else
>>>>           /* Setup trampoline PGD */
>>>> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
>>>> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>>>>                              load_pa, PGDIR_SIZE, PAGE_KERNEL_EXEC);
>>>>    #endif
>>>>
>>>>           /*
>>>> -        * Setup early PGD covering entire kernel which will allows
>>>> +        * Setup early PGD covering entire kernel which will allow
>>>>            * us to reach paging_init(). We map all memory banks later
>>>>            * in setup_vm_final() below.
>>>>            */
>>>> -       end_va = PAGE_OFFSET + load_sz;
>>>> -       for (va = PAGE_OFFSET; va < end_va; va += map_size)
>>>> -               create_pgd_mapping(early_pg_dir, va,
>>>> -                                  load_pa + (va - PAGE_OFFSET),
>>>> -                                  map_size, PAGE_KERNEL_EXEC);
>>>> +       create_kernel_page_table(early_pg_dir, map_size);
>>>>
>>>>           /* Create fixed mapping for early FDT parsing */
>>>>           end_va = __fix_to_virt(FIX_FDT) + FIX_FDT_SIZE;
>>>> @@ -441,6 +460,7 @@ static void __init setup_vm_final(void)
>>>>           uintptr_t va, map_size;
>>>>           phys_addr_t pa, start, end;
>>>>           struct memblock_region *reg;
>>>> +       static struct vm_struct vm_kernel = { 0 };
>>>>
>>>>           /* Set mmu_enabled flag */
>>>>           mmu_enabled = true;
>>>> @@ -467,10 +487,22 @@ static void __init setup_vm_final(void)
>>>>                   for (pa = start; pa < end; pa += map_size) {
>>>>                           va = (uintptr_t)__va(pa);
>>>>                           create_pgd_mapping(swapper_pg_dir, va, pa,
>>>> -                                          map_size, PAGE_KERNEL_EXEC);
>>>> +                                          map_size, PAGE_KERNEL);
>>>>                   }
>>>>           }
>>>>
>>>> +       /* Map the kernel */
>>>> +       create_kernel_page_table(swapper_pg_dir, PMD_SIZE);
>>>> +
>>>> +       /* Reserve the vmalloc area occupied by the kernel */
>>>> +       vm_kernel.addr = (void *)kernel_virt_addr;
>>>> +       vm_kernel.phys_addr = load_pa;
>>>> +       vm_kernel.size = (load_sz + PMD_SIZE) & ~(PMD_SIZE - 1);
>>>> +       vm_kernel.flags = VM_MAP | VM_NO_GUARD;
>>>> +       vm_kernel.caller = __builtin_return_address(0);
>>>> +
>>>> +       vm_area_add_early(&vm_kernel);
>>>> +
>>>>           /* Clear fixmap PTE and PMD mappings */
>>>>           clear_fixmap(FIX_PTE);
>>>>           clear_fixmap(FIX_PMD);
>>>> diff --git a/arch/riscv/mm/physaddr.c b/arch/riscv/mm/physaddr.c
>>>> index e8e4dcd39fed..35703d5ef5fd 100644
>>>> --- a/arch/riscv/mm/physaddr.c
>>>> +++ b/arch/riscv/mm/physaddr.c
>>>> @@ -23,7 +23,7 @@ EXPORT_SYMBOL(__virt_to_phys);
>>>>
>>>>    phys_addr_t __phys_addr_symbol(unsigned long x)
>>>>    {
>>>> -       unsigned long kernel_start = (unsigned long)PAGE_OFFSET;
>>>> +       unsigned long kernel_start = (unsigned long)kernel_virt_addr;
>>>>           unsigned long kernel_end = (unsigned long)_end;
>>>>
>>>>           /*
>>>> --
>>>> 2.20.1
>>>>

kernel test robot May 27, 2020, 7:33 a.m. UTC | #5

Hi Alexandre,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on powerpc/next]
[also build test WARNING on linus/master v5.7-rc7 next-20200526]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Alexandre-Ghiti/vmalloc-kernel-mapping-and-relocatable-kernel/20200524-170109
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: riscv-allyesconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>

All warnings (new ones prefixed by >>, old ones prefixed by <<):

>> arch/riscv/mm/init.c:383:6: warning: no previous prototype for 'create_kernel_page_table' [-Wmissing-prototypes]
383 | void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
|      ^~~~~~~~~~~~~~~~~~~~~~~~

vim +/create_kernel_page_table +383 arch/riscv/mm/init.c

   382	
 > 383	void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
   384	{
   385		uintptr_t va, end_va;
   386	
   387		end_va = kernel_virt_addr + load_sz;
   388		for (va = kernel_virt_addr; va < end_va; va += map_size)
   389			create_pgd_mapping(pgdir, va,
   390					   load_pa + (va - kernel_virt_addr),
   391					   map_size, PAGE_KERNEL_EXEC);
   392	}
   393	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Alexandre Ghiti May 28, 2020, 1:07 p.m. UTC | #6

Hi Zong,

Le 5/27/20 à 3:29 AM, Alex Ghiti a écrit :
> Le 5/27/20 à 2:05 AM, Zong Li a écrit :
>> On Wed, May 27, 2020 at 1:06 AM Alex Ghiti <alex@ghiti.fr> wrote:
>>> Hi Zong,
>>>
>>> Le 5/26/20 à 5:43 AM, Zong Li a écrit :
>>>> On Sun, May 24, 2020 at 4:54 PM Alexandre Ghiti <alex@ghiti.fr> wrote:
>>>>> This is a preparatory patch for relocatable kernel.
>>>>>
>>>>> The kernel used to be linked at PAGE_OFFSET address and used to be 
>>>>> loaded
>>>>> physically at the beginning of the main memory. Therefore, we 
>>>>> could use
>>>>> the linear mapping for the kernel mapping.
>>>>>
>>>>> But the relocated kernel base address will be different from 
>>>>> PAGE_OFFSET
>>>>> and since in the linear mapping, two different virtual addresses 
>>>>> cannot
>>>>> point to the same physical address, the kernel mapping needs to 
>>>>> lie outside
>>>>> the linear mapping.
>>>>>
>>>>> In addition, because modules and BPF must be close to the kernel 
>>>>> (inside
>>>>> +-2GB window), the kernel is placed at the end of the vmalloc zone 
>>>>> minus
>>>>> 2GB, which leaves room for modules and BPF. The kernel could not be
>>>>> placed at the beginning of the vmalloc zone since other vmalloc
>>>>> allocations from the kernel could get all the +-2GB window around the
>>>>> kernel which would prevent new modules and BPF programs to be loaded.
>>>>>
>>>>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>>>>> ---
>>>>>    arch/riscv/boot/loader.lds.S     |  3 +-
>>>>>    arch/riscv/include/asm/page.h    | 10 +++++-
>>>>>    arch/riscv/include/asm/pgtable.h | 37 +++++++++++++-------
>>>>>    arch/riscv/kernel/head.S         |  3 +-
>>>>>    arch/riscv/kernel/module.c       |  4 +--
>>>>>    arch/riscv/kernel/vmlinux.lds.S  |  3 +-
>>>>>    arch/riscv/mm/init.c             | 58 
>>>>> +++++++++++++++++++++++++-------
>>>>>    arch/riscv/mm/physaddr.c         |  2 +-
>>>>>    8 files changed, 87 insertions(+), 33 deletions(-)
>>>>>
>>>>> diff --git a/arch/riscv/boot/loader.lds.S 
>>>>> b/arch/riscv/boot/loader.lds.S
>>>>> index 47a5003c2e28..62d94696a19c 100644
>>>>> --- a/arch/riscv/boot/loader.lds.S
>>>>> +++ b/arch/riscv/boot/loader.lds.S
>>>>> @@ -1,13 +1,14 @@
>>>>>    /* SPDX-License-Identifier: GPL-2.0 */
>>>>>
>>>>>    #include <asm/page.h>
>>>>> +#include <asm/pgtable.h>
>>>>>
>>>>>    OUTPUT_ARCH(riscv)
>>>>>    ENTRY(_start)
>>>>>
>>>>>    SECTIONS
>>>>>    {
>>>>> -       . = PAGE_OFFSET;
>>>>> +       . = KERNEL_LINK_ADDR;
>>>>>
>>>>>           .payload : {
>>>>>                   *(.payload)
>>>>> diff --git a/arch/riscv/include/asm/page.h 
>>>>> b/arch/riscv/include/asm/page.h
>>>>> index 2d50f76efe48..48bb09b6a9b7 100644
>>>>> --- a/arch/riscv/include/asm/page.h
>>>>> +++ b/arch/riscv/include/asm/page.h
>>>>> @@ -90,18 +90,26 @@ typedef struct page *pgtable_t;
>>>>>
>>>>>    #ifdef CONFIG_MMU
>>>>>    extern unsigned long va_pa_offset;
>>>>> +extern unsigned long va_kernel_pa_offset;
>>>>>    extern unsigned long pfn_base;
>>>>>    #define ARCH_PFN_OFFSET                (pfn_base)
>>>>>    #else
>>>>>    #define va_pa_offset           0
>>>>> +#define va_kernel_pa_offset    0
>>>>>    #define ARCH_PFN_OFFSET                (PAGE_OFFSET >> PAGE_SHIFT)
>>>>>    #endif /* CONFIG_MMU */
>>>>>
>>>>>    extern unsigned long max_low_pfn;
>>>>>    extern unsigned long min_low_pfn;
>>>>> +extern unsigned long kernel_virt_addr;
>>>>>
>>>>>    #define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + 
>>>>> va_pa_offset))
>>>>> -#define __va_to_pa_nodebug(x)  ((unsigned long)(x) - va_pa_offset)
>>>>> +#define linear_mapping_va_to_pa(x)     ((unsigned long)(x) - 
>>>>> va_pa_offset)
>>>>> +#define kernel_mapping_va_to_pa(x)     \
>>>>> +       ((unsigned long)(x) - va_kernel_pa_offset)
>>>>> +#define __va_to_pa_nodebug(x)          \
>>>>> +       (((x) >= PAGE_OFFSET) ?         \
>>>>> +               linear_mapping_va_to_pa(x) : 
>>>>> kernel_mapping_va_to_pa(x))
>>>>>
>>>>>    #ifdef CONFIG_DEBUG_VIRTUAL
>>>>>    extern phys_addr_t __virt_to_phys(unsigned long x);
>>>>> diff --git a/arch/riscv/include/asm/pgtable.h 
>>>>> b/arch/riscv/include/asm/pgtable.h
>>>>> index 35b60035b6b0..25213cfaf680 100644
>>>>> --- a/arch/riscv/include/asm/pgtable.h
>>>>> +++ b/arch/riscv/include/asm/pgtable.h
>>>>> @@ -11,23 +11,29 @@
>>>>>
>>>>>    #include <asm/pgtable-bits.h>
>>>>>
>>>>> -#ifndef __ASSEMBLY__
>>>>> -
>>>>> -/* Page Upper Directory not used in RISC-V */
>>>>> -#include <asm-generic/pgtable-nopud.h>
>>>>> -#include <asm/page.h>
>>>>> -#include <asm/tlbflush.h>
>>>>> -#include <linux/mm_types.h>
>>>>> -
>>>>> -#ifdef CONFIG_MMU
>>>>> +#ifndef CONFIG_MMU
>>>>> +#define KERNEL_VIRT_ADDR       PAGE_OFFSET
>>>>> +#define KERNEL_LINK_ADDR       PAGE_OFFSET
>>>>> +#else
>>>>> +/*
>>>>> + * Leave 2GB for modules and BPF that must lie within a 2GB range 
>>>>> around
>>>>> + * the kernel.
>>>>> + */
>>>>> +#define KERNEL_VIRT_ADDR       (VMALLOC_END - SZ_2G + 1)
>>>>> +#define KERNEL_LINK_ADDR       KERNEL_VIRT_ADDR
>>>>>
>>>>>    #define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
>>>>>    #define VMALLOC_END      (PAGE_OFFSET - 1)
>>>>>    #define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
>>>>>
>>>>>    #define BPF_JIT_REGION_SIZE    (SZ_128M)
>>>>> -#define BPF_JIT_REGION_START   (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
>>>>> -#define BPF_JIT_REGION_END     (VMALLOC_END)
>>>>> +#define BPF_JIT_REGION_START   (kernel_virt_addr)
>>>>> +#define BPF_JIT_REGION_END     (kernel_virt_addr + 
>>>>> BPF_JIT_REGION_SIZE)
>>>> It seems to have a potential risk here, the region of bpf is
>>>> overlapping with kernel mapping, so if kernel size is bigger than
>>>> 128MB, bpf region would be occupied and run out by kernel mapping.
>> Is there the risk as I mentioned?
>
>
> Sorry I forgot to answer this one: I was confident that 128MB was 
> large enough for kernel
> and BPF. But I see no reason to leave this risk so I'll change 
> kernel_virt_addr for _end so
> BPF will have its 128MB reserved.
>
> Thanks !
>
> Alex
>
>
>>
>>>>> +
>>>>> +#ifdef CONFIG_64BIT
>>>>> +#define VMALLOC_MODULE_START   BPF_JIT_REGION_END
>>>>> +#define VMALLOC_MODULE_END     VMALLOC_END
>>>>> +#endif
>>>>>
>>>> Although kernel_virt_addr is a fixed address now, I think it could be
>>>> changed for the purpose of relocatable or KASLR, so if
>>>> kernel_virt_addr is moved to far from VMALLOC_END than 2G, the region
>>>> of module would be too big.
>>>
>>> Yes you're right, that's wrong to allow modules to lie outside
>>> the 2G window, thanks for noticing.
>>>
>>>
>>>> In addition, the region of module could be
>>>> +-2G around the kernel, so we don't be limited in one direction as
>>>> before. It seems to me that the region of the module could be decided
>>>> at runtime, for example, VMALLOC_MODULE_START is "&_end - 2G" and
>>>> VMLLOC_MODULE_END is "&_start + 2G".
>>>
>>> I had tried that, but as we need to make sure BPF region is different
>>> from the module's
>>> that makes the macro definitions really cumbersome. I'll give a try
>>> again anyway. And
>>> I tried to use _end and _start here but it failed, I have to debug 
>>> this.


I gave more thought about that and it is actually not possible to use 
the 2GB
before and after the kernel: modules can call exported functions from 
each other,
so we need to make sure that the "distance" between 2 modules is at most 
2GB.
And I assume BPF comes with the same restrictions with respect to 
modules so the
kernel + BPF + modules must live in the same 2GB region.

I'll come with a v4 quickly,

Thanks,

Alex


>>>
>>>
>>>>    I'm not sure whether the size of
>>>> region of bpf has to be 128MB for some particular reason, if not,
>>>> maybe the region of bpf could be the same with module to avoid being
>>>> run out by module.
>>>
>>> On the contrary, BPF region must not be the same as module's since in
>>> that case,
>>> modules could take all the space and make BPF fail.
>> ok, I got it. Thanks for the explaining.
>>
>>
>>>
>>> Thanks for your review Zong,
>>>
>>>
>>> Alex
>>>
>>>
>>>>>    /*
>>>>>     * Roughly size the vmemmap space to be large enough to fit enough
>>>>> @@ -57,9 +63,16 @@
>>>>>    #define FIXADDR_SIZE     PGDIR_SIZE
>>>>>    #endif
>>>>>    #define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
>>>>> -
>>>>>    #endif
>>>>>
>>>>> +#ifndef __ASSEMBLY__
>>>>> +
>>>>> +/* Page Upper Directory not used in RISC-V */
>>>>> +#include <asm-generic/pgtable-nopud.h>
>>>>> +#include <asm/page.h>
>>>>> +#include <asm/tlbflush.h>
>>>>> +#include <linux/mm_types.h>
>>>>> +
>>>>>    #ifdef CONFIG_64BIT
>>>>>    #include <asm/pgtable-64.h>
>>>>>    #else
>>>>> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
>>>>> index 98a406474e7d..8f5bb7731327 100644
>>>>> --- a/arch/riscv/kernel/head.S
>>>>> +++ b/arch/riscv/kernel/head.S
>>>>> @@ -49,7 +49,8 @@ ENTRY(_start)
>>>>>    #ifdef CONFIG_MMU
>>>>>    relocate:
>>>>>           /* Relocate return address */
>>>>> -       li a1, PAGE_OFFSET
>>>>> +       la a1, kernel_virt_addr
>>>>> +       REG_L a1, 0(a1)
>>>>>           la a2, _start
>>>>>           sub a1, a1, a2
>>>>>           add ra, ra, a1
>>>>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
>>>>> index 8bbe5dbe1341..1a8fbe05accf 100644
>>>>> --- a/arch/riscv/kernel/module.c
>>>>> +++ b/arch/riscv/kernel/module.c
>>>>> @@ -392,12 +392,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, 
>>>>> const char *strtab,
>>>>>    }
>>>>>
>>>>>    #if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
>>>>> -#define VMALLOC_MODULE_START \
>>>>> -        max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START)
>>>>>    void *module_alloc(unsigned long size)
>>>>>    {
>>>>>           return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START,
>>>>> -                                   VMALLOC_END, GFP_KERNEL,
>>>>> +                                   VMALLOC_MODULE_END, GFP_KERNEL,
>>>>>                                       PAGE_KERNEL_EXEC, 0, 
>>>>> NUMA_NO_NODE,
>>>>> __builtin_return_address(0));
>>>>>    }
>>>>> diff --git a/arch/riscv/kernel/vmlinux.lds.S 
>>>>> b/arch/riscv/kernel/vmlinux.lds.S
>>>>> index 0339b6bbe11a..a9abde62909f 100644
>>>>> --- a/arch/riscv/kernel/vmlinux.lds.S
>>>>> +++ b/arch/riscv/kernel/vmlinux.lds.S
>>>>> @@ -4,7 +4,8 @@
>>>>>     * Copyright (C) 2017 SiFive
>>>>>     */
>>>>>
>>>>> -#define LOAD_OFFSET PAGE_OFFSET
>>>>> +#include <asm/pgtable.h>
>>>>> +#define LOAD_OFFSET KERNEL_LINK_ADDR
>>>>>    #include <asm/vmlinux.lds.h>
>>>>>    #include <asm/page.h>
>>>>>    #include <asm/cache.h>
>>>>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>>>>> index 27a334106708..17f108baec4f 100644
>>>>> --- a/arch/riscv/mm/init.c
>>>>> +++ b/arch/riscv/mm/init.c
>>>>> @@ -22,6 +22,9 @@
>>>>>
>>>>>    #include "../kernel/head.h"
>>>>>
>>>>> +unsigned long kernel_virt_addr = KERNEL_VIRT_ADDR;
>>>>> +EXPORT_SYMBOL(kernel_virt_addr);
>>>>> +
>>>>>    unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
>>>>> __page_aligned_bss;
>>>>>    EXPORT_SYMBOL(empty_zero_page);
>>>>> @@ -178,8 +181,12 @@ void __init setup_bootmem(void)
>>>>>    }
>>>>>
>>>>>    #ifdef CONFIG_MMU
>>>>> +/* Offset between linear mapping virtual address and kernel load 
>>>>> address */
>>>>>    unsigned long va_pa_offset;
>>>>>    EXPORT_SYMBOL(va_pa_offset);
>>>>> +/* Offset between kernel mapping virtual address and kernel load 
>>>>> address */
>>>>> +unsigned long va_kernel_pa_offset;
>>>>> +EXPORT_SYMBOL(va_kernel_pa_offset);
>>>>>    unsigned long pfn_base;
>>>>>    EXPORT_SYMBOL(pfn_base);
>>>>>
>>>>> @@ -271,7 +278,7 @@ static phys_addr_t __init alloc_pmd(uintptr_t va)
>>>>>           if (mmu_enabled)
>>>>>                   return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>>>>>
>>>>> -       pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
>>>>> +       pmd_num = (va - kernel_virt_addr) >> PGDIR_SHIFT;
>>>>>           BUG_ON(pmd_num >= NUM_EARLY_PMDS);
>>>>>           return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
>>>>>    }
>>>>> @@ -372,14 +379,30 @@ static uintptr_t __init 
>>>>> best_map_size(phys_addr_t base, phys_addr_t size)
>>>>>    #error "setup_vm() is called from head.S before relocate so it 
>>>>> should not use absolute addressing."
>>>>>    #endif
>>>>>
>>>>> +static uintptr_t load_pa, load_sz;
>>>>> +
>>>>> +void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
>>>>> +{
>>>>> +       uintptr_t va, end_va;
>>>>> +
>>>>> +       end_va = kernel_virt_addr + load_sz;
>>>>> +       for (va = kernel_virt_addr; va < end_va; va += map_size)
>>>>> +               create_pgd_mapping(pgdir, va,
>>>>> +                                  load_pa + (va - kernel_virt_addr),
>>>>> +                                  map_size, PAGE_KERNEL_EXEC);
>>>>> +}
>>>>> +
>>>>>    asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>>>>    {
>>>>>           uintptr_t va, end_va;
>>>>> -       uintptr_t load_pa = (uintptr_t)(&_start);
>>>>> -       uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
>>>>>           uintptr_t map_size = best_map_size(load_pa, 
>>>>> MAX_EARLY_MAPPING_SIZE);
>>>>>
>>>>> +       load_pa = (uintptr_t)(&_start);
>>>>> +       load_sz = (uintptr_t)(&_end) - load_pa;
>>>>> +
>>>>>           va_pa_offset = PAGE_OFFSET - load_pa;
>>>>> +       va_kernel_pa_offset = kernel_virt_addr - load_pa;
>>>>> +
>>>>>           pfn_base = PFN_DOWN(load_pa);
>>>>>
>>>>>           /*
>>>>> @@ -402,26 +425,22 @@ asmlinkage void __init setup_vm(uintptr_t 
>>>>> dtb_pa)
>>>>>           create_pmd_mapping(fixmap_pmd, FIXADDR_START,
>>>>>                              (uintptr_t)fixmap_pte, PMD_SIZE, 
>>>>> PAGE_TABLE);
>>>>>           /* Setup trampoline PGD and PMD */
>>>>> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
>>>>> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>>>>>                              (uintptr_t)trampoline_pmd, 
>>>>> PGDIR_SIZE, PAGE_TABLE);
>>>>> -       create_pmd_mapping(trampoline_pmd, PAGE_OFFSET,
>>>>> +       create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
>>>>>                              load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);
>>>>>    #else
>>>>>           /* Setup trampoline PGD */
>>>>> -       create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,
>>>>> +       create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>>>>>                              load_pa, PGDIR_SIZE, PAGE_KERNEL_EXEC);
>>>>>    #endif
>>>>>
>>>>>           /*
>>>>> -        * Setup early PGD covering entire kernel which will allows
>>>>> +        * Setup early PGD covering entire kernel which will allow
>>>>>            * us to reach paging_init(). We map all memory banks later
>>>>>            * in setup_vm_final() below.
>>>>>            */
>>>>> -       end_va = PAGE_OFFSET + load_sz;
>>>>> -       for (va = PAGE_OFFSET; va < end_va; va += map_size)
>>>>> -               create_pgd_mapping(early_pg_dir, va,
>>>>> -                                  load_pa + (va - PAGE_OFFSET),
>>>>> -                                  map_size, PAGE_KERNEL_EXEC);
>>>>> +       create_kernel_page_table(early_pg_dir, map_size);
>>>>>
>>>>>           /* Create fixed mapping for early FDT parsing */
>>>>>           end_va = __fix_to_virt(FIX_FDT) + FIX_FDT_SIZE;
>>>>> @@ -441,6 +460,7 @@ static void __init setup_vm_final(void)
>>>>>           uintptr_t va, map_size;
>>>>>           phys_addr_t pa, start, end;
>>>>>           struct memblock_region *reg;
>>>>> +       static struct vm_struct vm_kernel = { 0 };
>>>>>
>>>>>           /* Set mmu_enabled flag */
>>>>>           mmu_enabled = true;
>>>>> @@ -467,10 +487,22 @@ static void __init setup_vm_final(void)
>>>>>                   for (pa = start; pa < end; pa += map_size) {
>>>>>                           va = (uintptr_t)__va(pa);
>>>>> create_pgd_mapping(swapper_pg_dir, va, pa,
>>>>> -                                          map_size, 
>>>>> PAGE_KERNEL_EXEC);
>>>>> +                                          map_size, PAGE_KERNEL);
>>>>>                   }
>>>>>           }
>>>>>
>>>>> +       /* Map the kernel */
>>>>> +       create_kernel_page_table(swapper_pg_dir, PMD_SIZE);
>>>>> +
>>>>> +       /* Reserve the vmalloc area occupied by the kernel */
>>>>> +       vm_kernel.addr = (void *)kernel_virt_addr;
>>>>> +       vm_kernel.phys_addr = load_pa;
>>>>> +       vm_kernel.size = (load_sz + PMD_SIZE) & ~(PMD_SIZE - 1);
>>>>> +       vm_kernel.flags = VM_MAP | VM_NO_GUARD;
>>>>> +       vm_kernel.caller = __builtin_return_address(0);
>>>>> +
>>>>> +       vm_area_add_early(&vm_kernel);
>>>>> +
>>>>>           /* Clear fixmap PTE and PMD mappings */
>>>>>           clear_fixmap(FIX_PTE);
>>>>>           clear_fixmap(FIX_PMD);
>>>>> diff --git a/arch/riscv/mm/physaddr.c b/arch/riscv/mm/physaddr.c
>>>>> index e8e4dcd39fed..35703d5ef5fd 100644
>>>>> --- a/arch/riscv/mm/physaddr.c
>>>>> +++ b/arch/riscv/mm/physaddr.c
>>>>> @@ -23,7 +23,7 @@ EXPORT_SYMBOL(__virt_to_phys);
>>>>>
>>>>>    phys_addr_t __phys_addr_symbol(unsigned long x)
>>>>>    {
>>>>> -       unsigned long kernel_start = (unsigned long)PAGE_OFFSET;
>>>>> +       unsigned long kernel_start = (unsigned long)kernel_virt_addr;
>>>>>           unsigned long kernel_end = (unsigned long)_end;
>>>>>
>>>>>           /*
>>>>> -- 
>>>>> 2.20.1
>>>>>

[v3,1/3] riscv: Move kernel mapping to vmalloc zone

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