| Message ID | 20210104195840.1593-3-alex@ghiti.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Introduce sv48 support without relocable kernel | expand |
On Tue, Jan 5, 2021 at 1:31 AM Alexandre Ghiti <alex@ghiti.fr> wrote: > > The kernel is now mapped at the end of the address space and it should > be accessed through this mapping only: so map the whole kernel in the > linear mapping as read only. > > Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> > --- > arch/riscv/include/asm/page.h | 9 ++++++++- > arch/riscv/mm/init.c | 29 +++++++++++++++++++++-------- > 2 files changed, 29 insertions(+), 9 deletions(-) > > diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h > index 98188e315e8d..a93e35aaa717 100644 > --- a/arch/riscv/include/asm/page.h > +++ b/arch/riscv/include/asm/page.h > @@ -102,8 +102,15 @@ extern unsigned long pfn_base; > extern unsigned long max_low_pfn; > extern unsigned long min_low_pfn; > extern unsigned long kernel_virt_addr; > +extern uintptr_t load_pa, load_sz; > + > +#define linear_mapping_pa_to_va(x) ((void *)((unsigned long)(x) + va_pa_offset)) > +#define kernel_mapping_pa_to_va(x) \ > + ((void *)((unsigned long) (x) + va_kernel_pa_offset)) > +#define __pa_to_va_nodebug(x) \ > + ((x >= load_pa && x < load_pa + load_sz) ? \ > + kernel_mapping_pa_to_va(x): linear_mapping_pa_to_va(x)) This change should be part of PATCH1 > > -#define __pa_to_va_nodebug(x) ((void *)((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) > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 9d06ff0e015a..7b87c14f1d24 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -159,8 +159,6 @@ void __init setup_bootmem(void) > { > phys_addr_t mem_start = 0; > phys_addr_t start, end = 0; > - phys_addr_t vmlinux_end = __pa_symbol(&_end); > - phys_addr_t vmlinux_start = __pa_symbol(&_start); This as well. > u64 i; > > /* Find the memory region containing the kernel */ > @@ -168,7 +166,7 @@ void __init setup_bootmem(void) > phys_addr_t size = end - start; > if (!mem_start) > mem_start = start; > - if (start <= vmlinux_start && vmlinux_end <= end) > + if (start <= load_pa && (load_pa + load_sz) <= end) > BUG_ON(size == 0); > } > > @@ -179,8 +177,13 @@ void __init setup_bootmem(void) > */ > memblock_enforce_memory_limit(mem_start - PAGE_OFFSET); > > - /* Reserve from the start of the kernel to the end of the kernel */ > - memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start); > + /* > + * Reserve from the start of the kernel to the end of the kernel > + * and make sure we align the reservation on PMD_SIZE since we will > + * map the kernel in the linear mapping as read-only: we do not want > + * any allocation to happen between _end and the next pmd aligned page. > + */ > + memblock_reserve(load_pa, (load_sz + PMD_SIZE - 1) & ~(PMD_SIZE - 1)); > > max_pfn = PFN_DOWN(memblock_end_of_DRAM()); > max_low_pfn = max_pfn; > @@ -438,7 +441,9 @@ 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; > +uintptr_t load_pa, load_sz; > +EXPORT_SYMBOL(load_pa); > +EXPORT_SYMBOL(load_sz); I think all changes till here should be in PATCH1. Only the changes here onwards seems to be as-per PATCH description. > > static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size) > { > @@ -596,9 +601,17 @@ static void __init setup_vm_final(void) > > map_size = best_map_size(start, end - start); > for (pa = start; pa < end; pa += map_size) { > - va = (uintptr_t)__va(pa); > + pgprot_t prot = PAGE_KERNEL; > + > + /* Protect the kernel mapping that lies in the linear mapping */ > + if (pa >= __pa(_start) && pa < __pa(_end)) > + prot = PAGE_KERNEL_READ; > + > + /* Make sure we get virtual addresses in the linear mapping */ > + va = (uintptr_t)linear_mapping_pa_to_va(pa); > + > create_pgd_mapping(swapper_pg_dir, va, pa, > - map_size, PAGE_KERNEL); > + map_size, prot); > } > } > > -- > 2.20.1 > Regards, Anup
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h index 98188e315e8d..a93e35aaa717 100644 --- a/arch/riscv/include/asm/page.h +++ b/arch/riscv/include/asm/page.h @@ -102,8 +102,15 @@ extern unsigned long pfn_base; extern unsigned long max_low_pfn; extern unsigned long min_low_pfn; extern unsigned long kernel_virt_addr; +extern uintptr_t load_pa, load_sz; + +#define linear_mapping_pa_to_va(x) ((void *)((unsigned long)(x) + va_pa_offset)) +#define kernel_mapping_pa_to_va(x) \ + ((void *)((unsigned long) (x) + va_kernel_pa_offset)) +#define __pa_to_va_nodebug(x) \ + ((x >= load_pa && x < load_pa + load_sz) ? \ + kernel_mapping_pa_to_va(x): linear_mapping_pa_to_va(x)) -#define __pa_to_va_nodebug(x) ((void *)((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) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 9d06ff0e015a..7b87c14f1d24 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -159,8 +159,6 @@ void __init setup_bootmem(void) { phys_addr_t mem_start = 0; phys_addr_t start, end = 0; - phys_addr_t vmlinux_end = __pa_symbol(&_end); - phys_addr_t vmlinux_start = __pa_symbol(&_start); u64 i; /* Find the memory region containing the kernel */ @@ -168,7 +166,7 @@ void __init setup_bootmem(void) phys_addr_t size = end - start; if (!mem_start) mem_start = start; - if (start <= vmlinux_start && vmlinux_end <= end) + if (start <= load_pa && (load_pa + load_sz) <= end) BUG_ON(size == 0); } @@ -179,8 +177,13 @@ void __init setup_bootmem(void) */ memblock_enforce_memory_limit(mem_start - PAGE_OFFSET); - /* Reserve from the start of the kernel to the end of the kernel */ - memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start); + /* + * Reserve from the start of the kernel to the end of the kernel + * and make sure we align the reservation on PMD_SIZE since we will + * map the kernel in the linear mapping as read-only: we do not want + * any allocation to happen between _end and the next pmd aligned page. + */ + memblock_reserve(load_pa, (load_sz + PMD_SIZE - 1) & ~(PMD_SIZE - 1)); max_pfn = PFN_DOWN(memblock_end_of_DRAM()); max_low_pfn = max_pfn; @@ -438,7 +441,9 @@ 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; +uintptr_t load_pa, load_sz; +EXPORT_SYMBOL(load_pa); +EXPORT_SYMBOL(load_sz); static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size) { @@ -596,9 +601,17 @@ static void __init setup_vm_final(void) map_size = best_map_size(start, end - start); for (pa = start; pa < end; pa += map_size) { - va = (uintptr_t)__va(pa); + pgprot_t prot = PAGE_KERNEL; + + /* Protect the kernel mapping that lies in the linear mapping */ + if (pa >= __pa(_start) && pa < __pa(_end)) + prot = PAGE_KERNEL_READ; + + /* Make sure we get virtual addresses in the linear mapping */ + va = (uintptr_t)linear_mapping_pa_to_va(pa); + create_pgd_mapping(swapper_pg_dir, va, pa, - map_size, PAGE_KERNEL); + map_size, prot); } }
The kernel is now mapped at the end of the address space and it should be accessed through this mapping only: so map the whole kernel in the linear mapping as read only. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> --- arch/riscv/include/asm/page.h | 9 ++++++++- arch/riscv/mm/init.c | 29 +++++++++++++++++++++-------- 2 files changed, 29 insertions(+), 9 deletions(-)