From patchwork Mon Nov 7 22:39:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 13035366 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF655C433FE for ; Mon, 7 Nov 2022 22:41:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5E7CE6B0074; Mon, 7 Nov 2022 17:41:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 571666B0075; Mon, 7 Nov 2022 17:41:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 439308E0001; Mon, 7 Nov 2022 17:41:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 31A0B6B0074 for ; Mon, 7 Nov 2022 17:41:42 -0500 (EST) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id EE6D3C0511 for ; Mon, 7 Nov 2022 22:41:41 +0000 (UTC) X-FDA: 80108119602.13.ECB9D85 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by imf18.hostedemail.com (Postfix) with ESMTP id 78D931C0005 for ; Mon, 7 Nov 2022 22:41:41 +0000 (UTC) Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 2A7LKoAr030595 for ; Mon, 7 Nov 2022 14:41:40 -0800 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3knkvkm08v-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 07 Nov 2022 14:41:40 -0800 Received: from twshared16963.27.frc3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 7 Nov 2022 14:41:37 -0800 Received: by devbig932.frc1.facebook.com (Postfix, from userid 4523) id E44CBF6B36D9; Mon, 7 Nov 2022 14:39:25 -0800 (PST) From: Song Liu To: , CC: , , , , , , , , Song Liu Subject: [PATCH bpf-next v2 1/5] vmalloc: introduce execmem_alloc, execmem_free, and execmem_fill Date: Mon, 7 Nov 2022 14:39:17 -0800 Message-ID: <20221107223921.3451913-2-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221107223921.3451913-1-song@kernel.org> References: <20221107223921.3451913-1-song@kernel.org> X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: 4eUO2WkZfnJ8Ip1APaOQq-8iAybiSnym X-Proofpoint-GUID: 4eUO2WkZfnJ8Ip1APaOQq-8iAybiSnym X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-07_11,2022-11-07_02,2022-06-22_01 ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=none; spf=pass (imf18.hostedemail.com: domain of "prvs=2310266901=songliubraving@meta.com" designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=2310266901=songliubraving@meta.com"; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=kernel.org (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667860901; a=rsa-sha256; cv=none; b=pDaJ+QgxQKAmE9omLteF76TaA2lqlH3H6/FIwQsIGT/gbjGA7n7oit4NYnyfeJRse+/ipp NwKS6hMCh3BGL3uMVBwX5VVFk98RGfRk+6tqdrYQYet16A4KWBnBIjF+WhB2jrVVdRPG5L A8xJF68ArVpBk5zEu6H/x3yfUpfP66E= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667860901; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9OY7amygRdMAksREHFwzx1Em8ml3t73Jkjwzudh7it8=; b=qpl1GNZDly68hysiYMSfTcf+nM+FLrKAba1hp7uVLF9FlfKwPOXvgr0sCwyG5Y1/ZclqF2 INPcrvp+QYrxdiFqHM6H2tm0Z0xkJkx2oiW6mxzE+eBCuTX79jJ33AklSi2RaoxIpA4hnA Rjsq1R3JYRYay5CAjW0xFzD5MUk5nq4= X-Stat-Signature: 8fczq3eumaxrodtt1jq11faygusfux86 X-Rspamd-Queue-Id: 78D931C0005 Authentication-Results: imf18.hostedemail.com; dkim=none; spf=pass (imf18.hostedemail.com: domain of "prvs=2310266901=songliubraving@meta.com" designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=2310266901=songliubraving@meta.com"; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=kernel.org (policy=none) X-Rspamd-Server: rspam05 X-Rspam-User: X-HE-Tag: 1667860901-899796 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: execmem_alloc is used to allocate memory to host dynamic kernel text (modules, BPF programs, etc.) with huge pages. This is similar to the proposal by Peter in [1]. A new tree of vmap_area, free_text_area_* tree, is introduced in addition to free_vmap_area_* and vmap_area_*. execmem_alloc allocates pages from free_text_area_*. When there isn't enough space left in free_text_area_*, new PMD_SIZE page(s) is allocated from free_vmap_area_* and added to free_text_area_*. To be more accurate, the vmap_area is first added to vmap_area_* tree and then moved to free_text_area_*. This extra move simplifies the logic of execmem_alloc. vmap_area in free_text_area_* tree are backed with memory, but we need subtree_max_size for tree operations. Therefore, vm_struct for these vmap_area are stored in a separate list, all_text_vm. The new tree allows separate handling of < PAGE_SIZE allocations, as current vmalloc code mostly assumes PAGE_SIZE aligned allocations. This version of execmem_alloc can handle bpf programs, which uses 64 byte aligned allocations), and modules, which uses PAGE_SIZE aligned allocations. Memory allocated by execmem_alloc() is set to RO+X before returning to the caller. Therefore, the caller cannot write directly write to the memory. Instead, the caller is required to use execmem_fill() to update the memory. For the safety and security of X memory, execmem_fill() checks the data being updated always in the memory allocated by one execmem_alloc() call. execmem_fill() uses text_poke like mechanism and requires arch support. Specifically, the arch need to implement arch_execmem_fill(). In execmem_free(), the memory is first erased with arch_invalidate_exec(). Then, the memory is added to free_text_area_*. If this free creates big enough continuous free space (> PMD_SIZE), execmem_free() will try to free the backing vm_struct. [1] https://lore.kernel.org/bpf/Ys6cWUMHO8XwyYgr@hirez.programming.kicks-ass.net/ Signed-off-by: Song Liu --- include/linux/vmalloc.h | 5 + mm/nommu.c | 12 ++ mm/vmalloc.c | 320 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 337 insertions(+) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 096d48aa3437..30aa8c187d40 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -154,6 +154,11 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align, void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask, int node, const void *caller) __alloc_size(1); void *vmalloc_huge(unsigned long size, gfp_t gfp_mask) __alloc_size(1); +void *execmem_alloc(unsigned long size, unsigned long align) __alloc_size(1); +void *execmem_fill(void *dst, void *src, size_t len); +void execmem_free(void *addr); +void *arch_fill_execmem(void *dst, void *src, size_t len); +int arch_invalidate_execmem(void *ptr, size_t len); extern void *__vmalloc_array(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2); extern void *vmalloc_array(size_t n, size_t size) __alloc_size(1, 2); diff --git a/mm/nommu.c b/mm/nommu.c index 214c70e1d059..e3039fd4f65b 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -371,6 +371,18 @@ int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, } EXPORT_SYMBOL(vm_map_pages_zero); +void *execmem_alloc(unsigned long size, unsigned long align) +{ + return NULL; +} + +void *execmem_fill(void *dst, void *src, size_t len) +{ + return ERR_PTR(-EOPNOTSUPP); +} + +void execmem_free(const void *addr) { } + /* * sys_brk() for the most part doesn't need the global kernel * lock, except when an application is doing something nasty diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ccaa461998f3..6cc72c795ee5 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -72,6 +72,11 @@ early_param("nohugevmalloc", set_nohugevmalloc); static const bool vmap_allow_huge = false; #endif /* CONFIG_HAVE_ARCH_HUGE_VMALLOC */ +#ifndef PMD_ALIGN +#define PMD_ALIGN(addr) ALIGN(addr, PMD_SIZE) +#endif +#define PMD_ALIGN_DOWN(addr) ALIGN_DOWN(addr, PMD_SIZE) + bool is_vmalloc_addr(const void *x) { unsigned long addr = (unsigned long)kasan_reset_tag(x); @@ -769,6 +774,38 @@ static LIST_HEAD(free_vmap_area_list); */ static struct rb_root free_vmap_area_root = RB_ROOT; +/* + * free_text_area for execmem_alloc() + */ +static DEFINE_SPINLOCK(free_text_area_lock); +/* + * This linked list is used in pair with free_text_area_root. + * It gives O(1) access to prev/next to perform fast coalescing. + */ +static LIST_HEAD(free_text_area_list); + +/* + * This augment red-black tree represents the free text space. + * All vmap_area objects in this tree are sorted by va->va_start + * address. It is used for allocation and merging when a vmap + * object is released. + * + * Each vmap_area node contains a maximum available free block + * of its sub-tree, right or left. Therefore it is possible to + * find a lowest match of free area. + * + * vmap_area in this tree are backed by RO+X memory, but they do + * not have valid vm pointer (because we need subtree_max_size). + * The vm for these vmap_area are stored in all_text_vm. + */ +static struct rb_root free_text_area_root = RB_ROOT; + +/* + * List of vm_struct for free_text_area_root. This list is rarely + * accessed, so the O(N) complexity is not likely a real issue. + */ +struct vm_struct *all_text_vm; + /* * Preload a CPU with one object for "no edge" split case. The * aim is to get rid of allocations from the atomic context, thus @@ -3313,6 +3350,289 @@ void *vmalloc(unsigned long size) } EXPORT_SYMBOL(vmalloc); +#if defined(CONFIG_MODULES) && defined(MODULES_VADDR) +#define EXEC_MEM_START MODULES_VADDR +#define EXEC_MEM_END MODULES_END +#else +#define EXEC_MEM_START VMALLOC_START +#define EXEC_MEM_END VMALLOC_END +#endif + +static void move_vmap_to_free_text_tree(void *addr) +{ + struct vmap_area *va; + + /* remove from vmap_area_root */ + spin_lock(&vmap_area_lock); + va = __find_vmap_area((unsigned long)addr, &vmap_area_root); + if (WARN_ON_ONCE(!va)) { + spin_unlock(&vmap_area_lock); + return; + } + unlink_va(va, &vmap_area_root); + spin_unlock(&vmap_area_lock); + + /* make the memory RO+X */ + memset(addr, 0, va->va_end - va->va_start); + set_memory_ro(va->va_start, (va->va_end - va->va_start) >> PAGE_SHIFT); + set_memory_x(va->va_start, (va->va_end - va->va_start) >> PAGE_SHIFT); + + /* add to all_text_vm */ + va->vm->next = all_text_vm; + all_text_vm = va->vm; + + /* add to free_text_area_root */ + spin_lock(&free_text_area_lock); + merge_or_add_vmap_area_augment(va, &free_text_area_root, &free_text_area_list); + spin_unlock(&free_text_area_lock); +} + +/** + * execmem_alloc - allocate virtually contiguous RO+X memory + * @size: allocation size + * + * This is used to allocate dynamic kernel text, such as module text, BPF + * programs, etc. User need to use text_poke to update the memory allocated + * by execmem_alloc. + * + * Return: pointer to the allocated memory or %NULL on error + */ +void *execmem_alloc(unsigned long size, unsigned long align) +{ + struct vmap_area *va, *tmp; + unsigned long addr; + enum fit_type type; + int ret; + + va = kmem_cache_alloc_node(vmap_area_cachep, GFP_KERNEL, NUMA_NO_NODE); + if (unlikely(!va)) + return NULL; + +again: + preload_this_cpu_lock(&free_text_area_lock, GFP_KERNEL, NUMA_NO_NODE); + tmp = find_vmap_lowest_match(&free_text_area_root, size, align, 1, false); + + if (!tmp) { + unsigned long alloc_size; + void *ptr; + + spin_unlock(&free_text_area_lock); + + /* + * Not enough continuous space in free_text_area_root, try + * allocate more memory. The memory is first added to + * vmap_area_root, and then moved to free_text_area_root. + */ + alloc_size = roundup(size, PMD_SIZE * num_online_nodes()); + ptr = __vmalloc_node_range(alloc_size, PMD_SIZE, EXEC_MEM_START, + EXEC_MEM_END, GFP_KERNEL, PAGE_KERNEL, + VM_ALLOW_HUGE_VMAP | VM_NO_GUARD, + NUMA_NO_NODE, __builtin_return_address(0)); + if (unlikely(!ptr)) + goto err_out; + + move_vmap_to_free_text_tree(ptr); + goto again; + } + + addr = roundup(tmp->va_start, align); + type = classify_va_fit_type(tmp, addr, size); + if (WARN_ON_ONCE(type == NOTHING_FIT)) + goto err_out; + + ret = adjust_va_to_fit_type(&free_text_area_root, &free_text_area_list, + tmp, addr, size); + if (ret) + goto err_out; + + spin_unlock(&free_text_area_lock); + + va->va_start = addr; + va->va_end = addr + size; + va->vm = NULL; + + spin_lock(&vmap_area_lock); + insert_vmap_area(va, &vmap_area_root, &vmap_area_list); + spin_unlock(&vmap_area_lock); + + return (void *)addr; + +err_out: + spin_unlock(&free_text_area_lock); + kmem_cache_free(vmap_area_cachep, va); + return NULL; +} + +void __weak *arch_fill_execmem(void *dst, void *src, size_t len) +{ + return ERR_PTR(-EOPNOTSUPP); +} + +int __weak arch_invalidate_execmem(void *ptr, size_t len) +{ + return -EOPNOTSUPP; +} + +/** + * execmem_fill - Copy text to RO+X memory allocated by execmem_alloc() + * @dst: pointer to memory allocated by execmem_alloc() + * @src: pointer to data being copied from + * @len: number of bytes to be copied + * + * execmem_fill() will only update memory allocated by a single execmem_fill() + * call. If dst + len goes beyond the boundary of one allocation, + * execmem_fill() is aborted. + * + * If @addr is NULL, no operation is performed. + */ +void *execmem_fill(void *dst, void *src, size_t len) +{ + struct vmap_area *va; + + spin_lock(&vmap_area_lock); + va = __find_vmap_area((unsigned long)dst, &vmap_area_root); + + /* + * If no va, or va has a vm attached, this memory is not allocated + * by execmem_alloc(). + */ + if (WARN_ON_ONCE(!va) || WARN_ON_ONCE(va->vm)) + goto err_out; + if (WARN_ON_ONCE((unsigned long)dst + len > va->va_end)) + goto err_out; + + spin_unlock(&vmap_area_lock); + + return arch_fill_execmem(dst, src, len); + +err_out: + spin_unlock(&vmap_area_lock); + return ERR_PTR(-EINVAL); +} + +static struct vm_struct *find_and_unlink_text_vm(unsigned long start, unsigned long end) +{ + struct vm_struct *vm, *prev_vm; + + lockdep_assert_held(&free_text_area_lock); + + vm = all_text_vm; + while (vm) { + unsigned long vm_addr = (unsigned long)vm->addr; + + /* vm is within this free space, we can free it */ + if ((vm_addr >= start) && ((vm_addr + vm->size) <= end)) + goto unlink_vm; + vm = vm->next; + } + return NULL; + +unlink_vm: + if (all_text_vm == vm) { + all_text_vm = vm->next; + } else { + prev_vm = all_text_vm; + while (prev_vm->next != vm) + prev_vm = prev_vm->next; + prev_vm = vm->next; + } + return vm; +} + +/** + * execmem_free - Release memory allocated by execmem_alloc() + * @addr: Memory base address + * + * If @addr is NULL, no operation is performed. + */ +void execmem_free(void *addr) +{ + unsigned long free_start, free_end, free_addr; + struct vm_struct *vm; + struct vmap_area *va; + + might_sleep(); + + if (!addr) + return; + + spin_lock(&vmap_area_lock); + va = __find_vmap_area((unsigned long)addr, &vmap_area_root); + if (WARN_ON_ONCE(!va)) { + spin_unlock(&vmap_area_lock); + return; + } + WARN_ON_ONCE(va->vm); + + unlink_va(va, &vmap_area_root); + spin_unlock(&vmap_area_lock); + + /* Invalidate text in the region */ + arch_invalidate_execmem(addr, va->va_end - va->va_start); + + spin_lock(&free_text_area_lock); + va = merge_or_add_vmap_area_augment(va, + &free_text_area_root, &free_text_area_list); + + if (WARN_ON_ONCE(!va)) + goto out; + + free_start = PMD_ALIGN(va->va_start); + free_end = PMD_ALIGN_DOWN(va->va_end); + + /* + * Only try to free vm when there is at least one PMD_SIZE free + * continuous memory. + */ + if (free_start >= free_end) + goto out; + + /* + * TODO: It is possible that multiple vm are ready to be freed + * after one execmem_free(). But we free at most one vm for now. + */ + vm = find_and_unlink_text_vm(free_start, free_end); + if (!vm) + goto out; + + va = kmem_cache_alloc_node(vmap_area_cachep, GFP_ATOMIC, NUMA_NO_NODE); + if (unlikely(!va)) + goto out_save_vm; + + free_addr = __alloc_vmap_area(&free_text_area_root, &free_text_area_list, + vm->size, 1, (unsigned long)vm->addr, + (unsigned long)vm->addr + vm->size); + + if (WARN_ON_ONCE(free_addr != (unsigned long)vm->addr)) + goto out_save_vm; + + va->va_start = (unsigned long)vm->addr; + va->va_end = va->va_start + vm->size; + va->vm = vm; + spin_unlock(&free_text_area_lock); + + set_memory_nx(va->va_start, vm->size >> PAGE_SHIFT); + set_memory_rw(va->va_start, vm->size >> PAGE_SHIFT); + + /* put the va to vmap_area_root, and then free it with vfree */ + spin_lock(&vmap_area_lock); + insert_vmap_area(va, &vmap_area_root, &vmap_area_list); + spin_unlock(&vmap_area_lock); + + vfree(vm->addr); + return; + +out_save_vm: + /* + * vm is removed from all_text_vm, but not freed. Add it back, + * so that we can use or free it later. + */ + vm->next = all_text_vm; + all_text_vm = vm; +out: + spin_unlock(&free_text_area_lock); +} + /** * vmalloc_huge - allocate virtually contiguous memory, allow huge pages * @size: allocation size From patchwork Mon Nov 7 22:39:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 13035365 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F895C433FE for ; Mon, 7 Nov 2022 22:41:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DFDFA6B0073; Mon, 7 Nov 2022 17:41:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DAE196B0074; Mon, 7 Nov 2022 17:41:39 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C4E976B0075; 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Mon, 07 Nov 2022 14:41:38 -0800 Received: from twshared15216.17.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 7 Nov 2022 14:41:37 -0800 Received: by devbig932.frc1.facebook.com (Postfix, from userid 4523) id A7435F6B36E1; Mon, 7 Nov 2022 14:39:27 -0800 (PST) From: Song Liu To: , CC: , , , , , , , , Song Liu Subject: [PATCH bpf-next v2 2/5] x86/alternative: support execmem_alloc() and execmem_free() Date: Mon, 7 Nov 2022 14:39:18 -0800 Message-ID: <20221107223921.3451913-3-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221107223921.3451913-1-song@kernel.org> References: <20221107223921.3451913-1-song@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: 0eduXI6i2dVOsd6iwJs_QG7hLzpVRDFw X-Proofpoint-GUID: 0eduXI6i2dVOsd6iwJs_QG7hLzpVRDFw X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-07_11,2022-11-07_02,2022-06-22_01 ARC-Message-Signature: i=1; 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dkim=none; spf=pass (imf12.hostedemail.com: domain of "prvs=2310266901=songliubraving@meta.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=2310266901=songliubraving@meta.com"; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=kernel.org (policy=none) X-Rspamd-Server: rspam07 X-HE-Tag: 1667860898-601619 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Implement arch_fill_execmem() and arch_invalidate_execmem() to support execmem_alloc. arch_fill_execmem() copies dynamic kernel text (such as BPF programs) to RO+X memory region allocated by execmem_alloc(). arch_invalidate_execmem() fills memory with 0xcc after it is released by execmem_free(). Signed-off-by: Song Liu --- arch/x86/kernel/alternative.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 5cadcea035e0..e38829f19a81 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -1270,6 +1270,18 @@ void *text_poke_copy(void *addr, const void *opcode, size_t len) return addr; } +void *arch_fill_execmem(void *dst, void *src, size_t len) +{ + if (text_poke_copy(dst, src, len) == NULL) + return ERR_PTR(-EINVAL); + return dst; +} + +int arch_invalidate_execmem(void *ptr, size_t len) +{ + return IS_ERR_OR_NULL(text_poke_set(ptr, 0xcc, len)); +} + /** * text_poke_set - memset into (an unused part of) RX memory * @addr: address to modify From patchwork Mon Nov 7 22:39:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 13035368 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E195C4332F for ; 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Mon, 7 Nov 2022 14:42:37 -0800 Received: from maileast.thefacebook.com ([163.114.130.8]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3knnnvb06y-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 07 Nov 2022 14:42:37 -0800 Received: from twshared15216.17.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 7 Nov 2022 14:42:35 -0800 Received: by devbig932.frc1.facebook.com (Postfix, from userid 4523) id 5DFB5F6B36E8; Mon, 7 Nov 2022 14:39:29 -0800 (PST) From: Song Liu To: , CC: , , , , , , , , Song Liu Subject: [PATCH bpf-next v2 3/5] bpf: use execmem_alloc for bpf program and bpf dispatcher Date: Mon, 7 Nov 2022 14:39:19 -0800 Message-ID: <20221107223921.3451913-4-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221107223921.3451913-1-song@kernel.org> References: <20221107223921.3451913-1-song@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: SBtwCXlm8Wa48Y4I5HMuv9B-vr5ktrpM X-Proofpoint-GUID: SBtwCXlm8Wa48Y4I5HMuv9B-vr5ktrpM X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-07_11,2022-11-07_02,2022-06-22_01 ARC-Message-Signature: i=1; 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dkim=none; spf=pass (imf13.hostedemail.com: domain of "prvs=2310266901=songliubraving@meta.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=2310266901=songliubraving@meta.com"; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=kernel.org (policy=none) X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 1276220006 X-Stat-Signature: 59p6f8dftnnnxp5m818bquzyrjhr6dun X-HE-Tag: 1667860957-845901 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Use execmem_alloc, execmem_free, and execmem_fill instead of bpf_prog_pack_alloc, bpf_prog_pack_free, and bpf_arch_text_copy. execmem_free doesn't require extra size information. Therefore, the free and error handling path can be simplified. Signed-off-by: Song Liu --- arch/x86/net/bpf_jit_comp.c | 23 +---- include/linux/bpf.h | 3 - include/linux/filter.h | 5 - kernel/bpf/core.c | 180 +++--------------------------------- kernel/bpf/dispatcher.c | 11 +-- 5 files changed, 21 insertions(+), 201 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index cec5195602bc..43b93570d8f9 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -229,11 +229,6 @@ static void jit_fill_hole(void *area, unsigned int size) memset(area, 0xcc, size); } -int bpf_arch_text_invalidate(void *dst, size_t len) -{ - return IS_ERR_OR_NULL(text_poke_set(dst, 0xcc, len)); -} - struct jit_context { int cleanup_addr; /* Epilogue code offset */ @@ -2509,11 +2504,9 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) if (proglen <= 0) { out_image: image = NULL; - if (header) { - bpf_arch_text_copy(&header->size, &rw_header->size, - sizeof(rw_header->size)); + if (header) bpf_jit_binary_pack_free(header, rw_header); - } + /* Fall back to interpreter mode */ prog = orig_prog; if (extra_pass) { @@ -2563,8 +2556,9 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) if (!prog->is_func || extra_pass) { /* * bpf_jit_binary_pack_finalize fails in two scenarios: - * 1) header is not pointing to proper module memory; - * 2) the arch doesn't support bpf_arch_text_copy(). + * 1) header is not pointing to memory allocated by + * execmem_alloc; + * 2) the arch doesn't support execmem_free(). * * Both cases are serious bugs and justify WARN_ON. */ @@ -2610,13 +2604,6 @@ bool bpf_jit_supports_kfunc_call(void) return true; } -void *bpf_arch_text_copy(void *dst, void *src, size_t len) -{ - if (text_poke_copy(dst, src, len) == NULL) - return ERR_PTR(-EINVAL); - return dst; -} - /* Indicate the JIT backend supports mixing bpf2bpf and tailcalls. */ bool bpf_jit_supports_subprog_tailcalls(void) { diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 798aec816970..e9f4806cec93 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2721,9 +2721,6 @@ enum bpf_text_poke_type { int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *addr1, void *addr2); -void *bpf_arch_text_copy(void *dst, void *src, size_t len); -int bpf_arch_text_invalidate(void *dst, size_t len); - struct btf_id_set; bool btf_id_set_contains(const struct btf_id_set *set, u32 id); diff --git a/include/linux/filter.h b/include/linux/filter.h index efc42a6e3aed..98e28126c24b 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1023,8 +1023,6 @@ extern long bpf_jit_limit_max; typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size); -void bpf_jit_fill_hole_with_zero(void *area, unsigned int size); - struct bpf_binary_header * bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, unsigned int alignment, @@ -1037,9 +1035,6 @@ void bpf_jit_free(struct bpf_prog *fp); struct bpf_binary_header * bpf_jit_binary_pack_hdr(const struct bpf_prog *fp); -void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns); -void bpf_prog_pack_free(struct bpf_binary_header *hdr); - static inline bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp) { return list_empty(&fp->aux->ksym.lnode) || diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 9c16338bcbe8..86b4f640e3c0 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -806,149 +806,6 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog, return slot; } -/* - * BPF program pack allocator. - * - * Most BPF programs are pretty small. Allocating a hole page for each - * program is sometime a waste. Many small bpf program also adds pressure - * to instruction TLB. To solve this issue, we introduce a BPF program pack - * allocator. The prog_pack allocator uses HPAGE_PMD_SIZE page (2MB on x86) - * to host BPF programs. - */ -#define BPF_PROG_CHUNK_SHIFT 6 -#define BPF_PROG_CHUNK_SIZE (1 << BPF_PROG_CHUNK_SHIFT) -#define BPF_PROG_CHUNK_MASK (~(BPF_PROG_CHUNK_SIZE - 1)) - -struct bpf_prog_pack { - struct list_head list; - void *ptr; - unsigned long bitmap[]; -}; - -void bpf_jit_fill_hole_with_zero(void *area, unsigned int size) -{ - memset(area, 0, size); -} - -#define BPF_PROG_SIZE_TO_NBITS(size) (round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE) - -static DEFINE_MUTEX(pack_mutex); -static LIST_HEAD(pack_list); - -/* PMD_SIZE is not available in some special config, e.g. ARCH=arm with - * CONFIG_MMU=n. Use PAGE_SIZE in these cases. - */ -#ifdef PMD_SIZE -#define BPF_PROG_PACK_SIZE (PMD_SIZE * num_possible_nodes()) -#else -#define BPF_PROG_PACK_SIZE PAGE_SIZE -#endif - -#define BPF_PROG_CHUNK_COUNT (BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE) - -static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_insns) -{ - struct bpf_prog_pack *pack; - - pack = kzalloc(struct_size(pack, bitmap, BITS_TO_LONGS(BPF_PROG_CHUNK_COUNT)), - GFP_KERNEL); - if (!pack) - return NULL; - pack->ptr = module_alloc(BPF_PROG_PACK_SIZE); - if (!pack->ptr) { - kfree(pack); - return NULL; - } - bpf_fill_ill_insns(pack->ptr, BPF_PROG_PACK_SIZE); - bitmap_zero(pack->bitmap, BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE); - list_add_tail(&pack->list, &pack_list); - - set_vm_flush_reset_perms(pack->ptr); - set_memory_ro((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE); - set_memory_x((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE); - return pack; -} - -void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) -{ - unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size); - struct bpf_prog_pack *pack; - unsigned long pos; - void *ptr = NULL; - - mutex_lock(&pack_mutex); - if (size > BPF_PROG_PACK_SIZE) { - size = round_up(size, PAGE_SIZE); - ptr = module_alloc(size); - if (ptr) { - bpf_fill_ill_insns(ptr, size); - set_vm_flush_reset_perms(ptr); - set_memory_ro((unsigned long)ptr, size / PAGE_SIZE); - set_memory_x((unsigned long)ptr, size / PAGE_SIZE); - } - goto out; - } - list_for_each_entry(pack, &pack_list, list) { - pos = bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0, - nbits, 0); - if (pos < BPF_PROG_CHUNK_COUNT) - goto found_free_area; - } - - pack = alloc_new_pack(bpf_fill_ill_insns); - if (!pack) - goto out; - - pos = 0; - -found_free_area: - bitmap_set(pack->bitmap, pos, nbits); - ptr = (void *)(pack->ptr) + (pos << BPF_PROG_CHUNK_SHIFT); - -out: - mutex_unlock(&pack_mutex); - return ptr; -} - -void bpf_prog_pack_free(struct bpf_binary_header *hdr) -{ - struct bpf_prog_pack *pack = NULL, *tmp; - unsigned int nbits; - unsigned long pos; - - mutex_lock(&pack_mutex); - if (hdr->size > BPF_PROG_PACK_SIZE) { - module_memfree(hdr); - goto out; - } - - list_for_each_entry(tmp, &pack_list, list) { - if ((void *)hdr >= tmp->ptr && (tmp->ptr + BPF_PROG_PACK_SIZE) > (void *)hdr) { - pack = tmp; - break; - } - } - - if (WARN_ONCE(!pack, "bpf_prog_pack bug\n")) - goto out; - - nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size); - pos = ((unsigned long)hdr - (unsigned long)pack->ptr) >> BPF_PROG_CHUNK_SHIFT; - - WARN_ONCE(bpf_arch_text_invalidate(hdr, hdr->size), - "bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n"); - - bitmap_clear(pack->bitmap, pos, nbits); - if (bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0, - BPF_PROG_CHUNK_COUNT, 0) == 0) { - list_del(&pack->list); - module_memfree(pack->ptr); - kfree(pack); - } -out: - mutex_unlock(&pack_mutex); -} - static atomic_long_t bpf_jit_current; /* Can be overridden by an arch's JIT compiler if it has a custom, @@ -1048,6 +905,9 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr) bpf_jit_uncharge_modmem(size); } +#define BPF_PROG_EXEC_ALIGN 64 +#define BPF_PROG_EXEC_MASK (~(BPF_PROG_EXEC_ALIGN - 1)) + /* Allocate jit binary from bpf_prog_pack allocator. * Since the allocated memory is RO+X, the JIT engine cannot write directly * to the memory. To solve this problem, a RW buffer is also allocated at @@ -1070,11 +930,11 @@ bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr, alignment > BPF_IMAGE_ALIGNMENT); /* add 16 bytes for a random section of illegal instructions */ - size = round_up(proglen + sizeof(*ro_header) + 16, BPF_PROG_CHUNK_SIZE); + size = round_up(proglen + sizeof(*ro_header) + 16, BPF_PROG_EXEC_ALIGN); if (bpf_jit_charge_modmem(size)) return NULL; - ro_header = bpf_prog_pack_alloc(size, bpf_fill_ill_insns); + ro_header = execmem_alloc(size, BPF_PROG_EXEC_ALIGN); if (!ro_header) { bpf_jit_uncharge_modmem(size); return NULL; @@ -1082,8 +942,7 @@ bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr, *rw_header = kvmalloc(size, GFP_KERNEL); if (!*rw_header) { - bpf_arch_text_copy(&ro_header->size, &size, sizeof(size)); - bpf_prog_pack_free(ro_header); + execmem_free(ro_header); bpf_jit_uncharge_modmem(size); return NULL; } @@ -1093,7 +952,7 @@ bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr, (*rw_header)->size = size; hole = min_t(unsigned int, size - (proglen + sizeof(*ro_header)), - BPF_PROG_CHUNK_SIZE - sizeof(*ro_header)); + BPF_PROG_EXEC_ALIGN - sizeof(*ro_header)); start = prandom_u32_max(hole) & ~(alignment - 1); *image_ptr = &ro_header->image[start]; @@ -1109,12 +968,12 @@ int bpf_jit_binary_pack_finalize(struct bpf_prog *prog, { void *ptr; - ptr = bpf_arch_text_copy(ro_header, rw_header, rw_header->size); + ptr = execmem_fill(ro_header, rw_header, rw_header->size); kvfree(rw_header); if (IS_ERR(ptr)) { - bpf_prog_pack_free(ro_header); + execmem_free(ro_header); return PTR_ERR(ptr); } return 0; @@ -1124,18 +983,13 @@ int bpf_jit_binary_pack_finalize(struct bpf_prog *prog, * 1) when the program is freed after; * 2) when the JIT engine fails (before bpf_jit_binary_pack_finalize). * For case 2), we need to free both the RO memory and the RW buffer. - * - * bpf_jit_binary_pack_free requires proper ro_header->size. However, - * bpf_jit_binary_pack_alloc does not set it. Therefore, ro_header->size - * must be set with either bpf_jit_binary_pack_finalize (normal path) or - * bpf_arch_text_copy (when jit fails). */ void bpf_jit_binary_pack_free(struct bpf_binary_header *ro_header, struct bpf_binary_header *rw_header) { - u32 size = ro_header->size; + u32 size = rw_header ? rw_header->size : ro_header->size; - bpf_prog_pack_free(ro_header); + execmem_free(ro_header); kvfree(rw_header); bpf_jit_uncharge_modmem(size); } @@ -1146,7 +1000,7 @@ bpf_jit_binary_pack_hdr(const struct bpf_prog *fp) unsigned long real_start = (unsigned long)fp->bpf_func; unsigned long addr; - addr = real_start & BPF_PROG_CHUNK_MASK; + addr = real_start & BPF_PROG_EXEC_MASK; return (void *)addr; } @@ -2736,16 +2590,6 @@ int __weak bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, return -ENOTSUPP; } -void * __weak bpf_arch_text_copy(void *dst, void *src, size_t len) -{ - return ERR_PTR(-ENOTSUPP); -} - -int __weak bpf_arch_text_invalidate(void *dst, size_t len) -{ - return -ENOTSUPP; -} - DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key); EXPORT_SYMBOL(bpf_stats_enabled_key); diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index 04f0a045dcaa..c41dff3379db 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -126,11 +126,11 @@ static void bpf_dispatcher_update(struct bpf_dispatcher *d, int prev_num_progs) tmp = d->num_progs ? d->rw_image + noff : NULL; if (new) { /* Prepare the dispatcher in d->rw_image. Then use - * bpf_arch_text_copy to update d->image, which is RO+X. + * execmem_fill to update d->image, which is RO+X. */ if (bpf_dispatcher_prepare(d, new, tmp)) return; - if (IS_ERR(bpf_arch_text_copy(new, tmp, PAGE_SIZE / 2))) + if (IS_ERR(execmem_fill(new, tmp, PAGE_SIZE / 2))) return; } @@ -152,15 +152,12 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, mutex_lock(&d->mutex); if (!d->image) { - d->image = bpf_prog_pack_alloc(PAGE_SIZE, bpf_jit_fill_hole_with_zero); + d->image = execmem_alloc(PAGE_SIZE, PAGE_SIZE /* align */); if (!d->image) goto out; d->rw_image = bpf_jit_alloc_exec(PAGE_SIZE); if (!d->rw_image) { - u32 size = PAGE_SIZE; - - bpf_arch_text_copy(d->image, &size, sizeof(size)); - bpf_prog_pack_free((struct bpf_binary_header *)d->image); + execmem_free((struct bpf_binary_header *)d->image); d->image = NULL; goto out; } From patchwork Mon Nov 7 22:39:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 13035369 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A318C4332F for ; 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dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=kernel.org (policy=none); spf=pass (imf02.hostedemail.com: domain of "prvs=2310266901=songliubraving@meta.com" designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=2310266901=songliubraving@meta.com" X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 114DA80006 X-Stat-Signature: ak84b1zjxyd47rrofmrquxmos83c5fdn X-HE-Tag: 1667860961-981173 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Allow arch code to register some memory to be used by execmem_alloc(). One possible use case is to allocate PMD pages for kernl text up to PMD_ALIGN(_etext), and use (_etext, PMD_ALIGN(_etext)) for execmem_alloc. Currently, only one such region is supported. Signed-off-by: Song Liu --- include/linux/vmalloc.h | 4 ++++ mm/vmalloc.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 30aa8c187d40..2babbe3031a5 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -132,11 +132,15 @@ extern void vm_unmap_aliases(void); #ifdef CONFIG_MMU extern void __init vmalloc_init(void); extern unsigned long vmalloc_nr_pages(void); +void register_text_tail_vm(unsigned long start, unsigned long end); #else static inline void vmalloc_init(void) { } static inline unsigned long vmalloc_nr_pages(void) { return 0; } +void register_text_tail_vm(unsigned long start, unsigned long end) +{ +} #endif extern void *vmalloc(unsigned long size) __alloc_size(1); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 6cc72c795ee5..cb54bce3725e 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -77,6 +77,9 @@ static const bool vmap_allow_huge = false; #endif #define PMD_ALIGN_DOWN(addr) ALIGN_DOWN(addr, PMD_SIZE) +static struct vm_struct text_tail_vm; +static struct vmap_area text_tail_va; + bool is_vmalloc_addr(const void *x) { unsigned long addr = (unsigned long)kasan_reset_tag(x); @@ -655,6 +658,8 @@ int is_vmalloc_or_module_addr(const void *x) unsigned long addr = (unsigned long)kasan_reset_tag(x); if (addr >= MODULES_VADDR && addr < MODULES_END) return 1; + if (addr >= text_tail_va.va_start && addr < text_tail_va.va_end) + return 1; #endif return is_vmalloc_addr(x); } @@ -2439,6 +2444,35 @@ static void vmap_init_free_space(void) } } +/* + * register_text_tail_vm() allows arch code to register memory regions + * for execmem_alloc. Unlike regular memory regions used by execmem_alloc, + * this region is never freed by vfree_exec. + * + * One possible use case is to allocate PMD pages for kernl text up to + * PMD_ALIGN(_etext), and use (_etext, PMD_ALIGN(_etext)) for + * execmem_alloc. + */ +void register_text_tail_vm(unsigned long start, unsigned long end) +{ + struct vmap_area *va; + + /* only support one region */ + if (WARN_ON_ONCE(text_tail_vm.addr)) + return; + + va = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT); + if (WARN_ON_ONCE(!va)) + return; + text_tail_vm.addr = (void *)start; + text_tail_vm.size = end - start; + text_tail_va.va_start = start; + text_tail_va.va_end = end; + text_tail_va.vm = &text_tail_vm; + memcpy(va, &text_tail_va, sizeof(*va)); + insert_vmap_area_augment(va, NULL, &free_text_area_root, &free_text_area_list); +} + void __init vmalloc_init(void) { struct vmap_area *va; From patchwork Mon Nov 7 22:39:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 13035367 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C56FC4332F for ; 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dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=kernel.org (policy=none); spf=pass (imf02.hostedemail.com: domain of "prvs=2310266901=songliubraving@meta.com" designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=2310266901=songliubraving@meta.com" X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 2EB2880009 X-Stat-Signature: snxf63931jkhdju31xfsqkzqo89resc5 X-HE-Tag: 1667860951-82903 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Allocate 2MB pages up to round_up(_etext, 2MB), and register memory [round_up(_etext, 4kb), round_up(_etext, 2MB)] with register_text_tail_vm so that we can use this part of memory for dynamic kernel text (BPF programs, etc.). Here is an example: [root@eth50-1 ~]# grep _etext /proc/kallsyms ffffffff82202a08 T _etext [root@eth50-1 ~]# grep bpf_prog_ /proc/kallsyms | tail -n 3 ffffffff8220f920 t bpf_prog_cc61a5364ac11d93_handle__sched_wakeup [bpf] ffffffff8220fa28 t bpf_prog_cc61a5364ac11d93_handle__sched_wakeup_new [bpf] ffffffff8220fad4 t bpf_prog_3bf73fa16f5e3d92_handle__sched_switch [bpf] [root@eth50-1 ~]# grep 0xffffffff82200000 /sys/kernel/debug/page_tables/kernel 0xffffffff82200000-0xffffffff82400000 2M ro PSE x pmd ffffffff82200000-ffffffff82400000 is a 2MB page, serving kernel text, and bpf programs. Signed-off-by: Song Liu --- arch/x86/include/asm/pgtable_64_types.h | 1 + arch/x86/mm/init_64.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 04f36063ad54..c0f9cceb109a 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -101,6 +101,7 @@ extern unsigned int ptrs_per_p4d; #define PUD_MASK (~(PUD_SIZE - 1)) #define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT) #define PGDIR_MASK (~(PGDIR_SIZE - 1)) +#define PMD_ALIGN(x) (((unsigned long)(x) + (PMD_SIZE - 1)) & PMD_MASK) /* * See Documentation/x86/x86_64/mm.rst for a description of the memory map. diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 3f040c6e5d13..5b42fc0c6099 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1373,7 +1373,7 @@ void mark_rodata_ro(void) unsigned long start = PFN_ALIGN(_text); unsigned long rodata_start = PFN_ALIGN(__start_rodata); unsigned long end = (unsigned long)__end_rodata_hpage_align; - unsigned long text_end = PFN_ALIGN(_etext); + unsigned long text_end = PMD_ALIGN(_etext); unsigned long rodata_end = PFN_ALIGN(__end_rodata); unsigned long all_end; @@ -1414,6 +1414,8 @@ void mark_rodata_ro(void) (void *)rodata_end, (void *)_sdata); debug_checkwx(); + register_text_tail_vm(PFN_ALIGN((unsigned long)_etext), + PMD_ALIGN((unsigned long)_etext)); } int kern_addr_valid(unsigned long addr)