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Howlett" , Luis Chamberlain , Mark Rutland , Masami Hiramatsu , Matt Turner , Max Filippov , Michael Ellerman , Michal Simek , Mike Rapoport , Oleg Nesterov , Palmer Dabbelt , Peter Zijlstra , Richard Weinberger , Russell King , Song Liu , Stafford Horne , Steven Rostedt , Thomas Bogendoerfer , Thomas Gleixner , Uladzislau Rezki , Vineet Gupta , Will Deacon , bpf@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-trace-kernel@vger.kernel.org, linux-um@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev, sparclinux@vger.kernel.org, x86@kernel.org Subject: [PATCH v4 7/8] execmem: add support for cache of large ROX pages Date: Mon, 7 Oct 2024 09:28:57 +0300 Message-ID: <20241007062858.44248-8-rppt@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241007062858.44248-1-rppt@kernel.org> References: <20241007062858.44248-1-rppt@kernel.org> MIME-Version: 1.0 X-Rspam-User: X-Stat-Signature: h9ef89h4ridr14fb4bcgmegs3j5u48ht X-Rspamd-Queue-Id: A9F561C0006 X-Rspamd-Server: rspam11 X-HE-Tag: 1728282673-772798 X-HE-Meta: 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 7jIa9/OY ua5kNrxOMLwB2Bfs/TOjxecb/QtKPrSk4g2cZ47GVXXfmR3bkgP1tRD83N2//NnndmLPjw9xpJJJpH/JOA6n0v/6px5cHiQafbygN6fYV1NDFHlUH99OcbAhxz/znPeLo/V3G0COLddPvUKfYbQlLOJmKFQ6Nu3d8juuRoy3p3JULPVh7EQxLaK1ohI+1vXa43+nNbrQVitZmNujFwZk6q4YHsUtYhOM4onZENTIz2+a3H6E= 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: List-Subscribe: List-Unsubscribe: From: "Mike Rapoport (Microsoft)" Using large pages to map text areas reduces iTLB pressure and improves performance. Extend execmem_alloc() with an ability to use huge pages with ROX permissions as a cache for smaller allocations. To populate the cache, a writable large page is allocated from vmalloc with VM_ALLOW_HUGE_VMAP, filled with invalid instructions and then remapped as ROX. Portions of that large page are handed out to execmem_alloc() callers without any changes to the permissions. When the memory is freed with execmem_free() it is invalidated again so that it won't contain stale instructions. The cache is enabled when an architecture sets EXECMEM_ROX_CACHE flag in definition of an execmem_range. Signed-off-by: Mike Rapoport (Microsoft) --- include/linux/execmem.h | 2 + mm/execmem.c | 317 +++++++++++++++++++++++++++++++++++++++- mm/internal.h | 1 + mm/vmalloc.c | 5 + 4 files changed, 320 insertions(+), 5 deletions(-) diff --git a/include/linux/execmem.h b/include/linux/execmem.h index dfdf19f8a5e8..7436aa547818 100644 --- a/include/linux/execmem.h +++ b/include/linux/execmem.h @@ -77,12 +77,14 @@ struct execmem_range { /** * struct execmem_info - architecture parameters for code allocations + * @fill_trapping_insns: set memory to contain instructions that will trap * @ranges: array of parameter sets defining architecture specific * parameters for executable memory allocations. The ranges that are not * explicitly initialized by an architecture use parameters defined for * @EXECMEM_DEFAULT. */ struct execmem_info { + void (*fill_trapping_insns)(void *ptr, size_t size, bool writable); struct execmem_range ranges[EXECMEM_TYPE_MAX]; }; diff --git a/mm/execmem.c b/mm/execmem.c index 0f6691e9ffe6..9c6ff9687860 100644 --- a/mm/execmem.c +++ b/mm/execmem.c @@ -7,28 +7,109 @@ */ #include +#include #include #include +#include +#include #include #include +#include + +#include "internal.h" + static struct execmem_info *execmem_info __ro_after_init; static struct execmem_info default_execmem_info __ro_after_init; -static void *__execmem_alloc(struct execmem_range *range, size_t size) +#ifdef CONFIG_MMU +struct execmem_cache { + struct mutex mutex; + struct maple_tree busy_areas; + struct maple_tree free_areas; +}; + +static struct execmem_cache execmem_cache = { + .mutex = __MUTEX_INITIALIZER(execmem_cache.mutex), + .busy_areas = MTREE_INIT_EXT(busy_areas, MT_FLAGS_LOCK_EXTERN, + execmem_cache.mutex), + .free_areas = MTREE_INIT_EXT(free_areas, MT_FLAGS_LOCK_EXTERN, + execmem_cache.mutex), +}; + +static inline unsigned long mas_range_len(struct ma_state *mas) +{ + return mas->last - mas->index + 1; +} + +static int execmem_set_direct_map_valid(struct vm_struct *vm, bool valid) +{ + unsigned int nr = (1 << get_vm_area_page_order(vm)); + unsigned int updated = 0; + int err = 0; + + for (int i = 0; i < vm->nr_pages; i += nr) { + err = set_direct_map_valid_noflush(vm->pages[i], nr, valid); + if (err) + goto err_restore; + updated += nr; + } + + return 0; + +err_restore: + for (int i = 0; i < updated; i += nr) + set_direct_map_valid_noflush(vm->pages[i], nr, !valid); + + return err; +} + +static void execmem_cache_clean(struct work_struct *work) +{ + struct maple_tree *free_areas = &execmem_cache.free_areas; + struct mutex *mutex = &execmem_cache.mutex; + MA_STATE(mas, free_areas, 0, ULONG_MAX); + void *area; + + mutex_lock(mutex); + mas_for_each(&mas, area, ULONG_MAX) { + size_t size; + + if (!area) + continue; + + size = mas_range_len(&mas); + + if (IS_ALIGNED(size, PMD_SIZE) && + IS_ALIGNED(mas.index, PMD_SIZE)) { + struct vm_struct *vm = find_vm_area(area); + + execmem_set_direct_map_valid(vm, true); + mas_store_gfp(&mas, NULL, GFP_KERNEL); + vfree(area); + } + } + mutex_unlock(mutex); +} + +static DECLARE_WORK(execmem_cache_clean_work, execmem_cache_clean); + +static void *execmem_vmalloc(struct execmem_range *range, size_t size, + pgprot_t pgprot, unsigned long vm_flags) { bool kasan = range->flags & EXECMEM_KASAN_SHADOW; - unsigned long vm_flags = VM_FLUSH_RESET_PERMS; gfp_t gfp_flags = GFP_KERNEL | __GFP_NOWARN; + unsigned int align = range->alignment; unsigned long start = range->start; unsigned long end = range->end; - unsigned int align = range->alignment; - pgprot_t pgprot = range->pgprot; void *p; if (kasan) vm_flags |= VM_DEFER_KMEMLEAK; + if (vm_flags & VM_ALLOW_HUGE_VMAP) + align = PMD_SIZE; + p = __vmalloc_node_range(size, align, start, end, gfp_flags, pgprot, vm_flags, NUMA_NO_NODE, __builtin_return_address(0)); @@ -50,8 +131,224 @@ static void *__execmem_alloc(struct execmem_range *range, size_t size) return NULL; } + return p; +} + +static int execmem_cache_add(void *ptr, size_t size) +{ + struct maple_tree *free_areas = &execmem_cache.free_areas; + struct mutex *mutex = &execmem_cache.mutex; + unsigned long addr = (unsigned long)ptr; + MA_STATE(mas, free_areas, addr - 1, addr + 1); + unsigned long lower, upper; + void *area = NULL; + int err; + + lower = addr; + upper = addr + size - 1; + + mutex_lock(mutex); + area = mas_walk(&mas); + if (area && mas.last == addr - 1) + lower = mas.index; + + area = mas_next(&mas, ULONG_MAX); + if (area && mas.index == addr + size) + upper = mas.last; + + mas_set_range(&mas, lower, upper); + err = mas_store_gfp(&mas, (void *)lower, GFP_KERNEL); + mutex_unlock(mutex); + if (err) + return err; + + return 0; +} + +static bool within_range(struct execmem_range *range, struct ma_state *mas, + size_t size) +{ + unsigned long addr = mas->index; + + if (addr >= range->start && addr + size < range->end) + return true; + + if (range->fallback_start && + addr >= range->fallback_start && addr + size < range->fallback_end) + return true; + + return false; +} + +static void *__execmem_cache_alloc(struct execmem_range *range, size_t size) +{ + struct maple_tree *free_areas = &execmem_cache.free_areas; + struct maple_tree *busy_areas = &execmem_cache.busy_areas; + MA_STATE(mas_free, free_areas, 0, ULONG_MAX); + MA_STATE(mas_busy, busy_areas, 0, ULONG_MAX); + struct mutex *mutex = &execmem_cache.mutex; + unsigned long addr, last, area_size = 0; + void *area, *ptr = NULL; + int err; + + mutex_lock(mutex); + mas_for_each(&mas_free, area, ULONG_MAX) { + area_size = mas_range_len(&mas_free); + + if (area_size >= size && within_range(range, &mas_free, size)) + break; + } + + if (area_size < size) + goto out_unlock; + + addr = mas_free.index; + last = mas_free.last; + + /* insert allocated size to busy_areas at range [addr, addr + size) */ + mas_set_range(&mas_busy, addr, addr + size - 1); + err = mas_store_gfp(&mas_busy, (void *)addr, GFP_KERNEL); + if (err) + goto out_unlock; + + mas_store_gfp(&mas_free, NULL, GFP_KERNEL); + if (area_size > size) { + void *ptr = (void *)(addr + size); + + /* + * re-insert remaining free size to free_areas at range + * [addr + size, last] + */ + mas_set_range(&mas_free, addr + size, last); + err = mas_store_gfp(&mas_free, ptr, GFP_KERNEL); + if (err) { + mas_store_gfp(&mas_busy, NULL, GFP_KERNEL); + goto out_unlock; + } + } + ptr = (void *)addr; + +out_unlock: + mutex_unlock(mutex); + return ptr; +} + +static int execmem_cache_populate(struct execmem_range *range, size_t size) +{ + unsigned long vm_flags = VM_ALLOW_HUGE_VMAP; + unsigned long start, end; + struct vm_struct *vm; + size_t alloc_size; + int err = -ENOMEM; + void *p; + + alloc_size = round_up(size, PMD_SIZE); + p = execmem_vmalloc(range, alloc_size, PAGE_KERNEL, vm_flags); + if (!p) + return err; + + vm = find_vm_area(p); + if (!vm) + goto err_free_mem; + + /* fill memory with instructions that will trap */ + execmem_info->fill_trapping_insns(p, alloc_size, /* writable = */ true); + + start = (unsigned long)p; + end = start + alloc_size; + + vunmap_range(start, end); + + err = execmem_set_direct_map_valid(vm, false); + if (err) + goto err_free_mem; + + err = vmap_pages_range_noflush(start, end, range->pgprot, vm->pages, + PMD_SHIFT); + if (err) + goto err_free_mem; + + err = execmem_cache_add(p, alloc_size); + if (err) + goto err_free_mem; + + return 0; + +err_free_mem: + vfree(p); + return err; +} + +static void *execmem_cache_alloc(struct execmem_range *range, size_t size) +{ + void *p; + int err; + + p = __execmem_cache_alloc(range, size); + if (p) + return p; + + err = execmem_cache_populate(range, size); + if (err) + return NULL; + + return __execmem_cache_alloc(range, size); +} + +static bool execmem_cache_free(void *ptr) +{ + struct maple_tree *busy_areas = &execmem_cache.busy_areas; + struct mutex *mutex = &execmem_cache.mutex; + unsigned long addr = (unsigned long)ptr; + MA_STATE(mas, busy_areas, addr, addr); + size_t size; + void *area; + + mutex_lock(mutex); + area = mas_walk(&mas); + if (!area) { + mutex_unlock(mutex); + return false; + } + size = mas_range_len(&mas); + + mas_store_gfp(&mas, NULL, GFP_KERNEL); + mutex_unlock(mutex); + + execmem_info->fill_trapping_insns(ptr, size, /* writable = */ false); + + execmem_cache_add(ptr, size); + + schedule_work(&execmem_cache_clean_work); + + return true; +} + +static void *__execmem_alloc(struct execmem_range *range, size_t size) +{ + bool use_cache = range->flags & EXECMEM_ROX_CACHE; + unsigned long vm_flags = VM_FLUSH_RESET_PERMS; + pgprot_t pgprot = range->pgprot; + void *p; + + if (use_cache) + p = execmem_cache_alloc(range, size); + else + p = execmem_vmalloc(range, size, pgprot, vm_flags); + return kasan_reset_tag(p); } +#else +static void *__execmem_alloc(struct execmem_range *range, size_t size) +{ + return vmalloc(size); +} + +static bool execmem_cache_free(void *ptr) +{ + return false; +} +#endif void *execmem_alloc(enum execmem_type type, size_t size) { @@ -67,7 +364,9 @@ void execmem_free(void *ptr) * supported by vmalloc. */ WARN_ON(in_interrupt()); - vfree(ptr); + + if (!execmem_cache_free(ptr)) + vfree(ptr); } void *execmem_update_copy(void *dst, const void *src, size_t size) @@ -92,6 +391,11 @@ static bool execmem_validate(struct execmem_info *info) return true; } +static void default_fill_trapping_insns(void *ptr, size_t size, bool writable) +{ + memset(ptr, 0, size); +} + static void execmem_init_missing(struct execmem_info *info) { struct execmem_range *default_range = &info->ranges[EXECMEM_DEFAULT]; @@ -112,6 +416,9 @@ static void execmem_init_missing(struct execmem_info *info) r->fallback_end = default_range->fallback_end; } } + + if (!info->fill_trapping_insns) + info->fill_trapping_insns = default_fill_trapping_insns; } struct execmem_info * __weak execmem_arch_setup(void) diff --git a/mm/internal.h b/mm/internal.h index 93083bbeeefa..95befbc19852 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1189,6 +1189,7 @@ size_t splice_folio_into_pipe(struct pipe_inode_info *pipe, void __init vmalloc_init(void); int __must_check vmap_pages_range_noflush(unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, unsigned int page_shift); +unsigned int get_vm_area_page_order(struct vm_struct *vm); #else static inline void vmalloc_init(void) { diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 86b2344d7461..f340e38716c0 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3007,6 +3007,11 @@ static inline unsigned int vm_area_page_order(struct vm_struct *vm) #endif } +unsigned int get_vm_area_page_order(struct vm_struct *vm) +{ + return vm_area_page_order(vm); +} + static inline void set_vm_area_page_order(struct vm_struct *vm, unsigned int order) { #ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC