diff options
Diffstat (limited to 'kernel/bpf/core.c')
-rw-r--r-- | kernel/bpf/core.c | 289 |
1 files changed, 259 insertions, 30 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 0a1cfd8544b9..42d96549a804 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -537,13 +537,10 @@ long bpf_jit_limit_max __read_mostly; static void bpf_prog_ksym_set_addr(struct bpf_prog *prog) { - const struct bpf_binary_header *hdr = bpf_jit_binary_hdr(prog); - unsigned long addr = (unsigned long)hdr; - WARN_ON_ONCE(!bpf_prog_ebpf_jited(prog)); prog->aux->ksym.start = (unsigned long) prog->bpf_func; - prog->aux->ksym.end = addr + hdr->pages * PAGE_SIZE; + prog->aux->ksym.end = prog->aux->ksym.start + prog->jited_len; } static void @@ -808,6 +805,137 @@ 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. + */ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#define BPF_PROG_PACK_SIZE HPAGE_PMD_SIZE +#else +#define BPF_PROG_PACK_SIZE PAGE_SIZE +#endif +#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)) +#define BPF_PROG_CHUNK_COUNT (BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE) + +struct bpf_prog_pack { + struct list_head list; + void *ptr; + unsigned long bitmap[BITS_TO_LONGS(BPF_PROG_CHUNK_COUNT)]; +}; + +#define BPF_PROG_MAX_PACK_PROG_SIZE BPF_PROG_PACK_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); + +static struct bpf_prog_pack *alloc_new_pack(void) +{ + struct bpf_prog_pack *pack; + + pack = kzalloc(sizeof(*pack), GFP_KERNEL); + if (!pack) + return NULL; + pack->ptr = module_alloc(BPF_PROG_PACK_SIZE); + if (!pack->ptr) { + kfree(pack); + return NULL; + } + 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; +} + +static void *bpf_prog_pack_alloc(u32 size) +{ + unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size); + struct bpf_prog_pack *pack; + unsigned long pos; + void *ptr = NULL; + + if (size > BPF_PROG_MAX_PACK_PROG_SIZE) { + size = round_up(size, PAGE_SIZE); + ptr = module_alloc(size); + if (ptr) { + set_vm_flush_reset_perms(ptr); + set_memory_ro((unsigned long)ptr, size / PAGE_SIZE); + set_memory_x((unsigned long)ptr, size / PAGE_SIZE); + } + return ptr; + } + mutex_lock(&pack_mutex); + 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(); + 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; +} + +static void bpf_prog_pack_free(struct bpf_binary_header *hdr) +{ + struct bpf_prog_pack *pack = NULL, *tmp; + unsigned int nbits; + unsigned long pos; + void *pack_ptr; + + if (hdr->size > BPF_PROG_MAX_PACK_PROG_SIZE) { + module_memfree(hdr); + return; + } + + pack_ptr = (void *)((unsigned long)hdr & ~(BPF_PROG_PACK_SIZE - 1)); + mutex_lock(&pack_mutex); + + list_for_each_entry(tmp, &pack_list, list) { + if (tmp->ptr == pack_ptr) { + 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; + + 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, @@ -833,12 +961,11 @@ static int __init bpf_jit_charge_init(void) } pure_initcall(bpf_jit_charge_init); -int bpf_jit_charge_modmem(u32 pages) +int bpf_jit_charge_modmem(u32 size) { - if (atomic_long_add_return(pages, &bpf_jit_current) > - (bpf_jit_limit >> PAGE_SHIFT)) { + if (atomic_long_add_return(size, &bpf_jit_current) > bpf_jit_limit) { if (!bpf_capable()) { - atomic_long_sub(pages, &bpf_jit_current); + atomic_long_sub(size, &bpf_jit_current); return -EPERM; } } @@ -846,9 +973,9 @@ int bpf_jit_charge_modmem(u32 pages) return 0; } -void bpf_jit_uncharge_modmem(u32 pages) +void bpf_jit_uncharge_modmem(u32 size) { - atomic_long_sub(pages, &bpf_jit_current); + atomic_long_sub(size, &bpf_jit_current); } void *__weak bpf_jit_alloc_exec(unsigned long size) @@ -867,7 +994,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, bpf_jit_fill_hole_t bpf_fill_ill_insns) { struct bpf_binary_header *hdr; - u32 size, hole, start, pages; + u32 size, hole, start; WARN_ON_ONCE(!is_power_of_2(alignment) || alignment > BPF_IMAGE_ALIGNMENT); @@ -877,20 +1004,19 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, * random section of illegal instructions. */ size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE); - pages = size / PAGE_SIZE; - if (bpf_jit_charge_modmem(pages)) + if (bpf_jit_charge_modmem(size)) return NULL; hdr = bpf_jit_alloc_exec(size); if (!hdr) { - bpf_jit_uncharge_modmem(pages); + bpf_jit_uncharge_modmem(size); return NULL; } /* Fill space with illegal/arch-dep instructions. */ bpf_fill_ill_insns(hdr, size); - hdr->pages = pages; + hdr->size = size; hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)), PAGE_SIZE - sizeof(*hdr)); start = (get_random_int() % hole) & ~(alignment - 1); @@ -903,10 +1029,113 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, void bpf_jit_binary_free(struct bpf_binary_header *hdr) { - u32 pages = hdr->pages; + u32 size = hdr->size; bpf_jit_free_exec(hdr); - bpf_jit_uncharge_modmem(pages); + bpf_jit_uncharge_modmem(size); +} + +/* 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 + * as the same time. The JIT engine should calculate offsets based on the + * RO memory address, but write JITed program to the RW buffer. Once the + * JIT engine finishes, it calls bpf_jit_binary_pack_finalize, which copies + * the JITed program to the RO memory. + */ +struct bpf_binary_header * +bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr, + unsigned int alignment, + struct bpf_binary_header **rw_header, + u8 **rw_image, + bpf_jit_fill_hole_t bpf_fill_ill_insns) +{ + struct bpf_binary_header *ro_header; + u32 size, hole, start; + + WARN_ON_ONCE(!is_power_of_2(alignment) || + 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); + + if (bpf_jit_charge_modmem(size)) + return NULL; + ro_header = bpf_prog_pack_alloc(size); + if (!ro_header) { + bpf_jit_uncharge_modmem(size); + return NULL; + } + + *rw_header = kvmalloc(size, GFP_KERNEL); + if (!*rw_header) { + bpf_prog_pack_free(ro_header); + bpf_jit_uncharge_modmem(size); + return NULL; + } + + /* Fill space with illegal/arch-dep instructions. */ + bpf_fill_ill_insns(*rw_header, size); + (*rw_header)->size = size; + + hole = min_t(unsigned int, size - (proglen + sizeof(*ro_header)), + BPF_PROG_CHUNK_SIZE - sizeof(*ro_header)); + start = (get_random_int() % hole) & ~(alignment - 1); + + *image_ptr = &ro_header->image[start]; + *rw_image = &(*rw_header)->image[start]; + + return ro_header; +} + +/* Copy JITed text from rw_header to its final location, the ro_header. */ +int bpf_jit_binary_pack_finalize(struct bpf_prog *prog, + struct bpf_binary_header *ro_header, + struct bpf_binary_header *rw_header) +{ + void *ptr; + + ptr = bpf_arch_text_copy(ro_header, rw_header, rw_header->size); + + kvfree(rw_header); + + if (IS_ERR(ptr)) { + bpf_prog_pack_free(ro_header); + return PTR_ERR(ptr); + } + prog->aux->use_bpf_prog_pack = true; + return 0; +} + +/* bpf_jit_binary_pack_free is called in two different scenarios: + * 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. + * Also, ro_header->size in 2) is not properly set yet, so rw_header->size + * is used for uncharge. + */ +void bpf_jit_binary_pack_free(struct bpf_binary_header *ro_header, + struct bpf_binary_header *rw_header) +{ + u32 size = rw_header ? rw_header->size : ro_header->size; + + bpf_prog_pack_free(ro_header); + kvfree(rw_header); + bpf_jit_uncharge_modmem(size); +} + +static inline struct bpf_binary_header * +bpf_jit_binary_hdr(const struct bpf_prog *fp) +{ + unsigned long real_start = (unsigned long)fp->bpf_func; + unsigned long addr; + + if (fp->aux->use_bpf_prog_pack) + addr = real_start & BPF_PROG_CHUNK_MASK; + else + addr = real_start & PAGE_MASK; + + return (void *)addr; } /* This symbol is only overridden by archs that have different @@ -918,7 +1147,10 @@ void __weak bpf_jit_free(struct bpf_prog *fp) if (fp->jited) { struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp); - bpf_jit_binary_free(hdr); + if (fp->aux->use_bpf_prog_pack) + bpf_jit_binary_pack_free(hdr, NULL /* rw_buffer */); + else + bpf_jit_binary_free(hdr); WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp)); } @@ -1968,18 +2200,10 @@ static struct bpf_prog_dummy { }, }; -/* to avoid allocating empty bpf_prog_array for cgroups that - * don't have bpf program attached use one global 'empty_prog_array' - * It will not be modified the caller of bpf_prog_array_alloc() - * (since caller requested prog_cnt == 0) - * that pointer should be 'freed' by bpf_prog_array_free() - */ -static struct { - struct bpf_prog_array hdr; - struct bpf_prog *null_prog; -} empty_prog_array = { +struct bpf_empty_prog_array bpf_empty_prog_array = { .null_prog = NULL, }; +EXPORT_SYMBOL(bpf_empty_prog_array); struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags) { @@ -1989,12 +2213,12 @@ struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags) (prog_cnt + 1), flags); - return &empty_prog_array.hdr; + return &bpf_empty_prog_array.hdr; } void bpf_prog_array_free(struct bpf_prog_array *progs) { - if (!progs || progs == &empty_prog_array.hdr) + if (!progs || progs == &bpf_empty_prog_array.hdr) return; kfree_rcu(progs, rcu); } @@ -2453,6 +2677,11 @@ 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); +} + DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key); EXPORT_SYMBOL(bpf_stats_enabled_key); |