This helper will be used to calculate the size of the trampoline before allocating the memory. arch_prepare_bpf_trampoline() for arm64 and riscv64 can use arch_bpf_trampoline_size() to check the trampoline fits in the image. OTOH, arch_prepare_bpf_trampoline() for s390 has to call the JIT process twice, so it cannot use arch_bpf_trampoline_size(). Signed-off-by: Song Liu <song@xxxxxxxxxx> Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> Tested-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> # on s390x --- arch/arm64/net/bpf_jit_comp.c | 56 ++++++++++++++++++++++++--------- arch/riscv/net/bpf_jit_comp64.c | 22 ++++++++++--- arch/s390/net/bpf_jit_comp.c | 56 ++++++++++++++++++++------------- arch/x86/net/bpf_jit_comp.c | 37 +++++++++++++++++++--- include/linux/bpf.h | 2 ++ kernel/bpf/trampoline.c | 6 ++++ 6 files changed, 133 insertions(+), 46 deletions(-) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index d81b886ea4df..a6671253b7ed 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -2026,18 +2026,10 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, return ctx->idx; } -int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, - void *image_end, const struct btf_func_model *m, - u32 flags, struct bpf_tramp_links *tlinks, - void *func_addr) +static int btf_func_model_nregs(const struct btf_func_model *m) { - int i, ret; int nregs = m->nr_args; - int max_insns = ((long)image_end - (long)image) / AARCH64_INSN_SIZE; - struct jit_ctx ctx = { - .image = NULL, - .idx = 0, - }; + int i; /* extra registers needed for struct argument */ for (i = 0; i < MAX_BPF_FUNC_ARGS; i++) { @@ -2046,19 +2038,53 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, nregs += (m->arg_size[i] + 7) / 8 - 1; } + return nregs; +} + +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + struct jit_ctx ctx = { + .image = NULL, + .idx = 0, + }; + struct bpf_tramp_image im; + int nregs, ret; + + nregs = btf_func_model_nregs(m); /* the first 8 registers are used for arguments */ if (nregs > 8) return -ENOTSUPP; - ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); + ret = prepare_trampoline(&ctx, &im, tlinks, func_addr, nregs, flags); if (ret < 0) return ret; - if (ret > max_insns) - return -EFBIG; + return ret < 0 ? ret : ret * AARCH64_INSN_SIZE; +} - ctx.image = image; - ctx.idx = 0; +int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, + void *image_end, const struct btf_func_model *m, + u32 flags, struct bpf_tramp_links *tlinks, + void *func_addr) +{ + int ret, nregs; + struct jit_ctx ctx = { + .image = image, + .idx = 0, + }; + + nregs = btf_func_model_nregs(m); + /* the first 8 registers are used for arguments */ + if (nregs > 8) + return -ENOTSUPP; + + ret = arch_bpf_trampoline_size(m, flags, tlinks, func_addr); + if (ret < 0) + return ret; + + if (ret > ((long)image_end - (long)image)) + return -EFBIG; jit_fill_hole(image, (unsigned int)(image_end - image)); ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 8581693e62d3..35747fafde57 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -1029,6 +1029,21 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, return ret; } +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + struct bpf_tramp_image im; + struct rv_jit_context ctx; + int ret; + + ctx.ninsns = 0; + ctx.insns = NULL; + ctx.ro_insns = NULL; + ret = __arch_prepare_bpf_trampoline(&im, m, tlinks, func_addr, flags, &ctx); + + return ret < 0 ? ret : ninsns_rvoff(ctx.ninsns); +} + int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, @@ -1037,14 +1052,11 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, int ret; struct rv_jit_context ctx; - ctx.ninsns = 0; - ctx.insns = NULL; - ctx.ro_insns = NULL; - ret = __arch_prepare_bpf_trampoline(im, m, tlinks, func_addr, flags, &ctx); + ret = arch_bpf_trampoline_size(im, m, flags, tlinks, func_addr); if (ret < 0) return ret; - if (ninsns_rvoff(ret) > (long)image_end - (long)image) + if (ret > (long)image_end - (long)image) return -EFBIG; ctx.ninsns = 0; diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index bf06b7283f0c..cc129617480a 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -2637,6 +2637,21 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, return 0; } +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *orig_call) +{ + struct bpf_tramp_image im; + struct bpf_tramp_jit tjit; + int ret; + + memset(&tjit, 0, sizeof(tjit)); + + ret = __arch_prepare_bpf_trampoline(&im, &tjit, m, flags, + tlinks, orig_call); + + return ret < 0 ? ret : tjit.common.prg; +} + int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, @@ -2644,30 +2659,27 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, { struct bpf_tramp_jit tjit; int ret; - int i; - for (i = 0; i < 2; i++) { - if (i == 0) { - /* Compute offsets, check whether the code fits. */ - memset(&tjit, 0, sizeof(tjit)); - } else { - /* Generate the code. */ - tjit.common.prg = 0; - tjit.common.prg_buf = image; - } - ret = __arch_prepare_bpf_trampoline(im, &tjit, m, flags, - tlinks, func_addr); - if (ret < 0) - return ret; - if (tjit.common.prg > (char *)image_end - (char *)image) - /* - * Use the same error code as for exceeding - * BPF_MAX_TRAMP_LINKS. - */ - return -E2BIG; - } + /* Compute offsets, check whether the code fits. */ + memset(&tjit, 0, sizeof(tjit)); + ret = __arch_prepare_bpf_trampoline(im, &tjit, m, flags, + tlinks, func_addr); + + if (ret < 0) + return ret; + if (tjit.common.prg > (char *)image_end - (char *)image) + /* + * Use the same error code as for exceeding + * BPF_MAX_TRAMP_LINKS. + */ + return -E2BIG; + + tjit.common.prg = 0; + tjit.common.prg_buf = image; + ret = __arch_prepare_bpf_trampoline(im, &tjit, m, flags, + tlinks, func_addr); - return tjit.common.prg; + return ret < 0 ? ret : tjit.common.prg; } bool bpf_jit_supports_subprog_tailcalls(void) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 5f7528cac344..561530ef2cdb 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2422,10 +2422,10 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog, * add rsp, 8 // skip eth_type_trans's frame * ret // return to its caller */ -int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, - const struct btf_func_model *m, u32 flags, - struct bpf_tramp_links *tlinks, - void *func_addr) +static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, + const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, + void *func_addr) { int i, ret, nr_regs = m->nr_args, stack_size = 0; int regs_off, nregs_off, ip_off, run_ctx_off, arg_stack_off, rbx_off; @@ -2678,6 +2678,35 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i return ret; } +int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, + const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, + void *func_addr) +{ + return __arch_prepare_bpf_trampoline(im, image, image_end, m, flags, tlinks, func_addr); +} + +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + struct bpf_tramp_image im; + void *image; + int ret; + + /* Allocate a temporary buffer for __arch_prepare_bpf_trampoline(). + * This will NOT cause fragmentation in direct map, as we do not + * call set_memory_*() on this buffer. + */ + image = bpf_jit_alloc_exec(PAGE_SIZE); + if (!image) + return -ENOMEM; + + ret = __arch_prepare_bpf_trampoline(&im, image, image + PAGE_SIZE, m, flags, + tlinks, func_addr); + bpf_jit_free_exec(image); + return ret; +} + static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs, u8 *image, u8 *buf) { u8 *jg_reloc, *prog = *pprog; diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 704a457e3199..0414464ba22e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1087,6 +1087,8 @@ void *arch_alloc_bpf_trampoline(unsigned int size); void arch_free_bpf_trampoline(void *image, unsigned int size); void arch_protect_bpf_trampoline(void *image, unsigned int size); void arch_unprotect_bpf_trampoline(void *image, unsigned int size); +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr); u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx); diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index affbcbf7e76e..b553cbd89e55 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -1072,6 +1072,12 @@ void __weak arch_unprotect_bpf_trampoline(void *image, unsigned int size) set_memory_rw((long)image, 1); } +int __weak arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + return -ENOTSUPP; +} + static int __init init_trampolines(void) { int i; -- 2.34.1