From patchwork Mon Sep 19 09:21:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xu Kuohai X-Patchwork-Id: 12979802 X-Patchwork-Delegate: bpf@iogearbox.net 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6D5AECAAD3 for ; Mon, 19 Sep 2022 09:04:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229966AbiISJEj (ORCPT ); Mon, 19 Sep 2022 05:04:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229574AbiISJEi (ORCPT ); Mon, 19 Sep 2022 05:04:38 -0400 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A74DC36; Mon, 19 Sep 2022 02:04:34 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.143]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4MWJbw5vwmzlC99; Mon, 19 Sep 2022 17:02:52 +0800 (CST) Received: from k01.huawei.com (unknown [10.67.174.197]) by APP2 (Coremail) with SMTP id Syh0CgDHY22cMChjI49JBA--.48437S4; Mon, 19 Sep 2022 17:04:32 +0800 (CST) From: Xu Kuohai To: bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Daniel Borkmann , Jean-Philippe Brucker , Alexei Starovoitov , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Zi Shen Lim , Catalin Marinas , Will Deacon Subject: [RESEND PATCH bpf-next 2/2] bpf, arm64: Eliminate false -EFBIG error in bpf trampoline Date: Mon, 19 Sep 2022 05:21:38 -0400 Message-Id: <20220919092138.1027353-3-xukuohai@huaweicloud.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220919092138.1027353-1-xukuohai@huaweicloud.com> References: <20220919092138.1027353-1-xukuohai@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: Syh0CgDHY22cMChjI49JBA--.48437S4 X-Coremail-Antispam: 1UD129KBjvJXoW3Jr4UGw18CF15ZFyfJF48Crg_yoWxCFyUpa yDGw4jyFW8Xrs8WaykXFWUAF1ak3Wqgry7CrWUG3yS9a4YqryDG3WUGFyYvrWYkrZYyr1x ZF4qyas8urWxGwUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBYb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUXw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMc Ij6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_ Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l42xK82IYc2Ij64 vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8G jcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2I x0cI8IcVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY6xAI w20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x 0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IUbp6wtUUUUU== X-CM-SenderInfo: 50xn30hkdlqx5xdzvxpfor3voofrz/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Xu Kuohai With jiting BPF_CALL to indirect call or direct call based on the jump distance, the bpf trampoline size calculated with NULL image address may be larger than the actual size needed, resulting in a fake -EFBIG error. So remove the estimate of the bpf trampoline size based on NULL image address, and check if there is enough space when emitting instructions. Signed-off-by: Xu Kuohai --- arch/arm64/net/bpf_jit_comp.c | 67 ++++++++++++++++------------------- 1 file changed, 30 insertions(+), 37 deletions(-) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 06437e34614b..a07742ee7860 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -73,6 +73,7 @@ struct jit_ctx { const struct bpf_prog *prog; int idx; bool write; + int max_insns; int epilogue_offset; int *offset; int exentry_idx; @@ -90,11 +91,15 @@ struct bpf_plt { #define PLT_TARGET_SIZE sizeof_field(struct bpf_plt, target) #define PLT_TARGET_OFFSET offsetof(struct bpf_plt, target) -static inline void emit(const u32 insn, struct jit_ctx *ctx) +static inline void __emit(u32 insn, struct jit_ctx *ctx, int idx) { - if (ctx->image != NULL && ctx->write) - ctx->image[ctx->idx] = cpu_to_le32(insn); + if (ctx->image != NULL && ctx->write && idx < ctx->max_insns) + ctx->image[idx] = cpu_to_le32(insn); +} +static inline void emit(u32 insn, struct jit_ctx *ctx) +{ + __emit(insn, ctx, ctx->idx); ctx->idx++; } @@ -1544,6 +1549,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) build_epilogue(&ctx); build_plt(&ctx); + ctx.max_insns = ctx.idx; extable_align = __alignof__(struct exception_table_entry); extable_size = prog->aux->num_exentries * sizeof(struct exception_table_entry); @@ -1603,7 +1609,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) build_plt(&ctx); /* 3. Extra pass to validate JITed code. */ - if (validate_ctx(&ctx)) { + if (WARN_ON_ONCE(ctx.idx > ctx.max_insns) || validate_ctx(&ctx)) { bpf_jit_binary_free(header); prog = orig_prog; goto out_off; @@ -1687,7 +1693,7 @@ static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l, int args_off, int retval_off, int run_ctx_off, bool save_ret) { - __le32 *branch; + int br_idx; u64 enter_prog; u64 exit_prog; struct bpf_prog *p = l->link.prog; @@ -1725,7 +1731,7 @@ static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l, /* if (__bpf_prog_enter(prog) == 0) * goto skip_exec_of_prog; */ - branch = ctx->image + ctx->idx; + br_idx = ctx->idx; emit(A64_NOP, ctx); /* save return value to callee saved register x20 */ @@ -1740,10 +1746,7 @@ static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l, if (save_ret) emit(A64_STR64I(A64_R(0), A64_SP, retval_off), ctx); - if (ctx->image) { - int offset = &ctx->image[ctx->idx] - branch; - *branch = cpu_to_le32(A64_CBZ(1, A64_R(0), offset)); - } + __emit(A64_CBZ(1, A64_R(0), ctx->idx - br_idx), ctx, br_idx); /* arg1: prog */ emit(A64_MOV(1, A64_R(0), A64_R(19)), ctx); @@ -1757,7 +1760,7 @@ static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l, static void invoke_bpf_mod_ret(struct jit_ctx *ctx, struct bpf_tramp_links *tl, int args_off, int retval_off, int run_ctx_off, - __le32 **branches) + int *br_idxes) { int i; @@ -1775,7 +1778,7 @@ static void invoke_bpf_mod_ret(struct jit_ctx *ctx, struct bpf_tramp_links *tl, /* Save the location of branch, and generate a nop. * This nop will be replaced with a cbnz later. */ - branches[i] = ctx->image + ctx->idx; + br_idxes[i] = ctx->idx; emit(A64_NOP, ctx); } } @@ -1828,7 +1831,7 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT]; struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN]; bool save_ret; - __le32 **branches = NULL; + int *br_idxes = NULL; /* trampoline stack layout: * [ parent ip ] @@ -1936,13 +1939,12 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, flags & BPF_TRAMP_F_RET_FENTRY_RET); if (fmod_ret->nr_links) { - branches = kcalloc(fmod_ret->nr_links, sizeof(__le32 *), - GFP_KERNEL); - if (!branches) + br_idxes = kcalloc(fmod_ret->nr_links, sizeof(int), GFP_KERNEL); + if (!br_idxes) return -ENOMEM; invoke_bpf_mod_ret(ctx, fmod_ret, args_off, retval_off, - run_ctx_off, branches); + run_ctx_off, br_idxes); } if (flags & BPF_TRAMP_F_CALL_ORIG) { @@ -1957,11 +1959,10 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, emit(A64_NOP, ctx); } - /* update the branches saved in invoke_bpf_mod_ret with cbnz */ - for (i = 0; i < fmod_ret->nr_links && ctx->image != NULL; i++) { - int offset = &ctx->image[ctx->idx] - branches[i]; - *branches[i] = cpu_to_le32(A64_CBNZ(1, A64_R(10), offset)); - } + /* update the bridx saved in invoke_bpf_mod_ret with cbnz */ + for (i = 0; i < fmod_ret->nr_links; i++) + __emit(A64_CBNZ(1, A64_R(10), ctx->idx - br_idxes[i]), ctx, + br_idxes[i]); for (i = 0; i < fexit->nr_links; i++) invoke_bpf_prog(ctx, fexit->links[i], args_off, retval_off, @@ -2004,7 +2005,7 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, if (ctx->image) bpf_flush_icache(ctx->image, ctx->image + ctx->idx); - kfree(branches); + kfree(br_idxes); return ctx->idx; } @@ -2018,9 +2019,10 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, int nargs = m->nr_args; int max_insns = ((long)image_end - (long)image) / AARCH64_INSN_SIZE; struct jit_ctx ctx = { - .image = NULL, + .image = image, .idx = 0, .write = true, + .max_insns = max_insns, }; /* the first 8 arguments are passed by registers */ @@ -2033,26 +2035,17 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, return -ENOTSUPP; } + jit_fill_hole(image, (unsigned int)(image_end - image)); + ret = prepare_trampoline(&ctx, im, tlinks, orig_call, nargs, flags); + if (ret < 0) return ret; if (ret > max_insns) return -EFBIG; - ctx.image = image; - ctx.idx = 0; - - jit_fill_hole(image, (unsigned int)(image_end - image)); - ret = prepare_trampoline(&ctx, im, tlinks, orig_call, nargs, flags); - - if (ret > 0 && validate_code(&ctx) < 0) - ret = -EINVAL; - - if (ret > 0) - ret *= AARCH64_INSN_SIZE; - - return ret; + return validate_code(&ctx) < 0 ? -EINVAL : ret * AARCH64_INSN_SIZE; } static bool is_long_jump(void *ip, void *target)