From patchwork Thu Oct 31 15:28:44 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13858082 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-176.mta1.migadu.com (out-176.mta1.migadu.com [95.215.58.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6A3171BC9ED for ; Thu, 31 Oct 2024 15:30:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.176 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730388633; cv=none; b=SsJ0xk5ThZfJ/6DNMryJ7zRYza0Dov/RJCs6RwIViSSU7rmYgnFaYWtg+OCgGAztYKqiIHfE1zLtnBB0NM/Z2v7b017Hl6oYKLv4ekG6pkmT0izLkD9zXEk5ybjhZj0Xbqc27PvEGsiF+snTk4uMUFN5cY5T3VJemY0dQnDfaAg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730388633; c=relaxed/simple; bh=5zV2I1qRueWnpKMMW5GwmIIJlIp480xJHgrPEpi+fpo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KndBiEkT0BlrHDvYcq3ip0LQZ9X2wtjQ+Bi9tbfJCTEk2r0ZcYPgJdrFOBeX4fSE4UlpwRHpLraAkICpzk7wtdNHqG5mVB44jJ/zhmAJ8l9o8G7EjE0xSPlX2NLAlCPXBiM81OBG7Hv5V/1bkz7sWmfCyIBVRVa5Ce5txOUhIcE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=K6KcBeA7; arc=none smtp.client-ip=95.215.58.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="K6KcBeA7" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1730388628; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=J5subX4YaWX/lsgLirC6S9tT02i+bceOMTMUn/I3QnA=; b=K6KcBeA7sDJ7dEGt92F6sF1U8V7oCC1kNrwVh7N1XSAh9PS4hSW+cjlfjrL54yfiJBZ8TZ uiL58y0soDenWWjo8rld+6SZFtCL7fqkQs/tSmqGEU+yHmOzMN60sdw1+p60HP5VT753Ua J81cKgWkmDBTw55Y8gkMAnLtbIwQ0iQ= From: Leon Hwang To: bpf@vger.kernel.org Cc: qmo@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, yonghong.song@linux.dev, gray.liang@isovalent.com, stfomichev@gmail.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf v3] bpf, bpftool: Fix incorrect disasm pc Date: Thu, 31 Oct 2024 23:28:44 +0800 Message-ID: <20241031152844.68817-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net This patch addresses the bpftool issue "Wrong callq address displayed"[0]. The issue stemmed from an incorrect program counter (PC) value used during disassembly with LLVM or libbfd. For LLVM: The PC argument must represent the actual address in the kernel to compute the correct relative address. For libbfd: The relative address can be adjusted by adding func_ksym within the custom info->print_address_func to yield the correct address. Links: [0] https://github.com/libbpf/bpftool/issues/109 Changes: v2 -> v3: * Address comment from Quentin: * Remove the typedef. v1 -> v2: * Fix the broken libbfd disassembler. Fixes: e1947c750ffe ("bpftool: Refactor disassembler for JIT-ed programs") Acked-by: Yonghong Song Signed-off-by: Leon Hwang Tested-by: Quentin Monnet Reviewed-by: Quentin Monnet --- tools/bpf/bpftool/jit_disasm.c | 40 ++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 11 deletions(-) diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c index 7b8d9ec89..c032d2c6a 100644 --- a/tools/bpf/bpftool/jit_disasm.c +++ b/tools/bpf/bpftool/jit_disasm.c @@ -80,7 +80,8 @@ symbol_lookup_callback(__maybe_unused void *disasm_info, static int init_context(disasm_ctx_t *ctx, const char *arch, __maybe_unused const char *disassembler_options, - __maybe_unused unsigned char *image, __maybe_unused ssize_t len) + __maybe_unused unsigned char *image, __maybe_unused ssize_t len, + __maybe_unused __u64 func_ksym) { char *triple; @@ -109,12 +110,13 @@ static void destroy_context(disasm_ctx_t *ctx) } static int -disassemble_insn(disasm_ctx_t *ctx, unsigned char *image, ssize_t len, int pc) +disassemble_insn(disasm_ctx_t *ctx, unsigned char *image, ssize_t len, int pc, + __u64 func_ksym) { char buf[256]; int count; - count = LLVMDisasmInstruction(*ctx, image + pc, len - pc, pc, + count = LLVMDisasmInstruction(*ctx, image + pc, len - pc, func_ksym + pc, buf, sizeof(buf)); if (json_output) printf_json(buf); @@ -136,8 +138,21 @@ int disasm_init(void) #ifdef HAVE_LIBBFD_SUPPORT #define DISASM_SPACER "\t" +struct disasm_info { + struct disassemble_info info; + __u64 func_ksym; +}; + +static void disasm_print_addr(bfd_vma addr, struct disassemble_info *info) +{ + struct disasm_info *dinfo = container_of(info, struct disasm_info, info); + + addr += dinfo->func_ksym; + generic_print_address(addr, info); +} + typedef struct { - struct disassemble_info *info; + struct disasm_info *info; disassembler_ftype disassemble; bfd *bfdf; } disasm_ctx_t; @@ -215,7 +230,7 @@ static int fprintf_json_styled(void *out, static int init_context(disasm_ctx_t *ctx, const char *arch, const char *disassembler_options, - unsigned char *image, ssize_t len) + unsigned char *image, ssize_t len, __u64 func_ksym) { struct disassemble_info *info; char tpath[PATH_MAX]; @@ -238,12 +253,13 @@ static int init_context(disasm_ctx_t *ctx, const char *arch, } bfdf = ctx->bfdf; - ctx->info = malloc(sizeof(struct disassemble_info)); + ctx->info = malloc(sizeof(struct disasm_info)); if (!ctx->info) { p_err("mem alloc failed"); goto err_close; } - info = ctx->info; + ctx->info->func_ksym = func_ksym; + info = &ctx->info->info; if (json_output) init_disassemble_info_compat(info, stdout, @@ -272,6 +288,7 @@ static int init_context(disasm_ctx_t *ctx, const char *arch, info->disassembler_options = disassembler_options; info->buffer = image; info->buffer_length = len; + info->print_address_func = disasm_print_addr; disassemble_init_for_target(info); @@ -304,9 +321,10 @@ static void destroy_context(disasm_ctx_t *ctx) static int disassemble_insn(disasm_ctx_t *ctx, __maybe_unused unsigned char *image, - __maybe_unused ssize_t len, int pc) + __maybe_unused ssize_t len, int pc, + __maybe_unused __u64 func_ksym) { - return ctx->disassemble(pc, ctx->info); + return ctx->disassemble(pc, &ctx->info->info); } int disasm_init(void) @@ -331,7 +349,7 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes, if (!len) return -1; - if (init_context(&ctx, arch, disassembler_options, image, len)) + if (init_context(&ctx, arch, disassembler_options, image, len, func_ksym)) return -1; if (json_output) @@ -360,7 +378,7 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes, printf("%4x:" DISASM_SPACER, pc); } - count = disassemble_insn(&ctx, image, len, pc); + count = disassemble_insn(&ctx, image, len, pc, func_ksym); if (json_output) { /* Operand array, was started in fprintf_json. Before