From patchwork Tue Aug 1 11:13:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 13336518 X-Patchwork-Delegate: bpf@iogearbox.net Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B37F846A0 for ; Tue, 1 Aug 2023 11:15:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED0A1C433C8; Tue, 1 Aug 2023 11:15:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690888506; bh=SUPU4JElphjAc9d7Elce3inE9nizslZjaxVDu35xOCQ=; h=From:To:Cc:Subject:Date:From; b=jtNNO4yO9pwcm5ECHjZSleO0iX8XIPoXHc1TFvNEteISUvS4aXCRCOlWYHm0jtuY4 vSRaDjuxQIoNtxRHV4nFQ+ZXNHCXhxgIc71dJte4Oo6RGWgZ9sYcdrH1/nlqJwWWCR EpjGhgogu1s3sotPQzFhuDpYk+Qkz9BntV7gExVMYeKeEkqDmoyochYjCqZ/kC3ICv nkqEIwHErz5Q8p66IjtdreGP5RBueqNzI4bSbt9SolGx52Oe7i5GrgpPa8PJyaVkjz nbhKn33aAdeLjEfF3i6nkYQXbn3Fjj5nblrQ0jubU41xrYbXfpj1L1EiI5jqS6OfvU /1GrQTN22TAGg== From: Arnd Bergmann To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Song Liu , Steven Rostedt , Masami Hiramatsu Cc: Arnd Bergmann , stable@vger.kernel.org, John Fastabend , Martin KaFai Lau , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Kumar Kartikeya Dwivedi , Dave Marchevsky , David Vernet , Peter Zijlstra , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH] [v5] bpf: fix bpf_probe_read_kernel prototype mismatch Date: Tue, 1 Aug 2023 13:13:58 +0200 Message-Id: <20230801111449.185301-1-arnd@kernel.org> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Arnd Bergmann bpf_probe_read_kernel() has a __weak definition in core.c and another definition with an incompatible prototype in kernel/trace/bpf_trace.c, when CONFIG_BPF_EVENTS is enabled. Since the two are incompatible, there cannot be a shared declaration in a header file, but the lack of a prototype causes a W=1 warning: kernel/bpf/core.c:1638:12: error: no previous prototype for 'bpf_probe_read_kernel' [-Werror=missing-prototypes] On 32-bit architectures, the local prototype u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) passes arguments in other registers as the one in bpf_trace.c BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size, const void *, unsafe_ptr) which uses 64-bit arguments in pairs of registers. As both versions of the function are fairly simple and only really differ in one line, just move them into a header file as an inline function that does not add any overhead for the bpf_trace.c callers and actually avoids a function call for the other one. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/ac25cb0f-b804-1649-3afb-1dc6138c2716@iogearbox.net/ Signed-off-by: Arnd Bergmann Acked-by: Yonghong Song --- v5: rebase on top of 1f9a1ea821ff2 ("bpf: Support new sign-extension load insns") v4: rewrite again to use a shared inline helper v3: clarify changelog text further. v2: rewrite completely to fix the mismatch. --- include/linux/bpf.h | 12 ++++++++++++ kernel/bpf/core.c | 12 +++--------- kernel/trace/bpf_trace.c | 11 ----------- 3 files changed, 15 insertions(+), 20 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ceaa8c23287fc..abe75063630b8 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2661,6 +2661,18 @@ static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr) } #endif /* CONFIG_BPF_SYSCALL */ +static __always_inline int +bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) +{ + int ret = -EFAULT; + + if (IS_ENABLED(CONFIG_BPF_EVENTS)) + ret = copy_from_kernel_nofault(dst, unsafe_ptr, size); + if (unlikely(ret < 0)) + memset(dst, 0, size); + return ret; +} + void __bpf_free_used_btfs(struct bpf_prog_aux *aux, struct btf_mod_pair *used_btfs, u32 len); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 245402e2229da..52b2a01d74721 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1649,12 +1649,6 @@ bool bpf_opcode_in_insntable(u8 code) } #ifndef CONFIG_BPF_JIT_ALWAYS_ON -u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) -{ - memset(dst, 0, size); - return -EFAULT; -} - /** * ___bpf_prog_run - run eBPF program on a given context * @regs: is the array of MAX_BPF_EXT_REG eBPF pseudo-registers @@ -2065,8 +2059,8 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) DST = *(SIZE *)(unsigned long) (SRC + insn->off); \ CONT; \ LDX_PROBE_MEM_##SIZEOP: \ - bpf_probe_read_kernel(&DST, sizeof(SIZE), \ - (const void *)(long) (SRC + insn->off)); \ + bpf_probe_read_kernel_common(&DST, sizeof(SIZE), \ + (const void *)(long) (SRC + insn->off)); \ DST = *((SIZE *)&DST); \ CONT; @@ -2081,7 +2075,7 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) DST = *(SIZE *)(unsigned long) (SRC + insn->off); \ CONT; \ LDX_PROBE_MEMSX_##SIZEOP: \ - bpf_probe_read_kernel(&DST, sizeof(SIZE), \ + bpf_probe_read_kernel_common(&DST, sizeof(SIZE), \ (const void *)(long) (SRC + insn->off)); \ DST = *((SIZE *)&DST); \ CONT; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 79719979a6355..d6296d51a826a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -223,17 +223,6 @@ const struct bpf_func_proto bpf_probe_read_user_str_proto = { .arg3_type = ARG_ANYTHING, }; -static __always_inline int -bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) -{ - int ret; - - ret = copy_from_kernel_nofault(dst, unsafe_ptr, size); - if (unlikely(ret < 0)) - memset(dst, 0, size); - return ret; -} - BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size, const void *, unsafe_ptr) {