From patchwork Sun Nov 10 15:52:21 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13869979 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 7FFDF13B2BB; Sun, 10 Nov 2024 15:52:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731253946; cv=none; b=UwSlu+neKg0wu/UHJ+Np4eOncFbG0kN74MZ2Hai83i5q1hC4HkvMfNDdGG2a60jcp826iBmfhoZ1wVWktDH+5rfirdT5BMvzfsN4TES56LTrcAVH0xA7hggOHBUggWTnzzYVP+gJhQZcswU+XXvPvI+SnutPphmHdWo88I/Fpm4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731253946; c=relaxed/simple; bh=ljV+7i1gHE0GvTLzOVr5+Punuc1M73hF7pzOK4hFm44=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Yl5XEHKXOi0M487ZPN+jCU81OR1FqwoduD6dXNEBlXZzPVAe4KRoJUt4dRXCUqkhr6Fjx+h2TMXpQkmg8E1MKCyHnjIZtFkHSLXjqhgd0vxyYonXkhVLO9qUN6FehUBG05LtuUe9Vua4b1IFUfAw5DmDH2ua1rW6mTGo/DPvVRM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Lin1a3x3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Lin1a3x3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 461D5C4CECD; Sun, 10 Nov 2024 15:52:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731253946; bh=ljV+7i1gHE0GvTLzOVr5+Punuc1M73hF7pzOK4hFm44=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lin1a3x3MSmgk9wJ/NIjgm7RnFE4+WmlXVL2U66a+fB0n5PeT0BwBbla/o28K+Boj yssTIfvtB2Ax6W8DL7uKoeIULorJTjpNp18r7bXvTFfpsUlBZ+llnka4fmKrqsAXam NAo+DzTU/+Z+/8b3Kl/RWcGSi1zvhIZ+3VgAEP3lSdtusLkO8hUNC+S5VQhJNZAOwQ O5NPICO5WFjg5BjJ73E9kd0dXY9WLl9MNNjNL7BUkKHdyR3gCp1ynSED4SqVhJWPNf 3MwF3leOKIVisU4pmsCZ04IxXL1z+SDE3ztPs7Xa1WXg4/PznTKNePwPYA4kzeBnC7 4KNK67sSPfL5w== From: "Masami Hiramatsu (Google)" To: Alexei Starovoitov , Steven Rostedt , Florent Revest Cc: linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Alexei Starovoitov , Jiri Olsa , Alan Maguire , Mark Rutland , linux-arch@vger.kernel.org Subject: [PATCH v19 18/19] ftrace: Add ftrace_get_symaddr to convert fentry_ip to symaddr Date: Mon, 11 Nov 2024 00:52:21 +0900 Message-ID: <173125394102.172790.7669548166614384865.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <173125372214.172790.6929368952404083802.stgit@devnote2> References: <173125372214.172790.6929368952404083802.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Masami Hiramatsu (Google) This introduces ftrace_get_symaddr() which tries to convert fentry_ip passed by ftrace or fgraph callback to symaddr without calling kallsyms API. It returns the symbol address or 0 if it fails to convert it. Signed-off-by: Masami Hiramatsu (Google) --- Changes in v19: - Newly added. --- arch/arm64/include/asm/ftrace.h | 2 + arch/arm64/kernel/ftrace.c | 63 +++++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/ftrace.h | 21 +++++++++++++ include/linux/ftrace.h | 13 ++++++++ 4 files changed, 99 insertions(+) diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 876e88ad4119..f08e70bf09ea 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -52,6 +52,8 @@ extern unsigned long ftrace_graph_call; extern void return_to_handler(void); unsigned long ftrace_call_adjust(unsigned long addr); +unsigned long arch_ftrace_call_adjust(unsigned long fentry_ip); +#define ftrace_call_adjust(fentry_ip) arch_ftrace_call_adjust(fentry_ip) #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS #define HAVE_ARCH_FTRACE_REGS diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index 606fd6994578..de1223669758 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -143,6 +143,69 @@ unsigned long ftrace_call_adjust(unsigned long addr) return addr; } +/* Convert fentry_ip to the symbol address without kallsyms */ +unsigned long arch_ftrace_get_symaddr(unsigned long fentry_ip) +{ + u32 insn; + + /* + * When using patchable-function-entry without pre-function NOPS, ftrace + * entry is the address of the first NOP after the function entry point. + * + * The compiler has either generated: + * + * func+00: func: NOP // To be patched to MOV X9, LR + * func+04: NOP // To be patched to BL + * + * Or: + * + * func-04: BTI C + * func+00: func: NOP // To be patched to MOV X9, LR + * func+04: NOP // To be patched to BL + * + * The fentry_ip is the address of `BL ` which is at `func + 4` + * bytes in either case. + */ + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)) + return fentry_ip - AARCH64_INSN_SIZE; + + /* + * When using patchable-function-entry with pre-function NOPs, BTI is + * a bit different. + * + * func+00: func: NOP // To be patched to MOV X9, LR + * func+04: NOP // To be patched to BL + * + * Or: + * + * func+00: func: BTI C + * func+04: NOP // To be patched to MOV X9, LR + * func+08: NOP // To be patched to BL + * + * The fentry_ip is the address of `BL ` which is at either + * `func + 4` or `func + 8` depends on whether there is a BTI. + */ + + /* If there is no BTI, the func address should be one instruction before. */ + if (!IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) + return fentry_ip - AARCH64_INSN_SIZE; + + /* We want to be extra safe in case entry ip is on the page edge, + * but otherwise we need to avoid get_kernel_nofault()'s overhead. + */ + if ((fentry_ip & ~PAGE_MASK) < AARCH64_INSN_SIZE * 2) { + if (get_kernel_nofault(insn, (u32 *)(fentry_ip - AARCH64_INSN_SIZE * 2))) + return 0; + } else { + insn = *(u32 *)(fentry_ip - AARCH64_INSN_SIZE * 2); + } + + if (aarch64_insn_is_bti(le32_to_cpu((__le32)insn))) + return fentry_ip - AARCH64_INSN_SIZE * 2; + + return fentry_ip - AARCH64_INSN_SIZE; +} + /* * Replace a single instruction, which may be a branch or NOP. * If @validate == true, a replaced instruction is checked against 'old'. diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h index cc92c99ef276..f9cb4d07df58 100644 --- a/arch/x86/include/asm/ftrace.h +++ b/arch/x86/include/asm/ftrace.h @@ -34,6 +34,27 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) return addr; } +static inline unsigned long arch_ftrace_get_symaddr(unsigned long fentry_ip) +{ +#ifdef CONFIG_X86_KERNEL_IBT + u32 instr; + + /* We want to be extra safe in case entry ip is on the page edge, + * but otherwise we need to avoid get_kernel_nofault()'s overhead. + */ + if ((fentry_ip & ~PAGE_MASK) < ENDBR_INSN_SIZE) { + if (get_kernel_nofault(instr, (u32 *)(fentry_ip - ENDBR_INSN_SIZE))) + return fentry_ip; + } else { + instr = *(u32 *)(fentry_ip - ENDBR_INSN_SIZE); + } + if (is_endbr(instr)) + fentry_ip -= ENDBR_INSN_SIZE; +#endif + return fentry_ip; +} +#define ftrace_get_symaddr(fentry_ip) arch_ftrace_get_symaddr(fentry_ip) + #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS #include diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 4c553fe9c026..9659bb2cd76c 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -652,6 +652,19 @@ struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr); bool is_ftrace_trampoline(unsigned long addr); +/* Arches can override ftrace_get_symaddr() to convert fentry_ip to symaddr. */ +#ifndef ftrace_get_symaddr +/** + * ftrace_get_symaddr - return the symbol address from fentry_ip + * @fentry_ip: the address of ftrace location + * + * Get the symbol address from @fentry_ip (fast path). If there is no fast + * search path, this returns 0. + * User may need to use kallsyms API to find the symbol address. + */ +#define ftrace_get_symaddr(fentry_ip) (0) +#endif + /* * The dyn_ftrace record's flags field is split into two parts. * the first part which is '0-FTRACE_REF_MAX' is a counter of