From mboxrd@z Thu Jan 1 00:00:00 1970 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 E2AD16D3F for ; Sun, 15 Oct 2023 14:15:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tEYUuYLT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4915C433C8; Sun, 15 Oct 2023 14:15:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697379328; bh=NaXfphS/Zcd+l913uaP1A96Tr5idfnErwwX2N84AFEU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=tEYUuYLTrq6Z/v3TDiLLPUrehqlQo+2odlPMHxp4ylZWKM/03hK1C++7y1FdKJc/9 qzxhwN3JNMIlO0CZ3o+Yiqn9YflWwLHAhpMC1nD6CeUriyOVqpbsRsfiX2P8DKoSyk h9EH6CyqzW3eo3LTbc6BuU6REcsUN4LcbSIQ/csn4WNiRUfY2JmOnlVxGZd/O1hY/d 9Iu4OYdWP98dfedgsgNqon/wGGGniYXdkGKJHBaO3RZzdgQkfB5vfvYt+1Av1nGOv7 ltBS0Dc4ze97aFuH/vKM1YzCnMPbAj0JpUR/4juHLbl8NEn+arMTJ9aGqE4ruL1A2b zdzZglGP9IDZA== Date: Sun, 15 Oct 2023 23:15:23 +0900 From: Masami Hiramatsu (Google) To: "Masami Hiramatsu (Google)" Cc: Paul Walmsley , Albert Ou , Palmer Dabbelt , Guo Ren , Steven Rostedt , linux-riscv@lists.infradead.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH] riscv: ftrace: Fix to pass correct ftrace_regs to ftrace_func_t functions Message-Id: <20231015231523.901bee54f885a7bb72e1f021@kernel.org> In-Reply-To: <169625103396.278295.15281009481727023114.stgit@devnote2> References: <169625103396.278295.15281009481727023114.stgit@devnote2> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Hi, Gentry ping. I think this should be an important fix because if a fprobe handler without FTRACE_OPS_FL_SAVE_REGS tries to access any register via ftrace_regs, that will get a wrong value. Thank you, On Mon, 2 Oct 2023 21:50:34 +0900 "Masami Hiramatsu (Google)" wrote: > From: Masami Hiramatsu (Google) > > Since ftrace_func_t requires to pass 'struct ftrace_regs *' as the 4th > argument even if FTRACE_OPS_FL_SAVE_REGS is not set, ftrace_caller must > pass 'struct ftrace_regs *', which is a partial pt_regs, on the stack > to the ftrace_func_t functions, so that the ftrace_func_t functions can > access some partial registers. > > Fix to allocate 'struct ftrace_regs' (which has the same size of 'struct > pt_regs') on the stack and save partial (argument) registers on it > instead of reduced size custom data structure. > > Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") > Signed-off-by: Masami Hiramatsu (Google) > --- > arch/riscv/kernel/mcount-dyn.S | 65 +++++++++++++++++----------------------- > 1 file changed, 28 insertions(+), 37 deletions(-) > > diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S > index 669b8697aa38..84963680eff4 100644 > --- a/arch/riscv/kernel/mcount-dyn.S > +++ b/arch/riscv/kernel/mcount-dyn.S > @@ -14,46 +14,37 @@ > .text > > #define FENTRY_RA_OFFSET 8 > -#define ABI_SIZE_ON_STACK 80 > -#define ABI_A0 0 > -#define ABI_A1 8 > -#define ABI_A2 16 > -#define ABI_A3 24 > -#define ABI_A4 32 > -#define ABI_A5 40 > -#define ABI_A6 48 > -#define ABI_A7 56 > -#define ABI_T0 64 > -#define ABI_RA 72 > > .macro SAVE_ABI > - addi sp, sp, -ABI_SIZE_ON_STACK > - > - REG_S a0, ABI_A0(sp) > - REG_S a1, ABI_A1(sp) > - REG_S a2, ABI_A2(sp) > - REG_S a3, ABI_A3(sp) > - REG_S a4, ABI_A4(sp) > - REG_S a5, ABI_A5(sp) > - REG_S a6, ABI_A6(sp) > - REG_S a7, ABI_A7(sp) > - REG_S t0, ABI_T0(sp) > - REG_S ra, ABI_RA(sp) > + addi sp, sp, -PT_SIZE_ON_STACK > + > + /* Save t0 as epc for ftrace_regs_get_instruction_pointer() */ > + REG_S t0, PT_EPC(sp) > + REG_S a0, PT_A0(sp) > + REG_S a1, PT_A1(sp) > + REG_S a2, PT_A2(sp) > + REG_S a3, PT_A3(sp) > + REG_S a4, PT_A4(sp) > + REG_S a5, PT_A5(sp) > + REG_S a6, PT_A6(sp) > + REG_S a7, PT_A7(sp) > + REG_S t0, PT_T0(sp) > + REG_S ra, PT_RA(sp) > .endm > > .macro RESTORE_ABI > - REG_L a0, ABI_A0(sp) > - REG_L a1, ABI_A1(sp) > - REG_L a2, ABI_A2(sp) > - REG_L a3, ABI_A3(sp) > - REG_L a4, ABI_A4(sp) > - REG_L a5, ABI_A5(sp) > - REG_L a6, ABI_A6(sp) > - REG_L a7, ABI_A7(sp) > - REG_L t0, ABI_T0(sp) > - REG_L ra, ABI_RA(sp) > - > - addi sp, sp, ABI_SIZE_ON_STACK > + REG_L a0, PT_A0(sp) > + REG_L a1, PT_A1(sp) > + REG_L a2, PT_A2(sp) > + REG_L a3, PT_A3(sp) > + REG_L a4, PT_A4(sp) > + REG_L a5, PT_A5(sp) > + REG_L a6, PT_A6(sp) > + REG_L a7, PT_A7(sp) > + REG_L t0, PT_T0(sp) > + REG_L ra, PT_RA(sp) > + > + addi sp, sp, PT_SIZE_ON_STACK > .endm > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > @@ -96,8 +87,8 @@ ftrace_call: > call ftrace_stub > > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > - addi a0, sp, ABI_RA > - REG_L a1, ABI_T0(sp) > + addi a0, sp, PT_RA > + REG_L a1, PT_T0(sp) > addi a1, a1, -FENTRY_RA_OFFSET > #ifdef HAVE_FUNCTION_GRAPH_FP_TEST > mv a2, s0 > > -- Masami Hiramatsu (Google)