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[92.21.58.28]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8e14d12sm3891457f8f.70.2025.07.11.01.43.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Jul 2025 01:43:23 -0700 (PDT) Date: Fri, 11 Jul 2025 09:43:21 +0100 From: David Laight To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Linus Torvalds , Andrew Morton , Jens Axboe , Florian Weimer , Sam James Subject: Re: [PATCH v13 13/14] unwind_user/x86: Enable frame pointer unwinding on x86 Message-ID: <20250711094321.3c64757c@pumpkin> In-Reply-To: <20250708012359.853818537@kernel.org> References: <20250708012239.268642741@kernel.org> <20250708012359.853818537@kernel.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-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 On Mon, 07 Jul 2025 21:22:52 -0400 Steven Rostedt wrote: > From: Josh Poimboeuf > > Use ARCH_INIT_USER_FP_FRAME to describe how frame pointers are unwound > on x86, and enable CONFIG_HAVE_UNWIND_USER_FP accordingly so the > unwind_user interfaces can be used. How is that going to work? Pretty much all x86 userspace is compiled with bp as a general purpose register not a frame pointer. David > > Signed-off-by: Josh Poimboeuf > Signed-off-by: Steven Rostedt (Google) > --- > arch/x86/Kconfig | 1 + > arch/x86/include/asm/unwind_user.h | 11 +++++++++++ > 2 files changed, 12 insertions(+) > create mode 100644 arch/x86/include/asm/unwind_user.h > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 71019b3b54ea..5862433c81e1 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -302,6 +302,7 @@ config X86 > select HAVE_SYSCALL_TRACEPOINTS > select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL > select HAVE_UNSTABLE_SCHED_CLOCK > + select HAVE_UNWIND_USER_FP if X86_64 > select HAVE_USER_RETURN_NOTIFIER > select HAVE_GENERIC_VDSO > select VDSO_GETRANDOM if X86_64 > diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwind_user.h > new file mode 100644 > index 000000000000..8597857bf896 > --- /dev/null > +++ b/arch/x86/include/asm/unwind_user.h > @@ -0,0 +1,11 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef _ASM_X86_UNWIND_USER_H > +#define _ASM_X86_UNWIND_USER_H > + > +#define ARCH_INIT_USER_FP_FRAME \ > + .cfa_off = (s32)sizeof(long) * 2, \ > + .ra_off = (s32)sizeof(long) * -1, \ > + .fp_off = (s32)sizeof(long) * -2, \ > + .use_fp = true, > + > +#endif /* _ASM_X86_UNWIND_USER_H */