On Mon, 07 Jul 2025 21:22:52 -0400
Steven Rostedt <rost...@kernel.org> wrote:
> From: Josh Poimboeuf <jpoim...@kernel.org>
>
> 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 <jpoim...@kernel.org>
> Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
> ---
> 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 */
