On Wed, Aug 27, 2025 at 03:36:45PM -0400, Steven Rostedt wrote:
> From: Josh Poimboeuf <[email protected]>
>
> 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.
>
> Signed-off-by: Josh Poimboeuf <[email protected]>
> Signed-off-by: Steven Rostedt (Google) <[email protected]>
> ---
> 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 58d890fe2100..8f94c58d4de8 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -299,6 +299,7 @@ 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 */
Moo, and now you have me look at unwind/user.c:
/* Make sure that the address is word aligned */
shift = sizeof(long) == 4 ? 2 : 3;
if (cfa & ((1 << shift) - 1))
return -EINVAL;
Isn't that just:
if (cfa & (sizeof(long) - 1))
?
Let me go add a patch to clean that up...
