[PATCH] nptl: x86_64: Use same code for CURRENT_STACK_FRAME and stackinfo_get_sp
Noah Goldstein
goldstein.w.n@gmail.com
Tue Aug 30 18:54:26 GMT 2022
On Tue, Aug 30, 2022 at 5:08 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> It avoids the possible warning of uninitialized 'frame' variable when
> building with clang:
>
> ../sysdeps/nptl/jmp-unwind.c:27:42: error: variable 'frame' is
> uninitialized when used here [-Werror,-Wuninitialized]
> __pthread_cleanup_upto (env->__jmpbuf, CURRENT_STACK_FRAME);
>
> The resulting code is similar to CURRENT_STACK_FRAME.
>
> Checked on x86_64-linux-gnu.
> ---
> sysdeps/x86/nptl/pthreaddef.h | 4 +++-
> sysdeps/x86_64/stackinfo.h | 4 +++-
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/x86/nptl/pthreaddef.h b/sysdeps/x86/nptl/pthreaddef.h
> index 63fdbcb27c..7df65931a3 100644
> --- a/sysdeps/x86/nptl/pthreaddef.h
> +++ b/sysdeps/x86/nptl/pthreaddef.h
> @@ -42,7 +42,9 @@
> #ifdef __x86_64__
> /* The frame pointer is not usable. */
> # define CURRENT_STACK_FRAME \
> - ({ register char *frame __asm__("rsp"); frame; })
> + ({ register void * p__ __asm__(RSP_REG); \
> + asm volatile("" : "=r" (p__)); \
> + p__; })
> #else
> # define CURRENT_STACK_FRAME __builtin_frame_address (0)
> #endif
> diff --git a/sysdeps/x86_64/stackinfo.h b/sysdeps/x86_64/stackinfo.h
> index 34c9d0b576..7354632132 100644
> --- a/sysdeps/x86_64/stackinfo.h
> +++ b/sysdeps/x86_64/stackinfo.h
> @@ -40,7 +40,9 @@
> for which they need to act as barriers as well, hence the additional
> (unnecessary) parameters. */
> #define stackinfo_get_sp() \
> - ({ void *p__; asm volatile ("mov %%" RSP_REG ", %0" : "=r" (p__)); p__; })
> + ({ register void * p__ __asm__(RSP_REG); \
> + asm volatile("" : "=r" (p__)); \
> + p__; })
This change addresses a different issue. Maybe two separate commits?
Otherwise LGTM.
> #define stackinfo_sub_sp(ptr) \
> ({ ptrdiff_t d__; \
> asm volatile ("sub %%" RSP_REG " , %0" : "=r" (d__) : "0" (ptr)); \
> --
> 2.34.1
>
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