[PATCH v2] sparc: Remove unwind information from signal return stubs [BZ #31244]

[Adhemerval Zanella Netto]

On 16/01/24 05:31, Daniel Cederman wrote:
> The functions were previously written in C, but were not compiled
> with unwind information. The ENTRY/END macros includes .cfi_startproc
> and .cfi_endproc which adds unwind information. This caused the
> tests cleanup-8 and cleanup-10 in the GCC testsuite to fail.
> This patch adds a version of the ENTRY/END macros without the
> CFI instructions that can be used instead.
> 
> sigaction registers a restorer address that is located two instructions
> before the stub function. This patch adds a two instruction padding to
> avoid that the unwinder accesses the unwind information from the function
> that the linker has placed right before it in memory. This fixes an issue
> with pthread_cancel that caused tst-mutex8-static (and other tests) to fail.
> 
> Signed-off-by: Daniel Cederman <cederman@gaisler.com>


LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  sysdeps/sparc/sysdep.h                                |  9 +++++++++
>  .../unix/sysv/linux/sparc/sparc32/sigreturn_stub.S    | 11 +++++++----
>  2 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/sysdeps/sparc/sysdep.h b/sysdeps/sparc/sysdep.h
> index c00fe79fec..44a6952bff 100644
> --- a/sysdeps/sparc/sysdep.h
> +++ b/sysdeps/sparc/sysdep.h
> @@ -76,6 +76,15 @@ C_LABEL(name)				\
>  	cfi_endproc;			\
>  	.size name, . - name
>  
> +#define ENTRY_NOCFI(name)			\
> +	.align	4;			\
> +	.global	C_SYMBOL_NAME(name);	\
> +	.type	name, @function;	\
> +C_LABEL(name)
> +
> +#define END_NOCFI(name)			\
> +	.size name, . - name
> +
>  #undef LOC
>  #define LOC(name)  .L##name
>  
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S b/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S
> index 832223f8ce..21d36c50df 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S
> @@ -23,12 +23,15 @@
>  
>     [1] https://lkml.org/lkml/2016/5/27/465  */
>  
> -ENTRY (__rt_sigreturn_stub)
> +	nop
> +	nop
> +
> +ENTRY_NOCFI (__rt_sigreturn_stub)
>  	mov	__NR_rt_sigreturn, %g1
>  	ta	0x10
> -END (__rt_sigreturn_stub)
> +END_NOCFI (__rt_sigreturn_stub)
>  
> -ENTRY (__sigreturn_stub)
> +ENTRY_NOCFI (__sigreturn_stub)
>  	mov	__NR_sigreturn, %g1
>  	ta	0x10
> -END (__sigreturn_stub)
> +END_NOCFI (__sigreturn_stub)