[PATCH] Fix a bug in setjmp for MIPS o32/o64 FPXX/FP64

[PATCH] Fix a bug in setjmp for MIPS o32/o64 FPXX/FP64

[Giovanni Bajo]

It seems there is a swapped logic in one of the subcases of
setjmp.S for MIPS: when the FPU registers are 64-bit within
a 32-bit aligned jmp_buf, the code realigns the pointers
before doing 64-bit writes, but the branch logic is swapped:
we must avoid the address adjustement when bit 2 is zero
(that is, the address is already 8-byte aligned).

This always triggers an address error when run, as tested
on a MIPS VR4300 with O64 ABI.

---
 newlib/libc/machine/mips/setjmp.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/newlib/libc/machine/mips/setjmp.S b/newlib/libc/machine/mips/setjmp.S
index 9a8b31d09..cfc1d517a 100644
--- a/newlib/libc/machine/mips/setjmp.S
+++ b/newlib/libc/machine/mips/setjmp.S
@@ -68,7 +68,7 @@
 
 #define FPR_LAYOUT		\
 	and $8, $4, 4;	 	\
-	bne $8, $0, 1f;		\
+	beq $8, $0, 1f;		\
 	GPR_OFFSET ($31, 22);	\
 	addiu $4, $4, -4;	\
 1:				\
-- 
2.37.0

Re: [PATCH] Fix a bug in setjmp for MIPS o32/o64 FPXX/FP64

[Corinna Vinschen]

On Dec 17 15:47, Giovanni Bajo wrote:
> It seems there is a swapped logic in one of the subcases of
> setjmp.S for MIPS: when the FPU registers are 64-bit within
> a 32-bit aligned jmp_buf, the code realigns the pointers
> before doing 64-bit writes, but the branch logic is swapped:
> we must avoid the address adjustement when bit 2 is zero
> (that is, the address is already 8-byte aligned).
> 
> This always triggers an address error when run, as tested
> on a MIPS VR4300 with O64 ABI.
> 
> ---
>  newlib/libc/machine/mips/setjmp.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/newlib/libc/machine/mips/setjmp.S b/newlib/libc/machine/mips/setjmp.S
> index 9a8b31d09..cfc1d517a 100644
> --- a/newlib/libc/machine/mips/setjmp.S
> +++ b/newlib/libc/machine/mips/setjmp.S
> @@ -68,7 +68,7 @@
>  
>  #define FPR_LAYOUT		\
>  	and $8, $4, 4;	 	\
> -	bne $8, $0, 1f;		\
> +	beq $8, $0, 1f;		\
>  	GPR_OFFSET ($31, 22);	\
>  	addiu $4, $4, -4;	\
>  1:				\
> -- 
> 2.37.0

Pushed.

Thanks,
Corinna