| Message ID | 20240115145345.3389246-3-cederman@gaisler.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] sparc: Use existing macros to avoid code duplication | expand |
On 15/01/24 11:53, Daniel Cederman wrote: > On LEON, if the stfsr instruction is immediately following a floating-point > operation instruction in a running program, with no other instruction in > between the two, the stfsr might behave as if the order was reversed > between the two instructions and the stfsr occurred before the > floating-point operation. > > Add a nop instruction before the stfsr to prevent this from happening. > > Signed-off-by: Daniel Cederman <cederman@gaisler.com> LGTM, thanks. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> > --- > sysdeps/sparc/fpu/fpu_control.h | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/sysdeps/sparc/fpu/fpu_control.h b/sysdeps/sparc/fpu/fpu_control.h > index dd18789573..48368a7ce1 100644 > --- a/sysdeps/sparc/fpu/fpu_control.h > +++ b/sysdeps/sparc/fpu/fpu_control.h > @@ -61,7 +61,12 @@ typedef unsigned long int fpu_control_t; > # define _FPU_GETCW(cw) __asm__ __volatile__ ("stx %%fsr,%0" : "=m" (*&cw)) > # define _FPU_SETCW(cw) __asm__ __volatile__ ("ldx %0,%%fsr" : : "m" (*&cw)) > #else > -# define _FPU_GETCW(cw) __asm__ __volatile__ ("st %%fsr,%0" : "=m" (*&cw)) > +# ifdef __leon__ > + /* Prevent stfsr from being placed directly after other fp instruction. */ > +# define _FPU_GETCW(cw) __asm__ __volatile__ ("nop; st %%fsr,%0" : "=m" (*&cw)) > +# else > +# define _FPU_GETCW(cw) __asm__ __volatile__ ("st %%fsr,%0" : "=m" (*&cw)) > +# endif > # define _FPU_SETCW(cw) __asm__ __volatile__ ("ld %0,%%fsr" : : "m" (*&cw)) > #endif >
diff --git a/sysdeps/sparc/fpu/fpu_control.h b/sysdeps/sparc/fpu/fpu_control.h index dd18789573..48368a7ce1 100644 --- a/sysdeps/sparc/fpu/fpu_control.h +++ b/sysdeps/sparc/fpu/fpu_control.h @@ -61,7 +61,12 @@ typedef unsigned long int fpu_control_t; # define _FPU_GETCW(cw) __asm__ __volatile__ ("stx %%fsr,%0" : "=m" (*&cw)) # define _FPU_SETCW(cw) __asm__ __volatile__ ("ldx %0,%%fsr" : : "m" (*&cw)) #else -# define _FPU_GETCW(cw) __asm__ __volatile__ ("st %%fsr,%0" : "=m" (*&cw)) +# ifdef __leon__ + /* Prevent stfsr from being placed directly after other fp instruction. */ +# define _FPU_GETCW(cw) __asm__ __volatile__ ("nop; st %%fsr,%0" : "=m" (*&cw)) +# else +# define _FPU_GETCW(cw) __asm__ __volatile__ ("st %%fsr,%0" : "=m" (*&cw)) +# endif # define _FPU_SETCW(cw) __asm__ __volatile__ ("ld %0,%%fsr" : : "m" (*&cw)) #endif
On LEON, if the stfsr instruction is immediately following a floating-point operation instruction in a running program, with no other instruction in between the two, the stfsr might behave as if the order was reversed between the two instructions and the stfsr occurred before the floating-point operation. Add a nop instruction before the stfsr to prevent this from happening. Signed-off-by: Daniel Cederman <cederman@gaisler.com> --- sysdeps/sparc/fpu/fpu_control.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)