Mark condition register 0 (cr0) as being clobbered by the inline asm in
get_cpu_clock(). Not doing this results in strange behaviour due to GCC
optimising away some checking. For example e.g:
$ ./fio examples/null.fio --output-format=json
time 5500 cycles_start=8085227422910 <--- bad!
{
"fio version" : "fio-2.21-89-gb034",
<snip>
The extra output is due to the flag checking in dprint being removed
at higher optimisation levels.
Signed-off-by: Oliver O'Halloran <oohall@xxxxxxxxx>
---
arch/arch-ppc.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arch-ppc.h b/arch/arch-ppc.h
index ba452b15b1ff..804d596aecc6 100644
--- a/arch/arch-ppc.h
+++ b/arch/arch-ppc.h
@@ -62,7 +62,8 @@ static inline unsigned long long get_cpu_clock(void)
" cmpwi %0,0;\n"
" beq- 90b;\n"
: "=r" (rval)
- : "i" (SPRN_TBRL));
+ : "i" (SPRN_TBRL)
+ : "cr0");
return rval;
}
--
2.9.4
--
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