From 2400fd822f467cb4c886c879d8ad99feac9cf319 Mon Sep 17 00:00:00 2001 From: Oliver O'Halloran Date: Thu, 6 Jul 2017 18:46:43 +1000 Subject: [PATCH] powerpc/asm: Mark cr0 as clobbered in mftb() The workaround for the CELL timebase bug does not correctly mark cr0 as being clobbered. This means GCC doesn't know that the asm block changes cr0 and might leave the result of an unrelated comparison in cr0 across the block, which we then trash, leading to basically random behaviour. Fixes: 859deea949c3 ("[POWERPC] Cell timebase bug workaround") Cc: stable@vger.kernel.org # v2.6.19+ Signed-off-by: Oliver O'Halloran [mpe: Tweak change log and flag for stable] Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/reg.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 7e50e47..a3b6575 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1303,7 +1303,7 @@ static inline void msr_check_and_clear(unsigned long bits) " .llong 0\n" \ ".previous" \ : "=r" (rval) \ - : "i" (CPU_FTR_CELL_TB_BUG), "i" (SPRN_TBRL)); \ + : "i" (CPU_FTR_CELL_TB_BUG), "i" (SPRN_TBRL) : "cr0"); \ rval;}) #else #define mftb() ({unsigned long rval; \ -- 2.7.4