Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/4] msm: scm: Mark inline asm as volatile | From | Will Deacon <> | Date | Fri, 25 Feb 2011 11:56:57 +0000 |
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Hi Stephen,
On Thu, 2011-02-24 at 18:44 +0000, Stephen Boyd wrote: > We don't want the compiler to remove these asm statements or > reorder them in any way. Mark them as volatile to be sure. > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > --- > arch/arm/mach-msm/scm.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/mach-msm/scm.c b/arch/arm/mach-msm/scm.c > index f4b9bc9..ba57b5a 100644 > --- a/arch/arm/mach-msm/scm.c > +++ b/arch/arm/mach-msm/scm.c > @@ -174,7 +174,7 @@ static u32 smc(u32 cmd_addr) > register u32 r0 asm("r0") = 1; > register u32 r1 asm("r1") = (u32)&context_id; > register u32 r2 asm("r2") = cmd_addr; > - asm( > + asm volatile( > __asmeq("%0", "r0") > __asmeq("%1", "r0") > __asmeq("%2", "r1") > @@ -271,7 +271,7 @@ u32 scm_get_version(void) > return version; > > mutex_lock(&scm_lock); > - asm( > + asm volatile( > __asmeq("%0", "r1") > __asmeq("%1", "r0") > __asmeq("%2", "r1")
These asm blocks all have sensible looking output constraints. Why do they need to be marked volatile?
Will
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