Thread (19 messages) 19 messages, 6 authors, 2011-03-09

[PATCH 1/4] msm: scm: Mark inline asm as volatile

From: Will Deacon <hidden>
Date: 2011-02-25 12:18:07
Also in: linux-arm-msm, lkml

Hi Stephen,

On Thu, 2011-02-24 at 18:44 +0000, Stephen Boyd wrote:
quoted hunk ↗ jump to hunk
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 <redacted>
---
 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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