[PATCH 2/4] msm: scm: Fix improper register assignment
From: Will Deacon <hidden>
Date: 2011-02-25 13:23:48
Also in:
linux-arm-msm, lkml
On Thu, 2011-02-24 at 18:44 +0000, Stephen Boyd wrote:
quoted hunk ↗ jump to hunk
Assign the registers used in the inline assembly immediately before the inline assembly block. This ensures the compiler doesn't optimize away dead register assignments when it shouldn't. Signed-off-by: Stephen Boyd <redacted> --- arch/arm/mach-msm/scm.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-)diff --git a/arch/arm/mach-msm/scm.c b/arch/arm/mach-msm/scm.c index ba57b5a..5eddf54 100644 --- a/arch/arm/mach-msm/scm.c +++ b/arch/arm/mach-msm/scm.c@@ -264,13 +264,16 @@ u32 scm_get_version(void) { int context_id; static u32 version = -1; - register u32 r0 asm("r0") = 0x1 << 8; - register u32 r1 asm("r1") = (u32)&context_id; + register u32 r0 asm("r0"); + register u32 r1 asm("r1"); if (version != -1) return version; mutex_lock(&scm_lock); + + r0 = 0x1 << 8; + r1 = (u32)&context_id; asm volatile( __asmeq("%0", "r1") __asmeq("%1", "r0")
Whoa, have you seen the compiler `optimise' the original assignments away? Since there is a use in the asm block, the definition shouldn't be omitted. What toolchain are you using? Will