ARM: mvebu: Fix the operand list in the inline asm of armada_370_xp_pmsu_idle_enter

In the inline asm part of the function armada_370_xp_pmsu_idle_enter()
the input operand was used. The intent here was to let the compiler
choose this register so it could do the optimization it
needed.

However an input operand is not supposed to be modified by the inline
asm code. This can lead to improper generated instructions.

In some case generated instruction the compiler made the choice to
reuse the same register to store the return value. But in the assembly
part this register was modified, so it can lead to return an wrong
value.

The fix is to use a clobber. Thanks to this the compiler will know
that the value of this register will be modified.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1404483736-16938-1-git-send-email-gregory.clement@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

diff --git a/arch/arm/mach-mvebu/pmsu.c b/arch/arm/mach-mvebu/pmsu.c
index a1d407c0febe9f673dab48ece9099d699eb64d76..25aa8237d66844ca5523ca6b81f1c48e8e2a7cb1 100644 (file)
--- a/arch/arm/mach-mvebu/pmsu.c
+++ b/arch/arm/mach-mvebu/pmsu.c
@@ -201,12 +201,12 @@ static noinline int do_armada_370_xp_cpu_suspend(unsigned long deepidle)
 
        /* Test the CR_C bit and set it if it was cleared */
        asm volatile(
-       "mrc    p15, 0, %0, c1, c0, 0 \n\t"
-       "tst    %0, #(1 << 2) \n\t"
-       "orreq  %0, %0, #(1 << 2) \n\t"
-       "mcreq  p15, 0, %0, c1, c0, 0 \n\t"
+       "mrc    p15, 0, r0, c1, c0, 0 \n\t"
+       "tst    r0, #(1 << 2) \n\t"
+       "orreq  r0, r0, #(1 << 2) \n\t"
+       "mcreq  p15, 0, r0, c1, c0, 0 \n\t"
        "isb    "
-       : : "r" (0));
+       : : : "r0");
 
        pr_warn("Failed to suspend the system\n");