[PATCH 2/3] MIPS: uaccess: Add micromips clobbers to bzero invocation

[Matt Redfearn]

The micromips implementation of bzero additionally clobbers registers t7
& t8. Specify this in the clobbers list when invoking bzero.

Reported-by: James Hogan <jho...@kernel.org>
Fixes: 26c5e07d1478 ("MIPS: microMIPS: Optimise 'memset' core library 
function.")
Cc: sta...@vger.kernel.org
Signed-off-by: Matt Redfearn <matt.redfe...@mips.com>
---

 arch/mips/include/asm/uaccess.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index b71306947290..06629011a434 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -654,6 +654,13 @@ __clear_user(void __user *addr, __kernel_size_t size)
 {
        __kernel_size_t res;
 
+#ifdef CONFIG_CPU_MICROMIPS
+/* micromips memset / bzero also clobbers t7 & t8 */
+#define bzero_clobbers "$4", "$5", "$6", __UA_t0, __UA_t1, "$15", "$24", "$31"
+#else
+#define bzero_clobbers "$4", "$5", "$6", __UA_t0, __UA_t1, "$31"
+#endif /* CONFIG_CPU_MICROMIPS */
+
        if (eva_kernel_access()) {
                __asm__ __volatile__(
                        "move\t$4, %1\n\t"
@@ -663,7 +670,7 @@ __clear_user(void __user *addr, __kernel_size_t size)
                        "move\t%0, $6"
                        : "=r" (res)
                        : "r" (addr), "r" (size)
-                       : "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
+                       : bzero_clobbers);
        } else {
                might_fault();
                __asm__ __volatile__(
@@ -674,7 +681,7 @@ __clear_user(void __user *addr, __kernel_size_t size)
                        "move\t%0, $6"
                        : "=r" (res)
                        : "r" (addr), "r" (size)
-                       : "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
+                       : bzero_clobbers);
        }
 
        return res;
-- 
2.7.4