MIPS: uaccess: Add micromips clobbers to bzero invocation

commit b3d7e55c3f886493235bfee08e1e5a4a27cbcce8 upstream.

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

Fixes: 26c5e07d1478 ("MIPS: microMIPS: Optimise 'memset' core library function.")
Reported-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Matt Redfearn <matt.redfearn@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.10+
Patchwork: https://patchwork.linux-mips.org/patch/19110/
Signed-off-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index 89fa5c0..c92f4c2 100644 (file)
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -1257,6 +1257,13 @@ __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"
@@ -1266,7 +1273,7 @@ __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__(
@@ -1277,7 +1284,7 @@ __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;