m68k: Fix assembler constraint to prevent overeager gcc optimisation

Passing the address of a variable as an operand to an asm statement
doesn't mark the value of this variable as used, so gcc may optimize its
initialisation away.  Fix this by using the "m" constraint instead.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@vger.kernel.org

1 files changed, 17 insertions, 19 deletions

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 89362f2bb56a..eb6746978083 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -552,13 +552,13 @@ static inline void bus_error030 (struct frame *fp)
 
 #ifdef DEBUG
                 asm volatile ("ptestr %3,%2@,#7,%0\n\t"
-                              "pmove %%psr,%1@"
-                              : "=a&" (desc)
-                              : "a" (&temp), "a" (addr), "d" (ssw));
+                              "pmove %%psr,%1"
+                              : "=a&" (desc), "=m" (temp)
+                              : "a" (addr), "d" (ssw));
 #else
                 asm volatile ("ptestr %2,%1@,#7\n\t"
-                              "pmove %%psr,%0@"
-                              : : "a" (&temp), "a" (addr), "d" (ssw));
+                              "pmove %%psr,%0"
+                              : "=m" (temp) : "a" (addr), "d" (ssw));
 #endif
                 mmusr = temp;
 
@@ -605,20 +605,18 @@ static inline void bus_error030 (struct frame *fp)
                                !(ssw & RW) ? "write" : "read", addr,
                                fp->ptregs.pc, ssw);
                         asm volatile ("ptestr #1,%1@,#0\n\t"
-                                      "pmove %%psr,%0@"
-                                      : /* no outputs */
-                                      : "a" (&temp), "a" (addr));
+                                      "pmove %%psr,%0"
+                                      : "=m" (temp)
+                                      : "a" (addr));
                         mmusr = temp;
 
                         printk ("level 0 mmusr is %#x\n", mmusr);
 #if 0
-                        asm volatile ("pmove %%tt0,%0@"
-                                      : /* no outputs */
-                                      : "a" (&tlong));
+                        asm volatile ("pmove %%tt0,%0"
+                                      : "=m" (tlong));
                         printk("tt0 is %#lx, ", tlong);
-                        asm volatile ("pmove %%tt1,%0@"
-                                      : /* no outputs */
-                                      : "a" (&tlong));
+                        asm volatile ("pmove %%tt1,%0"
+                                      : "=m" (tlong));
                         printk("tt1 is %#lx\n", tlong);
 #endif
 #ifdef DEBUG
@@ -668,13 +666,13 @@ static inline void bus_error030 (struct frame *fp)
 
 #ifdef DEBUG
         asm volatile ("ptestr #1,%2@,#7,%0\n\t"
-                      "pmove %%psr,%1@"
-                      : "=a&" (desc)
-                      : "a" (&temp), "a" (addr));
+                      "pmove %%psr,%1"
+                      : "=a&" (desc), "=m" (temp)
+                      : "a" (addr));
 #else
         asm volatile ("ptestr #1,%1@,#7\n\t"
-                      "pmove %%psr,%0@"
-                      : : "a" (&temp), "a" (addr));
+                      "pmove %%psr,%0"
+                      : "=m" (temp) : "a" (addr));
 #endif
         mmusr = temp;