m68k: Handle 68040 bus faults

Fix 68040 bus fault handling, so the standard kernel exception handling
can be used for i/o probing.

Contrary to normal access faults there is nothing to fix, but at least
we have to disable writebacks to avoid recursive faults.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 3 deletions

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index fd4858e2dd63..75b8340b254b 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -468,15 +468,26 @@ static inline void access_error040(struct frame *fp)
                          * (if do_page_fault didn't fix the mapping,
                          * the writeback won't do good)
                          */
+disable_wb:
 #ifdef DEBUG
                         printk(".. disabling wb2\n");
 #endif
                         if (fp->un.fmt7.wb2a == fp->un.fmt7.faddr)
                                 fp->un.fmt7.wb2s &= ~WBV_040;
+                        if (fp->un.fmt7.wb3a == fp->un.fmt7.faddr)
+                                fp->un.fmt7.wb3s &= ~WBV_040;
                 }
-        } else if (send_fault_sig(&fp->ptregs) > 0) {
-                printk("68040 access error, ssw=%x\n", ssw);
-                trap_c(fp);
+        } else {
+                /* In case of a bus error we either kill the process or expect
+                 * the kernel to catch the fault, which then is also responsible
+                 * for cleaning up the mess.
+                 */
+                current->thread.signo = SIGBUS;
+                current->thread.faddr = fp->un.fmt7.faddr;
+                if (send_fault_sig(&fp->ptregs) >= 0)
+                        printk("68040 bus error (ssw=%x, faddr=%lx)\n", ssw,
+                               fp->un.fmt7.faddr);
+                goto disable_wb;
         }
 
         do_040writebacks(fp);