MIPS: Watch exception handling for HARDWARE_WATCHPOINTS.
Here we hook up the watch exception handler so that it sends SIGTRAP when
the hardware watch registers are triggered.
Signed-off-by: David Daney <ddaney@avtrex.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index 01dcbe3..757d48f 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -453,7 +453,11 @@
BUILD_HANDLER tr tr sti silent /* #13 */
BUILD_HANDLER fpe fpe fpe silent /* #15 */
BUILD_HANDLER mdmx mdmx sti silent /* #22 */
+#ifdef CONFIG_HARDWARE_WATCHPOINTS
+ BUILD_HANDLER watch watch sti silent /* #23 */
+#else
BUILD_HANDLER watch watch sti verbose /* #23 */
+#endif
BUILD_HANDLER mcheck mcheck cli verbose /* #24 */
BUILD_HANDLER mt mt sti silent /* #25 */
BUILD_HANDLER dsp dsp sti silent /* #26 */
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index b602ac6..80b9e07 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -42,6 +42,7 @@
#include <asm/tlbdebug.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
+#include <asm/watch.h>
#include <asm/mmu_context.h>
#include <asm/types.h>
#include <asm/stacktrace.h>
@@ -912,13 +913,26 @@
asmlinkage void do_watch(struct pt_regs *regs)
{
+ u32 cause;
+
/*
- * We use the watch exception where available to detect stack
- * overflows.
+ * Clear WP (bit 22) bit of cause register so we don't loop
+ * forever.
*/
- dump_tlb_all();
- show_regs(regs);
- panic("Caught WATCH exception - probably caused by stack overflow.");
+ cause = read_c0_cause();
+ cause &= ~(1 << 22);
+ write_c0_cause(cause);
+
+ /*
+ * If the current thread has the watch registers loaded, save
+ * their values and send SIGTRAP. Otherwise another thread
+ * left the registers set, clear them and continue.
+ */
+ if (test_tsk_thread_flag(current, TIF_LOAD_WATCH)) {
+ mips_read_watch_registers();
+ force_sig(SIGTRAP, current);
+ } else
+ mips_clear_watch_registers();
}
asmlinkage void do_mcheck(struct pt_regs *regs)