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Subject[Patch 4/6] MIPS: Watch exception handling for HARDWARE_WATCHPOINTS.
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>
---
arch/mips/kernel/genex.S | 4 ++++
arch/mips/kernel/traps.c | 14 +++++++++-----
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index c6ada98..15a9bde 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -416,7 +416,11 @@ NESTED(nmi_handler, PT_SIZE, sp)
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 6bee290..5fbf591 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>
@@ -908,12 +909,15 @@ asmlinkage void do_mdmx(struct pt_regs *regs)
asmlinkage void do_watch(struct pt_regs *regs)
{
/*
- * We use the watch exception where available to detect stack
- * overflows.
+ * 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.
*/
- dump_tlb_all();
- show_regs(regs);
- panic("Caught WATCH exception - probably caused by stack overflow.");
+ 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)
--
1.5.5.1


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