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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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