linux-mips
[Top] [All Lists]

[Patch 4/6] Watch trap handling for HARDWARE_WATCHPOINTS.

To: linux-mips@linux-mips.org
Subject: [Patch 4/6] Watch trap handling for HARDWARE_WATCHPOINTS.
From: David Daney <ddaney@avtrex.com>
Date: Mon, 21 Apr 2008 17:21:50 -0700
Cc: linux-kernel@vger.kernel.org
In-reply-to: <480D2151.2020701@avtrex.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <480D2151.2020701@avtrex.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Thunderbird 2.0.0.12 (X11/20080226)
In this portion of the patch we hook up the watch trap handler.  When the
trap occurs, we copy the register contents into the thread_struct and send SIGTRAP. If the current thread was not expecting the trap, the
watch register values must have been left over from a different context and
we just clear the registers and return.

Also I turn off the message the prints on each trap, as these traps are now
expected.

Signed-off-by: David Daney <ddaney@avtrex.com>
---
arch/mips/kernel/genex.S |    4 ++++
arch/mips/kernel/traps.c |   13 +++++++++++++
2 files changed, 17 insertions(+), 0 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 984c0d0..6a5f3f0 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -887,6 +887,18 @@ asmlinkage void do_mdmx(struct pt_regs *regs)

asmlinkage void do_watch(struct pt_regs *regs)
{
+#ifdef CONFIG_HARDWARE_WATCHPOINTS
+       /*
+        * 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();
+#else
        if (board_watchpoint_handler) {
                (*board_watchpoint_handler)(regs);
                return;
@@ -899,6 +911,7 @@ asmlinkage void do_watch(struct pt_regs *regs)
        dump_tlb_all();
        show_regs(regs);
        panic("Caught WATCH exception - probably caused by stack overflow.");
+#endif
}

asmlinkage void do_mcheck(struct pt_regs *regs)
--
1.5.5


<Prev in Thread] Current Thread [Next in Thread>