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authorDavid Daney <ddaney@caviumnetworks.com>2009-01-05 15:29:58 -0800
committerRalf Baechle <ralf@linux-mips.org>2009-01-30 21:32:58 +0000
commit8bc6d05b481aa7dc79c81b8ffac0da755e149643 (patch)
tree0c6b7c62dbec9d598546c7e58cb13c0c78212a1e
parent7adbedaf4469dcdcd6a1ab9bdeb8ad854d4f9827 (diff)
MIPS: Read watch registers with interrupts disabled.
If a context switch occurred between the watch exception and reading the watch registers, it would be possible for the new process to corrupt their state. Enabling interrupts only after the watch registers are read avoids this race. Signed-off-by: David Daney <ddaney@caviumnetworks.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/kernel/genex.S6
-rw-r--r--arch/mips/kernel/traps.c8
2 files changed, 12 insertions, 2 deletions
diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index fb6f73148df2..8882e5766f27 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -458,7 +458,11 @@ NESTED(nmi_handler, PT_SIZE, sp)
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 */
+ /*
+ * For watch, interrupts will be enabled after the watch
+ * registers are read.
+ */
+ BUILD_HANDLER watch watch cli silent /* #23 */
#else
BUILD_HANDLER watch watch sti verbose /* #23 */
#endif
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index fa06460cbf2c..b2d7041341b8 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -944,6 +944,9 @@ asmlinkage void do_mdmx(struct pt_regs *regs)
force_sig(SIGILL, current);
}
+/*
+ * Called with interrupts disabled.
+ */
asmlinkage void do_watch(struct pt_regs *regs)
{
u32 cause;
@@ -963,9 +966,12 @@ asmlinkage void do_watch(struct pt_regs *regs)
*/
if (test_tsk_thread_flag(current, TIF_LOAD_WATCH)) {
mips_read_watch_registers();
+ local_irq_enable();
force_sig(SIGTRAP, current);
- } else
+ } else {
mips_clear_watch_registers();
+ local_irq_enable();
+ }
}
asmlinkage void do_mcheck(struct pt_regs *regs)