@@ -825,11 +826,6 @@ ENTRY(syscall_exit_rfi)
STREG %r19,PT_SR7(%r16)
intr_return:
- /* NOTE: Need to enable interrupts incase we schedule. */
- ssm PSW_SM_I, %r0
-
-intr_check_resched:
-
/* check for reschedule */
mfctl %cr30,%r1
LDREG TI_FLAGS(%r1),%r19 /* sched.h: TIF_NEED_RESCHED */
@@ -856,6 +852,11 @@ intr_check_sig:
LDREG PT_IASQ1(%r16), %r20
cmpib,COND(=),n 0,%r20,intr_restore /* backward */
+ /* NOTE: We need to enable interrupts if we have to deliver
+ * signals. We used to do this earlier but it caused kernel
+ * stack overflows. */
+ ssm PSW_SM_I, %r0
+
copy %r0, %r25 /* long in_syscall = 0 */
#ifdef CONFIG_64BIT
ldo -16(%r30),%r29 /* Reference param save area */
@@ -907,6 +908,10 @@ intr_do_resched:
cmpib,COND(=) 0, %r20, intr_do_preempt
nop
+ /* NOTE: We need to enable interrupts if we schedule. We used
+ * to do this earlier but it caused kernel stack overflows. */
+ ssm PSW_SM_I, %r0
+
#ifdef CONFIG_64BIT
ldo -16(%r30),%r29 /* Reference param save area */
#endif
Helge and I have found that we have a kernel stack overflow problem which causes a variety of random failures. Currently, we re-enable interrupts when returning from an external interrupt incase we need to schedule or delivery signals. As a result, a potentially unlimited number of interrupts can occur while we are running on the kernel stack. It is very limited in space (currently, 16k). This change defers enabling interrupts until we have actually decided to schedule or delivery signals. This only occurs when we about to return to userspace. This limits the number of interrupts on the kernel stack to one. In other cases, interrupts remain disabled until the final return from interrupt (rfi). Signed-off-by: John David Anglin <dave.anglin@bell.net> --- -- John David Anglin dave.anglin@bell.net