Since kernel 3.9 we re-enable interrupts quite late due to commit c207a76bf15
("parisc: only re-enable interrupts if we need to schedule or deliver signals
when returning to userspace"). At that time the parisc kernel had no dedicated
IRQ stack, and this commit prevented kernel stack overflows.
But since commit 200c880420a ("parisc: implement irq stacks") we now have an
IRQ stack, so we may be safe now. And when CONFIG_DEBUG_STACKOVERFLOW=y is
enabled, we can even check at runtime for overflows.
Signed-off-by: Helge Deller <deller@xxxxxx>
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index 4fcff2d..ad4cb16 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -878,6 +878,9 @@ ENTRY_CFI(syscall_exit_rfi)
STREG %r19,PT_SR7(%r16)
intr_return:
+ /* NOTE: Need to enable interrupts incase we schedule. */
+ ssm PSW_SM_I, %r0
+
/* check for reschedule */
mfctl %cr30,%r1
LDREG TI_FLAGS(%r1),%r19 /* sched.h: TIF_NEED_RESCHED */
@@ -904,11 +907,6 @@ 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 */
@@ -960,10 +958,6 @@ 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
--
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