* [PATCH] parisc: Re-enable interrupts early
@ 2016-10-24 19:55 Helge Deller
2016-11-22 17:18 ` Helge Deller
0 siblings, 1 reply; 2+ messages in thread
From: Helge Deller @ 2016-10-24 19:55 UTC (permalink / raw)
To: linux-parisc, James Bottomley, John David Anglin
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@gmx.de>
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
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] parisc: Re-enable interrupts early
2016-10-24 19:55 [PATCH] parisc: Re-enable interrupts early Helge Deller
@ 2016-11-22 17:18 ` Helge Deller
0 siblings, 0 replies; 2+ messages in thread
From: Helge Deller @ 2016-11-22 17:18 UTC (permalink / raw)
To: linux-parisc, James Bottomley, John David Anglin
On 24.10.2016 21:55, Helge Deller wrote:
> 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.
I've just seen a kernel panic, which I think to be triggered by this patch:
postfix: See http://www.postfix.org/COMPATIBILITY_README.html for details
postfix: To disable backwards compatibility use "postconf compatibility_level=2" and "postfix reload"
.
[ 64.880230] stackcheck: swapper/1 will most likely overflow irq stack (sp:413abc7a40, stk bottom-top:413abc4028-413abc8028)
[ 64.881281] Kernel panic - not syncing: low stack detected by irq handler - check messages
[ 64.881281]
[ 64.881281] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.0-rc6-64bit+ #564
[ 64.881281] Backtrace:
[ 64.881281] [<000000004021a7d8>] show_stack+0x68/0x80
[ 64.881281] [<00000000407fcb8c>] dump_stack+0xec/0x168
[ 64.881281] [<000000004024c364>] panic+0x204/0x500
[ 64.881281] [<000000004021ddac>] do_cpu_irq_mask+0x3c4/0x480
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281]
[ 64.881281] _______________________________
[ 64.881281] < Your System ate a SPARC! Gah! >
[ 64.881281] -------------------------------
[ 64.881281] \ ^__^
[ 64.881281] (__)\ )\/\
[ 64.881281] U ||----w |
[ 64.881281] || ||
[ 64.881281] swapper/1 (pid 0): Protection id trap (code 7)
[ 64.881281] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.0-rc6-64bit+ #564
[ 64.881281] task: 000000007fd0ea90 task.stack: 000000007fd5c000
[ 64.881281]
[ 64.881281] YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
[ 64.881281] PSW: 00001000000001101111110100001110 Not tainted
[ 64.881281] r00-03 000000ff0806fd0e 0000000040d8aca0 0000000140219ebc 000000413abc8070
[ 64.881281] r04-07 0000000040d0b4a0 000000413abc8400 000000413abc8328 000000413abc8078
[ 64.881281] r08-11 000000004021a7d8 000000413abc7fb0 00000000411860d0 000000413abc7a40
[ 64.881281] r12-15 000000007fd5c2c0 0000000000000041 0000000000000041 0000000040d8b4a0
[ 64.881281] r16-19 000000413abc7a40 0000000040d8c4a0 0000000000000004 000000000800000e
[ 64.881281] r20-23 0000000000000001 000000413abc83f0 0000000000000000 0000000000000384
[ 64.881281] r24-27 0000000000000000 000000004080e5d8 000000004036aed0 0000000040d0b4a0
[ 64.881281] r28-31 0000000000000000 000000413abc8a70 000000413abc8400 0000000041145d94
[ 64.881281] sr00-03 00000000003b2800 0000000000000000 0000000000000000 00000000003b2800
[ 64.881281] sr04-07 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[ 64.881281]
[ 64.881281] IASQ: 0000000000000001 0000000000000001 IAOQ: 0000000140219ebc 0000000140219ec0
[ 64.881281] IIR: 43ffff40 ISR: 0000000000000000 IOR: 0000000000000000
[ 64.881281] CPU: 1 CR30: 000000007fd5c000 CR31: 9cf8a6e3d01f680f
[ 64.881281] ORIG_R28: 000000413abc8540
[ 64.881281] IAOQ[0]: 0x140219ebc
[ 64.881281] IAOQ[1]: 0x140219ec0
[ 64.881281] RP(r2): 0x140219ebc
[ 64.881281] Backtrace:
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281]
[ 64.881281] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.0-rc6-64bit+ #564
[ 64.881281] Backtrace:
[ 64.881281] [<000000004021a7d8>] show_stack+0x68/0x80
[ 64.881281] [<00000000407fcb8c>] dump_stack+0xec/0x168
[ 64.881281] [<000000004021ab08>] die_if_kernel+0x2c0/0x3a8
[ 64.881281] [<000000004021b7fc>] handle_interruption+0x6dc/0xbb0
[ 64.881281] [<0000000040208084>] intr_check_sig+0x0/0x38
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281] [<0000000040208074>] intr_return+0x0/0x10
[ 64.881281]
[ 64.881281] Kernel panic - not syncing: Fatal exception in interrupt
<Cpu1> 78000c6201e00000 a0e008c01100b009 CC_PAT_ENCODED_FIELD_WARNING
<Cpu1> 76000c6801e00000 0000000000000520 CC_PAT_DATA_FIELD_WARNING
<Cpu1> 0300109101e00000 0000000000000000 CC_PROCS_ENTRY_OUT
^ permalink raw reply [flat|nested] 2+ messages in thread
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2016-10-24 19:55 [PATCH] parisc: Re-enable interrupts early Helge Deller
2016-11-22 17:18 ` Helge Deller
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