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arch: arc: fix the bug of nest interrupt handling in int exit

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* it's not reliable to use exc_nest_count to decide nest interrupt.
  A better option is to use IRQ_ACT

* ext_nest_count is just used to switch interrupt stack

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
This commit is contained in:
Wayne Ren 2019-04-09 17:09:54 +08:00 • committed by Anas Nashif
commit 1f0fc6d712
2 changed files with 24 additions and 4 deletions
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9
arch/arc/core/fast_irq.S
View file

@ -140,9 +140,14 @@ SECTION_FUNC(TEXT, _firq_exit)
mov r1, exc_nest_count
ld r0, [r1]
sub r0, r0, 1
cmp r0, 0
bne.d _firq_no_reschedule
st r0, [r1]
/* see comments in _rirq_exit */
lr r0, [_ARC_V2_AUX_IRQ_ACT]
and r0, r0, 0xffff
ffs r1, r0
fls r2, r0
cmp r1, r2
jne _firq_no_reschedule
#ifdef CONFIG_STACK_SENTINEL
bl z_check_stack_sentinel

19
arch/arc/core/regular_irq.S
View file

@ -99,9 +99,24 @@ SECTION_FUNC(TEXT, _rirq_exit)
mov r1, exc_nest_count
ld r0, [r1]
sub r0, r0, 1
cmp r0, 0
bne.d _rirq_return_from_rirq
st r0, [r1]
/*
* using exc_nest_count to decide whether is nest int is not reliable.
* a better option is to use IRQ_ACT
* A case is: a high priority int preempts a low priority int before
* rirq_enter/firq_enter, then in _rirq_exit/_firq_exit, it will see
* exc_nest_cout is 0, this will lead to possible thread switch, but
* a low priority int is still pending.
*
* If multi bits in IRQ_ACT are set, i.e. last bit != fist bit, it's
* in nest interrupt
*/
lr r0, [_ARC_V2_AUX_IRQ_ACT]
and r0, r0, 0xffff
ffs r1, r0
fls r2, r0
cmp r1, r2
jne _rirq_return_from_rirq
#ifdef CONFIG_STACK_SENTINEL
bl z_check_stack_sentinel