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arch: arc: not allowed to switch to thread preempted by exception

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it's not allowed to switch to thread preempted by exception as
its context is not saved.

So if a thread switch is required in exception handling, e.g.
kill a thread, the old thread cannot be switched back

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
This commit is contained in:
Wayne Ren 2019-08-13 20:37:51 +08:00 committed by Ioannis Glaropoulos
parent 5a73bf3966
commit 5dbd4ce738
1 changed files with 6 additions and 32 deletions
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38
arch/arc/core/switch.S
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@ -140,9 +140,6 @@ _switch_to_target_thread:
.balign 4
_switch_return_from_coop:
lr ilink, [_ARC_V2_STATUS32]
bbit1 ilink, _ARC_V2_STATUS32_AE_BIT, _return_from_exc
pop_s blink /* pc into blink */
#ifdef CONFIG_ARC_HAS_SECURE
pop_s r3 /* pop SEC_STAT */
@ -169,15 +166,15 @@ _switch_return_from_firq:
pop r3
sflag r3
#endif
lr r3, [_ARC_V2_STATUS32]
bbit1 r3, _ARC_V2_STATUS32_AE_BIT, _return_from_exc_irq
/* pretend interrupt happened to use rtie instruction */
lr r3, [_ARC_V2_AUX_IRQ_ACT]
brne r3, 0, _switch_already_in_irq
/* use lowest interrupt priority */
or r3, r3, (1 << (CONFIG_NUM_IRQ_PRIO_LEVELS-1))
#ifdef CONFIG_ARC_SECURE_FIRMWARE
or r3, r3, (1 << (ARC_N_IRQ_START_LEVEL - 1))
#else
or r3, r3, (1 << (CONFIG_NUM_IRQ_PRIO_LEVELS - 1))
#endif
#ifdef CONFIG_ARC_NORMAL_FIRMWARE
mov r0, _ARC_V2_AUX_IRQ_ACT
mov r1, r3
@ -186,31 +183,8 @@ _switch_return_from_firq:
#else
sr r3, [_ARC_V2_AUX_IRQ_ACT]
#endif
_switch_already_in_irq:
rtie
.balign 4
_return_from_exc_irq:
_pop_irq_stack_frame
sub_s sp, sp, ___isf_t_status32_OFFSET - ___isf_t_pc_OFFSET + 4
_return_from_exc:
/* put the return address to eret */
ld ilink, [sp] /* pc into ilink */
sr ilink, [_ARC_V2_ERET]
/* SEC_STAT is bypassed when CONFIG_ARC_HAS_SECURE */
/* put status32 into estatus */
ld ilink, [sp, ___isf_t_status32_OFFSET - ___isf_t_pc_OFFSET]
sr ilink, [_ARC_V2_ERSTATUS]
add_s sp, sp, ___isf_t_status32_OFFSET - ___isf_t_pc_OFFSET + 4
rtie
#ifdef CONFIG_EXECUTION_BENCHMARKING
.balign 4
_capture_value_for_benchmarking: