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Kirill Smelkov
linux
Commits
5f888087
Commit
5f888087
authored
Sep 06, 2015
by
Vineet Gupta
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ARC: [arcompact] entry.S: Document preemption games for L2 intr
Signed-off-by:
Vineet Gupta
<
vgupta@synopsys.com
>
parent
55a2ae77
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arch/arc/kernel/entry-compact.S
arch/arc/kernel/entry-compact.S
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arch/arc/kernel/entry-compact.S
View file @
5f888087
...
@@ -175,12 +175,25 @@ ENTRY(handle_interrupt_level2)
...
@@ -175,12 +175,25 @@ ENTRY(handle_interrupt_level2)
;------------------------------------------------------
;------------------------------------------------------
; if L2 IRQ interrupted a L1 ISR, disable preemption
; if L2 IRQ interrupted a L1 ISR, disable preemption
;
; This is to avoid a potential L1-L2-L1 scenario
; -L1 IRQ taken
; -L2 interrupts L1 (before L1 ISR could run)
; -preemption off IRQ, user task in syscall picked to run
; -RTIE to userspace
; Returns from L2 context fine
; But both L1 and L2 re-enabled, so another L1 can be taken
; while prev L1 is still unserviced
;
;------------------------------------------------------
;------------------------------------------------------
; L2 interrupting L1 implies both L2 and L1 active
; However both A2 and A1 are NOT set in STATUS32, thus
; need to check STATUS32_L2 to determine if L1 was active
ld
r9
,
[
sp
,
PT_status32
]
; get statu32_l2 (saved in pt_regs)
ld
r9
,
[
sp
,
PT_status32
]
; get statu32_l2 (saved in pt_regs)
bbit0
r9
,
STATUS_A1_BIT
,
1
f
; L1 not active when L2 IRQ, so normal
bbit0
r9
,
STATUS_A1_BIT
,
1
f
; L1 not active when L2 IRQ, so normal
; A1 is set in status32_l2
; bump thread_info->preempt_count (Disable preemption)
; bump thread_info->preempt_count (Disable preemption)
GET_CURR_THR_INFO_FROM_SP
r10
GET_CURR_THR_INFO_FROM_SP
r10
ld
r9
,
[
r10
,
THREAD_INFO_PREEMPT_COUNT
]
ld
r9
,
[
r10
,
THREAD_INFO_PREEMPT_COUNT
]
...
...
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