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arch: arc: fix the bug where firq comes out in user mode

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firq's case is similar to regular irq, it also needs to consider
the case of reg bank switch.

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
This commit is contained in:
Wayne Ren 2020-02-01 19:44:00 +08:00 • committed by Andrew Boie
commit 8450d26b34
1 changed files with 46 additions and 1 deletions
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47
arch/arc/core/fast_irq.S
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@ -207,12 +207,36 @@ _firq_reschedule:
* point, so when switching back to register bank 0, it will contain the
* registers from the interrupted thread.
*/
#if defined(CONFIG_USERSPACE)
/* when USERSPACE is configured, here need to consider the case where firq comes
* out in user mode, according to ARCv2 ISA and nsim, the following micro ops
* will be executed:
* sp<-reg bank1'sp
* switch between sp and _ARC_V2_USER_SP
* then:
* sp is the sp of kernel stack of interrupted thread
* _ARC_V2_USER_SP is reg bank1'sp
* the sp of user stack of interrupted thread is reg bank0'sp
* if firq comes out in kernel mode, the following micro ops will be executed:
* sp<-reg bank'sp
* so, sw needs to do necessary handling to set up the correct sp
*/
lr r0, [_ARC_V2_AUX_IRQ_ACT]
bbit0 r0, 31, _firq_from_kernel
aex sp, [_ARC_V2_USER_SP]
lr r0, [_ARC_V2_STATUS32]
and r0, r0, ~_ARC_V2_STATUS32_RB(7)
kflag r0
aex sp, [_ARC_V2_USER_SP]
b _firq_create_irq_stack_frame
_firq_from_kernel:
#endif
/* chose register bank #0 */
lr r0, [_ARC_V2_STATUS32]
and r0, r0, ~_ARC_V2_STATUS32_RB(7)
kflag r0
_firq_create_irq_stack_frame:
/* we're back on the outgoing thread's stack */
_create_irq_stack_frame
@ -225,6 +249,7 @@ _firq_reschedule:
st_s r0, [sp, ___isf_t_status32_OFFSET]
st ilink, [sp, ___isf_t_pc_OFFSET] /* ilink into pc */
#ifdef CONFIG_SMP
/*
* load r0, r1 from irq stack
@ -235,6 +260,16 @@ _firq_reschedule:
#endif
#endif
#if defined(CONFIG_USERSPACE)
/*
* need to remember the user/kernel status of interrupted thread, will be
* restored when thread switched back
*/
lr r3, [_ARC_V2_AUX_IRQ_ACT]
and r3, r3, 0x80000000
push_s r3
#endif
#ifdef CONFIG_SMP
mov_s r2, r1
#else
@ -300,6 +335,16 @@ _firq_return_from_coop:
_firq_return_from_rirq:
_firq_return_from_firq:
#if defined(CONFIG_USERSPACE)
/*
* need to recover the user/kernel status of interrupted thread
*/
pop_s r3
lr r2, [_ARC_V2_AUX_IRQ_ACT]
or r2, r2, r3
sr r2, [_ARC_V2_AUX_IRQ_ACT]
#endif
_pop_irq_stack_frame
ld ilink, [sp, -4] /* status32 into ilink */