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xtensa: clean up kernel exit assembly code

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Don't use numeric labels for complex branching logic. Mark each branch
with named local label and use them. Rearrange exit back to kernel mode
to avoid conditional label definition.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2022-03-19 05:52:07 -07:00
parent e6d423aaae
commit e7e9614b6b
1 changed files with 25 additions and 25 deletions
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50
arch/xtensa/kernel/entry.S
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@ -491,9 +491,9 @@ common_exception_return:
l32i abi_tmp0, a1, PT_EXCCAUSE
movi abi_tmp1, EXCCAUSE_MAPPED_NMI
l32i abi_saved1, a1, PT_PS
beq abi_tmp0, abi_tmp1, 4f
beq abi_tmp0, abi_tmp1, .Lrestore_state
#endif
1:
.Ltif_loop:
irq_save a2, a3
#ifdef CONFIG_TRACE_IRQFLAGS
abi_call trace_hardirqs_off
@ -504,7 +504,7 @@ common_exception_return:
l32i abi_saved1, a1, PT_PS
GET_THREAD_INFO(a2, a1)
l32i a4, a2, TI_FLAGS
_bbci.l abi_saved1, PS_UM_BIT, 6f
_bbci.l abi_saved1, PS_UM_BIT, .Lexit_tif_loop_kernel
/* Specific to a user exception exit:
* We need to check some flags for signal handling and rescheduling,
@ -513,12 +513,12 @@ common_exception_return:
* Note that we don't disable interrupts here.
*/
_bbsi.l a4, TIF_NEED_RESCHED, 3f
_bbsi.l a4, TIF_NEED_RESCHED, .Lresched
movi a2, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL
bnone a4, a2, 5f
bnone a4, a2, .Lexit_tif_loop_user
2: l32i a4, a1, PT_DEPC
bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
l32i a4, a1, PT_DEPC
bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lrestore_state
/* Call do_signal() */
@ -528,42 +528,41 @@ common_exception_return:
rsil a2, 0
mov abi_arg0, a1
abi_call do_notify_resume # int do_notify_resume(struct pt_regs*)
j 1b
3: /* Reschedule */
j .Ltif_loop
.Lresched:
#ifdef CONFIG_TRACE_IRQFLAGS
abi_call trace_hardirqs_on
#endif
rsil a2, 0
abi_call schedule # void schedule (void)
j 1b
j .Ltif_loop
.Lexit_tif_loop_kernel:
#ifdef CONFIG_PREEMPTION
6:
_bbci.l a4, TIF_NEED_RESCHED, 4f
_bbci.l a4, TIF_NEED_RESCHED, .Lrestore_state
/* Check current_thread_info->preempt_count */
l32i a4, a2, TI_PRE_COUNT
bnez a4, 4f
bnez a4, .Lrestore_state
abi_call preempt_schedule_irq
j 4f
#endif
j .Lrestore_state
5:
.Lexit_tif_loop_user:
#ifdef CONFIG_HAVE_HW_BREAKPOINT
_bbci.l a4, TIF_DB_DISABLED, 7f
_bbci.l a4, TIF_DB_DISABLED, 1f
abi_call restore_dbreak
7:
1:
#endif
#ifdef CONFIG_DEBUG_TLB_SANITY
l32i a4, a1, PT_DEPC
bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lrestore_state
abi_call check_tlb_sanity
#endif
6:
4:
.Lrestore_state:
#ifdef CONFIG_TRACE_IRQFLAGS
extui a4, abi_saved1, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
bgei a4, LOCKLEVEL, 1f
@ -601,7 +600,7 @@ user_exception_exit:
rsr a1, depc # restore stack pointer
l32i a2, a1, PT_WMASK # register frames saved (in bits 4...9)
rotw -1 # we restore a4..a7
_bltui a6, 16, 1f # only have to restore current window?
_bltui a6, 16, .Lclear_regs # only have to restore current window?
/* The working registers are a0 and a3. We are restoring to
* a4..a7. Be careful not to destroy what we have just restored.
@ -613,18 +612,19 @@ user_exception_exit:
mov a2, a6
mov a3, a5
2: rotw -1 # a0..a3 become a4..a7
1: rotw -1 # a0..a3 become a4..a7
addi a3, a7, -4*4 # next iteration
addi a2, a6, -16 # decrementing Y in WMASK
l32i a4, a3, PT_AREG_END + 0
l32i a5, a3, PT_AREG_END + 4
l32i a6, a3, PT_AREG_END + 8
l32i a7, a3, PT_AREG_END + 12
_bgeui a2, 16, 2b
_bgeui a2, 16, 1b
/* Clear unrestored registers (don't leak anything to user-land */
1: rsr a0, windowbase
.Lclear_regs:
rsr a0, windowbase
rsr a3, sar
sub a3, a0, a3
beqz a3, 2f