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Date: Mon, 18 Apr 2022 10:12:03 -0700
From: Max Filippov <jcmvbkbc@...il.com>
To: linux-xtensa@...ux-xtensa.org
Cc: Chris Zankel <chris@...kel.net>, linux-kernel@...r.kernel.org,
Max Filippov <jcmvbkbc@...il.com>
Subject: [PATCH 3/5] xtensa: use abi_* register names in the kernel exit code
Using plain register names is prone to errors when code is changed and
new calls are added between the register load and use. Change plain
register names to abi_* names in the call-heavy part of the kernel exit
code to clearly indicate what's supposed to be preserved and what's not.
Re-align code while at it.
Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
---
arch/xtensa/kernel/entry.S | 82 +++++++++++++++++++-------------------
1 file changed, 42 insertions(+), 40 deletions(-)
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index c85597a734aa..d09f2c38ba84 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -462,11 +462,11 @@ KABI_W or a3, a3, a2
* exception handler and call the exception handler.
*/
- l32i abi_arg1, a1, PT_EXCCAUSE # pass EXCCAUSE
- rsr abi_tmp0, excsave1
- addx4 abi_tmp0, abi_arg1, abi_tmp0
- l32i abi_tmp0, abi_tmp0, EXC_TABLE_DEFAULT # load handler
- mov abi_arg0, a1 # pass stack frame
+ l32i abi_arg1, a1, PT_EXCCAUSE # pass EXCCAUSE
+ rsr abi_tmp0, excsave1
+ addx4 abi_tmp0, abi_arg1, abi_tmp0
+ l32i abi_tmp0, abi_tmp0, EXC_TABLE_DEFAULT # load handler
+ mov abi_arg0, a1 # pass stack frame
/* Call the second-level handler */
@@ -477,23 +477,23 @@ KABI_W or a3, a3, a2
common_exception_return:
#if XTENSA_FAKE_NMI
- l32i abi_tmp0, a1, PT_EXCCAUSE
- movi abi_tmp1, EXCCAUSE_MAPPED_NMI
- l32i abi_saved1, a1, PT_PS
- beq abi_tmp0, abi_tmp1, .Lrestore_state
+ l32i abi_tmp0, a1, PT_EXCCAUSE
+ movi abi_tmp1, EXCCAUSE_MAPPED_NMI
+ l32i abi_saved1, a1, PT_PS
+ beq abi_tmp0, abi_tmp1, .Lrestore_state
#endif
.Ltif_loop:
- irq_save a2, a3
+ irq_save abi_tmp0, abi_tmp1
#ifdef CONFIG_TRACE_IRQFLAGS
abi_call trace_hardirqs_off
#endif
/* Jump if we are returning from kernel exceptions. */
- l32i abi_saved1, a1, PT_PS
- GET_THREAD_INFO(a2, a1)
- l32i a4, a2, TI_FLAGS
- _bbci.l abi_saved1, PS_UM_BIT, .Lexit_tif_loop_kernel
+ l32i abi_saved1, a1, PT_PS
+ GET_THREAD_INFO(abi_tmp0, a1)
+ l32i abi_saved0, abi_tmp0, TI_FLAGS
+ _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,
@@ -502,75 +502,77 @@ common_exception_return:
* Note that we don't disable interrupts here.
*/
- _bbsi.l a4, TIF_NEED_RESCHED, .Lresched
- movi a2, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL
- bnone a4, a2, .Lexit_tif_loop_user
+ _bbsi.l abi_saved0, TIF_NEED_RESCHED, .Lresched
+ movi abi_tmp0, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL
+ bnone abi_saved0, abi_tmp0, .Lexit_tif_loop_user
- l32i a4, a1, PT_DEPC
- bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lrestore_state
+ l32i abi_tmp0, a1, PT_DEPC
+ bgeui abi_tmp0, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lrestore_state
/* Call do_signal() */
#ifdef CONFIG_TRACE_IRQFLAGS
abi_call trace_hardirqs_on
#endif
- rsil a2, 0
- mov abi_arg0, a1
+ rsil abi_tmp0, 0
+ mov abi_arg0, a1
abi_call do_notify_resume # int do_notify_resume(struct pt_regs*)
- j .Ltif_loop
+ j .Ltif_loop
.Lresched:
#ifdef CONFIG_TRACE_IRQFLAGS
abi_call trace_hardirqs_on
#endif
- rsil a2, 0
+ rsil abi_tmp0, 0
abi_call schedule # void schedule (void)
- j .Ltif_loop
+ j .Ltif_loop
.Lexit_tif_loop_kernel:
#ifdef CONFIG_PREEMPTION
- _bbci.l a4, TIF_NEED_RESCHED, .Lrestore_state
+ _bbci.l abi_saved0, TIF_NEED_RESCHED, .Lrestore_state
/* Check current_thread_info->preempt_count */
- l32i a4, a2, TI_PRE_COUNT
- bnez a4, .Lrestore_state
+ l32i abi_tmp1, abi_tmp0, TI_PRE_COUNT
+ bnez abi_tmp1, .Lrestore_state
abi_call preempt_schedule_irq
#endif
- j .Lrestore_state
+ j .Lrestore_state
.Lexit_tif_loop_user:
#ifdef CONFIG_HAVE_HW_BREAKPOINT
- _bbci.l a4, TIF_DB_DISABLED, 1f
+ _bbci.l abi_saved0, TIF_DB_DISABLED, 1f
abi_call restore_dbreak
1:
#endif
#ifdef CONFIG_DEBUG_TLB_SANITY
- l32i a4, a1, PT_DEPC
- bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lrestore_state
+ l32i abi_tmp0, a1, PT_DEPC
+ bgeui abi_tmp0, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lrestore_state
abi_call check_tlb_sanity
#endif
.Lrestore_state:
#ifdef CONFIG_TRACE_IRQFLAGS
- extui a4, abi_saved1, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
- bgei a4, LOCKLEVEL, 1f
+ extui abi_tmp0, abi_saved1, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
+ bgei abi_tmp0, LOCKLEVEL, 1f
abi_call trace_hardirqs_on
1:
#endif
- /* Restore optional registers. */
+ /*
+ * Restore optional registers.
+ * abi_arg* are used as temporary registers here.
+ */
- load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
+ load_xtregs_opt a1 abi_tmp0 abi_arg0 abi_arg1 abi_arg2 abi_arg3 PT_XTREGS_OPT
/* Restore SCOMPARE1 */
#if XCHAL_HAVE_S32C1I
- l32i a2, a1, PT_SCOMPARE1
- wsr a2, scompare1
+ l32i abi_tmp0, a1, PT_SCOMPARE1
+ wsr abi_tmp0, scompare1
#endif
- wsr abi_saved1, ps /* disable interrupts */
-
- _bbci.l abi_saved1, PS_UM_BIT, kernel_exception_exit
+ wsr abi_saved1, ps /* disable interrupts */
+ _bbci.l abi_saved1, PS_UM_BIT, kernel_exception_exit
user_exception_exit:
--
2.30.2
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