From: Max Filippov <jcmvbkbc@gmail.com>
To: linux-xtensa@linux-xtensa.org
Cc: Chris Zankel <chris@zankel.net>,
linux-kernel@vger.kernel.org, Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH 3/5] xtensa: use abi_* register names in the kernel exit code
Date: Mon, 18 Apr 2022 10:12:03 -0700 [thread overview]
Message-ID: <20220418171205.2413168-4-jcmvbkbc@gmail.com> (raw)
In-Reply-To: <20220418171205.2413168-1-jcmvbkbc@gmail.com>
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@gmail.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
next prev parent reply other threads:[~2022-04-18 17:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-18 17:12 [PATCH 0/5] xtensa: enable context tracking and VIRT_CPU_ACCOUNTING_GEN Max Filippov
2022-04-18 17:12 ` [PATCH 1/5] xtensa: drop dead code from entry.S Max Filippov
2022-04-18 17:12 ` [PATCH 2/5] xtensa: move trace_hardirqs_off call back to entry.S Max Filippov
2022-04-18 17:12 ` Max Filippov [this message]
2022-04-18 17:12 ` [PATCH 4/5] xtensa: enable context tracking Max Filippov
2022-04-18 17:12 ` [PATCH 5/5] xtensa: enable HAVE_VIRT_CPU_ACCOUNTING_GEN Max Filippov
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