[PATCH 1/3] csky: Fixup CONFIG_PREEMPT panic

[PATCH 1/3] csky: Fixup CONFIG_PREEMPT panic

[guoren]

From: Guo Ren <guoren@linux.alibaba.com>

log:
[    0.13373200] Calibrating delay loop...
[    0.14077600] ------------[ cut here ]------------
[    0.14116700] WARNING: CPU: 0 PID: 0 at kernel/sched/core.c:3790 preempt_count_add+0xc8/0x11c
[    0.14348000] DEBUG_LOCKS_WARN_ON((preempt_count() < 0))Modules linked in:
[    0.14395100] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0 #7
[    0.14410800]
[    0.14427400] Call Trace:
[    0.14450700] [<807cd226>] dump_stack+0x8a/0xe4
[    0.14473500] [<80072792>] __warn+0x10e/0x15c
[    0.14495900] [<80072852>] warn_slowpath_fmt+0x72/0xc0
[    0.14518600] [<800a5240>] preempt_count_add+0xc8/0x11c
[    0.14544900] [<807ef918>] _raw_spin_lock+0x28/0x68
[    0.14572600] [<800e0eb8>] vprintk_emit+0x84/0x2d8
[    0.14599000] [<800e113a>] vprintk_default+0x2e/0x44
[    0.14625100] [<800e2042>] vprintk_func+0x12a/0x1d0
[    0.14651300] [<800e1804>] printk+0x30/0x48
[    0.14677600] [<80008052>] lockdep_init+0x12/0xb0
[    0.14703800] [<80002080>] start_kernel+0x558/0x7f8
[    0.14730000] [<800052bc>] csky_start+0x58/0x94
[    0.14756600] irq event stamp: 34
[    0.14775100] hardirqs last  enabled at (33): [<80067370>] ret_from_exception+0x2c/0x72
[    0.14793700] hardirqs last disabled at (34): [<800e0eae>] vprintk_emit+0x7a/0x2d8
[    0.14812300] softirqs last  enabled at (32): [<800655b0>] __do_softirq+0x578/0x6d8
[    0.14830800] softirqs last disabled at (25): [<8007b3b8>] irq_exit+0xec/0x128

The preempt_count of reg could be destroyed after csky_do_IRQ without reload
from memory.

After reference to other architectures (arm64, riscv), we move preempt entry
into ret_from_exception and disable irq at the beginning of
ret_from_exception instead of RESTORE_ALL.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reported-by: Lu Baoquan <lu.baoquan@intellif.com>
---
 arch/csky/abiv1/inc/abi/entry.h |  1 -
 arch/csky/abiv2/inc/abi/entry.h |  1 -
 arch/csky/kernel/entry.S        | 36 +++++++++++-------------------------
 3 files changed, 11 insertions(+), 27 deletions(-)

diff --git a/arch/csky/abiv1/inc/abi/entry.h b/arch/csky/abiv1/inc/abi/entry.h
index 61d94ec..b3559db 100644
--- a/arch/csky/abiv1/inc/abi/entry.h
+++ b/arch/csky/abiv1/inc/abi/entry.h
@@ -80,7 +80,6 @@
 .endm
 
 .macro	RESTORE_ALL
-	psrclr  ie
 	ldw	lr, (sp, 4)
 	ldw     a0, (sp, 8)
 	mtcr    a0, epc
diff --git a/arch/csky/abiv2/inc/abi/entry.h b/arch/csky/abiv2/inc/abi/entry.h
index ab63c41..698df2f 100644
--- a/arch/csky/abiv2/inc/abi/entry.h
+++ b/arch/csky/abiv2/inc/abi/entry.h
@@ -63,7 +63,6 @@
 .endm
 
 .macro	RESTORE_ALL
-	psrclr  ie
 	ldw	tls, (sp, 0)
 	ldw	lr, (sp, 4)
 	ldw	a0, (sp, 8)
diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S
index 3760397..bfbef30 100644
--- a/arch/csky/kernel/entry.S
+++ b/arch/csky/kernel/entry.S
@@ -208,9 +208,9 @@ ENTRY(ret_from_fork)
 	jbsr	syscall_trace_exit
 
 ret_from_exception:
+	psrclr	ie
 	ld	syscallid, (sp, LSAVE_PSR)
 	btsti	syscallid, 31
-	bt	1f
 
 	/*
 	 * Load address of current->thread_info, Then get address of task_struct
@@ -220,11 +220,20 @@ ret_from_exception:
 	bmaski	r10, THREAD_SHIFT
 	andn	r9, r10
 
+	bt	1f
 	ldw	r12, (r9, TINFO_FLAGS)
 	andi	r12, (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | _TIF_UPROBE)
 	cmpnei	r12, 0
 	bt	exit_work
 1:
+#ifdef CONFIG_PREEMPTION
+	ldw	r12, (r9, TINFO_PREEMPT)
+	cmpnei	r12, 0
+	bt	2f
+	jbsr	preempt_schedule_irq	/* irq en/disable is done inside */
+2:
+#endif
+
 #ifdef CONFIG_TRACE_IRQFLAGS
 	ld	r10, (sp, LSAVE_PSR)
 	btsti	r10, 6
@@ -241,6 +250,7 @@ exit_work:
 	btsti	r12, TIF_NEED_RESCHED
 	bt	work_resched
 
+	psrset	ie
 	mov	a0, sp
 	mov	a1, r12
 	jmpi	do_notify_resume
@@ -291,34 +301,10 @@ ENTRY(csky_irq)
 	jbsr	trace_hardirqs_off
 #endif
 
-#ifdef CONFIG_PREEMPTION
-	mov	r9, sp			/* Get current stack  pointer */
-	bmaski	r10, THREAD_SHIFT
-	andn	r9, r10			/* Get thread_info */
-
-	/*
-	 * Get task_struct->stack.preempt_count for current,
-	 * and increase 1.
-	 */
-	ldw	r12, (r9, TINFO_PREEMPT)
-	addi	r12, 1
-	stw	r12, (r9, TINFO_PREEMPT)
-#endif
 
 	mov	a0, sp
 	jbsr	csky_do_IRQ
 
-#ifdef CONFIG_PREEMPTION
-	subi	r12, 1
-	stw	r12, (r9, TINFO_PREEMPT)
-	cmpnei	r12, 0
-	bt	2f
-	ldw	r12, (r9, TINFO_FLAGS)
-	btsti	r12, TIF_NEED_RESCHED
-	bf	2f
-	jbsr	preempt_schedule_irq	/* irq en/disable is done inside */
-#endif
-2:
 	jmpi	ret_from_exception
 
 /*
-- 
2.7.4

[PATCH 2/3] csky: Fixup abiv2 syscall_trace break a4 & a5

[guoren]

From: Guo Ren <guoren@linux.alibaba.com>

Current implementation could destory a4 & a5 when strace, so we need to get them
from pt_regs by SAVE_ALL.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
 arch/csky/abiv2/inc/abi/entry.h | 2 ++
 arch/csky/kernel/entry.S        | 6 ++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/csky/abiv2/inc/abi/entry.h b/arch/csky/abiv2/inc/abi/entry.h
index 698df2f..6ee71bf 100644
--- a/arch/csky/abiv2/inc/abi/entry.h
+++ b/arch/csky/abiv2/inc/abi/entry.h
@@ -13,6 +13,8 @@
 #define LSAVE_A1	28
 #define LSAVE_A2	32
 #define LSAVE_A3	36
+#define LSAVE_A4	40
+#define LSAVE_A5	44
 
 #define KSPTOUSP
 #define USPTOKSP
diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S
index bfbef30..76dc729 100644
--- a/arch/csky/kernel/entry.S
+++ b/arch/csky/kernel/entry.S
@@ -173,8 +173,10 @@ csky_syscall_trace:
 	ldw	a3, (sp, LSAVE_A3)
 #if defined(__CSKYABIV2__)
 	subi	sp, 8
-	stw	r5, (sp, 0x4)
-	stw	r4, (sp, 0x0)
+	ldw	r9, (sp, LSAVE_A4)
+	stw	r9, (sp, 0x0)
+	ldw	r9, (sp, LSAVE_A5)
+	stw	r9, (sp, 0x4)
 #else
 	ldw	r6, (sp, LSAVE_A4)
 	ldw	r7, (sp, LSAVE_A5)
-- 
2.7.4

[PATCH 3/3] csky: Coding convention in entry.S

[guoren]

From: Guo Ren <guoren@linux.alibaba.com>

There is no fixup or feature in the patch, we only cleanup with:

 - Remove unnecessary reg used (r11, r12), just use r9 & r10 &
   syscallid regs as temp useage.
 - Add _TIF_SYSCALL_WORK and _TIF_WORK_MASK to gather macros.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
 arch/csky/abiv1/inc/abi/entry.h     |  5 ---
 arch/csky/abiv2/inc/abi/entry.h     |  5 ---
 arch/csky/include/asm/thread_info.h |  6 ++++
 arch/csky/kernel/entry.S            | 66 ++++++++++++++++++++-----------------
 4 files changed, 42 insertions(+), 40 deletions(-)

diff --git a/arch/csky/abiv1/inc/abi/entry.h b/arch/csky/abiv1/inc/abi/entry.h
index b3559db..13c23e2 100644
--- a/arch/csky/abiv1/inc/abi/entry.h
+++ b/arch/csky/abiv1/inc/abi/entry.h
@@ -174,9 +174,4 @@
 	movi	r6, 0
 	cpwcr	r6, cpcr31
 .endm
-
-.macro ANDI_R3 rx, imm
-	lsri	\rx, 3
-	andi	\rx, (\imm >> 3)
-.endm
 #endif /* __ASM_CSKY_ENTRY_H */
diff --git a/arch/csky/abiv2/inc/abi/entry.h b/arch/csky/abiv2/inc/abi/entry.h
index 6ee71bf..4fdd6c1 100644
--- a/arch/csky/abiv2/inc/abi/entry.h
+++ b/arch/csky/abiv2/inc/abi/entry.h
@@ -302,9 +302,4 @@
 	jmpi	3f /* jump to va */
 3:
 .endm
-
-.macro ANDI_R3 rx, imm
-	lsri	\rx, 3
-	andi	\rx, (\imm >> 3)
-.endm
 #endif /* __ASM_CSKY_ENTRY_H */
diff --git a/arch/csky/include/asm/thread_info.h b/arch/csky/include/asm/thread_info.h
index 5c61e84..8980e4e 100644
--- a/arch/csky/include/asm/thread_info.h
+++ b/arch/csky/include/asm/thread_info.h
@@ -81,4 +81,10 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 
+#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
+				 _TIF_NOTIFY_RESUME | _TIF_UPROBE)
+
+#define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
+				 _TIF_SYSCALL_TRACEPOINT)
+
 #endif	/* _ASM_CSKY_THREAD_INFO_H */
diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S
index 76dc729..9595e86 100644
--- a/arch/csky/kernel/entry.S
+++ b/arch/csky/kernel/entry.S
@@ -134,31 +134,32 @@ ENTRY(csky_systemcall)
 #endif
 	psrset  ee, ie
 
-	lrw     r11, __NR_syscalls
-	cmphs   syscallid, r11		/* Check nr of syscall */
+	lrw     r9, __NR_syscalls
+	cmphs   syscallid, r9		/* Check nr of syscall */
 	bt      ret_from_exception
 
-	lrw     r13, sys_call_table
-	ixw     r13, syscallid
-	ldw     r11, (r13)
-	cmpnei  r11, 0
+	lrw     r9, sys_call_table
+	ixw     r9, syscallid
+	ldw     syscallid, (r9)
+	cmpnei  syscallid, 0
 	bf      ret_from_exception
 
 	mov     r9, sp
 	bmaski  r10, THREAD_SHIFT
 	andn    r9, r10
-	ldw     r12, (r9, TINFO_FLAGS)
-	ANDI_R3	r12, (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_AUDIT)
-	cmpnei	r12, 0
+	ldw     r10, (r9, TINFO_FLAGS)
+	lrw	r9, _TIF_SYSCALL_WORK
+	and	r10, r9
+	cmpnei	r10, 0
 	bt      csky_syscall_trace
 #if defined(__CSKYABIV2__)
 	subi    sp, 8
 	stw  	r5, (sp, 0x4)
 	stw  	r4, (sp, 0x0)
-	jsr     r11                      /* Do system call */
+	jsr     syscallid                      /* Do system call */
 	addi 	sp, 8
 #else
-	jsr     r11
+	jsr     syscallid
 #endif
 	stw     a0, (sp, LSAVE_A0)      /* Save return value */
 	jmpi    ret_from_exception
@@ -177,13 +178,12 @@ csky_syscall_trace:
 	stw	r9, (sp, 0x0)
 	ldw	r9, (sp, LSAVE_A5)
 	stw	r9, (sp, 0x4)
+	jsr	syscallid                     /* Do system call */
+	addi	sp, 8
 #else
 	ldw	r6, (sp, LSAVE_A4)
 	ldw	r7, (sp, LSAVE_A5)
-#endif
-	jsr	r11                     /* Do system call */
-#if defined(__CSKYABIV2__)
-	addi	sp, 8
+	jsr	syscallid                     /* Do system call */
 #endif
 	stw	a0, (sp, LSAVE_A0)	/* Save return value */
 
@@ -202,18 +202,20 @@ ENTRY(ret_from_fork)
 	mov	r9, sp
 	bmaski	r10, THREAD_SHIFT
 	andn	r9, r10
-	ldw	r12, (r9, TINFO_FLAGS)
-	ANDI_R3	r12, (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_AUDIT)
-	cmpnei	r12, 0
+	ldw	r10, (r9, TINFO_FLAGS)
+	lrw	r9, _TIF_SYSCALL_WORK
+	and	r10, r9
+	cmpnei	r10, 0
 	bf	ret_from_exception
 	mov	a0, sp			/* sp = pt_regs pointer */
 	jbsr	syscall_trace_exit
 
 ret_from_exception:
 	psrclr	ie
-	ld	syscallid, (sp, LSAVE_PSR)
-	btsti	syscallid, 31
+	ld	r9, (sp, LSAVE_PSR)
+	btsti	r9, 31
 
+	bt	1f
 	/*
 	 * Load address of current->thread_info, Then get address of task_struct
 	 * Get task_needreshed in task_struct
@@ -222,15 +224,19 @@ ret_from_exception:
 	bmaski	r10, THREAD_SHIFT
 	andn	r9, r10
 
-	bt	1f
-	ldw	r12, (r9, TINFO_FLAGS)
-	andi	r12, (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | _TIF_UPROBE)
-	cmpnei	r12, 0
+	ldw	r10, (r9, TINFO_FLAGS)
+	lrw	r9, _TIF_WORK_MASK
+	and	r10, r9
+	cmpnei	r10, 0
 	bt	exit_work
 1:
 #ifdef CONFIG_PREEMPTION
-	ldw	r12, (r9, TINFO_PREEMPT)
-	cmpnei	r12, 0
+	mov	r9, sp
+	bmaski	r10, THREAD_SHIFT
+	andn	r9, r10
+
+	ldw	r10, (r9, TINFO_PREEMPT)
+	cmpnei	r10, 0
 	bt	2f
 	jbsr	preempt_schedule_irq	/* irq en/disable is done inside */
 2:
@@ -246,15 +252,15 @@ ret_from_exception:
 	RESTORE_ALL
 
 exit_work:
-	lrw	syscallid, ret_from_exception
-	mov	lr, syscallid
+	lrw	r9, ret_from_exception
+	mov	lr, r9
 
-	btsti	r12, TIF_NEED_RESCHED
+	btsti	r10, TIF_NEED_RESCHED
 	bt	work_resched
 
 	psrset	ie
 	mov	a0, sp
-	mov	a1, r12
+	mov	a1, r10
 	jmpi	do_notify_resume
 
 work_resched:
-- 
2.7.4