csky: Fixup CONFIG_PREEMPT panic

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>

diff --git a/arch/csky/abiv1/inc/abi/entry.h b/arch/csky/abiv1/inc/abi/entry.h
index 61d94ec..b3559db 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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
 
 /*