From: Ming Lei <tom.leim...@gmail.com>
This patch introduces macro of trace_ret_hardirqs_on, which will
call asm_trace_hardirqs_on if I flag in the stored CPSR is zero.
The patch adds trace_ret_hardirqs_on before returning to user
or exception mode once disable_irq was called explicitly, which does
fix the inbalance of hardirqs trace and make lockdep happy. The patch
does fix this kind of lockdep warning below:
PU: Testing write buffer coherency: ok
------------[ cut here ]------------
WARNING: at kernel/lockdep.c:3145 check_flags+0xcc/0x1dc()
Modules linked in:
[<c0035120>] (unwind_backtrace+0x0/0xf8) from [<c0355374>]
(dump_stack+0x20/0x24)
[<c0355374>] (dump_stack+0x20/0x24) from [<c0060c04>]
(warn_slowpath_common+0x58/0x70)
[<c0060c04>] (warn_slowpath_common+0x58/0x70) from [<c0060c3c>]
(warn_slowpath_null+0x20/0x24)
[<c0060c3c>] (warn_slowpath_null+0x20/0x24) from [<c008f224>]
(check_flags+0xcc/0x1dc)
[<c008f224>] (check_flags+0xcc/0x1dc) from [<c00945dc>]
(lock_acquire+0x50/0x140)
[<c00945dc>] (lock_acquire+0x50/0x140) from [<c0358434>]
(_raw_spin_lock+0x50/0x88)
[<c0358434>] (_raw_spin_lock+0x50/0x88) from [<c00fd114>]
(set_task_comm+0x2c/0x60)
[<c00fd114>] (set_task_comm+0x2c/0x60) from [<c007e184>]
(kthreadd+0x30/0x108)
[<c007e184>] (kthreadd+0x30/0x108) from [<c0030104>]
(kernel_thread_exit+0x0/0x8)
---[ end trace 1b75b31a2719ed1c ]---
possible reason: unannotated irqs-on.
irq event stamp: 3
hardirqs last enabled at (2): [<c0059bb0>] finish_task_switch+0x48/0xb0
hardirqs last disabled at (3): [<c002f0b0>] ret_slow_syscall+0xc/0x1c
softirqs last enabled at (0): [<c005f3e0>] copy_process+0x394/0xe5c
softirqs last disabled at (0): [<(null)>] (null)
devtmpfs: initialized
The patch refers to implementation on x86, suggested by Peter.
Signed-off-by: Ming Lei <tom.leim...@gmail.com>
---
arch/arm/kernel/entry-armv.S | 14 ++++++++++----
arch/arm/kernel/entry-common.S | 8 ++++++++
arch/arm/kernel/entry-header.S | 9 +++++++++
3 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index e6a0fb0..47abf42 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -210,6 +210,13 @@ __dabt_svc:
@ restore SPSR and restart the instruction
@
ldr r2, [sp, #S_PSR]
+
+ @
+ @trace hardirqs on if hardirq will be enabled before
+ @returning from exception
+ @
+ trace_ret_hardirqs_on r2
+
svc_exit r2 @ return from exception
UNWIND(.fnend )
ENDPROC(__dabt_svc)
@@ -235,10 +242,7 @@ __irq_svc:
blne svc_preempt
#endif
ldr r4, [sp, #S_PSR] @ irqs are already disabled
-#ifdef CONFIG_TRACE_IRQFLAGS
- tst r4, #PSR_I_BIT
- bleq trace_hardirqs_on
-#endif
+ trace_ret_hardirqs_on r4
svc_exit r4 @ return from exception
UNWIND(.fnend )
ENDPROC(__irq_svc)
@@ -297,6 +301,7 @@ __und_svc:
@ restore SPSR and restart the instruction
@
ldr r2, [sp, #S_PSR] @ Get SVC cpsr
+ trace_ret_hardirqs_on r2
svc_exit r2 @ return from exception
UNWIND(.fnend )
ENDPROC(__und_svc)
@@ -333,6 +338,7 @@ __pabt_svc:
@ restore SPSR and restart the instruction
@
ldr r2, [sp, #S_PSR]
+ trace_ret_hardirqs_on r2
svc_exit r2 @ return from exception
UNWIND(.fnend )
ENDPROC(__pabt_svc)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 2c1db77..282576f 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -66,6 +66,14 @@ no_work_pending:
/* perform architecture specific actions before user return */
arch_ret_to_user r1, lr
+ @
+ @trace hardirqs on if hardirq will be enabled before
+ @returning to user
+ @
+#ifdef CONFIG_TRACE_IRQFLAGS
+ ldr r1, [sp, #S_PSR] @ get calling cpsr
+ trace_ret_hardirqs_on r1
+#endif
restore_user_regs fast = 0, offset = 0
ENDPROC(ret_to_user)
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index d93f976..85f4b5b 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -30,6 +30,15 @@
#error "Please fix"
#endif
+ .macro trace_ret_hardirqs_on, rspsr
+#ifdef CONFIG_TRACE_IRQFLAGS
+ tst \rspsr, #PSR_I_BIT
+ bne 1f
+ asm_trace_hardirqs_on
+1:
+#endif
+ .endm
+
.macro zero_fp
#ifdef CONFIG_FRAME_POINTER
mov fp, #0
--
1.6.2.5
--
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