From: Ming Lei <tom.leiming@xxxxxxxxx> 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.leiming@xxxxxxxxx> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
