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[MIPS] lockdep: Deal with interrupt disable hazard in TRACE_IRQFLAGS

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Between the mtc0 or di instruction that disables interrupts and the
following hazard barrier a processor may still take interrupts.  If an
interrupt is taken after interrupts are disabled but before the state
is updated it will appear to restore_all that it is incorrectly returning
with interrupts disabled.

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Chris Dearman 2007-03-26 14:48:50 +01:00 committed by Ralf Baechle
parent cbde5ebc97
commit fe99f1b184
1 changed files with 31 additions and 0 deletions
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31
arch/mips/kernel/genex.S
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@ -128,6 +128,37 @@ handle_vcei:
.align 5
NESTED(handle_int, PT_SIZE, sp)
#ifdef CONFIG_TRACE_IRQFLAGS
/*
* Check to see if the interrupted code has just disabled
* interrupts and ignore this interrupt for now if so.
*
* local_irq_disable() disables interrupts and then calls
* trace_hardirqs_off() to track the state. If an interrupt is taken
* after interrupts are disabled but before the state is updated
* it will appear to restore_all that it is incorrectly returning with
* interrupts disabled
*/
.set push
.set noat
mfc0 k0, CP0_STATUS
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
and k0, ST0_IEP
bnez k0, 1f
mfc0 k0, EP0_EPC
.set noreorder
j k0
rfe
#else
and k0, ST0_IE
bnez k0, 1f
eret
#endif
1:
.set pop
#endif
SAVE_ALL
CLI
TRACE_IRQS_OFF