For non-mipsr2 processors, the local_irq_disable contains an mfc0-mtc0 pair with instructions inbetween. With preemption enabled, this sequence may get preempted and effect a stale value of CP0_STATUS when executing the mtc0 instruction. This commit avoids this scenario by incrementing the preempt count before the mfc0 and decrementing it after the mtc9. Signed-off-by: Jim Quinlan <jim2101024@xxxxxxxxx> --- arch/mips/include/asm/asmmacro.h | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/arch/mips/include/asm/asmmacro.h b/arch/mips/include/asm/asmmacro.h index 6c8342a..3f809a4 100644 --- a/arch/mips/include/asm/asmmacro.h +++ b/arch/mips/include/asm/asmmacro.h @@ -9,6 +9,7 @@ #define _ASM_ASMMACRO_H #include <asm/hazards.h> +//#include <asm/asm-offsets.h> #ifdef CONFIG_32BIT #include <asm/asmmacro-32.h> @@ -54,11 +55,21 @@ .endm .macro local_irq_disable reg=t0 +#ifdef CONFIG_PREEMPT + lw \reg, TI_PRE_COUNT($28) + addi \reg, \reg, 1 + sw \reg, TI_PRE_COUNT($28) +#endif mfc0 \reg, CP0_STATUS ori \reg, \reg, 1 xori \reg, \reg, 1 mtc0 \reg, CP0_STATUS irq_disable_hazard +#ifdef CONFIG_PREEMPT + lw \reg, TI_PRE_COUNT($28) + addi \reg, \reg, -1 + sw \reg, TI_PRE_COUNT($28) +#endif .endm #endif /* CONFIG_MIPS_MT_SMTC */ -- 1.7.6
