From 71ca75888953166b72cf7a65b4c2b6a50fc0ce3b Mon Sep 17 00:00:00 2001 From: Jim Quinlan Date: Wed, 27 Nov 2013 15:34:50 -0500 Subject: [PATCH] MIPS: Make local_irq_disable macro safe for non-Mipsr2 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. [ralf@linux-mips.org: This patch is sorting out the part that were missed by e97c5b6098 [MIPS: Make irqflags.h functions preempt-safe for non-mipsr2 cpus.] I also re-enabled the inclusion of at the top of ]. Signed-off-by: Jim Quinlan Cc: linux-mips@linux-mips.org Cc: cernekee@gmail.com Patchwork: https://patchwork.linux-mips.org/patch/6164/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/asmmacro.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/mips/include/asm/asmmacro.h b/arch/mips/include/asm/asmmacro.h index 69a9a22..4225e99 100644 --- a/arch/mips/include/asm/asmmacro.h +++ b/arch/mips/include/asm/asmmacro.h @@ -9,6 +9,7 @@ #define _ASM_ASMMACRO_H #include +#include #ifdef CONFIG_32BIT #include @@ -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 */ -- 2.7.4