diff options
| author | Jim Quinlan <jim2101024@gmail.com> | 2013-11-27 15:34:50 -0500 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2014-03-20 13:46:15 +0100 |
| commit | 71ca75888953166b72cf7a65b4c2b6a50fc0ce3b (patch) | |
| tree | 3b74c1898d1c6772c7c23c9eab21d3b6a99c39c9 /arch/mips | |
| parent | 2eddb708d83ead02b5d41c65bfb26bab5afc8210 (diff) | |
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 <asm/asm-offsets.h> at the top
of <asm/asmmacro.h>].
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: cernekee@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/6164/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips')
| -rw-r--r-- | 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 69a9a22d014a..4225e99bd7bf 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 */ |