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authorDavid Daney <ddaney@caviumnetworks.com>2009-07-08 10:07:50 -0700
committerRalf Baechle <ralf@linux-mips.org>2009-08-03 17:52:41 +0100
commit484889fc85a223ef56edc31828b86751b2296b7c (patch)
treef511d75b729c331260bc544a0f03b7d5bea26d9a /arch/mips/include
parent1de010a2702eb21d90883b83bf8c737d5e69d234 (diff)
downloadop-kernel-dev-484889fc85a223ef56edc31828b86751b2296b7c.zip
op-kernel-dev-484889fc85a223ef56edc31828b86751b2296b7c.tar.gz
MIPS: Avoid clobbering struct pt_regs in kthreads
The resume() implementation octeon_switch.S examines the saved cp0_status register. We were clobbering the entire pt_regs structure in kernel threads leading to random crashes. When switching away from a kernel thread, the saved cp0_status is examined and if bit 30 is set it is cleared and the CP2 state saved into the pt_regs structure. Since the kernel thread stack overlaid the pt_regs structure this resulted in a corrupt stack. When the kthread with the corrupt stack was resumed, it could crash if it used any of the data in the stack that was clobbered. We fix it by moving the kernel thread stack down so it doesn't overlay pt_regs. Signed-off-by: David Daney <ddaney@caviumnetworks.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include')
-rw-r--r--arch/mips/include/asm/processor.h5
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index 0f926aa..087a888 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -311,8 +311,9 @@ extern void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long
unsigned long get_wchan(struct task_struct *p);
-#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + THREAD_SIZE - 32)
-#define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk) - 1)
+#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
+ THREAD_SIZE - 32 - sizeof(struct pt_regs))
+#define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk))
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->cp0_epc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[29])
#define KSTK_STATUS(tsk) (task_pt_regs(tsk)->cp0_status)
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