sh: Fix occasional FPU register corruption under preempt.
Presently with preempt enabled there's the possibility to be preempted
after the TIF_USEDFPU test and the register save, leading to bogus
state post-__switch_to(). Use an explicit preempt_disable()/enable()
pair around unlazy_fpu()/clear_fpu() to avoid this. Follows the x86
change.
Reported-by: Takuo Koguchi <takuo.koguchi.sw@hitachi.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/include/asm-sh/fpu.h b/include/asm-sh/fpu.h
index f842988..f89abf5 100644
--- a/include/asm-sh/fpu.h
+++ b/include/asm-sh/fpu.h
@@ -1,9 +1,8 @@
#ifndef __ASM_SH_FPU_H
#define __ASM_SH_FPU_H
-#define SR_FD 0x00008000
-
#ifndef __ASSEMBLY__
+#include <linux/preempt.h>
#include <asm/ptrace.h>
#ifdef CONFIG_SH_FPU
@@ -28,18 +27,23 @@
extern int do_fpu_inst(unsigned short, struct pt_regs *);
-#define unlazy_fpu(tsk, regs) do { \
- if (test_tsk_thread_flag(tsk, TIF_USEDFPU)) { \
- save_fpu(tsk, regs); \
- } \
-} while (0)
+static inline void unlazy_fpu(struct task_struct *tsk, struct pt_regs *regs)
+{
+ preempt_disable();
+ if (test_tsk_thread_flag(tsk, TIF_USEDFPU))
+ save_fpu(tsk, regs);
+ preempt_enable();
+}
-#define clear_fpu(tsk, regs) do { \
- if (test_tsk_thread_flag(tsk, TIF_USEDFPU)) { \
- clear_tsk_thread_flag(tsk, TIF_USEDFPU); \
- release_fpu(regs); \
- } \
-} while (0)
+static inline void clear_fpu(struct task_struct *tsk, struct pt_regs *regs)
+{
+ preempt_disable();
+ if (test_tsk_thread_flag(tsk, TIF_USEDFPU)) {
+ clear_tsk_thread_flag(tsk, TIF_USEDFPU);
+ release_fpu(regs);
+ }
+ preempt_enable();
+}
#endif /* __ASSEMBLY__ */