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sh: Fix occasional FPU register corruption under preempt.

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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>
This commit is contained in:
Paul Mundt 2008-03-26 19:02:47 +09:00
parent 05dda977f2
commit 9bbafce2ee
10 changed files with 25 additions and 14 deletions
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1
arch/sh/kernel/cpu/sh2a/fpu.c
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@ -13,6 +13,7 @@
#include <linux/signal.h>
#include <asm/processor.h>
#include <asm/io.h>
#include <asm/fpu.h>
/* The PR (precision) bit in the FP Status Register must be clear when
* an frchg instruction is executed, otherwise the instruction is undefined.

1
arch/sh/kernel/cpu/sh4/fpu.c
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@ -16,6 +16,7 @@
#include <asm/cpu/fpu.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/fpu.h>
/* The PR (precision) bit in the FP Status Register must be clear when
* an frchg instruction is executed, otherwise the instruction is undefined.

1
arch/sh/kernel/cpu/sh5/fpu.c
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@ -17,6 +17,7 @@
#include <asm/processor.h>
#include <asm/user.h>
#include <asm/io.h>
#include <asm/fpu.h>
/*
* Initially load the FPU with signalling NANS. This bit pattern

1
arch/sh/kernel/dump_task.c
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@ -1,5 +1,6 @@
#include <linux/elfcore.h>
#include <linux/sched.h>
#include <asm/fpu.h>
/*
* Capture the user space registers if the task is not running (in user space)

1
arch/sh/kernel/process_32.c
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@ -25,6 +25,7 @@
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/ubc.h>
#include <asm/fpu.h>
static int hlt_counter;
int ubc_usercnt = 0;

1
arch/sh/kernel/signal_32.c
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@ -29,6 +29,7 @@
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/fpu.h>
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

30
include/asm-sh/fpu.h
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@ -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 void save_fpu(struct task_struct *__tsk, struct pt_regs *regs);
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__ */

1
include/asm-sh/processor.h
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@ -2,7 +2,6 @@
#define __ASM_SH_PROCESSOR_H
#include <asm/cpu-features.h>
#include <asm/fpu.h>
#ifndef __ASSEMBLY__
/*

1
include/asm-sh/processor_32.h
View File

@ -70,6 +70,7 @@ extern struct sh_cpuinfo cpu_data[];
*/
#define SR_DSP 0x00001000
#define SR_IMASK 0x000000f0
#define SR_FD 0x00008000
/*
* FPU structure and data

1
include/asm-sh/processor_64.h
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@ -112,6 +112,7 @@ extern struct sh_cpuinfo cpu_data[];
#endif
#define SR_IMASK 0x000000f0
#define SR_FD 0x00008000
#define SR_SSTEP 0x08000000
#ifndef __ASSEMBLY__