forked from Minki/linux
96d0161086
Correct the DSCR SPR becoming temporarily corrupted if a task is context switched during a transaction. The problem occurs while suspending the task and is caused by saving the DSCR to thread.dscr after it has already been set to the CPU's default value: __switch_to() calls __switch_to_tm() which calls tm_reclaim_task() which calls tm_reclaim_thread() which calls tm_reclaim() where the DSCR is set to the CPU's default __switch_to() calls _switch() where thread.dscr is set to the DSCR When the task is resumed, it's transaction will be doomed (as usual) and the DSCR SPR will be corrupted, although the checkpointed value will be correct. Therefore the DSCR will be immediately corrected by the transaction aborting, unless it has been suspended. In that case the incorrect value can be seen by the task until it resumes the transaction. The fix is to treat the DSCR similarly to the TAR and save it early in __switch_to(). A program exposing the problem is added to the kernel self tests as: tools/testing/selftests/powerpc/tm/tm-resched-dscr. Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com> CC: <stable@vger.kernel.org> [v3.10+] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
/*
|
|
* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
|
|
*/
|
|
#ifndef _ASM_POWERPC_SWITCH_TO_H
|
|
#define _ASM_POWERPC_SWITCH_TO_H
|
|
|
|
struct thread_struct;
|
|
struct task_struct;
|
|
struct pt_regs;
|
|
|
|
extern struct task_struct *__switch_to(struct task_struct *,
|
|
struct task_struct *);
|
|
#define switch_to(prev, next, last) ((last) = __switch_to((prev), (next)))
|
|
|
|
struct thread_struct;
|
|
extern struct task_struct *_switch(struct thread_struct *prev,
|
|
struct thread_struct *next);
|
|
#ifdef CONFIG_PPC_BOOK3S_64
|
|
static inline void save_early_sprs(struct thread_struct *prev)
|
|
{
|
|
if (cpu_has_feature(CPU_FTR_ARCH_207S))
|
|
prev->tar = mfspr(SPRN_TAR);
|
|
if (cpu_has_feature(CPU_FTR_DSCR))
|
|
prev->dscr = mfspr(SPRN_DSCR);
|
|
}
|
|
#else
|
|
static inline void save_early_sprs(struct thread_struct *prev) {}
|
|
#endif
|
|
|
|
extern void enable_kernel_fp(void);
|
|
extern void enable_kernel_altivec(void);
|
|
extern int emulate_altivec(struct pt_regs *);
|
|
extern void __giveup_vsx(struct task_struct *);
|
|
extern void giveup_vsx(struct task_struct *);
|
|
extern void enable_kernel_spe(void);
|
|
extern void giveup_spe(struct task_struct *);
|
|
extern void load_up_spe(struct task_struct *);
|
|
extern void switch_booke_debug_regs(struct debug_reg *new_debug);
|
|
|
|
#ifndef CONFIG_SMP
|
|
extern void discard_lazy_cpu_state(void);
|
|
#else
|
|
static inline void discard_lazy_cpu_state(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_PPC_FPU
|
|
extern void flush_fp_to_thread(struct task_struct *);
|
|
extern void giveup_fpu(struct task_struct *);
|
|
#else
|
|
static inline void flush_fp_to_thread(struct task_struct *t) { }
|
|
static inline void giveup_fpu(struct task_struct *t) { }
|
|
#endif
|
|
|
|
#ifdef CONFIG_ALTIVEC
|
|
extern void flush_altivec_to_thread(struct task_struct *);
|
|
extern void giveup_altivec(struct task_struct *);
|
|
extern void giveup_altivec_notask(void);
|
|
#else
|
|
static inline void flush_altivec_to_thread(struct task_struct *t)
|
|
{
|
|
}
|
|
static inline void giveup_altivec(struct task_struct *t)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_VSX
|
|
extern void flush_vsx_to_thread(struct task_struct *);
|
|
#else
|
|
static inline void flush_vsx_to_thread(struct task_struct *t)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SPE
|
|
extern void flush_spe_to_thread(struct task_struct *);
|
|
#else
|
|
static inline void flush_spe_to_thread(struct task_struct *t)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static inline void clear_task_ebb(struct task_struct *t)
|
|
{
|
|
#ifdef CONFIG_PPC_BOOK3S_64
|
|
/* EBB perf events are not inherited, so clear all EBB state. */
|
|
t->thread.bescr = 0;
|
|
t->thread.mmcr2 = 0;
|
|
t->thread.mmcr0 = 0;
|
|
t->thread.siar = 0;
|
|
t->thread.sdar = 0;
|
|
t->thread.sier = 0;
|
|
t->thread.used_ebb = 0;
|
|
#endif
|
|
}
|
|
|
|
#endif /* _ASM_POWERPC_SWITCH_TO_H */
|