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MIPS: Fix watchpoint restoration

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Commit f51246efee ("MIPS: Get rid of finish_arch_switch().") moved the
__restore_watch() call from finish_arch_switch() (i.e. after resume()
returns) to before the resume() call in switch_to(). This results in
watchpoints only being restored when a task is descheduled, preventing
the watchpoints from being effective most of the time, except due to
chance before the watchpoints are lazily removed.

Fix the call sequence from switch_to() through to
mips_install_watch_registers() to pass the task_struct pointer of the
next task, instead of using current. This allows the watchpoints for the
next (non-current) task to be restored without reintroducing
finish_arch_switch().

Fixes: f51246efee ("MIPS: Get rid of finish_arch_switch().")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 4.3.x-
Patchwork: https://patchwork.linux-mips.org/patch/12726/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
James Hogan
2016-03-01 22:19:36 +00:00
committed by Ralf Baechle
parent 81a76d7119
commit a7e89326b4
4 changed files with 9 additions and 10 deletions
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2
arch/mips/include/asm/switch_to.h
View File

@@ -105,7 +105,7 @@ do { \
__clear_software_ll_bit(); \
if (cpu_has_userlocal) \
write_c0_userlocal(task_thread_info(next)->tp_value); \
__restore_watch(); \
__restore_watch(next); \
(last) = resume(prev, next, task_thread_info(next)); \
} while (0)

10
arch/mips/include/asm/watch.h
View File

@@ -12,21 +12,21 @@
#include <asm/mipsregs.h>
void mips_install_watch_registers(void);
void mips_install_watch_registers(struct task_struct *t);
void mips_read_watch_registers(void);
void mips_clear_watch_registers(void);
void mips_probe_watch_registers(struct cpuinfo_mips *c);
#ifdef CONFIG_HARDWARE_WATCHPOINTS
#define __restore_watch() do { \
#define __restore_watch(task) do { \
if (unlikely(test_bit(TIF_LOAD_WATCH, \
&current_thread_info()->flags))) { \
mips_install_watch_registers(); \
&task_thread_info(task)->flags))) { \
mips_install_watch_registers(task); \
} \
} while (0)
#else
#define __restore_watch() do {} while (0)
#define __restore_watch(task) do {} while (0)
#endif
#endif /* _ASM_WATCH_H */