[PATCH 4.4 08/99] MIPS: Fix watchpoint restoration
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-06-05 23:02:43
Also in:
lkml, stable
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: James Hogan <redacted>
commit a7e89326b415b5d81c4b1016fd4a40db861eb58d upstream.
Commit f51246efee2b ("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: f51246efee2b ("MIPS: Get rid of finish_arch_switch().")
Signed-off-by: James Hogan <redacted>
Cc: Paul Burton <redacted>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12726/
Signed-off-by: Ralf Baechle <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/mips/include/asm/switch_to.h | 2 +-
arch/mips/include/asm/watch.h | 10 +++++-----
arch/mips/kernel/pm.c | 2 +-
arch/mips/kernel/watch.c | 5 ++---
4 files changed, 9 insertions(+), 10 deletions(-)
--- a/arch/mips/include/asm/switch_to.h
+++ b/arch/mips/include/asm/switch_to.h@@ -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) --- a/arch/mips/include/asm/watch.h +++ b/arch/mips/include/asm/watch.h
@@ -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, \ - ¤t_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 */ --- a/arch/mips/kernel/pm.c +++ b/arch/mips/kernel/pm.c
@@ -56,7 +56,7 @@ static void mips_cpu_restore(void) write_c0_userlocal(current_thread_info()->tp_value); /* Restore watch registers */ - __restore_watch(); + __restore_watch(current); } /** --- a/arch/mips/kernel/watch.c +++ b/arch/mips/kernel/watch.c
@@ -15,10 +15,9 @@ * Install the watch registers for the current thread. A maximum of * four registers are installed although the machine may have more. */ -void mips_install_watch_registers(void) +void mips_install_watch_registers(struct task_struct *t) { - struct mips3264_watch_reg_state *watches = - ¤t->thread.watch.mips3264; + struct mips3264_watch_reg_state *watches = &t->thread.watch.mips3264; switch (current_cpu_data.watch_reg_use_cnt) { default: BUG();