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| author | Miroslav Benes <mbenes@suse.cz> | 2017-02-14 04:42:34 +0300 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2017-03-08 11:22:40 +0300 |
| commit | 2f09ca60a56dd9c217d32d68340e1b08cbbe1ace (patch) | |
| tree | 15f594f9cb6cc851cd771a3dfc22c6cd32284b1e /arch/s390/include/asm/thread_info.h | |
| parent | 30d64f1904d44a7e52a93d711d57aabbac2efd72 (diff) | |
| download | linux-2f09ca60a56dd9c217d32d68340e1b08cbbe1ace.tar.xz | |
livepatch/s390: add TIF_PATCH_PENDING thread flag
Update a task's patch state when returning from a system call or user
space interrupt, or after handling a signal.
This greatly increases the chances of a patch operation succeeding. If
a task is I/O bound, it can be patched when returning from a system
call. If a task is CPU bound, it can be patched when returning from an
interrupt. If a task is sleeping on a to-be-patched function, the user
can send SIGSTOP and SIGCONT to force it to switch.
Since there are two ways the syscall can be restarted on return from a
signal handling process, it is important to clear the flag before
do_signal() is called. Otherwise we could miss the migration if we used
SIGSTOP/SIGCONT procedure or fake signal to migrate patching blocking
tasks. If we place our hook to sysc_work label in entry before
TIF_SIGPENDING is evaluated we kill two birds with one stone. The task
is correctly migrated in all return paths from a syscall.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'arch/s390/include/asm/thread_info.h')
| -rw-r--r-- | arch/s390/include/asm/thread_info.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h index 4977668788d7..646845edf148 100644 --- a/arch/s390/include/asm/thread_info.h +++ b/arch/s390/include/asm/thread_info.h @@ -56,6 +56,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #define TIF_SIGPENDING 1 /* signal pending */ #define TIF_NEED_RESCHED 2 /* rescheduling necessary */ #define TIF_UPROBE 3 /* breakpointed or single-stepping */ +#define TIF_PATCH_PENDING 4 /* pending live patching update */ #define TIF_31BIT 16 /* 32bit process */ #define TIF_MEMDIE 17 /* is terminating due to OOM killer */ @@ -74,6 +75,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #define _TIF_SIGPENDING _BITUL(TIF_SIGPENDING) #define _TIF_NEED_RESCHED _BITUL(TIF_NEED_RESCHED) #define _TIF_UPROBE _BITUL(TIF_UPROBE) +#define _TIF_PATCH_PENDING _BITUL(TIF_PATCH_PENDING) #define _TIF_31BIT _BITUL(TIF_31BIT) #define _TIF_SINGLE_STEP _BITUL(TIF_SINGLE_STEP) |