The patch titled
Subject: c/r: prctl: add ability to get clear_tid_address
has been added to the -mm tree. Its filename is
c-r-prctl-add-ability-to-get-clear_tid_address.patch
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------------------------------------------------------
From: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Subject: c/r: prctl: add ability to get clear_tid_address
Zero is written at clear_tid_address when the process exits. This
functionality is used by pthread_join().
We already have sys_set_tid_address() to change this address for the
current task but there is no way to obtain it from user space.
Without the ability to find this address and dump it we can't restore
pthread'ed apps which call pthread_join() once they have been restored.
This patch introduces the PR_GET_TID_ADDRESS prctl option which allows the
current process to obtain own clear_tid_address.
This feature is available iif CONFIG_CHECKPOINT_RESTORE is set.
Signed-off-by: Andrew Vagin <avagin@xxxxxxxxxx>
Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Pedro Alves <palves@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/prctl.h | 2 ++
kernel/sys.c | 13 +++++++++++++
2 files changed, 15 insertions(+)
diff -puN include/linux/prctl.h~c-r-prctl-add-ability-to-get-clear_tid_address include/linux/prctl.h
--- a/include/linux/prctl.h~c-r-prctl-add-ability-to-get-clear_tid_address
+++ a/include/linux/prctl.h
@@ -130,4 +130,6 @@
#define PR_SET_CHILD_SUBREAPER 36
#define PR_GET_CHILD_SUBREAPER 37
+#define PR_GET_TID_ADDRESS 36
+
#endif /* _LINUX_PRCTL_H */
diff -puN kernel/sys.c~c-r-prctl-add-ability-to-get-clear_tid_address kernel/sys.c
--- a/kernel/sys.c~c-r-prctl-add-ability-to-get-clear_tid_address
+++ a/kernel/sys.c
@@ -1912,12 +1912,22 @@ out:
up_read(&mm->mmap_sem);
return error;
}
+
+static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
+{
+ return put_user(me->clear_child_tid, tid_addr);
+}
+
#else /* CONFIG_CHECKPOINT_RESTORE */
static int prctl_set_mm(int opt, unsigned long addr,
unsigned long arg4, unsigned long arg5)
{
return -EINVAL;
}
+static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
+{
+ return -EINVAL;
+}
#endif
SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
@@ -2080,6 +2090,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
error = put_user(me->signal->is_child_subreaper,
(int __user *) arg2);
break;
+ case PR_GET_TID_ADDRESS:
+ error = prctl_get_tid_address(me, (int __user **)arg2);
+ break;
default:
error = -EINVAL;
break;
_
Subject: Subject: c/r: prctl: add ability to get clear_tid_address
Patches currently in -mm which might be from gorcunov@xxxxxxxxxx are
linux-next.patch
sysctl-make-kernelns_last_pid-control-being-checkpoint_restore-dependent.patch
fs-proc-introduce-proc-pid-task-tid-children-entry-v9.patch
syscalls-x86-add-__nr_kcmp-syscall-v8.patch
syscalls-x86-add-__nr_kcmp-syscall-v8-fix.patch
syscalls-x86-add-__nr_kcmp-syscall-v8-fix-2.patch
c-r-procfs-add-arg_start-end-env_start-end-and-exit_code-members-to-proc-pid-stat.patch
c-r-prctl-extend-pr_set_mm-to-set-up-more-mm_struct-entries-v2.patch
c-r-prctl-add-ability-to-set-new-mm_struct-exe_file.patch
c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-fix.patch
c-r-prctl-add-ability-to-get-clear_tid_address.patch
c-r-prctl-add-ability-to-get-clear_tid_address-fix.patch
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