From 894c55c3a11f0d32c9d5420b748fd16c68cf3377 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 1 Feb 2021 18:46:41 +0100
Subject: [PATCH 1/1] kernel, fs: Introduce and use set_restart_fn() and
 arch_set_restart_data()

Git-commit: 5abbe51a526253b9f003e9a0a195638dc882d660
Patch-mainline: v5.12-rc4
References: bsc#1191713

Preparation for fixing get_nr_restart_syscall() on X86 for COMPAT.

Add a new helper which sets restart_block->fn and calls a dummy
arch_set_restart_data() helper.

Fixes: 609c19a385c8 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210201174641.GA17871@redhat.com

(cherry picked from commit 5abbe51a526253b9f003e9a0a195638dc882d660)

Signed-off-by: Firo Yang <firo.yang@suse.com>
---
 fs/select.c                    | 10 ++++------
 include/linux/thread_info.h    | 13 +++++++++++++
 kernel/futex.c                 |  3 +--
 kernel/time/alarmtimer.c       |  3 +--
 kernel/time/hrtimer.c          |  4 +---
 kernel/time/posix-cpu-timers.c |  2 +-
 6 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 5b524a977d91..c26d4a773269 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -1005,10 +1005,9 @@ static long do_restart_poll(struct restart_block *restart_block)
 
 	ret = do_sys_poll(ufds, nfds, to);
 
-	if (ret == -EINTR) {
-		restart_block->fn = do_restart_poll;
-		ret = -ERESTART_RESTARTBLOCK;
-	}
+	if (ret == -EINTR)
+		ret = set_restart_fn(restart_block, do_restart_poll);
+
 	return ret;
 }
 
@@ -1030,7 +1029,6 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
 		struct restart_block *restart_block;
 
 		restart_block = &current->restart_block;
-		restart_block->fn = do_restart_poll;
 		restart_block->poll.ufds = ufds;
 		restart_block->poll.nfds = nfds;
 
@@ -1041,7 +1039,7 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
 		} else
 			restart_block->poll.has_timeout = 0;
 
-		ret = -ERESTART_RESTARTBLOCK;
+		ret = set_restart_fn(restart_block, do_restart_poll);
 	}
 	return ret;
 }
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index bd9478cb1392..0870f0dc0856 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -10,6 +10,7 @@
 #include <linux/types.h>
 #include <linux/bug.h>
 #include <linux/restart_block.h>
+#include <linux/errno.h>
 
 #ifdef CONFIG_THREAD_INFO_IN_TASK
 /*
@@ -38,6 +39,18 @@ enum {
 
 #ifdef __KERNEL__
 
+#ifndef arch_set_restart_data
+#define arch_set_restart_data(restart) do { } while (0)
+#endif
+
+static inline long set_restart_fn(struct restart_block *restart,
+					long (*fn)(struct restart_block *))
+{
+	restart->fn = fn;
+	arch_set_restart_data(restart);
+	return -ERESTART_RESTARTBLOCK;
+}
+
 #ifndef THREAD_ALIGN
 #define THREAD_ALIGN	THREAD_SIZE
 #endif
diff --git a/kernel/futex.c b/kernel/futex.c
index 92a5e7453434..f6e1f8365684 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2740,14 +2740,13 @@ static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
 		goto out;
 
 	restart = &current->restart_block;
-	restart->fn = futex_wait_restart;
 	restart->futex.uaddr = uaddr;
 	restart->futex.val = val;
 	restart->futex.time = *abs_time;
 	restart->futex.bitset = bitset;
 	restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;
 
-	ret = -ERESTART_RESTARTBLOCK;
+	ret = set_restart_fn(restart, futex_wait_restart);
 
 out:
 	if (to) {
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 799f3a9fecdf..015eba649d60 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -845,11 +845,10 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 	}
 
 	restart = &current->restart_block;
-	restart->fn = alarm_timer_nsleep_restart;
 	restart->nanosleep.clockid = type;
 	restart->nanosleep.expires = exp;
 	restart->nanosleep.rmtp = rmtp;
-	ret = -ERESTART_RESTARTBLOCK;
+	set_restart_fn(restart, alarm_timer_nsleep_restart);
 
 out:
 	return ret;
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 0f9dda89d45c..c69ccca2a382 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1522,9 +1522,9 @@ long hrtimer_nanosleep(struct timespec64
 	}
 
 	restart = &current->restart_block;
-	restart->fn = hrtimer_nanosleep_restart;
 	restart->nanosleep.clockid = t.timer.base->clockid;
 	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
+	set_restart_fn(restart, hrtimer_nanosleep_restart);
 out:
 	destroy_hrtimer_on_stack(&t.timer);
 	return ret;
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index f1ebcd0ed719..f5aa1c3149b8 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1342,10 +1342,10 @@ static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
 		if (rmtp && copy_to_user(rmtp, &ts, sizeof(*rmtp)))
 			return -EFAULT;
 
-		restart_block->fn = posix_cpu_nsleep_restart;
 		restart_block->nanosleep.clockid = which_clock;
 		restart_block->nanosleep.rmtp = rmtp;
 		restart_block->nanosleep.expires = timespec64_to_ns(rqtp);
+		set_restart_fn(restart_block, posix_cpu_nsleep_restart);
 	}
 	return error;
 }
-- 
2.26.2