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59d5af67 | 1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
321d628a FG |
2 | From: Will Deacon <will.deacon@arm.com> |
3 | Date: Tue, 24 Oct 2017 11:22:47 +0100 | |
59d5af67 FG |
4 | Subject: [PATCH] locking/barriers: Add implicit smp_read_barrier_depends() to |
5 | READ_ONCE() | |
321d628a FG |
6 | MIME-Version: 1.0 |
7 | Content-Type: text/plain; charset=UTF-8 | |
8 | Content-Transfer-Encoding: 8bit | |
9 | ||
10 | CVE-2017-5754 | |
11 | ||
12 | [ Note, this is a Git cherry-pick of the following commit: | |
13 | ||
14 | 76ebbe78f739 ("locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()") | |
15 | ||
16 | ... for easier x86 PTI code testing and back-porting. ] | |
17 | ||
18 | In preparation for the removal of lockless_dereference(), which is the | |
19 | same as READ_ONCE() on all architectures other than Alpha, add an | |
20 | implicit smp_read_barrier_depends() to READ_ONCE() so that it can be | |
21 | used to head dependency chains on all architectures. | |
22 | ||
23 | Signed-off-by: Will Deacon <will.deacon@arm.com> | |
24 | Cc: Linus Torvalds <torvalds@linux-foundation.org> | |
25 | Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
26 | Cc: Peter Zijlstra <peterz@infradead.org> | |
27 | Cc: Thomas Gleixner <tglx@linutronix.de> | |
28 | Link: http://lkml.kernel.org/r/1508840570-22169-3-git-send-email-will.deacon@arm.com | |
29 | Signed-off-by: Ingo Molnar <mingo@kernel.org> | |
30 | (cherry picked from commit c2bc66082e1048c7573d72e62f597bdc5ce13fea) | |
31 | Signed-off-by: Andy Whitcroft <apw@canonical.com> | |
32 | Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> | |
33 | (cherry picked from commit 6ef3d843f8f1a8b72ca83d4b1d457c2896278ccd) | |
34 | Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> | |
35 | --- | |
36 | include/linux/compiler.h | 1 + | |
37 | 1 file changed, 1 insertion(+) | |
38 | ||
39 | diff --git a/include/linux/compiler.h b/include/linux/compiler.h | |
40 | index 043b60de041e..8af8814ebe7a 100644 | |
41 | --- a/include/linux/compiler.h | |
42 | +++ b/include/linux/compiler.h | |
43 | @@ -314,6 +314,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s | |
44 | __read_once_size(&(x), __u.__c, sizeof(x)); \ | |
45 | else \ | |
46 | __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ | |
47 | + smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ | |
48 | __u.__val; \ | |
49 | }) | |
50 | #define READ_ONCE(x) __READ_ONCE(x, 1) | |
51 | -- | |
52 | 2.14.2 | |
53 |