1From f7b3134457e764badb5b24d6fcd1636d1950b1ef Mon Sep 17 00:00:00 2001
2From: Catalin Marinas <catalin.marinas@arm.com>
3Date: Tue, 23 Jul 2019 19:58:39 +0200
4Subject: [PATCH] BACKPORT: arm64: Introduce prctl() options to control the
5 tagged user addresses ABI
6
7(Upstream commit 63f0c60379650d82250f22e4cf4137ef3dc4f43d).
8
9It is not desirable to relax the ABI to allow tagged user addresses into
10the kernel indiscriminately. This patch introduces a prctl() interface
11for enabling or disabling the tagged ABI with a global sysctl control
12for preventing applications from enabling the relaxed ABI (meant for
13testing user-space prctl() return error checking without reconfiguring
14the kernel). The ABI properties are inherited by threads of the same
15application and fork()'ed children but cleared on execve(). A Kconfig
16option allows the overall disabling of the relaxed ABI.
17
18The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle
19MTE-specific settings like imprecise vs precise exceptions.
20
21Reviewed-by: Kees Cook <keescook@chromium.org>
22Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
23Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
24Signed-off-by: Will Deacon <will@kernel.org>
25Change-Id: I2d52c5589b05415faab315c116245f1058d64750
26Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
27Bug: 135692346
28(cherry picked from commit f077ee260964eb925a593dcf30553432b3243ac8)
29
30Conflicts:
31      arch/arm64/Kconfig
32      arch/arm64/include/asm/processor.h
33      arch/arm64/include/asm/thread_info.h
34      arch/arm64/include/asm/uaccess.h
35      arch/arm64/kernel/process.c
36      include/uapi/linux/prctl.h
37      kernel/sys.c
38
39Only port definations to pass newest glibc compiling.
40
41Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
42---
43 include/uapi/linux/prctl.h | 5 +++++
44 1 file changed, 5 insertions(+)
45
46diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
47index 4d05aad2e4c5..eabab9f1ee38 100644
48--- a/include/uapi/linux/prctl.h
49+++ b/include/uapi/linux/prctl.h
50@@ -219,4 +219,9 @@ struct prctl_mm_map {
51 # define PR_SPEC_DISABLE		(1UL << 2)
52 # define PR_SPEC_FORCE_DISABLE		(1UL << 3)
53
54+/* Tagged user address controls for arm64 */
55+#define PR_SET_TAGGED_ADDR_CTRL		55
56+#define PR_GET_TAGGED_ADDR_CTRL		56
57+# define PR_TAGGED_ADDR_ENABLE		(1UL << 0)
58+
59 #endif /* _LINUX_PRCTL_H */
60--
612.20.1
62
63