From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: libc-alpha@sourceware.org
Subject: [PATCH v6 13/14] aarch64: redefine RETURN_ADDRESS to strip PAC
Date: Wed, 1 Jul 2020 15:40:56 +0100 [thread overview]
Message-ID: <61ed62f8934fab4c73c2b6d871a5363eeb2f3c91.1593612309.git.szabolcs.nagy@arm.com> (raw)
In-Reply-To: <cover.1593612309.git.szabolcs.nagy@arm.com>
RETURN_ADDRESS is used at several places in glibc to mean a valid
code address of the call site, but with pac-ret it may contain a
pointer authentication code (PAC), so its definition is adjusted.
This is gcc PR target/94891: __builtin_return_address should not
expose signed pointers to user code where it can cause ABI issues.
In glibc RETURN_ADDRESS is only changed if it is built with pac-ret.
There is no detection for the specific gcc issue because it is
hard to test and the additional xpac does not cause problems.
---
sysdeps/aarch64/sysdep.h | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/sysdeps/aarch64/sysdep.h b/sysdeps/aarch64/sysdep.h
index 2879aeaa5c..48fa8e9e90 100644
--- a/sysdeps/aarch64/sysdep.h
+++ b/sysdeps/aarch64/sysdep.h
@@ -44,6 +44,13 @@ strip_pac (void *p)
asm ("hint 7 // xpaclri" : "+r"(ra));
return ra;
}
+
+/* This is needed when glibc is built with -mbranch-protection=pac-ret
+ with a gcc that is affected by PR target/94891. */
+# if HAVE_AARCH64_PAC_RET
+# undef RETURN_ADDRESS
+# define RETURN_ADDRESS(n) strip_pac (__builtin_return_address (n))
+# endif
#endif
#ifdef __ASSEMBLER__
--
2.17.1
next prev parent reply other threads:[~2020-07-01 14:41 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 14:37 [PATCH v6 00/14] aarch64: branch protection support Szabolcs Nagy
2020-07-01 14:37 ` [PATCH v6 01/14] Rewrite abi-note.S in C Szabolcs Nagy
2020-07-01 14:41 ` H.J. Lu
2020-07-01 17:31 ` Szabolcs Nagy
2020-07-01 17:43 ` H.J. Lu
2020-07-02 8:39 ` Szabolcs Nagy
2020-07-01 14:38 ` [PATCH v6 02/14] aarch64: configure test for BTI support Szabolcs Nagy
2020-07-06 14:11 ` Adhemerval Zanella
2020-07-06 18:07 ` Szabolcs Nagy
2020-07-06 18:12 ` Adhemerval Zanella
2020-07-07 14:26 ` Szabolcs Nagy
2020-07-07 14:39 ` H.J. Lu
2020-07-07 16:58 ` Szabolcs Nagy
2020-07-07 17:24 ` H.J. Lu
2020-07-01 14:38 ` [PATCH v6 03/14] aarch64: Rename place holder .S files to .c Szabolcs Nagy
2020-07-01 14:38 ` [PATCH v6 04/14] aarch64: Add BTI support to assembly files Szabolcs Nagy
2020-07-03 16:19 ` Szabolcs Nagy
2020-07-01 14:38 ` [PATCH v6 05/14] aarch64: fix swapcontext for BTI Szabolcs Nagy
2020-07-01 14:39 ` [PATCH v6 06/14] aarch64: fix RTLD_START " Szabolcs Nagy
2020-07-01 14:39 ` [PATCH v6 07/14] rtld: Clean up PT_NOTE and add PT_GNU_PROPERTY handling Szabolcs Nagy
2020-07-06 16:11 ` Adhemerval Zanella
2020-07-01 14:39 ` [PATCH v6 08/14] aarch64: enable BTI at runtime Szabolcs Nagy
2020-07-06 17:28 ` Adhemerval Zanella
2020-07-11 15:58 ` Richard Henderson
2020-07-13 8:32 ` Szabolcs Nagy
2020-07-13 13:14 ` Szabolcs Nagy
2020-07-13 13:28 ` Szabolcs Nagy
2020-07-13 16:55 ` Richard Henderson
2020-07-01 14:39 ` [PATCH v6 09/14] aarch64: ensure objects are BTI compatible Szabolcs Nagy
2020-07-06 17:37 ` Adhemerval Zanella
2020-07-06 18:01 ` Szabolcs Nagy
2020-07-06 18:17 ` Adhemerval Zanella
2020-07-01 14:40 ` [PATCH v6 10/14] aarch64: configure check for pac-ret code generation Szabolcs Nagy
2020-07-01 14:40 ` [PATCH v6 11/14] aarch64: Add pac-ret support to assembly files Szabolcs Nagy
2020-07-01 14:40 ` [PATCH v6 12/14] aarch64: fix pac-ret support in _mcount Szabolcs Nagy
2020-07-06 18:33 ` Adhemerval Zanella
2020-07-01 14:40 ` Szabolcs Nagy [this message]
2020-07-06 18:34 ` [PATCH v6 13/14] aarch64: redefine RETURN_ADDRESS to strip PAC Adhemerval Zanella
2020-07-01 14:41 ` [PATCH v6 14/14] aarch64: add NEWS entry about branch protection support Szabolcs Nagy
2020-07-06 18:41 ` Adhemerval Zanella
2020-07-08 10:04 ` Szabolcs Nagy
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