From d174ec248d5b6bba3842f425f036495b682c313f Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Wed, 15 Apr 2020 17:40:45 +0100 Subject: aarch64: redefine RETURN_ADDRESS to strip PAC 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. Reviewed-by: Adhemerval Zanella --- sysdeps/aarch64/sysdep.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'sysdeps/aarch64') diff --git a/sysdeps/aarch64/sysdep.h b/sysdeps/aarch64/sysdep.h index f442506952..ae269146e3 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__ -- cgit 1.4.1