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| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2020-04-15 17:40:45 +0100 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2020-06-12 14:34:39 +0100 |
| commit | a8aad403a6d9e4904a5699ebd4c26424ab105076 (patch) | |
| tree | 173554f292f353dd3c6e221582edb9abedbff48f | |
| parent | f70dbaf7a1d2664fbed2cdcf6a3da40c37a442c0 (diff) | |
| download | glibc-a8aad403a6d9e4904a5699ebd4c26424ab105076.tar.gz glibc-a8aad403a6d9e4904a5699ebd4c26424ab105076.tar.xz glibc-a8aad403a6d9e4904a5699ebd4c26424ab105076.zip | |
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/95891: __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.
| -rw-r--r-- | sysdeps/aarch64/sysdep.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/sysdeps/aarch64/sysdep.h b/sysdeps/aarch64/sysdep.h index 2879aeaa5c..593bdd35a2 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/95891. */ +# if HAVE_AARCH64_PAC_RET +# undef RETURN_ADDRESS +# define RETURN_ADDRESS(n) strip_pac (__builtin_return_address (n)) +# endif #endif #ifdef __ASSEMBLER__ |