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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> | 2020-07-08 13:04:04 +0100 |
| commit | 0119a5f4785e77d21df99968a751b1bb65af9a9b (patch) | |
| tree | 95d07bd286814d5edade54ff3cb600c53830622e | |
| parent | a8601c3f0da98f7179288be1a9a2950aad5b2f5f (diff) | |
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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 <adhemerval.zanella@linaro.org>
| -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 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__ |