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| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2021-01-22 16:14:05 +0000 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2021-01-25 15:35:43 +0000 |
| commit | c3c4a25e651d4d78b1751664a613807b7140ed7e (patch) | |
| tree | 34706a538d61e100227da580e9e99200ca4ffeb7 | |
| parent | 31f64887222597bb15b7a814d8dadb7cb667bcb9 (diff) | |
| download | glibc-c3c4a25e651d4d78b1751664a613807b7140ed7e.zip glibc-c3c4a25e651d4d78b1751664a613807b7140ed7e.tar.gz glibc-c3c4a25e651d4d78b1751664a613807b7140ed7e.tar.bz2 | |
aarch64: Move and update the definition of MTE_ENABLED
The hwcap value is now in linux 5.10 and in glibc bits/hwcap.h, so use
that definition.
Move the definition to init-arch.h so all ifunc selectors can use it
and expose an "mte" shorthand for mte enabled runtime.
For now we allow user code to enable tag checks and use PROT_MTE
mappings without libc involvment, this is not guaranteed ABI, but
can be useful for testing and debugging with MTE.
| -rw-r--r-- | sysdeps/aarch64/multiarch/init-arch.h | 11 | ||||
| -rw-r--r-- | sysdeps/aarch64/multiarch/strlen.c | 11 |
2 files changed, 11 insertions, 11 deletions
diff --git a/sysdeps/aarch64/multiarch/init-arch.h b/sysdeps/aarch64/multiarch/init-arch.h index bf8264b..fce260d 100644 --- a/sysdeps/aarch64/multiarch/init-arch.h +++ b/sysdeps/aarch64/multiarch/init-arch.h @@ -17,9 +17,18 @@ <https://www.gnu.org/licenses/>. */ #include <ldsodefs.h> +#include <sys/auxv.h> + +/* Make glibc MTE-safe on a system that supports MTE in case user code + enables tag checks independently of the mte_status of glibc. There + is currently no ABI contract for enabling tag checks in user code, + but this can be useful for debugging with MTE. */ +#define MTE_ENABLED() (GLRO(dl_hwcap2) & HWCAP2_MTE) #define INIT_ARCH() \ uint64_t __attribute__((unused)) midr = \ GLRO(dl_aarch64_cpu_features).midr_el1; \ unsigned __attribute__((unused)) zva_size = \ - GLRO(dl_aarch64_cpu_features).zva_size; + GLRO(dl_aarch64_cpu_features).zva_size; \ + bool __attribute__((unused)) mte = \ + MTE_ENABLED (); diff --git a/sysdeps/aarch64/multiarch/strlen.c b/sysdeps/aarch64/multiarch/strlen.c index f3c018a..8f38de6 100644 --- a/sysdeps/aarch64/multiarch/strlen.c +++ b/sysdeps/aarch64/multiarch/strlen.c @@ -26,21 +26,12 @@ # include <string.h> # include <init-arch.h> -/* This should check HWCAP2_MTE when it is available: current - linux kernel does not expose it, but its value is reserved. - This is needed to make glibc MTE-safe on future systems in - case user code enables MTE. The ABI contract for enabling - MTE is not yet specified, but it can be useful for at least - debugging which does not need a contract. */ -#define FUTURE_HWCAP2_MTE (1 << 18) -#define MTE_ENABLED() (GLRO(dl_hwcap2) & FUTURE_HWCAP2_MTE) - extern __typeof (__redirect_strlen) __strlen; extern __typeof (__redirect_strlen) __strlen_mte attribute_hidden; extern __typeof (__redirect_strlen) __strlen_asimd attribute_hidden; -libc_ifunc (__strlen, (MTE_ENABLED () ? __strlen_mte : __strlen_asimd)); +libc_ifunc (__strlen, (mte ? __strlen_mte : __strlen_asimd)); # undef strlen strong_alias (__strlen, strlen); |