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| author |   H.J. Lu <hjl.tools@gmail.com> | 2017-12-19 02:45:16 -0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2017-12-19 02:45:34 -0800 |
| commit | cba595c350e52194e10c0006732e1991e3d0803b (patch) | |
| tree | 833da57e0eae667c21ce447aa9502a64e3c05527 /sysdeps/x86_64 | |
| parent | Linux/x86: Update cancel_jmp_buf to match __jmp_buf_tag [BZ #22563] (diff) | |
| download | glibc-cba595c350e52194e10c0006732e1991e3d0803b.tar.gz glibc-cba595c350e52194e10c0006732e1991e3d0803b.tar.bz2 glibc-cba595c350e52194e10c0006732e1991e3d0803b.zip | |
x86: Add feature_1 to tcbhead_t [BZ #22563]
On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer
to support Shadow Stack in Intel Control-flow Enforcemen Technology.
cancel_jmp_buf has been updated to include saved_mask so that it is as
large as struct __jmp_buf_tag. We must suport the old cancel_jmp_buf
in existing binaries. Since symbol versioning doesn't work on
cancel_jmp_buf, feature_1 is added to tcbhead_t so that setjmp and
longjmp can check if shadow stack is enabled. NB: Shadow stack is
enabled only if all modules are shadow stack enabled.
[BZ #22563]
* sysdeps/i386/nptl/tcb-offsets.sym (FEATURE_1_OFFSET): New.
* sysdeps/i386/nptl/tls.h (tcbhead_t): Add feature_1.
* sysdeps/x86_64/nptl/tcb-offsets.sym (FEATURE_1_OFFSET): New.
* sysdeps/x86_64/nptl/tls.h (tcbhead_t): Rename __glibc_unused1
to feature_1.
Diffstat (limited to 'sysdeps/x86_64')
| -rw-r--r-- | sysdeps/x86_64/nptl/tcb-offsets.sym | 1 | ||||
| -rw-r--r-- | sysdeps/x86_64/nptl/tls.h | 5 |
2 files changed, 5 insertions, 1 deletions
diff --git a/sysdeps/x86_64/nptl/tcb-offsets.sym b/sysdeps/x86_64/nptl/tcb-offsets.sym index 8a25c482cb..03b6dba5c3 100644 --- a/sysdeps/x86_64/nptl/tcb-offsets.sym +++ b/sysdeps/x86_64/nptl/tcb-offsets.sym @@ -15,6 +15,7 @@ VGETCPU_CACHE_OFFSET offsetof (tcbhead_t, vgetcpu_cache) #ifndef __ASSUME_PRIVATE_FUTEX PRIVATE_FUTEX offsetof (tcbhead_t, private_futex) #endif +FEATURE_1_OFFSET offsetof (tcbhead_t, feature_1) -- Not strictly offsets, but these values are also used in the TCB. TCB_CANCELSTATE_BITMASK CANCELSTATE_BITMASK diff --git a/sysdeps/x86_64/nptl/tls.h b/sysdeps/x86_64/nptl/tls.h index 9b8ad82550..cec864f231 100644 --- a/sysdeps/x86_64/nptl/tls.h +++ b/sysdeps/x86_64/nptl/tls.h @@ -56,7 +56,10 @@ typedef struct # else int __glibc_reserved1; # endif - int __glibc_unused1; + /* Bit 0: IBT. + Bit 1: SHSTK. + */ + unsigned int feature_1; /* Reservation of some values for the TM ABI. */ void *__private_tm[4]; /* GCC split stack support. */ |