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| author | Florian Weimer <fweimer@redhat.com> | 2025-01-07 08:34:13 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2025-01-07 09:17:01 +0100 |
| commit | a257f201dd557aa82c7efb7528277afe675c0468 (patch) | |
| tree | f7524a3e0079709b1ba14e36a299136501713678 | |
| parent | c4ed6a380ed7b7b9670e3974ecb5d2db7d455123 (diff) | |
| download | glibc-a257f201dd557aa82c7efb7528277afe675c0468.zip glibc-a257f201dd557aa82c7efb7528277afe675c0468.tar.gz glibc-a257f201dd557aa82c7efb7528277afe675c0468.tar.bz2 | |
Revert "x86_64: Remove unused padding from tcbhead_t"
This reverts commit 30d3fd7f4f4bc8f767d73ad4e4b005c1bd234310.
The padding is required by Chromium's MaybeUpdateGlibcTidCache
in sandbox/linux/services/namespace_sandbox.cc.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
| -rw-r--r-- | sysdeps/x86_64/nptl/tls.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/sysdeps/x86_64/nptl/tls.h b/sysdeps/x86_64/nptl/tls.h index a9c348e..551d342 100644 --- a/sysdeps/x86_64/nptl/tls.h +++ b/sysdeps/x86_64/nptl/tls.h @@ -62,16 +62,28 @@ typedef struct void *__private_ss; /* The marker for the current shadow stack. */ unsigned long long int ssp_base; + /* Must be kept even if it is no longer used by glibc since programs, + like AddressSanitizer, depend on the size of tcbhead_t. */ + __128bits __glibc_unused2[8][4] __attribute__ ((aligned (32))); + + void *__padding[8]; } tcbhead_t; # ifdef __ILP32__ /* morestack.S in libgcc uses offset 0x40 to access __private_ss, */ _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x40, "offset of __private_ss != 0x40"); +/* NB: ssp_base used to be "long int __glibc_reserved2", which was + changed from 32 bits to 64 bits. Make sure that the offset of the + next field, __glibc_unused2, is unchanged. */ +_Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x60, + "offset of __glibc_unused2 != 0x60"); # else /* morestack.S in libgcc uses offset 0x70 to access __private_ss, */ _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x70, "offset of __private_ss != 0x70"); +_Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x80, + "offset of __glibc_unused2 != 0x80"); # endif #else /* __ASSEMBLER__ */ |