glibc/sysdeps/x86_64/rtld-offsets.sym
H.J. Lu 031e519c95 x86-64: Align the stack in __tls_get_addr [BZ #21609]
This change forces realignment of the stack pointer in __tls_get_addr, so
that binaries compiled by GCCs older than GCC 4.9:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066

continue to work even if vector instructions are used in glibc which
require the ABI stack realignment.

__tls_get_addr_slow is added to handle the slow paths in the default
implementation of__tls_get_addr in elf/dl-tls.c.  The new __tls_get_addr
calls __tls_get_addr_slow after realigning the stack.  Internal calls
within ld.so go directly to the default implementation of __tls_get_addr
because they do not need stack realignment.

	[BZ #21609]
	* sysdeps/x86_64/Makefile (sysdep-dl-routines): Add tls_get_addr.
	(gen-as-const-headers): Add rtld-offsets.sym.
	* sysdeps/x86_64/dl-tls.c: New file.
	* sysdeps/x86_64/rtld-offsets.sym: Likwise.
	* sysdeps/x86_64/tls_get_addr.S: Likewise.
	* sysdeps/x86_64/dl-tls.h: Add multiple inclusion guards.
	* sysdeps/x86_64/tlsdesc.sym (TI_MODULE_OFFSET): New.
	(TI_OFFSET_OFFSET): Likwise.
2017-07-06 04:43:20 -07:00

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#define SHARED
#include <ldsodefs.h>
--
GL_TLS_GENERATION_OFFSET offsetof (struct rtld_global, _dl_tls_generation)