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authorH.J. Lu <hjl.tools@gmail.com>2024-02-26 06:37:03 -0800
committerH.J. Lu <hjl.tools@gmail.com>2024-02-28 09:02:56 -0800
commit0aac205a814a8511e98d02b91a8dc908f1c53cde (patch)
treee9ad8dfa06abd2f6d9b521bb95e9b7cfaa0d7de7 /elf/tst-auditmod23.c
parente6350be7e9cae8f71c96c1f06eab61b9acb227c8 (diff)
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x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers
Compiler generates the following instruction sequence for GNU2 dynamic
TLS access:

	leaq	tls_var@TLSDESC(%rip), %rax
	call	*tls_var@TLSCALL(%rax)

or

	leal	tls_var@TLSDESC(%ebx), %eax
	call	*tls_var@TLSCALL(%eax)

CALL instruction is transparent to compiler which assumes all registers,
except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
_dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
path.  __tls_get_addr is a normal function which doesn't preserve any
caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
caller-saved registers, but didn't preserve any other caller-saved
registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
XSAVE and XSAVEC to save and restore all caller-saved registers.  This
fixes BZ #31372.

Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
to optimize elf_machine_runtime_setup.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
Diffstat (limited to 'elf/tst-auditmod23.c')
0 files changed, 0 insertions, 0 deletions