forked from rpms/glibc
444 lines
14 KiB
Diff
444 lines
14 KiB
Diff
commit a75a02a696f9f869d77b17b99964823aa8833a8b
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Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
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Date: Thu Feb 11 11:58:20 2021 +0000
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i386: Remove lazy tlsdesc relocation related code
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Like in commit e75711ebfa976d5468ec292282566a18b07e4d67 for x86_64,
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remove unused lazy tlsdesc relocation processing code:
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_dl_tlsdesc_resolve_abs_plus_addend
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_dl_tlsdesc_resolve_rel
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_dl_tlsdesc_resolve_rela
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_dl_tlsdesc_resolve_hold
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diff --git a/sysdeps/i386/dl-tlsdesc.S b/sysdeps/i386/dl-tlsdesc.S
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index 128f0af3188f46bb..22ecb2c6adc6cc6e 100644
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--- a/sysdeps/i386/dl-tlsdesc.S
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+++ b/sysdeps/i386/dl-tlsdesc.S
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@@ -138,159 +138,3 @@ _dl_tlsdesc_dynamic:
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cfi_endproc
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.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
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#endif /* SHARED */
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-
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- /* This function is a wrapper for a lazy resolver for TLS_DESC
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- REL relocations that reference the *ABS* segment in their own
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- link maps. %ebx points to the caller's GOT. %eax points to a
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- TLS descriptor, such that 0(%eax) holds the address of the
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- resolver wrapper itself (unless some other thread beat us to
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- it) and 4(%eax) holds the addend in the relocation.
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-
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- When the actual resolver returns, it will have adjusted the
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- TLS descriptor such that we can tail-call it for it to return
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- the TP offset of the symbol. */
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-
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- .hidden _dl_tlsdesc_resolve_abs_plus_addend
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- .global _dl_tlsdesc_resolve_abs_plus_addend
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- .type _dl_tlsdesc_resolve_abs_plus_addend,@function
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- cfi_startproc
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- .align 16
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-_dl_tlsdesc_resolve_abs_plus_addend:
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-0:
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- _CET_ENDBR
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- pushl %eax
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- cfi_adjust_cfa_offset (4)
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- pushl %ecx
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- cfi_adjust_cfa_offset (4)
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- pushl %edx
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- cfi_adjust_cfa_offset (4)
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- movl $1f - 0b, %ecx
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- movl 4(%ebx), %edx
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- call _dl_tlsdesc_resolve_abs_plus_addend_fixup
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-1:
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- popl %edx
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- cfi_adjust_cfa_offset (-4)
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- popl %ecx
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- cfi_adjust_cfa_offset (-4)
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- popl %eax
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- cfi_adjust_cfa_offset (-4)
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- jmp *(%eax)
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- cfi_endproc
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- .size _dl_tlsdesc_resolve_abs_plus_addend, .-_dl_tlsdesc_resolve_abs_plus_addend
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-
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- /* This function is a wrapper for a lazy resolver for TLS_DESC
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- REL relocations that had zero addends. %ebx points to the
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- caller's GOT. %eax points to a TLS descriptor, such that
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- 0(%eax) holds the address of the resolver wrapper itself
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- (unless some other thread beat us to it) and 4(%eax) holds a
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- pointer to the relocation.
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-
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- When the actual resolver returns, it will have adjusted the
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- TLS descriptor such that we can tail-call it for it to return
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- the TP offset of the symbol. */
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-
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- .hidden _dl_tlsdesc_resolve_rel
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- .global _dl_tlsdesc_resolve_rel
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- .type _dl_tlsdesc_resolve_rel,@function
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- cfi_startproc
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- .align 16
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-_dl_tlsdesc_resolve_rel:
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-0:
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- _CET_ENDBR
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- pushl %eax
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- cfi_adjust_cfa_offset (4)
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- pushl %ecx
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- cfi_adjust_cfa_offset (4)
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- pushl %edx
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- cfi_adjust_cfa_offset (4)
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- movl $1f - 0b, %ecx
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- movl 4(%ebx), %edx
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- call _dl_tlsdesc_resolve_rel_fixup
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-1:
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- popl %edx
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- cfi_adjust_cfa_offset (-4)
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- popl %ecx
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- cfi_adjust_cfa_offset (-4)
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- popl %eax
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- cfi_adjust_cfa_offset (-4)
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- jmp *(%eax)
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- cfi_endproc
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- .size _dl_tlsdesc_resolve_rel, .-_dl_tlsdesc_resolve_rel
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-
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- /* This function is a wrapper for a lazy resolver for TLS_DESC
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- RELA relocations. %ebx points to the caller's GOT. %eax
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- points to a TLS descriptor, such that 0(%eax) holds the
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- address of the resolver wrapper itself (unless some other
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- thread beat us to it) and 4(%eax) holds a pointer to the
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- relocation.
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-
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- When the actual resolver returns, it will have adjusted the
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- TLS descriptor such that we can tail-call it for it to return
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- the TP offset of the symbol. */
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-
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- .hidden _dl_tlsdesc_resolve_rela
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- .global _dl_tlsdesc_resolve_rela
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- .type _dl_tlsdesc_resolve_rela,@function
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- cfi_startproc
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- .align 16
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-_dl_tlsdesc_resolve_rela:
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-0:
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- _CET_ENDBR
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- pushl %eax
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- cfi_adjust_cfa_offset (4)
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- pushl %ecx
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- cfi_adjust_cfa_offset (4)
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- pushl %edx
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- cfi_adjust_cfa_offset (4)
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- movl $1f - 0b, %ecx
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- movl 4(%ebx), %edx
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- call _dl_tlsdesc_resolve_rela_fixup
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-1:
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- popl %edx
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- cfi_adjust_cfa_offset (-4)
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- popl %ecx
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- cfi_adjust_cfa_offset (-4)
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- popl %eax
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- cfi_adjust_cfa_offset (-4)
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- jmp *(%eax)
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- cfi_endproc
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- .size _dl_tlsdesc_resolve_rela, .-_dl_tlsdesc_resolve_rela
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-
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- /* This function is a placeholder for lazy resolving of TLS
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- relocations. Once some thread starts resolving a TLS
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- relocation, it sets up the TLS descriptor to use this
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- resolver, such that other threads that would attempt to
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- resolve it concurrently may skip the call to the original lazy
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- resolver and go straight to a condition wait.
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-
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- When the actual resolver returns, it will have adjusted the
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- TLS descriptor such that we can tail-call it for it to return
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- the TP offset of the symbol. */
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-
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- .hidden _dl_tlsdesc_resolve_hold
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- .global _dl_tlsdesc_resolve_hold
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- .type _dl_tlsdesc_resolve_hold,@function
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- cfi_startproc
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- .align 16
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-_dl_tlsdesc_resolve_hold:
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-0:
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- _CET_ENDBR
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- pushl %eax
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- cfi_adjust_cfa_offset (4)
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- pushl %ecx
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- cfi_adjust_cfa_offset (4)
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- pushl %edx
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- cfi_adjust_cfa_offset (4)
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- movl $1f - 0b, %ecx
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- movl 4(%ebx), %edx
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- call _dl_tlsdesc_resolve_hold_fixup
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-1:
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- popl %edx
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- cfi_adjust_cfa_offset (-4)
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- popl %ecx
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- cfi_adjust_cfa_offset (-4)
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- popl %eax
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- cfi_adjust_cfa_offset (-4)
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- jmp *(%eax)
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- cfi_endproc
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- .size _dl_tlsdesc_resolve_hold, .-_dl_tlsdesc_resolve_hold
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diff --git a/sysdeps/i386/dl-tlsdesc.h b/sysdeps/i386/dl-tlsdesc.h
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index c8a1e056150dc418..1a1a22c303baf85b 100644
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--- a/sysdeps/i386/dl-tlsdesc.h
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+++ b/sysdeps/i386/dl-tlsdesc.h
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@@ -43,11 +43,7 @@ struct tlsdesc_dynamic_arg
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extern ptrdiff_t attribute_hidden __attribute__ ((regparm (1)))
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_dl_tlsdesc_return (struct tlsdesc *),
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- _dl_tlsdesc_undefweak (struct tlsdesc *),
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- _dl_tlsdesc_resolve_abs_plus_addend (struct tlsdesc *),
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- _dl_tlsdesc_resolve_rel (struct tlsdesc *),
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- _dl_tlsdesc_resolve_rela (struct tlsdesc *),
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- _dl_tlsdesc_resolve_hold (struct tlsdesc *);
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+ _dl_tlsdesc_undefweak (struct tlsdesc *);
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# ifdef SHARED
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extern void *_dl_make_tlsdesc_dynamic (struct link_map *map,
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diff --git a/sysdeps/i386/tlsdesc.c b/sysdeps/i386/tlsdesc.c
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index 82fa8a1d35fd1912..1b4227c8381e1b3d 100644
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--- a/sysdeps/i386/tlsdesc.c
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+++ b/sysdeps/i386/tlsdesc.c
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@@ -16,242 +16,13 @@
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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-#include <link.h>
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#include <ldsodefs.h>
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-#include <elf/dynamic-link.h>
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#include <tls.h>
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#include <dl-tlsdesc.h>
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#include <dl-unmap-segments.h>
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+#define _dl_tlsdesc_resolve_hold 0
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#include <tlsdeschtab.h>
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-/* The following 4 functions take an entry_check_offset argument.
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- It's computed by the caller as an offset between its entry point
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- and the call site, such that by adding the built-in return address
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- that is implicitly passed to the function with this offset, we can
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- easily obtain the caller's entry point to compare with the entry
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- point given in the TLS descriptor. If it's changed, we want to
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- return immediately. */
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-
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-/* This function is used to lazily resolve TLS_DESC REL relocations
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- that reference the *ABS* segment in their own link maps. The
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- argument is the addend originally stored there. */
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-
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-void
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-__attribute__ ((regparm (3))) attribute_hidden
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-_dl_tlsdesc_resolve_abs_plus_addend_fixup (struct tlsdesc volatile *td,
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- struct link_map *l,
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- ptrdiff_t entry_check_offset)
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-{
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- ptrdiff_t addend = (ptrdiff_t) td->arg;
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-
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- if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
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- - entry_check_offset))
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- return;
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-
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-#ifndef SHARED
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- CHECK_STATIC_TLS (l, l);
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-#else
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- if (!TRY_STATIC_TLS (l, l))
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- {
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- td->arg = _dl_make_tlsdesc_dynamic (l, addend);
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- td->entry = _dl_tlsdesc_dynamic;
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- }
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- else
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-#endif
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- {
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- td->arg = (void*) (addend - l->l_tls_offset);
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- td->entry = _dl_tlsdesc_return;
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- }
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-
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- _dl_tlsdesc_wake_up_held_fixups ();
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-}
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-
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-/* This function is used to lazily resolve TLS_DESC REL relocations
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- that originally had zero addends. The argument location, that
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- originally held the addend, is used to hold a pointer to the
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- relocation, but it has to be restored before we call the function
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- that applies relocations. */
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-
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-void
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-__attribute__ ((regparm (3))) attribute_hidden
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-_dl_tlsdesc_resolve_rel_fixup (struct tlsdesc volatile *td,
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- struct link_map *l,
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- ptrdiff_t entry_check_offset)
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-{
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- const ElfW(Rel) *reloc = td->arg;
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-
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- if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
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- - entry_check_offset))
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- return;
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-
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- /* The code below was borrowed from _dl_fixup(),
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- except for checking for STB_LOCAL. */
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- const ElfW(Sym) *const symtab
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- = (const void *) D_PTR (l, l_info[DT_SYMTAB]);
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- const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
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- const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
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- lookup_t result;
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-
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- /* Look up the target symbol. If the normal lookup rules are not
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- used don't look in the global scope. */
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- if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL
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- && __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
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- {
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- const struct r_found_version *version = NULL;
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-
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- if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
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- {
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- const ElfW(Half) *vernum =
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- (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
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- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
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- version = &l->l_versions[ndx];
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- if (version->hash == 0)
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- version = NULL;
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- }
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-
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- result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
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- l->l_scope, version, ELF_RTYPE_CLASS_PLT,
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- DL_LOOKUP_ADD_DEPENDENCY, NULL);
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- }
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- else
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- {
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- /* We already found the symbol. The module (and therefore its load
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- address) is also known. */
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- result = l;
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- }
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-
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- if (!sym)
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- {
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- td->arg = 0;
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- td->entry = _dl_tlsdesc_undefweak;
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- }
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- else
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- {
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-# ifndef SHARED
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- CHECK_STATIC_TLS (l, result);
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-# else
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- if (!TRY_STATIC_TLS (l, result))
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- {
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- td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value);
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- td->entry = _dl_tlsdesc_dynamic;
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- }
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- else
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-# endif
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- {
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- td->arg = (void*)(sym->st_value - result->l_tls_offset);
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- td->entry = _dl_tlsdesc_return;
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- }
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- }
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-
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- _dl_tlsdesc_wake_up_held_fixups ();
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-}
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-
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-/* This function is used to lazily resolve TLS_DESC RELA relocations.
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- The argument location is used to hold a pointer to the relocation. */
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-
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-void
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-__attribute__ ((regparm (3))) attribute_hidden
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-_dl_tlsdesc_resolve_rela_fixup (struct tlsdesc volatile *td,
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- struct link_map *l,
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- ptrdiff_t entry_check_offset)
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-{
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- const ElfW(Rela) *reloc = td->arg;
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-
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- if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
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- - entry_check_offset))
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- return;
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-
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- /* The code below was borrowed from _dl_fixup(),
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- except for checking for STB_LOCAL. */
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- const ElfW(Sym) *const symtab
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- = (const void *) D_PTR (l, l_info[DT_SYMTAB]);
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- const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
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- const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
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- lookup_t result;
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-
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- /* Look up the target symbol. If the normal lookup rules are not
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- used don't look in the global scope. */
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- if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL
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- && __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
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- {
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- const struct r_found_version *version = NULL;
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-
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- if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
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- {
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- const ElfW(Half) *vernum =
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- (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
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- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
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- version = &l->l_versions[ndx];
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- if (version->hash == 0)
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- version = NULL;
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- }
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-
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- result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
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- l->l_scope, version, ELF_RTYPE_CLASS_PLT,
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- DL_LOOKUP_ADD_DEPENDENCY, NULL);
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- }
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- else
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- {
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- /* We already found the symbol. The module (and therefore its load
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- address) is also known. */
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- result = l;
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- }
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-
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- if (!sym)
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- {
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- td->arg = (void*) reloc->r_addend;
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- td->entry = _dl_tlsdesc_undefweak;
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- }
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- else
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- {
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-# ifndef SHARED
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- CHECK_STATIC_TLS (l, result);
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-# else
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- if (!TRY_STATIC_TLS (l, result))
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- {
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- td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value
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- + reloc->r_addend);
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- td->entry = _dl_tlsdesc_dynamic;
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- }
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- else
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-# endif
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- {
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- td->arg = (void*) (sym->st_value - result->l_tls_offset
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- + reloc->r_addend);
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- td->entry = _dl_tlsdesc_return;
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- }
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- }
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-
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- _dl_tlsdesc_wake_up_held_fixups ();
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-}
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-
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-/* This function is used to avoid busy waiting for other threads to
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- complete the lazy relocation. Once another thread wins the race to
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- relocate a TLS descriptor, it sets the descriptor up such that this
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- function is called to wait until the resolver releases the
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- lock. */
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-
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-void
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-__attribute__ ((regparm (3))) attribute_hidden
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-_dl_tlsdesc_resolve_hold_fixup (struct tlsdesc volatile *td,
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- struct link_map *l __attribute__((__unused__)),
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- ptrdiff_t entry_check_offset)
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-{
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- /* Maybe we're lucky and can return early. */
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- if (__builtin_return_address (0) - entry_check_offset != td->entry)
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- return;
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-
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- /* Locking here will stop execution until the running resolver runs
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- _dl_tlsdesc_wake_up_held_fixups(), releasing the lock.
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-
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- FIXME: We'd be better off waiting on a condition variable, such
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- that we didn't have to hold the lock throughout the relocation
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- processing. */
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- __rtld_lock_lock_recursive (GL(dl_load_lock));
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- __rtld_lock_unlock_recursive (GL(dl_load_lock));
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-}
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-
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-
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/* Unmap the dynamic object, but also release its TLS descriptor table
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if there is one. */
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