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authorH.J. Lu <hjl.tools@gmail.com>2023-12-20 19:42:12 -0800
committerH.J. Lu <hjl.tools@gmail.com>2023-12-22 05:37:17 -0800
commit81be2a61dafc168327c1639e97b6dae128c7ccf3 (patch)
tree0f56678699b9deab602178f811dd9f0c45a22472
parent3502440397bbb840e2f7223734aa5cc2cc0e29b6 (diff)
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x86-64: Fix the tcb field load for x32 [BZ #31185]
_dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic access the thread pointer
via the tcb field in TCB:

_dl_tlsdesc_undefweak:
        _CET_ENDBR
        movq    8(%rax), %rax
        subq    %fs:0, %rax
        ret

_dl_tlsdesc_dynamic:
	...
        subq    %fs:0, %rax
        movq    -8(%rsp), %rdi
        ret

Since the tcb field in TCB is a pointer, %fs:0 is a 32-bit location,
not 64-bit. It should use "sub %fs:0, %RAX_LP" instead.  Since
_dl_tlsdesc_undefweak returns ptrdiff_t and _dl_make_tlsdesc_dynamic
returns void *, RAX_LP is appropriate here for x32 and x86-64.  This
fixes BZ #31185.
-rw-r--r--sysdeps/x86_64/dl-tlsdesc.S4
1 files changed, 2 insertions, 2 deletions
diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
index c4823547d7..4579424bf7 100644
--- a/sysdeps/x86_64/dl-tlsdesc.S
+++ b/sysdeps/x86_64/dl-tlsdesc.S
@@ -61,7 +61,7 @@ _dl_tlsdesc_return:
 _dl_tlsdesc_undefweak:
 	_CET_ENDBR
 	movq	8(%rax), %rax
-	subq	%fs:0, %rax
+	sub	%fs:0, %RAX_LP
 	ret
 	cfi_endproc
 	.size	_dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
@@ -116,7 +116,7 @@ _dl_tlsdesc_dynamic:
 	addq	TLSDESC_MODOFF(%rdi), %rax
 .Lret:
 	movq	-16(%rsp), %rsi
-	subq	%fs:0, %rax
+	sub	%fs:0, %RAX_LP
 	movq	-8(%rsp), %rdi
 	ret
 .Lslow: