From 81be2a61dafc168327c1639e97b6dae128c7ccf3 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Wed, 20 Dec 2023 19:42:12 -0800 Subject: [PATCH] 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. --- sysdeps/x86_64/dl-tlsdesc.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S index c482354..4579424 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: -- 2.7.4