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From 35ea7549751d4f13a28c732e6ad68204f5e60a06 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 20 Dec 2023 16:31:43 -0800
Subject: [PATCH 4/9] x86-64: Fix the dtv field load for x32 [BZ #31184]
On x32, I got
FAIL: elf/tst-tlsgap
$ gdb elf/tst-tlsgap
...
open tst-tlsgap-mod1.so
Thread 2 "tst-tlsgap" received signal SIGSEGV, Segmentation fault.
[Switching to LWP 2268754]
_dl_tlsdesc_dynamic () at ../sysdeps/x86_64/dl-tlsdesc.S:108
108 movq (%rsi), %rax
(gdb) p/x $rsi
$4 = 0xf7dbf9005655fb18
(gdb)
This is caused by
_dl_tlsdesc_dynamic:
_CET_ENDBR
/* Preserve call-clobbered registers that we modify.
We need two scratch regs anyway. */
movq %rsi, -16(%rsp)
movq %fs:DTV_OFFSET, %rsi
Since the dtv field in TCB is a pointer, %fs:DTV_OFFSET is a 32-bit
location, not 64-bit. Load the dtv field to RSI_LP instead of rsi.
This fixes BZ #31184.
(cherry picked from commit 3502440397bbb840e2f7223734aa5cc2cc0e29b6)
---
NEWS | 1 +
sysdeps/x86_64/dl-tlsdesc.S | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/NEWS b/NEWS
index 5ac488bf9b..71057e4793 100644
--- a/NEWS
+++ b/NEWS
@@ -37,6 +37,7 @@ The following bugs are resolved with this release:
[30804] F_GETLK, F_SETLK, and F_SETLKW value change for powerpc64 with
-D_FILE_OFFSET_BITS=64
[30842] Stack read overflow in getaddrinfo in no-aaaa mode (CVE-2023-4527)
+ [31184] FAIL: elf/tst-tlsgap
Version 2.38
diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
index 5593897e29..c4823547d7 100644
--- a/sysdeps/x86_64/dl-tlsdesc.S
+++ b/sysdeps/x86_64/dl-tlsdesc.S
@@ -102,7 +102,7 @@ _dl_tlsdesc_dynamic:
/* Preserve call-clobbered registers that we modify.
We need two scratch regs anyway. */
movq %rsi, -16(%rsp)
- movq %fs:DTV_OFFSET, %rsi
+ mov %fs:DTV_OFFSET, %RSI_LP
movq %rdi, -8(%rsp)
movq TLSDESC_ARG(%rax), %rdi
movq (%rsi), %rax
--
2.33.0
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