[glibc/release/2.35/master] x86-64: Fix the dtv field load for x32 [BZ #31184]

[H.J. Lu <hjl@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2d87262c1c4ed877a51a4689db0ac2e08fba2f43

commit 2d87262c1c4ed877a51a4689db0ac2e08fba2f43
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Dec 20 16:31:43 2023 -0800

    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)

Diff:
---
 NEWS                        | 1 +
 sysdeps/x86_64/dl-tlsdesc.S | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 70936f90a9..e4777c13da 100644
--- a/NEWS
+++ b/NEWS
@@ -84,6 +84,7 @@ The following bugs are resolved with this release:
   [30515] _dl_find_object incorrectly returns 1 during early startup
   [30804] F_GETLK, F_SETLK, and F_SETLKW value change for powerpc64 with
     -D_FILE_OFFSET_BITS=64
+  [31184] FAIL: elf/tst-tlsgap
 
 Security related changes:
 
diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
index 0db2cb4152..706856e095 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