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.

diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
index 5593897..c482354 100644 (file)
--- 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