From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org,
Libc-stable Mailing List <libc-stable@sourceware.org>
Subject: Re: [PATCH] x86-64: Fix the dtv field load for x32 [BZ #31184]
Date: Thu, 21 Dec 2023 08:08:19 -0800 [thread overview]
Message-ID: <CAMe9rOqT=KoPZNjRGNBakfS2gtzZaHONc8s79rYVedHJC=1nig@mail.gmail.com> (raw)
In-Reply-To: <20231221003143.2289327-1-hjl.tools@gmail.com>
On Wed, Dec 20, 2023 at 4:31 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> 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.
> ---
> sysdeps/x86_64/dl-tlsdesc.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> 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
> --
> 2.43.0
>
I will check it in tomorrow and back it to release branches later.
Thanks.
--
H.J.
parent reply other threads:[~2023-12-21 16:08 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20231221003143.2289327-1-hjl.tools@gmail.com>]
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