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Message-Id: <20230826141632.1488740-1-ammarfaizi2@gnuweeb.org>
Date: Sat, 26 Aug 2023 21:16:31 +0700
From: Ammar Faizi <ammarfaizi2@...weeb.org>
To: Willy Tarreau <w@....eu>,
Thomas Weißschuh <linux@...ssschuh.net>
Cc: Ammar Faizi <ammarfaizi2@...weeb.org>,
Zhangjin Wu <falcon@...ylab.org>,
Nicholas Rosenberg <inori@...x.org>,
GNU/Weeb Mailing List <gwml@...r.gnuweeb.org>,
Michael William Jonathan <moe@...weeb.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH v1 0/1] Fix a stack misalign bug on _start
Hi Willy,
Just a single quick fix.
The ABI mandates that the %esp register must be a multiple of 16 when
executing a call instruction.
Commit 2ab446336b17 simplified the _start function, but it didn't take
care of the %esp alignment, causing SIGSEGV on SSE and AVX programs that
use aligned move instruction (e.g., movdqa, movaps, and vmovdqa).
$eax : 0x56559000 → 0x00003f90
$ebx : 0x56559000 → 0x00003f90
$ecx : 0x1
$edx : 0xf7fcaaa0 → endbr32
$esp : 0xffffcdbc → 0x00000001
$ebp : 0x0
$esi : 0xffffce7c → 0xffffd096
$edi : 0x56556060 → <_start+0> xor %ebp, %ebp
$eip : 0x56556489 → <sse_pq_add+25> movaps %xmm0, 0x30(%esp)
<sse_pq_add+11> pop %eax
<sse_pq_add+12> add $0x2b85, %eax
<sse_pq_add+18> movups -0x1fd0(%eax), %xmm0
→ <sse_pq_add+25> movaps %xmm0, 0x30(%esp) <== trapping instruction
<sse_pq_add+30> movups -0x1fe0(%eax), %xmm1
<sse_pq_add+37> movaps %xmm1, 0x20(%esp)
<sse_pq_add+42> movups -0x1ff0(%eax), %xmm2
<sse_pq_add+49> movaps %xmm2, 0x10(%esp)
<sse_pq_add+54> movups -0x2000(%eax), %xmm3
[#0] Id 1, Name: "test", stopped 0x56556489 in sse_pq_add (), reason: SIGSEGV
(gdb) bt
#0 0x56556489 in sse_pq_add ()
#1 0x5655608e in main ()
Ensure the %esp is a multiple of 16 when executing the call instruction.
Signed-off-by: Ammar Faizi <ammarfaizi2@...weeb.org>
---
Ammar Faizi (1):
tools/nolibc: i386: Fix a stack misalign bug on _start
tools/include/nolibc/arch-i386.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
base-commit: 6269320850097903b30be8f07a5c61d9f7592393
--
Ammar Faizi
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