From: Richard Henderson <1903833@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1903833] Re: User mode qemu-aarch: SIGGSEGV signal handler works wrong
Date: Thu, 12 Nov 2020 21:37:50 -0000 [thread overview]
Message-ID: <160521707016.4731.18065852811276703137.malone@soybean.canonical.com> (raw)
In-Reply-To: 160508996361.28374.9424687449463676251.malonedeb@gac.canonical.com
The patch is most definitely wrong. The page protection
is required to implement self-modifying code, of which a
signal trampoline is a subset.
Moreover, your test case works for me using both
x86_64-linux and aarch64-linux as hosts.
There may be a bug, but I suspect it to be within WSL.
I have no way to test that one way or another.
** Changed in: qemu
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/1903833
Title:
User mode qemu-aarch: SIGGSEGV signal handler works wrong
Status in QEMU:
Incomplete
Bug description:
I have a user mode qemu-aarch issue. Program with SIGSEGV signal handler works wrong under qemu-aarch:
once the progam handles the SEGV signal, qemu marks the program's page protected, and signal handler gets SEGV on each subsequent memory access instruction within a program.
The issue is reproduced on WSL Ubuntu 20.04 under Windows 10, qemu-aarch64 version 5.1.50
The issue is also reproducible on the latest upstream qemu-aarch build.
The following workaround disables mprotect call and fixes the issue:
https://github.com/BorisUlasevich/qemu/commit/3063d9a64f8395185d65c6b6710d28ee92cd8be5
The issue can be reproduced on OpenJDK which reports SIGSEGV
immediately after start. The small reproducer program is attached.
To manage notifications about this bug go to:
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next prev parent reply other threads:[~2020-11-12 22:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-11 10:19 [Bug 1903833] [NEW] User mode qemu-aarch: SIGGSEGV signal handler works wrong Boris
2020-11-12 21:37 ` Richard Henderson [this message]
2021-01-12 4:17 ` [Bug 1903833] " Launchpad Bug Tracker
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