From: Andreas Rammhold <andi@notmuch.email>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Babu Moger <Babu.Moger@amd.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Jason Yan <yanaijie@huawei.com>,
Brendan Shanks <bshanks@codeweavers.com>,
linux-kernel@vger.kernel.org
Subject: umip: AMD Ryzen 3900X, pagefault after emulate SLDT/SIDT instruction
Date: Tue, 19 May 2020 16:38:15 +0200 [thread overview]
Message-ID: <20200519143815.cpsd2xfx2kl3khsq@wrt> (raw)
Hi,
I've been running into a weird problem with UMIP on a current Ryzen
3900x with kernel 5.6.11 where a process receives a page fault after the
kernel handled the SLDT (or SIDT) instruction (emulation).
The program I am running is run through WINE in 32bit mode and tries to
figure out if it is running in a VMWare machine by comparing the results
of SLDT against well known constants (basically as shown in the
[example] linked below).
In dmesg I see the following log lines:
> [99970.004756] umip: Program.exe[3080] ip:4373fb sp:32f3e0: SIDT instruction cannot be used by applications.
> [99970.004757] umip: Program.exe[3080] ip:4373fb sp:32f3e0: For now, expensive software emulation returns the result.
> [99970.004758] umip: Program.exe[3080] ip:437415 sp:32f3e0: SLDT instruction cannot be used by applications.
Following that the process terminates with a page fault:
> Unhandled exception: page fault on read access to 0xffffffff in 32-bit code (0x0000000000437415).
Assembly at that address:
> 0x0000000000437415: sldt 0xffffffe8(%ebp)
Running the same executable on the exact same kernel (and userland) but
on a Intel i7-8565U doesn't crash at this point. I am guessing the
emulation is supposed to do something different on AMD CPUs?
On the Ryzen the code executes successfully after setting CONFIG_X86_UMIP=n.
I'd love to contriubte a patch but I have no knowledge of the inner
workings of how UMIP actually works.
Is there anything else I can provide to help debugging/fixing this? Very
happy to test patches as well.
[example] https://www.aldeid.com/wiki/X86-assembly/Instructions/sldt
next reply other threads:[~2020-05-19 14:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 14:38 Andreas Rammhold [this message]
2020-05-19 18:56 ` umip: AMD Ryzen 3900X, pagefault after emulate SLDT/SIDT instruction Brendan Shanks
2020-05-19 19:43 ` Ricardo Neri
2020-05-20 0:54 ` Andy Lutomirski
2020-05-21 0:56 ` Ricardo Neri
2020-05-21 1:16 ` Andy Lutomirski
2020-05-20 1:04 ` andi
2020-05-23 2:17 ` Andreas Rammhold
2020-05-26 13:33 ` Ricardo Neri
2020-05-28 11:36 ` Andreas Rammhold
2020-05-20 1:08 ` andi
2020-05-23 2:21 ` andi
2020-05-20 0:17 ` H. Peter Anvin
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