linux-kernel - Re: x86/fpu/xsave: protection key test failures

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Message-ID: <e0dbd490-0209-9f74-36b7-c55992060b44@intel.com>
Date:   Tue, 25 May 2021 17:20:22 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Babu Moger <babu.moger@....com>, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, dave.hansen@...ux.intel.com, luto@...nel.org,
        peterz@...radead.org, shuah@...nel.org, jroedel@...e.de,
        ubizjak@...il.com, viro@...iv.linux.org.uk, jpa@....mail.kapsi.fi,
        fenghua.yu@...el.com, kan.liang@...ux.intel.com,
        akpm@...ux-foundation.org, rppt@...nel.org, Fan_Yang@...u.edu.cn,
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        dave.kleikamp@...cle.com
Subject: Re: x86/fpu/xsave: protection key test failures

On 5/25/21 5:03 PM, Babu Moger wrote:
>> What values do PKRU and the shadow have when the test fails?  Is PKRU 0?
> It goes back to default value 0x55555554. The test is expecting it to be
> 0. Printed them below.
> 
> test_ptrace_of_child()::1346, pkey_reg: 0x0000000055555554 shadow:
> 0000000000000000
> protection_keys_64: pkey-helpers.h:127: _read_pkey_reg: Assertion
> `pkey_reg == shadow_pkey_reg' failed.

That's backwards (shadow vs pkru) from what I was expecting.

Can you turn on all the debuging?

Just compile with -DDEBUG_LEVEL=5