From: Ram Pai <linuxram@us.ibm.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: shuahkh@osg.samsung.com, linux-kselftest@vger.kernel.org,
mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org,
mingo@redhat.com, mhocko@kernel.org, bauerman@linux.vnet.ibm.com,
fweimer@redhat.com, msuchanek@suse.de,
aneesh.kumar@linux.vnet.ibm.com
Subject: Re: [PATCH v13 08/24] selftests/vm: fix the wrong assert in pkey_disable_set()
Date: Tue, 17 Jul 2018 08:58:48 -0700 [thread overview]
Message-ID: <20180717155848.GA5790@ram.oc3035372033.ibm.com> (raw)
In-Reply-To: <3c441309-1d35-eead-0c5d-1d7d20018219@intel.com>
On Wed, Jun 20, 2018 at 07:47:02AM -0700, Dave Hansen wrote:
> On 06/13/2018 05:44 PM, Ram Pai wrote:
> > If the flag is 0, no bits will be set. Hence we cant expect
> > the resulting bitmap to have a higher value than what it
> > was earlier
> ...
> > if (flags)
> > - pkey_assert(read_pkey_reg() > orig_pkey_reg);
> > + pkey_assert(read_pkey_reg() >= orig_pkey_reg);
> > dprintf1("END<---%s(%d, 0x%x)\n", __func__,
> > pkey, flags);
> > }
>
> This is the kind of thing where I'd love to hear the motivation and
> background. This "disable a key that was already disabled" operation
> obviously doesn't happen today. What motivated you to change it now?
On powerpc, hardware supports READ_DISABLE and WRITE_DISABLE.
ACCESS_DISABLE is basically READ_DISABLE|WRITE_DISABLE on powerpc.
If access disable is called on a key followed by a write disable, the
second operation becomes a nop. In such cases,
read_pkey_reg() == orig_pkey_reg
Hence the code above is modified to
pkey_assert(read_pkey_reg() >= orig_pkey_reg);
--
Ram Pai
next prev parent reply other threads:[~2018-07-17 15:59 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-14 0:44 [PATCH v13 00/24] selftests, powerpc, x86 : Memory Protection Keys Ram Pai
2018-06-14 0:44 ` [PATCH v13 01/24] selftests/x86: Move protecton key selftest to arch neutral directory Ram Pai
2018-06-14 0:44 ` [PATCH v13 02/24] selftests/vm: rename all references to pkru to a generic name Ram Pai
2018-06-14 0:44 ` [PATCH v13 03/24] selftests/vm: move generic definitions to header file Ram Pai
2018-06-14 0:44 ` [PATCH v13 04/24] selftests/vm: move arch-specific definitions to arch-specific header Ram Pai
2018-06-14 0:44 ` [PATCH v13 05/24] selftests/vm: Make gcc check arguments of sigsafe_printf() Ram Pai
2018-06-14 0:44 ` [PATCH v13 06/24] selftests/vm: typecast the pkey register Ram Pai
2018-06-14 0:44 ` [PATCH v13 07/24] selftests/vm: generic function to handle shadow key register Ram Pai
2018-06-14 0:44 ` [PATCH v13 08/24] selftests/vm: fix the wrong assert in pkey_disable_set() Ram Pai
2018-06-20 14:47 ` Dave Hansen
2018-07-17 15:58 ` Ram Pai [this message]
2018-07-17 17:53 ` Dave Hansen
2018-06-14 0:45 ` [PATCH v13 09/24] selftests/vm: fixed bugs in pkey_disable_clear() Ram Pai
2018-06-14 0:45 ` [PATCH v13 10/24] selftests/vm: clear the bits in shadow reg when a pkey is freed Ram Pai
2018-06-20 14:49 ` Dave Hansen
2018-07-17 16:00 ` Ram Pai
2018-06-14 0:45 ` [PATCH v13 11/24] selftests/vm: fix alloc_random_pkey() to make it really random Ram Pai
2018-06-14 0:45 ` [PATCH v13 12/24] selftests/vm: introduce two arch independent abstraction Ram Pai
2018-06-14 0:45 ` [PATCH v13 13/24] selftests/vm: pkey register should match shadow pkey Ram Pai
2018-06-20 14:53 ` Dave Hansen
2018-07-17 16:02 ` Ram Pai
2018-06-14 0:45 ` [PATCH v13 14/24] selftests/vm: generic cleanup Ram Pai
2018-06-20 14:57 ` Dave Hansen
2018-06-14 0:45 ` [PATCH v13 15/24] selftests/vm: powerpc implementation for generic abstraction Ram Pai
2018-06-20 15:06 ` Dave Hansen
2018-06-14 0:45 ` [PATCH v13 16/24] selftests/vm: clear the bits in shadow reg when a pkey is freed Ram Pai
2018-06-20 15:07 ` Dave Hansen
2018-07-17 16:03 ` Ram Pai
2018-06-14 0:45 ` [PATCH v13 17/24] selftests/vm: powerpc implementation to check support for pkey Ram Pai
2018-06-20 15:09 ` Dave Hansen
2018-07-17 16:05 ` Ram Pai
2018-06-14 0:45 ` [PATCH v13 18/24] selftests/vm: fix an assertion in test_pkey_alloc_exhaust() Ram Pai
2018-06-20 15:11 ` Dave Hansen
2018-07-17 16:08 ` Ram Pai
2018-06-14 0:45 ` [PATCH v13 19/24] selftests/vm: associate key on a mapped page and detect access violation Ram Pai
2018-06-20 15:16 ` Dave Hansen
2018-07-17 16:13 ` Ram Pai
2018-07-17 17:56 ` Dave Hansen
2018-07-17 19:10 ` Ram Pai
2018-06-14 0:45 ` [PATCH v13 20/24] selftests/vm: associate key on a mapped page and detect write violation Ram Pai
2018-06-14 0:45 ` [PATCH v13 21/24] selftests/vm: detect write violation on a mapped access-denied-key page Ram Pai
2018-06-14 0:45 ` [PATCH v13 22/24] selftests/vm: testcases must restore pkey-permissions Ram Pai
2018-06-20 15:20 ` Dave Hansen
2018-07-17 16:09 ` Ram Pai
2018-06-14 0:45 ` [PATCH v13 23/24] selftests/vm: sub-page allocator Ram Pai
2018-06-14 0:45 ` [PATCH v13 24/24] selftests/vm: test correct behavior of pkey-0 Ram Pai
2018-06-20 15:22 ` Dave Hansen
2018-06-14 20:19 ` [PATCH v13 00/24] selftests, powerpc, x86 : Memory Protection Keys Florian Weimer
2018-06-15 0:58 ` Ram Pai
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