From: Dave Hansen <dave.hansen@intel.com>
To: Ram Pai <linuxram@us.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linux-arch@vger.kernel.org, corbet@lwn.net, arnd@arndb.de,
linux-doc@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
mingo@redhat.com, paulus@samba.org,
aneesh.kumar@linux.vnet.ibm.com, linux-kselftest@vger.kernel.org,
akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org,
khandual@linux.vnet.ibm.com
Subject: Re: [RFC v5 12/38] mm: ability to disable execute permission on a key at creation
Date: Tue, 11 Jul 2017 15:19:31 -0700 [thread overview]
Message-ID: <9fbe72be-453f-57e2-861e-5d35fbe95c41@intel.com> (raw)
In-Reply-To: <20170711221434.GB5542@ram.oc3035372033.ibm.com>
On 07/11/2017 03:14 PM, Ram Pai wrote:
> Now how many does the kernel use to reserve for itself is something
> the kernel knows too and hence can expose it, though the information
> may change dynamically as the kernel reserves and releases the key
> based on its internal needs.
>
> So i think we can expose this informaton through procfs/sysfs and let
> the application decide how it wants to use the information.
Why bother? On x86, you'll be told either 14 or 15 depending on whether
you tried to create a mapping in the process without execute permission.
You can't use all 14 or 15 unless you actually call pkey_alloc() anyway
because the /proc check is inherently racy.
I'm just not sure I see the value in creating a new ABI for it.
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: Ram Pai <linuxram@us.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linux-arch@vger.kernel.org, corbet@lwn.net, arnd@arndb.de,
linux-doc@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
mingo@redhat.com, paulus@samba.org,
aneesh.kumar@linux.vnet.ibm.com, linux-kselftest@vger.kernel.org,
akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org,
khandual@linux.vnet.ibm.com
Subject: Re: [RFC v5 12/38] mm: ability to disable execute permission on a key at creation
Date: Tue, 11 Jul 2017 15:19:31 -0700 [thread overview]
Message-ID: <9fbe72be-453f-57e2-861e-5d35fbe95c41@intel.com> (raw)
In-Reply-To: <20170711221434.GB5542@ram.oc3035372033.ibm.com>
On 07/11/2017 03:14 PM, Ram Pai wrote:
> Now how many does the kernel use to reserve for itself is something
> the kernel knows too and hence can expose it, though the information
> may change dynamically as the kernel reserves and releases the key
> based on its internal needs.
>
> So i think we can expose this informaton through procfs/sysfs and let
> the application decide how it wants to use the information.
Why bother? On x86, you'll be told either 14 or 15 depending on whether
you tried to create a mapping in the process without execute permission.
You can't use all 14 or 15 unless you actually call pkey_alloc() anyway
because the /proc check is inherently racy.
I'm just not sure I see the value in creating a new ABI for it.
--
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next prev parent reply other threads:[~2017-07-11 22:19 UTC|newest]
Thread overview: 191+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-05 21:21 [RFC v5 00/38] powerpc: Memory Protection Keys Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 01/38] powerpc: Free up four 64K PTE bits in 4K backed HPTE pages Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-07 7:25 ` Balbir Singh
2017-07-07 7:25 ` Balbir Singh
2017-07-07 7:25 ` Balbir Singh
2017-07-05 21:21 ` [RFC v5 02/38] powerpc: Free up four 64K PTE bits in 64K " Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-11 5:59 ` Balbir Singh
2017-07-11 5:59 ` Balbir Singh
2017-07-11 15:44 ` Ram Pai
2017-07-11 15:44 ` Ram Pai
2017-07-12 3:10 ` Balbir Singh
2017-07-12 3:10 ` Balbir Singh
2017-07-13 7:39 ` Ram Pai
2017-07-13 7:39 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 03/38] powerpc: introduce pte_set_hash_slot() helper Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 04/38] powerpc: introduce pte_get_hash_gslot() helper Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 05/38] powerpc: capture the PTE format changes in the dump pte report Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 06/38] powerpc: use helper functions in __hash_page_64K() for 64K PTE Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 07/38] powerpc: use helper functions in __hash_page_huge() " Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 08/38] powerpc: use helper functions in __hash_page_4K() " Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 09/38] powerpc: use helper functions in __hash_page_4K() for 4K PTE Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 10/38] powerpc: use helper functions in flush_hash_page() Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 11/38] mm: introduce an additional vma bit for powerpc pkey Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-11 18:10 ` Dave Hansen
2017-07-11 18:10 ` Dave Hansen
2017-07-12 22:23 ` Ram Pai
2017-07-12 22:23 ` Ram Pai
2017-07-12 22:40 ` Benjamin Herrenschmidt
2017-07-12 22:40 ` Benjamin Herrenschmidt
2017-07-05 21:21 ` [RFC v5 12/38] mm: ability to disable execute permission on a key at creation Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-11 18:11 ` Dave Hansen
2017-07-11 18:11 ` Dave Hansen
2017-07-11 21:29 ` Benjamin Herrenschmidt
2017-07-11 21:29 ` Benjamin Herrenschmidt
2017-07-11 21:51 ` Ram Pai
2017-07-11 21:51 ` Ram Pai
2017-07-11 21:57 ` Dave Hansen
2017-07-11 21:57 ` Dave Hansen
2017-07-11 22:14 ` Ram Pai
2017-07-11 22:14 ` Ram Pai
2017-07-11 22:19 ` Dave Hansen [this message]
2017-07-11 22:19 ` Dave Hansen
2017-07-11 22:08 ` Benjamin Herrenschmidt
2017-07-11 22:08 ` Benjamin Herrenschmidt
2017-07-11 22:19 ` Ram Pai
2017-07-11 22:19 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 13/38] x86: disallow pkey creation with PKEY_DISABLE_EXECUTE Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-11 18:12 ` Dave Hansen
2017-07-11 18:12 ` Dave Hansen
2017-07-05 21:21 ` [RFC v5 14/38] powerpc: initial plumbing for key management Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-12 3:28 ` Balbir Singh
2017-07-12 3:28 ` Balbir Singh
2017-07-13 7:45 ` Ram Pai
2017-07-13 7:45 ` Ram Pai
2017-07-13 20:37 ` Ram Pai
2017-07-13 20:37 ` Ram Pai
2017-07-13 21:30 ` Balbir Singh
2017-07-13 21:30 ` Balbir Singh
2017-07-13 21:30 ` Balbir Singh
2017-07-13 21:30 ` Balbir Singh
2017-07-05 21:21 ` [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers Ram Pai
2017-07-05 21:21 ` [RFC v5 15/38] powerpc: helper function to read, write AMR, IAMR, UAMOR registers Ram Pai
2017-07-05 21:21 ` [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers Ram Pai
2017-07-12 5:26 ` Balbir Singh
2017-07-12 5:26 ` Balbir Singh
2017-07-13 7:55 ` Ram Pai
2017-07-13 7:55 ` Ram Pai
2017-07-13 9:49 ` Balbir Singh
2017-07-13 9:49 ` Balbir Singh
2017-07-13 9:49 ` Balbir Singh
2017-07-13 23:29 ` Ram Pai
2017-07-13 23:29 ` Ram Pai
2017-07-13 23:29 ` Ram Pai
2017-07-13 23:29 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 16/38] powerpc: implementation for arch_set_user_pkey_access() Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 17/38] powerpc: sys_pkey_alloc() and sys_pkey_free() system calls Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 18/38] powerpc: store and restore the pkey state across context switches Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 19/38] powerpc: introduce execute-only pkey Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 20/38] powerpc: ability to associate pkey to a vma Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 21/38] powerpc: implementation for arch_override_mprotect_pkey() Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:21 ` [RFC v5 22/38] powerpc: map vma key-protection bits to pte key bits Ram Pai
2017-07-05 21:21 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 23/38] powerpc: sys_pkey_mprotect() system call Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 24/38] powerpc: Program HPTE key protection bits Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 25/38] powerpc: helper to validate key-access permissions of a pte Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 26/38] powerpc: check key protection for user page access Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 27/38] powerpc: Macro the mask used for checking DSI exception Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 28/38] powerpc: implementation for arch_vma_access_permitted() Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 29/38] powerpc: Handle exceptions caused by pkey violation Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 30/38] powerpc: capture AMR register content on " Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 31/38] powerpc: introduce get_pte_pkey() helper Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-10 3:11 ` Anshuman Khandual
2017-07-10 3:11 ` Anshuman Khandual
2017-07-10 5:55 ` Ram Pai
2017-07-10 5:55 ` Ram Pai
2017-07-11 11:22 ` Anshuman Khandual
2017-07-11 11:22 ` Anshuman Khandual
2017-07-05 21:22 ` [RFC v5 32/38] powerpc: capture the violated protection key on fault Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-10 3:10 ` Anshuman Khandual
2017-07-10 3:10 ` Anshuman Khandual
2017-07-10 5:49 ` Ram Pai
2017-07-10 5:49 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 33/38] powerpc: Deliver SEGV signal on pkey violation Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-10 3:08 ` Anshuman Khandual
2017-07-10 3:08 ` Anshuman Khandual
2017-07-05 21:22 ` [RFC v5 34/38] procfs: display the protection-key number associated with a vma Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-10 3:07 ` Anshuman Khandual
2017-07-10 3:07 ` Anshuman Khandual
2017-07-10 6:01 ` Ram Pai
2017-07-10 6:01 ` Ram Pai
2017-07-11 18:13 ` Dave Hansen
2017-07-11 18:13 ` Dave Hansen
2017-07-13 8:03 ` Ram Pai
2017-07-13 8:03 ` Ram Pai
2017-07-13 14:07 ` Dave Hansen
2017-07-13 14:07 ` Dave Hansen
2017-07-13 17:04 ` Ram Pai
2017-07-13 17:04 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 35/38] selftest: Move protecton key selftest to arch neutral directory Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 36/38] selftest: PowerPC specific test updates to memory protection keys Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-11 17:33 ` Dave Hansen
2017-07-11 17:33 ` Dave Hansen
2017-07-12 21:57 ` Ram Pai
2017-07-12 21:57 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 37/38] Documentation: Move protecton key documentation to arch neutral directory Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-05 21:22 ` [RFC v5 38/38] Documentation: PowerPC specific updates to memory protection keys Ram Pai
2017-07-05 21:22 ` Ram Pai
2017-07-10 3:07 ` Anshuman Khandual
2017-07-10 3:07 ` Anshuman Khandual
2017-07-10 5:59 ` Ram Pai
2017-07-10 5:59 ` Ram Pai
2017-07-11 18:23 ` Dave Hansen
2017-07-11 18:23 ` Dave Hansen
2017-07-13 19:56 ` Ram Pai
2017-07-13 19:56 ` Ram Pai
2017-07-10 5:43 ` [RFC v5 00/38] powerpc: Memory Protection Keys Anshuman Khandual
2017-07-10 5:43 ` Anshuman Khandual
2017-07-10 6:05 ` Ram Pai
2017-07-10 6:05 ` Ram Pai
2017-07-10 17:15 ` Ram Pai
2017-07-10 17:15 ` Ram Pai
2017-07-11 14:52 ` Michal Hocko
2017-07-11 14:52 ` Michal Hocko
2017-07-11 19:32 ` Ram Pai
2017-07-11 19:32 ` Ram Pai
2017-07-11 21:30 ` Benjamin Herrenschmidt
2017-07-11 21:30 ` Benjamin Herrenschmidt
2017-07-12 7:23 ` Michal Hocko
2017-07-12 7:23 ` Michal Hocko
2017-07-12 7:39 ` Michal Hocko
2017-07-12 7:39 ` Michal Hocko
2017-07-12 22:53 ` Benjamin Herrenschmidt
2017-07-12 22:53 ` Benjamin Herrenschmidt
2017-07-13 6:20 ` Michal Hocko
2017-07-13 6:20 ` Michal Hocko
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