From: Changbin Du <changbin.du@gmail.com>
To: Jonathan Corbet <corbet@lwn.net>
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
x86@kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, mchehab+samsung@kernel.org,
Changbin Du <changbin.du@gmail.com>
Subject: [PATCH 12/27] Documentation: x86: convert protection-keys.txt to reST
Date: Fri, 26 Apr 2019 23:31:35 +0800 [thread overview]
Message-ID: <20190426153150.21228-13-changbin.du@gmail.com> (raw)
In-Reply-To: <20190426153150.21228-1-changbin.du@gmail.com>
This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.
Signed-off-by: Changbin Du <changbin.du@gmail.com>
---
Documentation/x86/index.rst | 1 +
...rotection-keys.txt => protection-keys.rst} | 33 ++++++++++++-------
2 files changed, 22 insertions(+), 12 deletions(-)
rename Documentation/x86/{protection-keys.txt => protection-keys.rst} (83%)
diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
index e06b5c0ea883..576628b121cc 100644
--- a/Documentation/x86/index.rst
+++ b/Documentation/x86/index.rst
@@ -18,3 +18,4 @@ Linux x86 Support
tlb
mtrr
pat
+ protection-keys
diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.rst
similarity index 83%
rename from Documentation/x86/protection-keys.txt
rename to Documentation/x86/protection-keys.rst
index ecb0d2dadfb7..49d9833af871 100644
--- a/Documentation/x86/protection-keys.txt
+++ b/Documentation/x86/protection-keys.rst
@@ -1,3 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+Memory Protection Keys
+======================
+
Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature
which is found on Intel's Skylake "Scalable Processor" Server CPUs.
It will be avalable in future non-server parts.
@@ -23,9 +29,10 @@ even though there is theoretically space in the PAE PTEs. These
permissions are enforced on data access only and have no effect on
instruction fetches.
-=========================== Syscalls ===========================
+Syscalls
+========
-There are 3 system calls which directly interact with pkeys:
+There are 3 system calls which directly interact with pkeys::
int pkey_alloc(unsigned long flags, unsigned long init_access_rights)
int pkey_free(int pkey);
@@ -37,6 +44,7 @@ pkey_alloc(). An application calls the WRPKRU instruction
directly in order to change access permissions to memory covered
with a key. In this example WRPKRU is wrapped by a C function
called pkey_set().
+::
int real_prot = PROT_READ|PROT_WRITE;
pkey = pkey_alloc(0, PKEY_DISABLE_WRITE);
@@ -45,43 +53,44 @@ called pkey_set().
... application runs here
Now, if the application needs to update the data at 'ptr', it can
-gain access, do the update, then remove its write access:
+gain access, do the update, then remove its write access::
pkey_set(pkey, 0); // clear PKEY_DISABLE_WRITE
*ptr = foo; // assign something
pkey_set(pkey, PKEY_DISABLE_WRITE); // set PKEY_DISABLE_WRITE again
Now when it frees the memory, it will also free the pkey since it
-is no longer in use:
+is no longer in use::
munmap(ptr, PAGE_SIZE);
pkey_free(pkey);
-(Note: pkey_set() is a wrapper for the RDPKRU and WRPKRU instructions.
- An example implementation can be found in
- tools/testing/selftests/x86/protection_keys.c)
+.. note:: pkey_set() is a wrapper for the RDPKRU and WRPKRU instructions.
+ An example implementation can be found in
+ tools/testing/selftests/x86/protection_keys.c.
-=========================== Behavior ===========================
+Behavior
+========
The kernel attempts to make protection keys consistent with the
-behavior of a plain mprotect(). For instance if you do this:
+behavior of a plain mprotect(). For instance if you do this::
mprotect(ptr, size, PROT_NONE);
something(ptr);
-you can expect the same effects with protection keys when doing this:
+you can expect the same effects with protection keys when doing this::
pkey = pkey_alloc(0, PKEY_DISABLE_WRITE | PKEY_DISABLE_READ);
pkey_mprotect(ptr, size, PROT_READ|PROT_WRITE, pkey);
something(ptr);
That should be true whether something() is a direct access to 'ptr'
-like:
+like::
*ptr = foo;
or when the kernel does the access on the application's behalf like
-with a read():
+with a read()::
read(fd, ptr, 1);
--
2.20.1
next prev parent reply other threads:[~2019-04-26 15:33 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 15:31 [PATCH 00/27] Include linux x86 docs into Sphinx TOC tree Changbin Du
2019-04-26 15:31 ` [PATCH 01/27] Documentation: add Linux x86 docs to " Changbin Du
2019-04-26 16:16 ` Borislav Petkov
2019-04-27 2:43 ` Changbin Du
2019-04-26 15:31 ` [PATCH 02/27] Documentation: x86: convert boot.txt to reST Changbin Du
2019-04-27 14:31 ` Mauro Carvalho Chehab
2019-05-02 6:59 ` Changbin Du
2019-04-26 15:31 ` [PATCH 03/27] Documentation: x86: convert topology.txt " Changbin Du
2019-04-27 14:41 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 04/27] Documentation: x86: convert exception-tables.txt " Changbin Du
2019-04-27 14:48 ` Mauro Carvalho Chehab
2019-05-02 3:19 ` Changbin Du
2019-04-26 15:31 ` [PATCH 05/27] Documentation: x86: convert kernel-stacks " Changbin Du
2019-04-27 14:50 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 06/27] Documentation: x86: convert entry_64.txt " Changbin Du
2019-04-27 14:52 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 07/27] Documentation: x86: convert earlyprintk.txt " Changbin Du
2019-04-27 17:17 ` Mauro Carvalho Chehab
2019-05-02 3:27 ` Changbin Du
2019-04-26 15:31 ` [PATCH 08/27] Documentation: x86: convert zero-page.txt " Changbin Du
2019-04-27 17:19 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 09/27] Documentation: x86: convert tlb.txt " Changbin Du
2019-04-27 17:21 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 10/27] Documentation: x86: convert mtrr.txt " Changbin Du
2019-04-27 17:32 ` Mauro Carvalho Chehab
2019-04-27 18:10 ` Mauro Carvalho Chehab
2019-05-02 5:03 ` Changbin Du
2019-04-26 15:31 ` [PATCH 11/27] Documentation: x86: convert pat.txt " Changbin Du
2019-04-27 17:51 ` Mauro Carvalho Chehab
2019-05-02 5:25 ` Changbin Du
2019-04-26 15:31 ` Changbin Du [this message]
2019-04-27 17:53 ` [PATCH 12/27] Documentation: x86: convert protection-keys.txt " Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 13/27] Documentation: x86: convert intel_mpx.txt " Changbin Du
2019-04-27 17:54 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 14/27] Documentation: x86: convert amd-memory-encryption.txt " Changbin Du
2019-04-27 17:55 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 15/27] Documentation: x86: convert pti.txt " Changbin Du
2019-04-27 17:57 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 16/27] Documentation: x86: convert microcode.txt " Changbin Du
2019-04-27 17:58 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 17/27] Documentation: x86: convert resctrl_ui.txt " Changbin Du
2019-04-27 18:09 ` Mauro Carvalho Chehab
2019-05-02 5:37 ` Changbin Du
2019-04-26 15:31 ` [PATCH 18/27] Documentation: x86: convert orc-unwinder.txt " Changbin Du
2019-04-27 18:16 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 19/27] Documentation: x86: convert usb-legacy-support.txt " Changbin Du
2019-04-27 18:20 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 20/27] Documentation: x86: convert i386/IO-APIC.txt " Changbin Du
2019-04-27 18:24 ` Mauro Carvalho Chehab
2019-05-02 5:42 ` Changbin Du
2019-04-26 15:31 ` [PATCH 21/27] Documentation: x86: convert x86_64/boot-options.txt " Changbin Du
2019-04-27 18:30 ` Mauro Carvalho Chehab
2019-05-02 5:49 ` Changbin Du
2019-04-26 15:31 ` [PATCH 22/27] Documentation: x86: convert x86_64/uefi.txt " Changbin Du
2019-04-27 18:31 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 23/27] Documentation: x86: convert x86_64/mm.txt " Changbin Du
2019-04-27 18:35 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 24/27] Documentation: x86: convert x86_64/5level-paging.txt " Changbin Du
2019-04-27 18:36 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 25/27] Documentation: x86: convert x86_64/fake-numa-for-cpusets " Changbin Du
2019-04-27 18:38 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 26/27] Documentation: x86: convert x86_64/cpu-hotplug-spec " Changbin Du
2019-04-27 18:40 ` Mauro Carvalho Chehab
2019-04-26 15:31 ` [PATCH 27/27] Documentation: x86: convert x86_64/machinecheck " Changbin Du
2019-04-27 18:42 ` Mauro Carvalho Chehab
2019-04-26 15:39 ` [PATCH 00/27] Include linux x86 docs into Sphinx TOC tree Mauro Carvalho Chehab
2019-04-27 2:47 ` Changbin Du
2019-04-27 9:54 ` Mauro Carvalho Chehab
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