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Filename Latest commit message Latest commit date
Christophe Leroy da929f6af4 powerpc/mm: Evaluate user_mode(regs) only once in do_page_fault()
Analysis of the assembly code shows that when using user_mode(regs),
at least the 'andi.' is redone all the time, and also
the 'lwz ,132(r31)' most of the time. With the new form, the 'is_user'
is mapped to cr4, then all further use of is_user results in just
things like 'beq cr4,218 <do_page_fault+0x218>'

Without the patch:

  50:	81 1e 00 84 	lwz     r8,132(r30)
  54:	71 09 40 00 	andi.   r9,r8,16384
  58:	40 82 00 0c 	bne     64 <do_page_fault+0x64>

  84:	81 3e 00 84 	lwz     r9,132(r30)
  8c:	71 2a 40 00 	andi.   r10,r9,16384
  90:	41 a2 01 64 	beq     1f4 <do_page_fault+0x1f4>

  d4:	81 3e 00 84 	lwz     r9,132(r30)
  dc:	71 28 40 00 	andi.   r8,r9,16384
  e0:	41 82 02 08 	beq     2e8 <do_page_fault+0x2e8>

 108:	81 3e 00 84 	lwz     r9,132(r30)
 110:	71 28 40 00 	andi.   r8,r9,16384
 118:	41 82 02 28 	beq     340 <do_page_fault+0x340>

 1e4:	81 3e 00 84 	lwz     r9,132(r30)
 1e8:	71 2a 40 00 	andi.   r10,r9,16384
 1ec:	40 82 01 68 	bne     354 <do_page_fault+0x354>

 228:	81 3e 00 84 	lwz     r9,132(r30)
 22c:	71 28 40 00 	andi.   r8,r9,16384
 230:	41 82 ff c4 	beq     1f4 <do_page_fault+0x1f4>

 288:	71 2a 40 00 	andi.   r10,r9,16384
 294:	41 a2 fe 60 	beq     f4 <do_page_fault+0xf4>

 50c:	81 3e 00 84 	lwz     r9,132(r30)
 514:	71 2a 40 00 	andi.   r10,r9,16384
 518:	40 a2 fc e0 	bne     1f8 <do_page_fault+0x1f8>

 534:	81 3e 00 84 	lwz     r9,132(r30)
 53c:	71 2a 40 00 	andi.   r10,r9,16384
 540:	41 82 fc b8 	beq     1f8 <do_page_fault+0x1f8>

This patch creates a local var called 'is_user' which contains the
result of user_mode(regs)

With the patch:

  20:	81 03 00 84 	lwz     r8,132(r3)
  48:	55 09 97 fe 	rlwinm  r9,r8,18,31,31
  58:	2e 09 00 00 	cmpwi   cr4,r9,0
  5c:	40 92 00 0c 	bne     cr4,68 <do_page_fault+0x68>

  88:	41 b2 01 90 	beq     cr4,218 <do_page_fault+0x218>

  d4:	40 92 01 d0 	bne     cr4,2a4 <do_page_fault+0x2a4>

 120:	41 b2 00 f8 	beq     cr4,218 <do_page_fault+0x218>

 138:	41 b2 ff a0 	beq     cr4,d8 <do_page_fault+0xd8>

 1d4:	40 92 00 e0 	bne     cr4,2b4 <do_page_fault+0x2b4>

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-06-02 19:19:45 +10:00
arch powerpc/mm: Evaluate user_mode(regs) only once in do_page_fault() 2017-06-02 19:19:45 +10:00
block Merge branch 'nvme-4.12' of git://git.infradead.org/nvme into for-linus 2017-05-26 09:11:19 -06:00
certs
crypto crypto: skcipher - Add missing API setkey checks 2017-05-18 13:04:05 +08:00
Documentation Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2017-05-26 16:45:13 -07:00
drivers cpuidle-powernv: Allow Deep stop states that don't stop time 2017-05-30 14:59:51 +10:00
firmware
fs Changed since last update: 2017-05-26 12:13:08 -07:00
include powerpc: Link warning for orphan sections 2017-05-30 14:59:51 +10:00
init
ipc
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-27 09:14:24 -07:00
lib test_bpf: Add a couple of tests for BPF_JSGE. 2017-05-25 14:37:56 -04:00
mm mm: vmscan: scan until it finds eligible pages 2017-05-12 15:57:16 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-05-26 13:51:01 -07:00
samples samples/bpf: run cleanup routines when receiving SIGTERM 2017-05-11 21:43:30 -04:00
scripts DeviceTree fixes for 4.12-rc: 2017-05-19 15:03:24 -07:00
security
sound sound fixes for 4.12-rc3 2017-05-26 09:03:09 -07:00
tools powerpc fixes for 4.12 #4 2017-05-27 09:28:34 -07:00
usr
virt KVM: arm/arm64: Hold slots_lock when unregistering kvm io bus devices 2017-05-18 11:18:16 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS TTY/Serial fixes for 4.12-rc3 2017-05-27 09:39:09 -07:00
Makefile Linux 4.12-rc3 2017-05-28 17:20:53 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.