Commit Graph

14 Commits

Author SHA1 Message Date
Kirill A. Shutemov
3677d4c6a2 x86/boot: Detect 5-level paging support
In this initial implementation we force-require 5-level paging support
from the hardware, when compiled with CONFIG_X86_5LEVEL=y. (The kernel
will panic during boot on CPUs that don't support 5-level paging.)

We will implement boot-time switch between 4- and 5-level paging later.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170330080731.65421-2-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-04 08:22:33 +02:00
Dave Hansen
e4a84be6f0 x86/mm: Disallow running with 32-bit PTEs to work around erratum
The Intel(R) Xeon Phi(TM) Processor x200 Family (codename: Knights
Landing) has an erratum where a processor thread setting the Accessed
or Dirty bits may not do so atomically against its checks for the
Present bit.  This may cause a thread (which is about to page fault)
to set A and/or D, even though the Present bit had already been
atomically cleared.

These bits are truly "stray".  In the case of the Dirty bit, the
thread associated with the stray set was *not* allowed to write to
the page.  This means that we do not have to launder the bit(s); we
can simply ignore them.

If the PTE is used for storing a swap index or a NUMA migration index,
the A bit could be misinterpreted as part of the swap type.  The stray
bits being set cause a software-cleared PTE to be interpreted as a
swap entry.  In some cases (like when the swap index ends up being
for a non-existent swapfile), the kernel detects the stray value
and WARN()s about it, but there is no guarantee that the kernel can
always detect it.

When we have 64-bit PTEs (64-bit mode or 32-bit PAE), we were able
to move the swap PTE format around to avoid these troublesome bits.
But, 32-bit non-PAE is tight on bits.  So, disallow it from running
on this hardware.  I can't imagine anyone wanting to run 32-bit
non-highmem kernels on this hardware, but disallowing them from
running entirely is surely the safe thing to do.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: dave.hansen@intel.com
Cc: linux-mm@kvack.org
Cc: mhocko@suse.com
Link: http://lkml.kernel.org/r/20160708001914.D0B50110@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-13 09:43:25 +02:00
Linus Torvalds
9447dc4394 Merge branch 'x86/boot' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 boot changes from Peter Anvin:
 "This patchset is a set of cleanups aiming at librarize some of the
  common code from the boot environments.  We currently have three
  different "little environments" (boot, boot/compressed, and
  realmode/rm) in x86, and we are likely to soon get a fourth one
  (kexec/purgatory, which will have to be integrated in the kernel to
  support secure kexec).  This is primarily a cleanup in the
  anticipation of the latter.

  While Vivek implemented this, he ran into some bugs, in particular the
  memcmp implementation for when gcc punts from using the builtin would
  have a misnamed symbol, causing compilation errors if we were ever
  unlucky enough that gcc didn't want to inline the test"

* 'x86/boot' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, boot: Move memset() definition in compressed/string.c
  x86, boot: Move memcmp() into string.h and string.c
  x86, boot: Move optimized memcpy() 32/64 bit versions to compressed/string.c
  x86, boot: Create a separate string.h file to provide standard string functions
  x86, boot: Undef memcmp before providing a new definition
2014-04-02 12:23:49 -07:00
Chris Bainbridge
69f2366c94 x86, cpu: Add forcepae parameter for booting PAE kernels on PAE-disabled Pentium M
Many Pentium M systems disable PAE but may have a functionally usable PAE
implementation. This adds the "forcepae" parameter which bypasses the boot
check for PAE, and sets the CPU as being PAE capable. Using this parameter
will taint the kernel with TAINT_CPU_OUT_OF_SPEC.

Signed-off-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Link: http://lkml.kernel.org/r/20140307114040.GA4997@localhost
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2014-03-20 16:31:54 -07:00
Vivek Goyal
c041b5ad86 x86, boot: Create a separate string.h file to provide standard string functions
Create a separate arch/x86/boot/string.h file to provide declaration of
some of the common string functions.

By default memcpy, memset and memcmp functions will default to gcc
builtin functions. If code wants to use an optimized version of any
of these functions, they need to #undef the respective macro and link
against a local file providing definition of undefed function.

For example, arch/x86/boot/* code links against copy.S to get memcpy()
and memcmp() definitions. arch/86/boot/compressed/* links against
compressed/string.c.

There are quite a few places in arch/x86/ where these functions are
used. Idea is to try to consilidate  their declaration and possibly
definitions so that it can be reused.

I am planning to reuse boot/string.h in arch/x86/purgatory/ and use
gcc builtin functions for memcpy, memset and memcmp.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: http://lkml.kernel.org/r/1395170800-11059-3-git-send-email-vgoyal@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-03-19 15:43:45 -07:00
H. Peter Anvin
6e6a4932b0 x86, boot: Rename get_flags() and check_flags() to *_cpuflags()
When a function is used in more than one file it may not be possible
to immediately tell from context what the intended meaning is.  As
such, it is more important that the naming be self-evident.  Thus,
change get_flags() to get_cpuflags().

For consistency, change check_flags() to check_cpuflags() even though
it is only used in cpucheck.c.

Link: http://lkml.kernel.org/r/1381450698-28710-2-git-send-email-keescook@chromium.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-10-13 04:08:56 -07:00
Kees Cook
dd78b97367 x86, boot: Move CPU flags out of cpucheck
Refactor the CPU flags handling out of the cpucheck routines so that
they can be reused by the future ASLR routines (in order to detect CPU
features like RDRAND and RDTSC).

This reworks has_eflag() and has_fpu() to be used on both 32-bit and
64-bit, and refactors the calls to cpuid to make them PIC-safe on 32-bit.

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/1381450698-28710-2-git-send-email-keescook@chromium.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-10-13 03:12:02 -07:00
H. Peter Anvin
b74b06c5f6 x86: boot: stub out unimplemented CPU feature words
The CPU feature detection code in the boot code is somewhat minimal,
and doesn't include all possible CPUID words.  In particular, it
doesn't contain the code for CPU feature words 2 (Transmeta),
3 (Linux-specific), 5 (VIA), or 7 (scattered).  Zero them out, so we
can still set those bits as known at compile time; in particular, this
allows creating a Linux-specific NOPL flag and have it required (and
therefore resolvable at compile time) in 64-bit mode.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-09-05 16:13:44 -07:00
H. Peter Anvin
c2dcfde827 x86: cleanup for setup code crashes during IST probe
Clean up the code for crashes during SpeedStep probing on older
machines.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-14 00:13:52 +02:00
Joerg Roedel
7b27718bdb x86: fix setup code crashes on my old 486 box
yesterday I tried to reactivate my old 486 box and wanted to install a
current Linux with latest kernel on it. But it turned out that the
latest kernel does not boot because the machine crashes early in the
setup code.

After some debugging it turned out that the problem is the query_ist()
function. If this interrupt with that function is called the machine
simply locks up. It looks like a BIOS bug. Looking for a workaround for
this problem I wrote the attached patch. It checks for the CPUID
instruction and if it is not implemented it does not call the speedstep
BIOS function. As far as I know speedstep should be available since some
Pentium earliest.

Alan Cox observed that it's available since the Pentium II, so cpuid
levels 4 and 5 can be excluded altogether.

H. Peter Anvin cleaned up the code some more:

> Right in concept, but I dislike the implementation (duplication of the
> CPU detect code we already have).  Could you try this patch and see if
> it works for you?

which, with a small modification to fix a build error with it the
resulting kernel boots on my machine.

Signed-off-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-13 11:59:18 +02:00
WANG Cong
cf9b111c17 x86: remove pointless comments
Remove old comments that include the old arch/i386 directory.

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-19 19:19:54 +02:00
Paolo Ciarrocchi
7030760ae5 x86: coding style fixes to arch/x86/boot/cpucheck.c
Before:
   total: 30 errors, 0 warnings, 262 lines checked
After:
   total: 0 errors, 0 warnings, 262 lines checked

No code changed:

arch/x86/boot/cpucheck.o:

   text	   data	    bss	    dec	    hex	filename
    989	      0	     96	   1085	    43d	cpucheck.o.before
    989	      0	     96	   1085	    43d	cpucheck.o.after

md5:
   06634cfefb8438fa284ff903b4cafbce  cpucheck.o.before.asm
   06634cfefb8438fa284ff903b4cafbce  cpucheck.o.after.asm

Signed-off-by: Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-17 17:40:50 +02:00
Sam Ravnborg
1032c0ba9d x86: arch/x86/Kconfig.cpu unification
Move all CPU definitions to Kconfig.cpu
Always define X86_MINIMUM_CPU_FAMILY and do the
obvious code cleanup in boot/cpucheck.c

Comments from: Adrian Bunk <bunk@kernel.org> incorporated.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Brian Gerst <bgerst@didntduck.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
2007-11-12 21:02:19 +01:00
Thomas Gleixner
96ae6ea0be i386: move boot
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-11 11:16:45 +02:00