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  1. 19 11月, 2015 1 次提交
  3. 12 11月, 2015 2 次提交
    • H
      x86/fpu: Fix get_xsave_addr() behavior under virtualization · a05917b6
      由 Huaitong Han 提交于 
      KVM uses the get_xsave_addr() function in a different fashion from
the native kernel, in that the 'xsave' parameter belongs to guest vcpu,
not the currently running task.

But 'xsave' is replaced with current task's (host) xsave structure, so
get_xsave_addr() will incorrectly return the bad xsave address to KVM.

Fix it so that the passed in 'xsave' address is used - as intended
originally.
Signed-off-by: NHuaitong Han <huaitong.han@intel.com>
Reviewed-by: NDave Hansen <dave.hansen@linux.intel.com>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@intel.com
Link: http://lkml.kernel.org/r/1446800423-21622-1-git-send-email-huaitong.han@intel.com
[ Tidied up the changelog. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      a05917b6
    • D
      x86/fpu: Fix 32-bit signal frame handling · ab6b5294
      由 Dave Hansen 提交于 
      (This should have gone to LKML originally. Sorry for the extra
 noise, folks on the cc.)

Background:

Signal frames on x86 have two formats:

  1. For 32-bit executables (whether on a real 32-bit kernel or
     under 32-bit emulation on a 64-bit kernel) we have a
    'fpregset_t' that includes the "FSAVE" registers.

  2. For 64-bit executables (on 64-bit kernels obviously), the
     'fpregset_t' is smaller and does not contain the "FSAVE"
     state.

When creating the signal frame, we have to be aware of whether
we are running a 32 or 64-bit executable so we create the
correct format signal frame.

Problem:

save_xstate_epilog() uses 'fx_sw_reserved_ia32' whenever it is
called for a 32-bit executable.  This is for real 32-bit and
ia32 emulation.

But, fpu__init_prepare_fx_sw_frame() only initializes
'fx_sw_reserved_ia32' when emulation is enabled, *NOT* for real
32-bit kernels.

This leads to really wierd situations where 32-bit programs
lose their extended state when returning from a signal handler.
The kernel copies the uninitialized (zero) 'fx_sw_reserved_ia32'
out to userspace in save_xstate_epilog().  But when returning
from the signal, the kernel errors out in check_for_xstate()
when it does not see FP_XSTATE_MAGIC1 present (because it was
zeroed).  This leads to the FPU/XSAVE state being initialized.

For MPX, this leads to the most permissive state and means we
silently lose bounds violations.  I think this would also mean
that we could lose *ANY* FPU/SSE/AVX state.  I'm not sure why
no one has spotted this bug.

I believe this was broken by:

	72a671ce ("x86, fpu: Unify signal handling code paths for x86 and x86_64 kernels")

way back in 2012.
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@sr71.net
Cc: fenghua.yu@intel.com
Cc: yu-cheng.yu@intel.com
Link: http://lkml.kernel.org/r/20151111002354.A0799571@viggo.jf.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      ab6b5294
  5. 07 11月, 2015 5 次提交
  7. 01 11月, 2015 3 次提交
  9. 31 10月, 2015 1 次提交
  11. 27 10月, 2015 1 次提交
    • W
      x86/ioapic: Prevent NULL pointer dereference in setup_ioapic_dest() · ababae44
      由 Werner Pawlitschko 提交于 
      Commit 4857c91f changed the way how irq affinity is setup in
setup_ioapic_dest() from using the core helper function to
unconditionally calling the irq_set_affinity() callback of the
underlying irq chip.

That results in a NULL pointer dereference for the rare case where the
underlying irq chip is lapic_chip which has no irq_set_affinity()
callback. lapic_chip is occasionally used for the timer interrupt (irq
0).

The fix is simple: Check the availability of the callback instead of
calling it unconditionally.

Fixes: 4857c91f "x86/ioapic: Force affinity setting in setup_ioapic_dest()"
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
      ababae44
  13. 26 10月, 2015 1 次提交
  15. 21 10月, 2015 12 次提交
    • B
      x86/microcode/intel: Move #ifdef DEBUG inside the function · c595ac2b
      由 Borislav Petkov 提交于 
      ... and save us the stub.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1445334889-300-6-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      c595ac2b
    • B
      x86/microcode/amd: Remove maintainers from comments · 6f7fc44b
      由 Borislav Petkov 提交于 
      We have the MAINTAINERS file for that. Also, Andreas doesn't
have the time for this work anymore.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andreas Herrmann <herrmann.der.user@googlemail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1445334889-300-5-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6f7fc44b
    • B
      x86/microcode: Remove modularization leftovers · 6b26e1bf
      由 Borislav Petkov 提交于 
      Remove the remaining module functionality leftovers. Make
"dis_ucode_ldr" an early_param and make it static again. Drop
module aliases, autoloading table, description, etc.

Bump version number, while at it.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1445334889-300-4-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6b26e1bf
    • B
      x86/microcode: Merge the early microcode loader · fe055896
      由 Borislav Petkov 提交于 
      Merge the early loader functionality into the driver proper. The
diff is huge but logically, it is simply moving code from the
_early.c files into the main driver.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1445334889-300-3-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      fe055896
    • B
      x86/microcode: Unmodularize the microcode driver · 9a2bc335
      由 Borislav Petkov 提交于 
      Make CONFIG_MICROCODE a bool. It was practically a bool already anyway,
since early loader was forcing it to =y.

Regardless, there's no real reason to have something be a module which
gets built-in on the majority of installations out there. And its not
like there's noticeable change in functionality - we still can load late
microcode - just the module glue disappears.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1445334889-300-2-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      9a2bc335
    • J
      timers/x86/hpet: Type adjustments · 3d45ac4b
      由 Jan Beulich 提交于 
      Standardize on bool instead of an inconsistent mixture of u8 and plain 'int'.

Also use u32 or 'unsigned int' instead of 'unsigned long' when a 32-bit type
suffices, generating slightly better code on x86-64.
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5624E3A002000078000AC49A@prv-mh.provo.novell.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      3d45ac4b
    • A
      x86/mce: Fix thermal throttling reporting after kexec · 81ffdcdd
      由 Andi Kleen 提交于 
      The per CPU thermal vector init code checks if the thermal
vector is already installed and complains and bails out if it
is.

This happens after kexec, as kernel shut down does not clear the
thermal vector APIC register.

This causes two problems:

1. So we always do not fully initialize thermal reports after
   kexec. The CPU is still likely initialized, as the previous
   kernel should have done it. But we don't set up the software
   pointer to the thermal vector, so reporting may end up with a
   unknown thermal interrupt message.

2. Also it complains for every logical CPU, even though the
   value is actually derived from BP only.

The problem is that we end up with one message per CPU, so on
larger systems it becomes very noisy and messes up the otherwise
nicely formatted CPU bootup numbers in the kernel log.

Just remove the check. I checked the code and there's no valid
code paths where the thermal init code for a CPU could be called
multiple times.

Why the kernel does not clean up this value on shutdown:

The thermal monitoring is controlled per logical CPU thread.
Normal shutdown code is just running on one CPU. To disable it
we would need a broadcast NMI to all CPUs on shut down. That's
overkill for this. So we just ignore it after kexec.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1445246268-26285-9-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      81ffdcdd
    • B
      x86/setup/crash: Check memblock_reserve() retval · 6f376057
      由 Borislav Petkov 提交于 
      memblock_reserve() can fail but the crashkernel reservation code
doesn't check that and this can lead the user into believing
that the crashkernel region was actually reserved. Make sure we
check that return value and we exit early with a failure message
in the error case.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NDave Young <dyoung@redhat.com>
Reviewed-by: NJoerg Roedel <jroedel@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Chao <chaowang@redhat.com>
Cc: jerry_hoemann@hp.com
Link: http://lkml.kernel.org/r/1445246268-26285-7-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6f376057
    • B
      x86/setup/crash: Cleanup some more · f56d5578
      由 Borislav Petkov 提交于 
      * Remove unused auto_set variable
* Cleanup local function variable declarations
* Reformat printk string and use pr_info()

No functionality change.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NDave Young <dyoung@redhat.com>
Reviewed-by: NJoerg Roedel <jroedel@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Chao <chaowang@redhat.com>
Cc: jerry_hoemann@hp.com
Link: http://lkml.kernel.org/r/1445246268-26285-6-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f56d5578
    • B
      x86/setup/crash: Remove alignment variable · 606134f7
      由 Borislav Petkov 提交于 
      Use a macro instead. No functionality change.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NDave Young <dyoung@redhat.com>
Reviewed-by: NJoerg Roedel <jroedel@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Chao <chaowang@redhat.com>
Cc: jerry_hoemann@hp.com
Link: http://lkml.kernel.org/r/1445246268-26285-5-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      606134f7
    • B
      x86/setup: Cleanup crashkernel reservation functions · 97eac21b
      由 Borislav Petkov 提交于 
      * Shorten variable names
* Realign code, space out for better readability

No code changed:

  # arch/x86/kernel/setup.o:

   text    data     bss     dec     hex filename
   4543    3096   69904   77543   12ee7 setup.o.before
   4543    3096   69904   77543   12ee7 setup.o.after

md5:
   8a1b7c6738a553ca207b56bd84a8f359  setup.o.before.asm
   8a1b7c6738a553ca207b56bd84a8f359  setup.o.after.asm
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NDave Young <dyoung@redhat.com>
Reviewed-by: NJoerg Roedel <jroedel@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Chao <chaowang@redhat.com>
Cc: jerry_hoemann@hp.com
Link: http://lkml.kernel.org/r/1445246268-26285-4-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      97eac21b
    • B
      x86/setup: Do not reserve crashkernel high memory if low reservation failed · eb6db83d
      由 Baoquan He 提交于 
      People reported that when allocating crashkernel memory using
the ",high" and ",low" syntax, there were cases where the
reservation of the high portion succeeds but the reservation of
the low portion fails.

Then kexec can load the kdump kernel successfully, but booting
the kdump kernel fails as there's no low memory.

The low memory allocation for the kdump kernel can fail on large
systems for a couple of reasons. For example, the manually
specified crashkernel low memory can be too large and thus no
adequate memblock region would be found.

Therefore, we try to reserve low memory for the crash kernel
*after* the high memory portion has been allocated. If that
fails, we free crashkernel high memory too and return. The user
can then take measures accordingly.
Tested-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NBaoquan He <bhe@redhat.com>
[ Massage text. ]
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NJoerg Roedel <jroedel@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Young <dyoung@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Chao <chaowang@redhat.com>
Cc: jerry_hoemann@hp.com
Cc: yinghai@kernel.org
Link: http://lkml.kernel.org/r/1445246268-26285-2-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      eb6db83d
  17. 20 10月, 2015 3 次提交
  19. 19 10月, 2015 3 次提交
  21. 16 10月, 2015 2 次提交
    • V
      x86/ioapic: Disable interrupts when re-routing legacy IRQs · c0ff971e
      由 Vitaly Kuznetsov 提交于 
      A sporadic hang with consequent crash is observed when booting Hyper-V Gen1
guests:

 Call Trace:
  <IRQ>
  [<ffffffff810ab68d>] ? trace_hardirqs_off+0xd/0x10
  [<ffffffff8107b616>] queue_work_on+0x46/0x90
  [<ffffffff81365696>] ? add_interrupt_randomness+0x176/0x1d0
  ...
  <EOI>
  [<ffffffff81471ddb>] ? _raw_spin_unlock_irqrestore+0x3b/0x60
  [<ffffffff810c295e>] __irq_put_desc_unlock+0x1e/0x40
  [<ffffffff810c5c35>] irq_modify_status+0xb5/0xd0
  [<ffffffff8104adbb>] mp_register_handler+0x4b/0x70
  [<ffffffff8104c55a>] mp_irqdomain_alloc+0x1ea/0x2a0
  [<ffffffff810c7f10>] irq_domain_alloc_irqs_recursive+0x40/0xa0
  [<ffffffff810c860c>] __irq_domain_alloc_irqs+0x13c/0x2b0
  [<ffffffff8104b070>] alloc_isa_irq_from_domain.isra.1+0xc0/0xe0
  [<ffffffff8104bfa5>] mp_map_pin_to_irq+0x165/0x2d0
  [<ffffffff8104c157>] pin_2_irq+0x47/0x80
  [<ffffffff81744253>] setup_IO_APIC+0xfe/0x802
  ...
  [<ffffffff814631c0>] ? rest_init+0x140/0x140

The issue is easily reproducible with a simple instrumentation: if
mdelay(10) is put between mp_setup_entry() and mp_register_handler() calls
in mp_irqdomain_alloc() Hyper-V guest always fails to boot when re-routing
IRQ0. The issue seems to be caused by the fact that we don't disable
interrupts while doing IOPIC programming for legacy IRQs and IRQ0 actually
happens. 

Protect the setup sequence against concurrent interrupts.

[ tglx: Make the protection unconditional and not only for legacy
  	interrupts ]
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1444930943-19336-1-git-send-email-vkuznets@redhat.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      c0ff971e
    • P
      x86/setup: Extend low identity map to cover whole kernel range · f5f3497c
      由 Paolo Bonzini 提交于 
      On 32-bit systems, the initial_page_table is reused by
efi_call_phys_prolog as an identity map to call
SetVirtualAddressMap.  efi_call_phys_prolog takes care of
converting the current CPU's GDT to a physical address too.

For PAE kernels the identity mapping is achieved by aliasing the
first PDPE for the kernel memory mapping into the first PDPE
of initial_page_table.  This makes the EFI stub's trick "just work".

However, for non-PAE kernels there is no guarantee that the identity
mapping in the initial_page_table extends as far as the GDT; in this
case, accesses to the GDT will cause a page fault (which quickly becomes
a triple fault).  Fix this by copying the kernel mappings from
swapper_pg_dir to initial_page_table twice, both at PAGE_OFFSET and at
identity mapping.

For some reason, this is only reproducible with QEMU's dynamic translation
mode, and not for example with KVM.  However, even under KVM one can clearly
see that the page table is bogus:

    $ qemu-system-i386 -pflash OVMF.fd -M q35 vmlinuz0 -s -S -daemonize
    $ gdb
    (gdb) target remote localhost:1234
    (gdb) hb *0x02858f6f
    Hardware assisted breakpoint 1 at 0x2858f6f
    (gdb) c
    Continuing.

    Breakpoint 1, 0x02858f6f in ?? ()
    (gdb) monitor info registers
    ...
    GDT=     0724e000 000000ff
    IDT=     fffbb000 000007ff
    CR0=0005003b CR2=ff896000 CR3=032b7000 CR4=00000690
    ...

The page directory is sane:

    (gdb) x/4wx 0x32b7000
    0x32b7000:	0x03398063	0x03399063	0x0339a063	0x0339b063
    (gdb) x/4wx 0x3398000
    0x3398000:	0x00000163	0x00001163	0x00002163	0x00003163
    (gdb) x/4wx 0x3399000
    0x3399000:	0x00400003	0x00401003	0x00402003	0x00403003

but our particular page directory entry is empty:

    (gdb) x/1wx 0x32b7000 + (0x724e000 >> 22) * 4
    0x32b7070:	0x00000000

[ It appears that you can skate past this issue if you don't receive
  any interrupts while the bogus GDT pointer is loaded, or if you avoid
  reloading the segment registers in general.

  Andy Lutomirski provides some additional insight:

   "AFAICT it's entirely permissible for the GDTR and/or LDT
    descriptor to point to unmapped memory.  Any attempt to use them
    (segment loads, interrupts, IRET, etc) will try to access that memory
    as if the access came from CPL 0 and, if the access fails, will
    generate a valid page fault with CR2 pointing into the GDT or
    LDT."

  Up until commit 23a0d4e8 ("efi: Disable interrupts around EFI
  calls, not in the epilog/prolog calls") interrupts were disabled
  around the prolog and epilog calls, and the functional GDT was
  re-installed before interrupts were re-enabled.

  Which explains why no one has hit this issue until now. ]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reported-by: NLaszlo Ersek <lersek@redhat.com>
Cc: <stable@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>
[ Updated changelog. ]
      f5f3497c
  23. 14 10月, 2015 1 次提交
  25. 12 10月, 2015 5 次提交