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  1. 12 11月, 2015 4 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
    • D
      x86/mpx: Fix 32-bit address space calculation · f3119b83
      由 Dave Hansen 提交于 
      I received a bug report that running 32-bit MPX binaries on
64-bit kernels was broken.  I traced it down to this little code
snippet.  We were switching our "number of bounds directory
entries" calculation correctly.  But, we didn't switch the other
side of the calculation: the virtual space size.

This meant that we were calculating an absurd size for
bd_entry_virt_space() on 32-bit because we used the 64-bit
virt_space.

This was _also_ broken for 32-bit kernels running on 64-bit
hardware since boot_cpu_data.x86_virt_bits=48 even when running
in 32-bit mode.

Correct that and properly handle all 3 possible cases:

 1. 32-bit binary on 64-bit kernel
 2. 64-bit binary on 64-bit kernel
 3. 32-bit binary on 32-bit kernel

This manifested in having bounds tables not properly unmapped.
It "leaked" memory but had no functional impact otherwise.
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: Dave Hansen <dave@sr71.net>
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/20151111181934.FA7FAC34@viggo.jf.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f3119b83
    • D
      x86/mpx: Do proper get_user() when running 32-bit binaries on 64-bit kernels · 46561c39
      由 Dave Hansen 提交于 
      When you call get_user(foo, bar), you effectively do a

	copy_from_user(&foo, bar, sizeof(*bar));

Note that the sizeof() is implicit.

When we reach out to userspace to try to zap an entire "bounds
table" we need to go read a "bounds directory entry" in order to
locate the table's address.  The size of a "directory entry"
depends on the binary being run and is always the size of a
pointer.

But, when we have a 64-bit kernel and a 32-bit application, the
directory entry is still only 32-bits long, but we fetch it with
a 64-bit pointer which makes get_user() does a 64-bit fetch.
Reading 4 extra bytes isn't harmful, unless we are at the end of
and run off the table.  It might also cause the zero page to get
faulted in unnecessarily even if you are not at the end.

Fix it up by doing a special 32-bit get_user() via a cast when
we have 32-bit userspace.
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: Dave Hansen <dave@sr71.net>
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/20151111181931.3ACF6822@viggo.jf.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      46561c39
  3. 07 11月, 2015 6 次提交
  5. 03 11月, 2015 17 次提交
  7. 01 11月, 2015 3 次提交
  9. 31 10月, 2015 1 次提交
  11. 30 10月, 2015 1 次提交
  13. 29 10月, 2015 6 次提交
  15. 28 10月, 2015 2 次提交