linux.git/arch, branch v3.18.86

KVM: x86: inject exceptions produced by x86_decode_insn

2017-12-05T10:20:46+00:00

commit 6ea6e84309ca7e0e850b3083e6b09344ee15c290 upstream.

Sometimes, a processor might execute an instruction while another
processor is updating the page tables for that instruction's code page,
but before the TLB shootdown completes.  The interesting case happens
if the page is in the TLB.

In general, the processor will succeed in executing the instruction and
nothing bad happens.  However, what if the instruction is an MMIO access?
If *that* happens, KVM invokes the emulator, and the emulator gets the
updated page tables.  If the update side had marked the code page as non
present, the page table walk then will fail and so will x86_decode_insn.

Unfortunately, even though kvm_fetch_guest_virt is correctly returning
X86EMUL_PROPAGATE_FAULT, x86_decode_insn's caller treats the failure as
a fatal error if the instruction cannot simply be reexecuted (as is the
case for MMIO).  And this in fact happened sometimes when rebooting
Windows 2012r2 guests.  Just checking ctxt->have_exception and injecting
the exception if true is enough to fix the case.

Thanks to Eduardo Habkost for helping in the debugging of this issue.

Reported-by: Yanan Fu 
Cc: Eduardo Habkost 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Radim Krčmář 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: Exit to user-mode on #UD intercept when emulator requires

2017-12-05T10:20:46+00:00

commit 61cb57c9ed631c95b54f8e9090c89d18b3695b3c upstream.

Instruction emulation after trapping a #UD exception can result in an
MMIO access, for example when emulating a MOVBE on a processor that
doesn't support the instruction.  In this case, the #UD vmexit handler
must exit to user mode, but there wasn't any code to do so.  Add it for
both VMX and SVM.

Signed-off-by: Liran Alon 
Reviewed-by: Nikita Leshenko 
Reviewed-by: Konrad Rzeszutek Wilk 
Signed-off-by: Konrad Rzeszutek Wilk 
Reviewed-by: Wanpeng Li 
Reviewed-by: Paolo Bonzini 
Signed-off-by: Radim Krčmář 
Signed-off-by: Greg Kroah-Hartman

s390/kbuild: enable modversions for symbols exported from asm

2017-11-30T08:35:55+00:00

[ Upstream commit cabab3f9f5ca077535080b3252e6168935b914af ]

s390 version of commit 334bb7738764 ("x86/kbuild: enable modversions
for symbols exported from asm") so we get also rid of all these
warnings:

WARNING: EXPORT symbol "_mcount" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "memcpy" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "memmove" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "memset" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "save_fpu_regs" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "sie64a" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "sie_exit" [vmlinux] version generation failed, symbol will not be versioned.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

powerpc/signal: Properly handle return value from uprobe_deny_signal()

2017-11-30T08:35:53+00:00

commit 46725b17f1c6c815a41429259b3f070c01e71bc1 upstream.

When a uprobe is installed on an instruction that we currently do not
emulate, we copy the instruction into a xol buffer and single step
that instruction. If that instruction generates a fault, we abort the
single stepping before invoking the signal handler. Once the signal
handler is done, the uprobe trap is hit again since the instruction is
retried and the process repeats.

We use uprobe_deny_signal() to detect if the xol instruction triggered
a signal. If so, we clear TIF_SIGPENDING and set TIF_UPROBE so that the
signal is not handled until after the single stepping is aborted. In
this case, uprobe_deny_signal() returns true and get_signal() ends up
returning 0. However, in do_signal(), we are not looking at the return
value, but depending on ksig.sig for further action, all with an
uninitialized ksig that is not touched in this scenario. Fix the same
by initializing ksig.sig to 0.

Fixes: 129b69df9c90 ("powerpc: Use get_signal() signal_setup_done()")
Reported-by: Anton Blanchard 
Signed-off-by: Naveen N. Rao 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

parisc: Fix validity check of pointer size argument in new CAS implementation

2017-11-30T08:35:53+00:00

commit 05f016d2ca7a4fab99d5d5472168506ddf95e74f upstream.

As noted by Christoph Biedl, passing a pointer size of 4 in the new CAS
implementation causes a kernel crash.  The attached patch corrects the
off by one error in the argument validity check.

In reviewing the code, I noticed that we only perform word operations
with the pointer size argument.  The subi instruction intentionally uses
a word condition on 64-bit kernels.  Nullification was used instead of a
cmpib instruction as the branch should never be taken.  The shlw
pseudo-operation generates a depw,z instruction and it clears the target
before doing a shift left word deposit.  Thus, we don't need to clip the
upper 32 bits of this argument on 64-bit kernels.

Tested with a gcc testsuite run with a 64-bit kernel.  The gcc atomic
code in libgcc is the only direct user of the new CAS implementation
that I am aware of.

Signed-off-by: John David Anglin 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

KVM: SVM: obey guest PAT

2017-11-30T08:35:51+00:00

commit 15038e14724799b8c205beb5f20f9e54896013c3 upstream.

For many years some users of assigned devices have reported worse
performance on AMD processors with NPT than on AMD without NPT,
Intel or bare metal.

The reason turned out to be that SVM is discarding the guest PAT
setting and uses the default (PA0=PA4=WB, PA1=PA5=WT, PA2=PA6=UC-,
PA3=UC).  The guest might be using a different setting, and
especially might want write combining but isn't getting it
(instead getting slow UC or UC- accesses).

Thanks a lot to geoff@hostfission.com for noticing the relation
to the g_pat setting.  The patch has been tested also by a bunch
of people on VFIO users forums.

Fixes: 709ddebf81cb40e3c36c6109a7892e8b93a09464
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=196409
Signed-off-by: Paolo Bonzini 
Reviewed-by: David Hildenbrand 
Tested-by: Nick Sarnie 
Signed-off-by: Radim Krčmář 
Signed-off-by: Greg Kroah-Hartman

KVM: nVMX: set IDTR and GDTR limits when loading L1 host state

2017-11-30T08:35:51+00:00

commit 21f2d551183847bc7fbe8d866151d00cdad18752 upstream.

Intel SDM 27.5.2 Loading Host Segment and Descriptor-Table Registers:

"The GDTR and IDTR limits are each set to FFFFH."

Signed-off-by: Ladi Prosek 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

MIPS: BCM47XX: Fix LED inversion for WRT54GSv1

2017-11-30T08:35:50+00:00

commit 56a46acf62af5ba44fca2f3f1c7c25a2d5385b19 upstream.

The WLAN LED on the Linksys WRT54GSv1 is active low, but the software
treats it as active high. Fix the inverted logic.

Fixes: 7bb26b169116 ("MIPS: BCM47xx: Fix LEDs on WRT54GS V1.0")
Signed-off-by: Mirko Parthey 
Looks-ok-by: Rafał Miłecki 
Cc: Hauke Mehrtens 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16071/
Signed-off-by: James Hogan 
Signed-off-by: Greg Kroah-Hartman

MIPS: Fix an n32 core file generation regset support regression

2017-11-30T08:35:49+00:00

commit 547da673173de51f73887377eb275304775064ad upstream.

Fix a commit 7aeb753b5353 ("MIPS: Implement task_user_regset_view.")
regression, then activated by commit 6a9c001b7ec3 ("MIPS: Switch ELF
core dumper to use regsets.)", that caused n32 processes to dump o32
core files by failing to set the EF_MIPS_ABI2 flag in the ELF core file
header's `e_flags' member:

$ file tls-core
tls-core: ELF 32-bit MSB executable, MIPS, N32 MIPS64 rel2 version 1 (SYSV), [...]
$ ./tls-core
Aborted (core dumped)
$ file core
core: ELF 32-bit MSB core file MIPS, MIPS-I version 1 (SYSV), SVR4-style
$

Previously the flag was set as the result of a:

statement placed in arch/mips/kernel/binfmt_elfn32.c, however in the
regset case, i.e. when CORE_DUMP_USE_REGSET is set, ELF_CORE_EFLAGS is
no longer used by `fill_note_info' in fs/binfmt_elf.c, and instead the
`->e_flags' member of the regset view chosen is.  We have the views
defined in arch/mips/kernel/ptrace.c, however only an o32 and an n64
one, and the latter is used for n32 as well.  Consequently an o32 core
file is incorrectly dumped from n32 processes (the ELF32 vs ELF64 class
is chosen elsewhere, and the 32-bit one is correctly selected for n32).

Correct the issue then by defining an n32 regset view and using it as
appropriate.  Issue discovered in GDB testing.

Fixes: 7aeb753b5353 ("MIPS: Implement task_user_regset_view.")
Signed-off-by: Maciej W. Rozycki 
Cc: Ralf Baechle 
Cc: Djordje Todorovic 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17617/
Signed-off-by: James Hogan 
Signed-off-by: Greg Kroah-Hartman

ARM: 8721/1: mm: dump: check hardware RO bit for LPAE

2017-11-30T08:35:49+00:00

commit 3b0c0c922ff4be275a8beb87ce5657d16f355b54 upstream.

When CONFIG_ARM_LPAE is set, the PMD dump relies on the software
read-only bit to determine whether a page is writable. This
concealed a bug which left the kernel text section writable
(AP2=0) while marked read-only in the software bit.

In a kernel with the AP2 bug, the dump looks like this:

    ---[ Kernel Mapping ]---
    0xc0000000-0xc0200000           2M RW NX SHD
    0xc0200000-0xc0600000           4M ro x  SHD
    0xc0600000-0xc0800000           2M ro NX SHD
    0xc0800000-0xc4800000          64M RW NX SHD

The fix is to check that the software and hardware bits are both
set before displaying "ro". The dump then shows the true perms:

    ---[ Kernel Mapping ]---
    0xc0000000-0xc0200000           2M RW NX SHD
    0xc0200000-0xc0600000           4M RW x  SHD
    0xc0600000-0xc0800000           2M RW NX SHD
    0xc0800000-0xc4800000          64M RW NX SHD

Fixes: ded947798469 ("ARM: 8109/1: mm: Modify pte_write and pmd_write logic for LPAE")
Signed-off-by: Philip Derrin 
Tested-by: Neil Dick 
Reviewed-by: Kees Cook 
Signed-off-by: Russell King 
Signed-off-by: Greg Kroah-Hartman