linux.git/arch/powerpc, branch v4.12 Linux kernel source tree Merge tag 'powerpc-4.12-8' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2017-06-30T17:55:34+00:00 Linus Torvalds torvalds@linux-foundation.org 2017-06-30T17:55:34+00:00 b4df2e3537bef7d867338063da56b557c50f68f2 Pull powerpc fixes from Michael Ellerman: "Hopefully the last two powerpc fixes for 4.12. The CXL one is larger than I'd usually send at rc7, but it fixes new code this cycle, so better to have it working for the release. It was actually sent a few weeks back but got blocked in testing behind another fix that was causing issues. We are still tracking one crash in v4.12-rc7, but only one person has reproduced it and the commit identified by bisect doesn't touch any of the relevant code, so I think it's 50/50 whether that commit is actually the problem or it's some code layout / toolchain issue. Two fixes for code we merged this cycle: - cxl: Fixes for Coherent Accelerator Interface Architecture 2.0 - Avoid miscompilation w/GCC 4.6.3 on 32-bit - don't inline copy_to/from_user() Thanks to Al Viro, Larry Finger, Christophe Lombard" * tag 'powerpc-4.12-8' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/32: Avoid miscompilation w/GCC 4.6.3 - don't inline copy_to/from_user() cxl: Fixes for Coherent Accelerator Interface Architecture 2.0 
Pull powerpc fixes from Michael Ellerman:
 "Hopefully the last two powerpc fixes for 4.12.

  The CXL one is larger than I'd usually send at rc7, but it fixes new
  code this cycle, so better to have it working for the release. It was
  actually sent a few weeks back but got blocked in testing behind
  another fix that was causing issues.

  We are still tracking one crash in v4.12-rc7, but only one person has
  reproduced it and the commit identified by bisect doesn't touch any of
  the relevant code, so I think it's 50/50 whether that commit is
  actually the problem or it's some code layout / toolchain issue.

  Two fixes for code we merged this cycle:

   - cxl: Fixes for Coherent Accelerator Interface Architecture 2.0

   - Avoid miscompilation w/GCC 4.6.3 on 32-bit - don't inline
     copy_to/from_user()

  Thanks to Al Viro, Larry Finger, Christophe Lombard"

* tag 'powerpc-4.12-8' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/32: Avoid miscompilation w/GCC 4.6.3 - don't inline copy_to/from_user()
  cxl: Fixes for Coherent Accelerator Interface Architecture 2.0
arch: remove unused macro/function thread_saved_pc() 2017-06-28T23:13:57+00:00 Tobias Klauser tklauser@distanz.ch 2017-06-28T13:30:02+00:00 6474924e2b5ddb0030c355558966adcbe3b49022 The only user of thread_saved_pc() in non-arch-specific code was removed in commit 8243d5597793 ("sched/core: Remove pointless printout in sched_show_task()"). Remove the implementations as well. Some architectures use thread_saved_pc() in their arch-specific code. Leave their thread_saved_pc() intact. Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
The only user of thread_saved_pc() in non-arch-specific code was removed
in commit 8243d5597793 ("sched/core: Remove pointless printout in
sched_show_task()").  Remove the implementations as well.

Some architectures use thread_saved_pc() in their arch-specific code.
Leave their thread_saved_pc() intact.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
powerpc/32: Avoid miscompilation w/GCC 4.6.3 - don't inline copy_to/from_user() 2017-06-26T13:25:08+00:00 Michael Ellerman mpe@ellerman.id.au 2017-06-26T01:30:57+00:00 d6bd8194e2867e85ac2de63486d3b83ccfae4e62 Larry Finger reported that his Powerbook G4 was no longer booting with v4.12-rc, userspace was up but giving weird errors such as: udevd[64]: starting version 175 udevd[64]: Unable to receive ctrl message: Bad address. modprobe: chdir(4.12-rc1): No such file or directory He bisected the problem to commit 3448890c32c3 ("powerpc: get rid of zeroing, switch to RAW_COPY_USER"). Al identified that the problem is actually a miscompilation by GCC 4.6.3, which is exposed by the above commit. Al also pointed out that inlining copy_to/from_user() is probably of little or no benefit, which is correct. Using Anton's copy_to_user benchmark, with a pathological single byte copy, we see a small increase in performance by *removing* inlining: Before (inlined): # time ./copy_to_user -w -l 1 -i 10000000 ( x 3 ) real 0m22.063s real 0m22.059s real 0m22.076s After: # time ./copy_to_user -w -l 1 -i 10000000 ( x 3 ) real 0m21.325s real 0m21.299s real 0m21.364s So as a small performance improvement and to avoid the miscompilation, drop inlining copy_to/from_user() on 32-bit. Fixes: 3448890c32c3 ("powerpc: get rid of zeroing, switch to RAW_COPY_USER") Reported-by: Larry Finger <Larry.Finger@lwfinger.net> Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
Larry Finger reported that his Powerbook G4 was no longer booting with v4.12-rc,
userspace was up but giving weird errors such as:

  udevd[64]: starting version 175
  udevd[64]: Unable to receive ctrl message: Bad address.
  modprobe: chdir(4.12-rc1): No such file or directory

He bisected the problem to commit 3448890c32c3 ("powerpc: get rid of zeroing,
switch to RAW_COPY_USER").

Al identified that the problem is actually a miscompilation by GCC 4.6.3, which
is exposed by the above commit.

Al also pointed out that inlining copy_to/from_user() is probably of little or
no benefit, which is correct. Using Anton's copy_to_user benchmark, with a
pathological single byte copy, we see a small increase in performance
by *removing* inlining:

  Before (inlined):
  # time ./copy_to_user -w -l 1 -i 10000000	( x 3 )
  real	0m22.063s
  real	0m22.059s
  real	0m22.076s

  After:
  # time ./copy_to_user -w -l 1 -i 10000000	( x 3 )
  real	0m21.325s
  real	0m21.299s
  real	0m21.364s

So as a small performance improvement and to avoid the miscompilation, drop
inlining copy_to/from_user() on 32-bit.

Fixes: 3448890c32c3 ("powerpc: get rid of zeroing, switch to RAW_COPY_USER")
Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Merge tag 'powerpc-4.12-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2017-06-24T00:53:16+00:00 Linus Torvalds torvalds@linux-foundation.org 2017-06-24T00:53:16+00:00 94a6df251dd08c6436ebd6d10c68f03659148ce1 Pull powerpc fixes from Michael Ellerman: "Some more powerpc fixes for 4.12. Most of these actually came in last week but got held up for some more testing. - three fixes for kprobes/ftrace/livepatch interactions. - properly handle data breakpoints when using the Radix MMU. - fix for perf sampling of registers during call_usermodehelper(). - properly initialise the thread_info on our emergency stacks - add an explicit flush when doing TLB invalidations for a process using NPU2. Thanks to: Alistair Popple, Naveen N. Rao, Nicholas Piggin, Ravi Bangoria, Masami Hiramatsu" * tag 'powerpc-4.12-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/64: Initialise thread_info for emergency stacks powerpc/powernv/npu-dma: Add explicit flush when sending an ATSD powerpc/perf: Fix oops when kthread execs user process powerpc/64s: Handle data breakpoints in Radix mode powerpc/kprobes: Skip livepatch_handler() for jprobes powerpc/ftrace: Pass the correct stack pointer for DYNAMIC_FTRACE_WITH_REGS powerpc/kprobes: Pause function_graph tracing during jprobes handling 
Pull powerpc fixes from Michael Ellerman:
 "Some more powerpc fixes for 4.12. Most of these actually came in last
  week but got held up for some more testing.

   - three fixes for kprobes/ftrace/livepatch interactions.

   - properly handle data breakpoints when using the Radix MMU.

   - fix for perf sampling of registers during call_usermodehelper().

   - properly initialise the thread_info on our emergency stacks

   - add an explicit flush when doing TLB invalidations for a process
     using NPU2.

  Thanks to: Alistair Popple, Naveen N. Rao, Nicholas Piggin, Ravi
  Bangoria, Masami Hiramatsu"

* tag 'powerpc-4.12-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64: Initialise thread_info for emergency stacks
  powerpc/powernv/npu-dma: Add explicit flush when sending an ATSD
  powerpc/perf: Fix oops when kthread execs user process
  powerpc/64s: Handle data breakpoints in Radix mode
  powerpc/kprobes: Skip livepatch_handler() for jprobes
  powerpc/ftrace: Pass the correct stack pointer for DYNAMIC_FTRACE_WITH_REGS
  powerpc/kprobes: Pause function_graph tracing during jprobes handling
powerpc/64: Initialise thread_info for emergency stacks 2017-06-23T03:25:38+00:00 Nicholas Piggin npiggin@gmail.com 2017-06-21T05:58:29+00:00 34f19ff1b5a0d11e46df479623d6936460105c9f Emergency stacks have their thread_info mostly uninitialised, which in particular means garbage preempt_count values. Emergency stack code runs with interrupts disabled entirely, and is used very rarely, so this has been unnoticed so far. It was found by a proposed new powerpc watchdog that takes a soft-NMI directly from the masked_interrupt handler and using the emergency stack. That crashed at BUG_ON(in_nmi()) in nmi_enter(). preempt_count()s were found to be garbage. To fix this, zero the entire THREAD_SIZE allocation, and initialize the thread_info. Cc: stable@vger.kernel.org Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Move it all into setup_64.c, use a function not a macro. Fix crashes on Cell by setting preempt_count to 0 not HARDIRQ_OFFSET] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
Emergency stacks have their thread_info mostly uninitialised, which in
particular means garbage preempt_count values.

Emergency stack code runs with interrupts disabled entirely, and is
used very rarely, so this has been unnoticed so far. It was found by a
proposed new powerpc watchdog that takes a soft-NMI directly from the
masked_interrupt handler and using the emergency stack. That crashed
at BUG_ON(in_nmi()) in nmi_enter(). preempt_count()s were found to be
garbage.

To fix this, zero the entire THREAD_SIZE allocation, and initialize
the thread_info.

Cc: stable@vger.kernel.org
Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Move it all into setup_64.c, use a function not a macro. Fix
      crashes on Cell by setting preempt_count to 0 not HARDIRQ_OFFSET]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
powerpc/powernv/npu-dma: Add explicit flush when sending an ATSD 2017-06-22T11:21:08+00:00 Alistair Popple alistair@popple.id.au 2017-06-20T08:37:28+00:00 bbd5ff50afffcf4a01d05367524736c57607a478 NPU2 requires an extra explicit flush to an active GPU PID when sending address translation shoot downs (ATSDs) to reliably flush the GPU TLB. This patch adds just such a flush at the end of each sequence of ATSDs. We can safely use PID 0 which is always reserved and active on the GPU. PID 0 is only used for init_mm which will never be a user mm on the GPU. To enforce this we add a check in pnv_npu2_init_context() just in case someone tries to use PID 0 on the GPU. Signed-off-by: Alistair Popple <alistair@popple.id.au> [mpe: Use true/false for bool literals] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
NPU2 requires an extra explicit flush to an active GPU PID when
sending address translation shoot downs (ATSDs) to reliably flush the
GPU TLB. This patch adds just such a flush at the end of each sequence
of ATSDs.

We can safely use PID 0 which is always reserved and active on the
GPU. PID 0 is only used for init_mm which will never be a user mm on
the GPU. To enforce this we add a check in pnv_npu2_init_context()
just in case someone tries to use PID 0 on the GPU.

Signed-off-by: Alistair Popple <alistair@popple.id.au>
[mpe: Use true/false for bool literals]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Merge branch 'kvm-ppc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc 2017-06-20T12:32:57+00:00 Radim Krčmář rkrcmar@redhat.com 2017-06-20T12:32:57+00:00 c72544d85fd6e46cfca6056ba775a17dc272d810 * fix problems that could cause hangs or crashes in the host on POWER9 * fix problems that could allow guests to potentially affect or disrupt the execution of the controlling userspace 
* fix problems that could cause hangs or crashes in the host on POWER9
* fix problems that could allow guests to potentially affect or disrupt
  the execution of the controlling userspace
mm: larger stack guard gap, between vmas 2017-06-19T13:50:20+00:00 Hugh Dickins hughd@google.com 2017-06-19T11:03:24+00:00 1be7107fbe18eed3e319a6c3e83c78254b693acb Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov <oleg@redhat.com> Original-patch-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Tested-by: Helge Deller <deller@gmx.de> # parisc Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.

This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.

Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.

One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications.  For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).

Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.

Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.

Original-patch-by: Oleg Nesterov <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'powerpc-4.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2017-06-16T20:57:54+00:00 Linus Torvalds torvalds@linux-foundation.org 2017-06-16T20:57:54+00:00 5ac447d268601f88264ad18a13e7177a455007bb Pull powerpc fixes from Michael Ellerman: "Three small fixes for recently merged code: - remove a spurious WARN_ON when a PCI device has no of_node, it's allowed in some circumstances for there to be no of_node. - fix the offset for store EOI MMIOs in the XIVE interrupt controller. - fix non-const WARN_ONs which were becoming BUGs due to them losing BUGFLAG_WARNING in a recent cleanup patch. Thanks to: Alexey Kardashevskiy, Alistair Popple, Benjamin Herrenschmidt" * tag 'powerpc-4.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/debug: Add missing warn flag to WARN_ON's non-builtin path powerpc/xive: Fix offset for store EOI MMIOs powerpc/npu-dma: Remove spurious WARN_ON when a PCI device has no of_node 
Pull powerpc fixes from Michael Ellerman:
 "Three small fixes for recently merged code:

   - remove a spurious WARN_ON when a PCI device has no of_node, it's
     allowed in some circumstances for there to be no of_node.

   - fix the offset for store EOI MMIOs in the XIVE interrupt
     controller.

   - fix non-const WARN_ONs which were becoming BUGs due to them losing
     BUGFLAG_WARNING in a recent cleanup patch.

  Thanks to: Alexey Kardashevskiy, Alistair Popple, Benjamin
  Herrenschmidt"

* tag 'powerpc-4.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/debug: Add missing warn flag to WARN_ON's non-builtin path
  powerpc/xive: Fix offset for store EOI MMIOs
  powerpc/npu-dma: Remove spurious WARN_ON when a PCI device has no of_node
powerpc/perf: Fix oops when kthread execs user process 2017-06-16T11:02:46+00:00 Ravi Bangoria ravi.bangoria@linux.vnet.ibm.com 2017-06-15T13:46:48+00:00 bf05fc25f268cd62f147f368fe65ad3e5b04fe9f When a kthread calls call_usermodehelper() the steps are: 1. allocate current->mm 2. load_elf_binary() 3. populate current->thread.regs While doing this, interrupts are not disabled. If there is a perf interrupt in the middle of this process (i.e. step 1 has completed but not yet reached to step 3) and if perf tries to read userspace regs, kernel oops with following log: Unable to handle kernel paging request for data at address 0x00000000 Faulting instruction address: 0xc0000000000da0fc ... Call Trace: perf_output_sample_regs+0x6c/0xd0 perf_output_sample+0x4e4/0x830 perf_event_output_forward+0x64/0x90 __perf_event_overflow+0x8c/0x1e0 record_and_restart+0x220/0x5c0 perf_event_interrupt+0x2d8/0x4d0 performance_monitor_exception+0x54/0x70 performance_monitor_common+0x158/0x160 --- interrupt: f01 at avtab_search_node+0x150/0x1a0 LR = avtab_search_node+0x100/0x1a0 ... load_elf_binary+0x6e8/0x15a0 search_binary_handler+0xe8/0x290 do_execveat_common.isra.14+0x5f4/0x840 call_usermodehelper_exec_async+0x170/0x210 ret_from_kernel_thread+0x5c/0x7c Fix it by setting abi to PERF_SAMPLE_REGS_ABI_NONE when userspace pt_regs are not set. Fixes: ed4a4ef85cf5 ("powerpc/perf: Add support for sampling interrupt register state") Cc: stable@vger.kernel.org # v4.7+ Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
When a kthread calls call_usermodehelper() the steps are:
  1. allocate current->mm
  2. load_elf_binary()
  3. populate current->thread.regs

While doing this, interrupts are not disabled. If there is a perf
interrupt in the middle of this process (i.e. step 1 has completed
but not yet reached to step 3) and if perf tries to read userspace
regs, kernel oops with following log:

  Unable to handle kernel paging request for data at address 0x00000000
  Faulting instruction address: 0xc0000000000da0fc
  ...
  Call Trace:
  perf_output_sample_regs+0x6c/0xd0
  perf_output_sample+0x4e4/0x830
  perf_event_output_forward+0x64/0x90
  __perf_event_overflow+0x8c/0x1e0
  record_and_restart+0x220/0x5c0
  perf_event_interrupt+0x2d8/0x4d0
  performance_monitor_exception+0x54/0x70
  performance_monitor_common+0x158/0x160
  --- interrupt: f01 at avtab_search_node+0x150/0x1a0
      LR = avtab_search_node+0x100/0x1a0
  ...
  load_elf_binary+0x6e8/0x15a0
  search_binary_handler+0xe8/0x290
  do_execveat_common.isra.14+0x5f4/0x840
  call_usermodehelper_exec_async+0x170/0x210
  ret_from_kernel_thread+0x5c/0x7c

Fix it by setting abi to PERF_SAMPLE_REGS_ABI_NONE when userspace
pt_regs are not set.

Fixes: ed4a4ef85cf5 ("powerpc/perf: Add support for sampling interrupt register state")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>