x86/unwind: Warn on bad frame pointer

Detect situations in the unwinder where the frame pointer refers to a
bad address, and print an appropriate warning.

Use printk_deferred_once() because the unw

x86/unwind: Warn on bad frame pointer

Detect situations in the unwinder where the frame pointer refers to a
bad address, and print an appropriate warning.

Use printk_deferred_once() because the unwinder can be called with the
console lock by lockdep via save_stack_trace().

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
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/03c888f6f7414d54fa56b393ea25482be6899b5f.1477496147.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc

Backmerge latest drm-next to have a baseline for the
s/fence/dma_fence/ patch from Chris.

Signed-off-by: Daniel Vetter <daniel.ve

Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc

Backmerge latest drm-next to have a baseline for the
s/fence/dma_fence/ patch from Chris.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

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Merge remote-tracking branch 'airlied/drm-next' into drm-intel-next-queued

Backmerge because Chris Wilson needs the very latest&greates of
Gustavo Padovan's sync_file work, specifically the refcount

Merge remote-tracking branch 'airlied/drm-next' into drm-intel-next-queued

Backmerge because Chris Wilson needs the very latest&greates of
Gustavo Padovan's sync_file work, specifically the refcounting changes
from:

commit 30cd85dd6edc86ea8d8589efb813f1fad41ef233
Author: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Date: Wed Oct 19 15:48:32 2016 -0200

dma-buf/sync_file: hold reference to fence when creating sync_file

Also good to sync in general since git tends to get confused with the
cherry-picking going on.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

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x86/unwind: Create stack frames for saved syscall registers

The entry code doesn't encode the pt_regs pointer for syscalls. But the
pt_regs are always at the same location, so we can add a manual c

x86/unwind: Create stack frames for saved syscall registers

The entry code doesn't encode the pt_regs pointer for syscalls. But the
pt_regs are always at the same location, so we can add a manual check
for them.

A later patch prints them as part of the oops stack dump. They could be
useful, for example, to determine the arguments to a system call.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
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/e176aa9272930cd3f51fda0b94e2eae356677da4.1476973742.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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x86/entry/unwind: Create stack frames for saved interrupt registers

With frame pointers, when a task is interrupted, its stack is no longer
completely reliable because the function could have been i

x86/entry/unwind: Create stack frames for saved interrupt registers

With frame pointers, when a task is interrupted, its stack is no longer
completely reliable because the function could have been interrupted
before it had a chance to save the previous frame pointer on the stack.
So the caller of the interrupted function could get skipped by a stack
trace.

This is problematic for live patching, which needs to know whether a
stack trace of a sleeping task can be relied upon. There's currently no
way to detect if a sleeping task was interrupted by a page fault
exception or preemption before it went to sleep.

Another issue is that when dumping the stack of an interrupted task, the
unwinder has no way of knowing where the saved pt_regs registers are, so
it can't print them.

This solves those issues by encoding the pt_regs pointer in the frame
pointer on entry from an interrupt or an exception.

This patch also updates the unwinder to be able to decode it, because
otherwise the unwinder would be broken by this change.

Note that this causes a change in the behavior of the unwinder: each
instance of a pt_regs on the stack is now considered a "frame". So
callers of unwind_get_return_address() will now get an occasional
'regs->ip' address that would have previously been skipped over.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
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/8b9f84a21e39d249049e0547b559ff8da0df0988.1476973742.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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Merge tag 'v4.9-rc1' into patchwork

Linux 4.9-rc1

* tag 'v4.9-rc1': (13774 commits)
Linux 4.9-rc1
score: traps: Add missing include file to fix build error
fs/super.c: don't fool lockdep in f

Merge tag 'v4.9-rc1' into patchwork

Linux 4.9-rc1

* tag 'v4.9-rc1': (13774 commits)
Linux 4.9-rc1
score: traps: Add missing include file to fix build error
fs/super.c: don't fool lockdep in freeze_super() and thaw_super() paths
fs/super.c: fix race between freeze_super() and thaw_super()
overlayfs: Fix setting IOP_XATTR flag
iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector()
CIFS: Retrieve uid and gid from special sid if enabled
CIFS: Add new mount option to set owner uid and gid from special sids in acl
qedr: Add events support and register IB device
qedr: Add GSI support
qedr: Add LL2 RoCE interface
qedr: Add support for data path
qedr: Add support for memory registeration verbs
qedr: Add support for QP verbs
qedr: Add support for PD,PKEY and CQ verbs
qedr: Add support for user context verbs
qedr: Add support for RoCE HW init
qedr: Add RoCE driver framework
pkeys: Remove easily triggered WARN
MIPS: Wire up new pkey_{mprotect,alloc,free} syscalls
...

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Merge branches 'pm-cpufreq-fixes' and 'pm-sleep-fixes'

* pm-cpufreq-fixes:
cpufreq: intel_pstate: Always set max P-state in performance mode
cpufreq: intel_pstate: Set P-state upfront in perform

Merge branches 'pm-cpufreq-fixes' and 'pm-sleep-fixes'

* pm-cpufreq-fixes:
cpufreq: intel_pstate: Always set max P-state in performance mode
cpufreq: intel_pstate: Set P-state upfront in performance mode

* pm-sleep-fixes:
PM / suspend: Fix missing KERN_CONT for suspend message

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Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull low-level x86 updates from Ingo Molnar:
"In this cycle this topic tree has become one of those 'super

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull low-level x86 updates from Ingo Molnar:
"In this cycle this topic tree has become one of those 'super topics'
that accumulated a lot of changes:

- Add CONFIG_VMAP_STACK=y support to the core kernel and enable it on
x86 - preceded by an array of changes. v4.8 saw preparatory changes
in this area already - this is the rest of the work. Includes the
thread stack caching performance optimization. (Andy Lutomirski)

- switch_to() cleanups and all around enhancements. (Brian Gerst)

- A large number of dumpstack infrastructure enhancements and an
unwinder abstraction. The secret long term plan is safe(r) live
patching plus maybe another attempt at debuginfo based unwinding -
but all these current bits are standalone enhancements in a frame
pointer based debug environment as well. (Josh Poimboeuf)

- More __ro_after_init and const annotations. (Kees Cook)

- Enable KASLR for the vmemmap memory region. (Thomas Garnier)"

[ The virtually mapped stack changes are pretty fundamental, and not
x86-specific per se, even if they are only used on x86 right now. ]

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
x86/asm: Get rid of __read_cr4_safe()
thread_info: Use unsigned long for flags
x86/alternatives: Add stack frame dependency to alternative_call_2()
x86/dumpstack: Fix show_stack() task pointer regression
x86/dumpstack: Remove dump_trace() and related callbacks
x86/dumpstack: Convert show_trace_log_lvl() to use the new unwinder
oprofile/x86: Convert x86_backtrace() to use the new unwinder
x86/stacktrace: Convert save_stack_trace_*() to use the new unwinder
perf/x86: Convert perf_callchain_kernel() to use the new unwinder
x86/unwind: Add new unwind interface and implementations
x86/dumpstack: Remove NULL task pointer convention
fork: Optimize task creation by caching two thread stacks per CPU if CONFIG_VMAP_STACK=y
sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK
lib/syscall: Pin the task stack in collect_syscall()
x86/process: Pin the target stack in get_wchan()
x86/dumpstack: Pin the target stack when dumping it
kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function
sched/core: Add try_get_task_stack() and put_task_stack()
x86/entry/64: Fix a minor comment rebase error
iommu/amd: Don't put completion-wait semaphore on stack
...

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x86/unwind: Add new unwind interface and implementations

The x86 stack dump code is a bit of a mess. dump_trace() uses
callbacks, and each user of it seems to have slightly different
requirements,

x86/unwind: Add new unwind interface and implementations

The x86 stack dump code is a bit of a mess. dump_trace() uses
callbacks, and each user of it seems to have slightly different
requirements, so there are several slightly different callbacks floating
around.

Also there are some upcoming features which will need more changes to
the stack dump code, including the printing of stack pt_regs, reliable
stack detection for live patching, and a DWARF unwinder. Each of those
features would at least need more callbacks and/or callback interfaces,
resulting in a much bigger mess than what we have today.

Before doing all that, we should try to clean things up and replace
dump_trace() with something cleaner and more flexible.

The new unwinder is a simple state machine which was heavily inspired by
a suggestion from Andy Lutomirski:

https://lkml.kernel.org/r/CALCETrUbNTqaM2LRyXGRx=kVLRPeY5A3Pc6k4TtQxF320rUT=w@mail.gmail.com

It's also similar to the libunwind API:

http://www.nongnu.org/libunwind/man/libunwind(3).html

Some if its advantages:

- Simplicity: no more callback sprawl and less code duplication.

- Flexibility: it allows the caller to stop and inspect the stack state
at each step in the unwinding process.

- Modularity: the unwinder code, console stack dump code, and stack
metadata analysis code are all better separated so that changing one
of them shouldn't have much of an impact on any of the others.

Two implementations are added which conform to the new unwind interface:

- The frame pointer unwinder which is used for CONFIG_FRAME_POINTER=y.

- The "guess" unwinder which is used for CONFIG_FRAME_POINTER=n. This
isn't an "unwinder" per se. All it does is scan the stack for kernel
text addresses. But with no frame pointers, guesses are better than
nothing in most cases.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/6dc2f909c47533d213d0505f0a113e64585bec82.1474045023.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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