I'm not sure how we missed this problem before.  When I take a function
address and size from an oops and give it to faddr2line, it usually
complains about a size mismatch:

  $ scripts/faddr2line ~/k/vmlinux write_sysrq_trigger+0x51/0x60
  skipping write_sysrq_trigger address at 0xffffffff815731a1 due to size mismatch (0x60 != 83)
  no match for write_sysrq_trigger+0x51/0x60

The problem is caused by differences in how kallsyms and faddr2line
determine a function's size.

kallsyms calculates a function's size by parsing the output of 'nm -n'
and subtracting the next function's address from the current function's
address.  This means that nop instructions after the end of the function
are included in the size.

In contrast, faddr2line reads the size from the symbol table, which does
*not* include the ending nops in the function's size.

Change faddr2line to calculate the size from the output of 'nm -n' to be
consistent with kallsyms and oops outputs.

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/bd313ed7c4003f6b1fda63e825325c44a9d837de.1477405374.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

These macros were added in the following commit:

  86a1c34a ("x86_64 syscall audit fast-path")

They were used in two-phase sycalls entry tracing, but this functionality
was then moved to the arch/x86/entry/common.c:syscall_trace_enter() function,
in the following commit:

  1f484aa6

 ("x86/entry: Move C entry and exit code to arch/x86/entry/common.c")

syscall_trace_enter() now uses the defines from <linux/audit.h>,
so these defines entry_64.S are no longer used anywhere.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161023135646.4453-1-kuleshovmail@gmail.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

The value of regs->orig_ax contains potentially useful debugging data:
For syscalls it contains the syscall number.  For interrupts it contains
the (negated) vector number.  To reduce noise, print it only if it has a
useful value (i.e., something other than -1).

Here's what it looks like for a write syscall:

  RIP: 0033:[<00007f53ad7b1940>] 0x7f53ad7b1940
  RSP: 002b:00007fff8de66558 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
  RAX: ffffffffffffffda RBX: 0000000000000046 RCX: 00007f53ad7b1940
  RDX: 0000000000000002 RSI: 00007f53ae0ca000 RDI: 0000000000000001
  ...

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/93f0fe0307a4af884d3fca00edabcc8cff236002.1476973742.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

The RIP address is shown twice in __show_regs().  Before:

  RIP: 0010:[<ffffffff81070446>]  [<ffffffff81070446>] native_write_msr+0x6/0x30

After:

  RIP: 0010:[<ffffffff81070446>] native_write_msr+0x6/0x30

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/b3fda66f36761759b000883b059cdd9a7649dcc1.1476973742.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Now that we can find pt_regs registers on the stack, print them.  Here's
an example of what it looks like:

  Call Trace:
   <IRQ>
   [<ffffffff8144b793>] dump_stack+0x86/0xc3
   [<ffffffff81142c73>] hrtimer_interrupt+0xb3/0x1c0
   [<ffffffff8105eb86>] local_apic_timer_interrupt+0x36/0x60
   [<ffffffff818b27cd>] smp_apic_timer_interrupt+0x3d/0x50
   [<ffffffff818b06ee>] apic_timer_interrupt+0x9e/0xb0
  RIP: 0010:[<ffffffff818aef43>]  [<ffffffff818aef43>] _raw_spin_unlock_irq+0x33/0x60
  RSP: 0018:ffff880079c4f760  EFLAGS: 00000202
  RAX: ffff880078738000 RBX: ffff88007d3da0c0 RCX: 0000000000000007
  RDX: 0000000000006d78 RSI: ffff8800787388f0 RDI: ffff880078738000
  RBP: ffff880079c4f768 R08: 0000002199088f38 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff81e0d540
  R13: ffff8800369fb700 R14: 0000000000000000 R15: ffff880078738000
   <EOI>
   [<ffffffff810e1f14>] finish_task_switch+0xb4/0x250
   [<ffffffff810e1ed6>] ? finish_task_switch+0x76/0x250
   [<ffffffff818a7b61>] __schedule+0x3e1/0xb20
   ...
   [<ffffffff810759c8>] trace_do_page_fault+0x58/0x2c0
   [<ffffffff8106f7dc>] do_async_page_fault+0x2c/0xa0
   [<ffffffff818b1dd8>] async_page_fault+0x28/0x30
  RIP: 0010:[<ffffffff8145b062>]  [<ffffffff8145b062>] __clear_user+0x42/0x70
  RSP: 0018:ffff880079c4fd38  EFLAGS: 00010202
  RAX: 0000000000000000 RBX: 0000000000000138 RCX: 0000000000000138
  RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000000000061b640
  RBP: ffff880079c4fd48 R08: 0000002198feefd7 R09: ffffffff82a40928
  R10: 0000000000000001 R11: 0000000000000000 R12: 000000000061b640
  R13: 0000000000000000 R14: ffff880079c50000 R15: ffff8800791d7400
   [<ffffffff8145b043>] ? __clear_user+0x23/0x70
   [<ffffffff8145b0fb>] clear_user+0x2b/0x40
   [<ffffffff812fbda2>] load_elf_binary+0x1472/0x1750
   [<ffffffff8129a591>] search_binary_handler+0xa1/0x200
   [<ffffffff8129b69b>] do_execveat_common.isra.36+0x6cb/0x9f0
   [<ffffffff8129b5f3>] ? do_execveat_common.isra.36+0x623/0x9f0
   [<ffffffff8129bcaa>] SyS_execve+0x3a/0x50
   [<ffffffff81003f5c>] do_syscall_64+0x6c/0x1e0
   [<ffffffff818afa3f>] entry_SYSCALL64_slow_path+0x25/0x25
  RIP: 0033:[<00007fd2e2f2e537>]  [<00007fd2e2f2e537>] 0x7fd2e2f2e537
  RSP: 002b:00007ffc449c5fc8  EFLAGS: 00000246
  RAX: ffffffffffffffda RBX: 00007ffc449c8860 RCX: 00007fd2e2f2e537
  RDX: 000000000127cc40 RSI: 00007ffc449c8860 RDI: 00007ffc449c6029
  RBP: 00007ffc449c60b0 R08: 65726f632d667265 R09: 00007ffc449c5e20
  R10: 00000000000005a7 R11: 0000000000000246 R12: 000000000127cc40
  R13: 000000000127ce05 R14: 00007ffc449c6029 R15: 000000000127ce01

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/5cc2c512ec82cfba00dd22467644d4ed751a48c0.1476973742.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

show_trace_log_lvl() prints the stack id (e.g. "<IRQ>") without a
newline so that any stack address printed after it will appear on the
same line.  That causes the first stack address to be vertically
misaligned with the rest, making it visually cluttered and slightly
confusing:

  Call Trace:
   <IRQ> [<ffffffff814431c3>] dump_stack+0x86/0xc3
   [<ffffffff8100828b>] perf_callchain_kernel+0x14b/0x160
   [<ffffffff811e915f>] get_perf_callchain+0x15f/0x2b0
   ...
   <EOI> [<ffffffff8189c6c3>] ? _raw_spin_unlock_irq+0x33/0x60
   [<ffffffff810e1c84>] finish_task_switch+0xb4/0x250
   [<ffffffff8106f7dc>] do_async_page_fault+0x2c/0xa0

It will look worse once we start printing pt_regs registers found in the
middle of the stack:

  <IRQ> RIP: 0010:[<ffffffff8189c6c3>]  [<ffffffff8189c6c3>] _raw_spin_unlock_irq+0x33/0x60
  RSP: 0018:ffff88007876f720  EFLAGS: 00000206
  RAX: ffff8800786caa40 RBX: ffff88007d5da140 RCX: 0000000000000007
  ...

Improve readability by adding a newline to the stack name:

  Call Trace:
   <IRQ>
   [<ffffffff814431c3>] dump_stack+0x86/0xc3
   [<ffffffff8100828b>] perf_callchain_kernel+0x14b/0x160
   [<ffffffff811e915f>] get_perf_callchain+0x15f/0x2b0
   ...
   <EOI>
   [<ffffffff8189c6c3>] ? _raw_spin_unlock_irq+0x33/0x60
   [<ffffffff810e1c84>] finish_task_switch+0xb4/0x250
   [<ffffffff8106f7dc>] do_async_page_fault+0x2c/0xa0

Now that "continued" lines are no longer needed, we can also remove the
hack of using the empty string (aka KERN_CONT) and replace it with
KERN_DEFAULT.

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/9bdd6dee2c74555d45500939fcc155997dc7889e.1476973742.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

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>

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>

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Link: http://lkml.kernel.org/r/20161020120704.24042-1-kuleshovmail@gmail.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

When core_kernel_text() is used to determine whether an address on a
task's stack trace is a kernel text address, it incorrectly returns
false for early text addresses for the head code between the _text and
_stext markers.  Among other things, this can cause the unwinder to
behave incorrectly when unwinding to x86 head code.

Head code is text code too, so mark it as such.  This seems to match the
intent of other users of the _stext symbol, and it also seems consistent
with what other architectures are already doing.

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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/789cf978866420e72fa89df44aa2849426ac378d.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Thanks to all the recent x86 entry code refactoring, most tasks' kernel
stacks start at the same offset right below their saved pt_regs,
regardless of which syscall was used to enter the kernel.  That creates
a nice convention which makes it straightforward to identify the end of
the stack, which can be useful for the unwinder to verify the stack is
sane.

However, the boot CPU's idle "swapper" task doesn't follow that
convention.  Fix that by starting its stack at a sizeof(pt_regs) offset
from the end of the stack page.

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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/81aee3beb6ed88e44f1bea6986bb7b65c368f77a.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

The frame at the end of each idle task stack has a zeroed return
address.  This is inconsistent with real task stacks, which have a real
return address at that spot.  This inconsistency can be confusing for
stack unwinders.  It also hides useful information about what asm code
was involved in calling into C.

Make it a real address by using the side effect of a call instruction to
push the instruction pointer on the stack.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: 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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f59593ae7b15d5126f872b0a23143173d28aa32d.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

There are two different pieces of code for starting a CPU: start_cpu0()
and the end of secondary_startup_64().  They're identical except for the
stack setup.  Combine the common parts into a shared start_cpu()
function.

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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1d692ffa62fcb3cc835a5b254e953f2d9bab3549.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

On 32-bit kernels, the initial idle stack calculation doesn't take into
account the TOP_OF_KERNEL_STACK_PADDING, making the stack end address
inconsistent with other tasks on 32-bit.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: 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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/6cf569410bfa84cf923902fc4d628444cace94be.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

The frame at the end of each idle task stack is inconsistent with real
task stacks, which have a stack frame header and a real return address
before the pt_regs area.  This inconsistency can be confusing for stack
unwinders.  It also hides useful information about what asm code was
involved in calling into C.

Fix that by changing the initial code jumps to calls.  Also add infinite
loops after the calls to make it clear that the calls don't return, and
to hang if they do.

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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2588f34b6fbac4ae6f6f9ead2a78d7f8d58a6341.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Thanks to all the recent x86 entry code refactoring, most tasks' kernel
stacks start at the same offset right below their saved pt_regs,
regardless of which syscall was used to enter the kernel.  That creates
a nice convention which makes it straightforward to identify the end of
the stack, which can be useful for the unwinder to verify the stack is
sane.

Calling schedule_tail() directly breaks that convention because its an
asmlinkage function so its argument has to be pushed on the stack.  Add
a wrapper which creates a proper "end of stack" frame header before the
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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ecafcd882676bf48ceaf50483782552bb98476e5.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

The 'error_code' label is awkwardly named, especially when it shows up
in a stack trace.  Move it to its own local function and rename it to
'common_exception', analagous to the existing 'common_interrupt'.

This also makes related stack traces more sensible.

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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/cca1734a93e52799556d946281b32468f9b93950.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Add the local label prefix to all non-function named labels in head_32.S
and entry_32.S.  In addition to decluttering the symbol table, it also
will help stack traces to be more sensible.  For example, the last
reported function in the idle task stack trace will be startup_32_smp()
instead of is486().

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: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/14f9f7afd478b23a762f40734da1a57c0c273f6e.1474480779.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161019191108.2230-1-kuleshovmail@gmail.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge tag 'platform-drivers-x86-v4.9-2' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull x86 platform driver fixes from Darren Hart:
 "Fix a Kconfig issue leading potential link failure, and add a DMI
  match for an existing quirk.

  asus-wmi:
   - add SERIO_I8042 dependency

  ideapad-laptop:
   - Add Lenovo Yoga 910-13IKB to no_hw_rfkill dmi list"

* tag 'platform-drivers-x86-v4.9-2' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  platform/x86: asus-wmi: add SERIO_I8042 dependency
  platform/x86: ideapad-laptop: Add Lenovo Yoga 910-13IKB to no_hw_rfkill dmi list

Pull arch/sh updates from Rich Felker:
 "Minor changes to improve J2 support and match Kconfig expectations of
  other subsystems"

* tag 'sh-for-4.9' of git://git.libc.org/linux-sh:
  sh: add earlycon support to j2_defconfig
  sh: add Kconfig option for J-Core SoC core drivers
  sh: support CPU_J2 when compiler lacks -mj2

Pull scheduler fix from Ingo Molnar:
 "This fixes a group scheduling related performance/interactivity
  regression introduced in v4.8, which affects certain hardware
  environments where cpu_possible_mask != cpu_present_mask"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix incorrect task group ->load_avg

Pull HID fixes from Jiri Kosina:

 - hid-dr regression fix for certain dragonrise gamepads (device ID
   0079:0006), from Ioan-Adrian Ratiu

 - dma-on-stack fix for hid-led driver, from Heiner Kallweit

 - quirk for Akai MIDImix device

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
  HID: add quirk for Akai MIDImix.
  Revert "HID: dragonrise: fix HID Descriptor for 0x0006 PID"
  HID: hid-dr: add input mapping for axis selection
  HID: hid-led: fix issue with transfer buffer not being dma capable

Pull first round of pin control fixes from Linus Walleij:

 - a bunch of barnsjukdomar/kinderkrankheiten/maladie infantile in the
   Aspeed driver. (Why doesn't English have a word for this?)

   [ Maybe "teething problems" is the closest English idiom? - Linus T ]

 - fix a lockdep bug on the Intel BayTrail.

 - fix a few special laptop issues on the Intel pin controller solving
   suspend issues.

* tag 'pinctrl-v4.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: intel: Only restore pins that are used by the driver
  pinctrl: baytrail: Fix lockdep
  pinctrl: aspeed-g5: Fix pin association of SPI1 function
  pinctrl: aspeed-g5: Fix GPIOE1 typo
  pinctrl: aspeed-g5: Fix names of GPID2 pins
  pinctrl: aspeed: "Not enabled" is a significant mux state

We have a fairly common pattern where you print several things as
continuations on one single line in a loop, and then at the end you do

	printk(KERN_CONT "\n");

to flush the buffered output.

But if the output was flushed by something else (concurrent printk
activity, or just system logging), we don't want that final flushing to
just print an empty line.

So just suppress empty continuation lines when they couldn't be merged
into the line they are a continuation of.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge the gup_flags cleanups from Lorenzo Stoakes:
 "This patch series adjusts functions in the get_user_pages* family such
  that desired FOLL_* flags are passed as an argument rather than
  implied by flags.

  The purpose of this change is to make the use of FOLL_FORCE explicit
  so it is easier to grep for and clearer to callers that this flag is
  being used.  The use of FOLL_FORCE is an issue as it overrides missing
  VM_READ/VM_WRITE flags for the VMA whose pages we are reading
  from/writing to, which can result in surprising behaviour.

  The patch series came out of the discussion around commit 38e08854
  ("mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing"),
  which addressed a BUG_ON() being triggered when a page was faulted in
  with PROT_NONE set but having been overridden by FOLL_FORCE.
  do_numa_page() was run on the assumption the page _must_ be one marked
  for NUMA node migration as an actual PROT_NONE page would have been
  dealt with prior to this code path, however FOLL_FORCE introduced a
  situation where this assumption did not hold.

  See

      https://marc.info/?l=linux-mm&m=147585445805166

  for the patch proposal"

Additionally, there's a fix for an ancient bug related to FOLL_FORCE and
FOLL_WRITE by me.

[ This branch was rebased recently to add a few more acked-by's and
  reviewed-by's ]

* gup_flag-cleanups:
  mm: replace access_process_vm() write parameter with gup_flags
  mm: replace access_remote_vm() write parameter with gup_flags
  mm: replace __access_remote_vm() write parameter with gup_flags
  mm: replace get_user_pages_remote() write/force parameters with gup_flags
  mm: replace get_user_pages() write/force parameters with gup_flags
  mm: replace get_vaddr_frames() write/force parameters with gup_flags
  mm: replace get_user_pages_locked() write/force parameters with gup_flags
  mm: replace get_user_pages_unlocked() write/force parameters with gup_flags
  mm: remove write/force parameters from __get_user_pages_unlocked()
  mm: remove write/force parameters from __get_user_pages_locked()
  mm: remove gup_flags FOLL_WRITE games from __get_user_pages()

This removes the 'write' argument from access_process_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the 'write' argument from access_remote_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the 'write' argument from __access_remote_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the 'write' and 'force' from get_user_pages_remote() and
replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the 'write' and 'force' from get_user_pages() and replaces
them with 'gup_flags' to make the use of FOLL_FORCE explicit in callers
as use of this flag can result in surprising behaviour (and hence bugs)
within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the 'write' and 'force' from get_vaddr_frames() and
replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the 'write' and 'force' use from get_user_pages_locked()
and replaces them with 'gup_flags' to make the use of FOLL_FORCE
explicit in callers as use of this flag can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A scheduler performance regression has been reported by Joseph Salisbury,
which he bisected back to:

  3d30544f

 ("sched/fair: Apply more PELT fixes)

The regression triggers when several levels of task groups are involved
(read: SystemD) and cpu_possible_mask != cpu_present_mask.

The root cause is that group entity's load (tg_child->se[i]->avg.load_avg)
is initialized to scale_load_down(se->load.weight). During the creation of
a child task group, its group entities on possible CPUs are attached to
parent's cfs_rq (tg_parent) and their loads are added to the parent's load
(tg_parent->load_avg) with update_tg_load_avg().

But only the load on online CPUs will then be updated to reflect real load,
whereas load on other CPUs will stay at the initial value.

The result is a tg_parent->load_avg that is higher than the real load, the
weight of group entities (tg_parent->se[i]->load.weight) on online CPUs is
smaller than it should be, and the task group gets a less running time than
what it could expect.

( This situation can be detected with /proc/sched_debug. The ".tg_load_avg"
  of the task group will be much higher than sum of ".tg_load_avg_contrib"
  of online cfs_rqs of the task group. )

The load of group entities don't have to be intialized to something else
than 0 because their load will increase when an entity is attached.

Reported-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@vger.kernel.org> # 4.8.x
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: joonwoop@codeaurora.org
Fixes: 3d30544f ("sched/fair: Apply more PELT fixes)
Link: http://lkml.kernel.org/r/1476881123-10159-1-git-send-email-vincent.guittot@linaro.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Rich Felker <dalias@libc.org>

Signed-off-by: Rich Felker <dalias@libc.org>

Pull f2fs bugfix from Jaegeuk Kim:
 "This fixes a bug which referenced the wrong pointer, sum_page, in
  f2fs_gc.  It was newly introduced in 4.9-rc1.

* tag 'for-f2fs-4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
  f2fs: fix wrong sum_page pointer in f2fs_gc

This removes the 'write' and 'force' use from get_user_pages_unlocked()
and replaces them with 'gup_flags' to make the use of FOLL_FORCE
explicit in callers as use of this flag can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the redundant 'write' and 'force' parameters from
__get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This removes the redundant 'write' and 'force' parameters from
__get_user_pages_locked() to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>