linux-stable.git/arch/s390/kernel/stacktrace.c, branch linux-4.7.y

s390/dumpstack: merge all four stack tracers

2016-02-23T07:56:20+00:00

We have four different stack tracers of which three had bugs. So it's
time to merge them to a single stack tracer which allows to specify a
call back function which will be called for each step.

This patch changes behavior a bit:

- the "nosched" and "in_sched_functions" check within
  save_stack_trace_tsk did work only for the last stack frame within a
  context. Now it considers the check for each stack frame like it
  should.

- both the oprofile variant and the perf_events variant did save a
  return address twice if a zero back chain was detected, which
  indicates an interrupt frame. The new dump_trace function will call
  the oprofile and perf_events backends with the psw address that is
  contained within the corresponding pt_regs structure instead.

- the original show_trace and save_context_stack functions did already
  use the psw address of the pt_regs structure if a zero back chain
  was detected. However now we ignore the psw address if it is a user
  space address. After all we trace the kernel stack and not the user
  space stack. This way we also get rid of the garbage user space
  address in case of warnings and / or panic call traces.

So this should make life easier since now there is only one stack
tracer left which we can break.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: add current_stack_pointer() helper function

2016-02-23T07:56:18+00:00

Implement current_stack_pointer() helper function and use it
everywhere, instead of having several different inline assembly
variants.

Signed-off-by: Heiko Carstens 
Tested-by: Peter Oberparleiter 
Signed-off-by: Martin Schwidefsky

s390/stacktrace: use nosched instead of savesched parameter

2016-02-23T07:56:17+00:00

Use the inversed "nosched" logic like all other architectures.

Signed-off-by: Heiko Carstens 
Tested-by: Peter Oberparleiter 
Signed-off-by: Martin Schwidefsky

s390/stacktrace: add save_stack_trace_regs()

2016-02-10T08:25:22+00:00

Implement save_stack_trace_regs, so that a stack trace of a kprobe
event can be obtained.

Without this we see following warning:
"save_stack_trace_regs() not implemented yet."
when we execute:
echo stacktrace > /sys/kernel/debug/tracing/trace_options
echo "p kfree" >> /sys/kernel/debug/tracing/kprobe_events
echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable

Reported-by: Chunyu Hu 
Signed-off-by: Pratyush Anand 
[heiko.carstens@de.ibm.com]: changed patch to use __save_stack_trace()
Signed-off-by: Heiko Carstens 
Tested-by: Peter Oberparleiter 
Signed-off-by: Martin Schwidefsky

s390/stacktrace: save full stack traces

2016-02-10T08:25:21+00:00

save_stack_trace() only saves the stack trace of the current context
(interrupt or process context). This is different to what other
architectures like x86 do, which save the full stack trace across
different contexts.

Also extract a __save_stack_trace() helper function which will be used
by a follow on patch.

Signed-off-by: Heiko Carstens 
Tested-by: Peter Oberparleiter 
Signed-off-by: Martin Schwidefsky

s390/stacktrace: add missing end marker

2016-02-10T08:25:21+00:00

save_stack_trace() did not write the ULONG_MAX end marker if there is
enough space left. So simply follow x86 and arm64.

Signed-off-by: Heiko Carstens 
Tested-by: Peter Oberparleiter 
Signed-off-by: Martin Schwidefsky

s390/stacktrace: fix address ranges for asynchronous and panic stack

2016-02-10T08:25:20+00:00

git commit dc7ee00d4771 ("s390: lowcore stack pointer offsets")
introduced a regression in regard to save_stack_trace(). The stack
pointer for the asynchronous and the panic stack in the lowcore now
have an additional offset applied to them. This offset needs to be
taken into account in the calculation for the low and high address for
the stacks.

This bug was already partially fixed with 9cc5c206d9b4
("s390/dumpstack: fix address ranges for asynchronous and panic
stack"). This patch fixes it also for the stacktrace code.

Fixes: dc7ee00d4771 ("s390: lowcore stack pointer offsets")
Signed-off-by: Heiko Carstens 
Tested-by: Peter Oberparleiter 
Signed-off-by: Martin Schwidefsky

s390/stacktrace: fix save_stack_trace_tsk() for current task

2016-02-10T08:25:20+00:00

The function save_stack_trace_tsk() did not consider that it can be
used for tsk == current, for which the current stack pointer obviously
cannot be found in the thread structure.

Fix this and get the stack pointer with an inline assembly.

This fixes e.g. the output of "cat /proc/self/stack".

Before:
[<0000000000000000>]           (null)
[] 0xffffffffffffffff

After:
[<000000000011b3ee>] save_stack_trace_tsk+0x56/0x98
[<0000000000366cde>] proc_pid_stack+0xae/0x108
[<00000000003636f0>] proc_single_show+0x70/0xc0
[<0000000000311fbc>] seq_read+0xcc/0x448
[<00000000002e7716>] __vfs_read+0x36/0x100
[<00000000002e872e>] vfs_read+0x76/0x130
[<00000000002e975e>] SyS_read+0x66/0xd8
[<000000000089490e>] system_call+0xd6/0x264
[] 0xffffffffffffffff

Signed-off-by: Heiko Carstens 
Tested-by: Peter Oberparleiter 
Signed-off-by: Martin Schwidefsky

s390: remove all usages of PSW_ADDR_INSN

2016-01-19T11:14:03+00:00

Yet another leftover from the 31 bit era. The usual operation
"y = x & PSW_ADDR_INSN" with the PSW_ADDR_INSN mask is a nop for
CONFIG_64BIT.

Therefore remove all usages and hope the code is a bit less confusing.

Signed-off-by: Heiko Carstens 
Reviewed-by: David Hildenbrand

s390/comments: unify copyright messages and remove file names

2012-07-20T09:15:04+00:00

Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.

Signed-off-by: Heiko Carstens