linux-toradex.git/arch/s390/oprofile, branch v4.9.90

s390/dumpstack: restore reliable indicator for call traces

2016-10-17T12:44:30+00:00

Before merging all different stack tracers the call traces printed had
an indicator if an entry can be considered reliable or not.
Unreliable entries were put in braces, reliable not. Currently all
lines contain these extra braces.

This patch restores the old behaviour by adding an extra "reliable"
parameter to the callback functions. Only show_trace makes currently
use of it.

Before:
[    0.804751] Call Trace:
[    0.804753] ([<000000000017d0e0>] try_to_wake_up+0x318/0x5e0)
[    0.804756] ([<0000000000161d64>] create_worker+0x174/0x1c0)

After:
[    0.804751] Call Trace:
[    0.804753] ([<000000000017d0e0>] try_to_wake_up+0x318/0x5e0)
[    0.804756]  [<0000000000161d64>] create_worker+0x174/0x1c0

Fixes: 758d39ebd3d5 ("s390/dumpstack: merge all four stack tracers")
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/oprofile: remove hardware sampler support

2016-06-28T07:32:22+00:00

Remove hardware sampler support from oprofile module.

The oprofile user space utilty has been switched to use the kernel
perf interface, for which we also provide hardware sampling support.

In addition the hardware sampling support is also slightly broken: it
supports only 16 bits for the pid and therefore would generate wrong
results on machines which have a pid >64k.

Also the pt_regs structure which was passed to oprofile common code
cannot necessarily be used to generate sane backtraces, since the
task(s) in question may run while the samples are fed to oprofile.
So the result would be more or less random.

However given that the only user space tools switched to the perf
interface already four years ago the hardware sampler code seems to be
unused code, and therefore it should be reasonable to remove it.

The timer based oprofile support continues to work.

Signed-off-by: Heiko Carstens 
Acked-by: Andreas Arnez 
Acked-by: Andreas Krebbel 
Acked-by: Robert Richter 
Reviewed-by: Hendrik Brueckner 
Signed-off-by: Martin Schwidefsky

s390/oprofile: add z13/z13s model numbers

2016-02-24T11:18:10+00:00

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

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/oprofile: fix address range for asynchronous stack

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

git commit dc7ee00d4771 ("s390: lowcore stack pointer offsets")
introduced a regression in regard to s390_backtrace(). The stack
pointer for the asynchronous stack in the lowcore now has an
additional offset applied. This offset needs to be taken into account
in the calculation for the low and high address for the stack.

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

Fixes: dc7ee00d4771 ("s390: lowcore stack pointer offsets")
Signed-off-by: Heiko Carstens 
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/oprofile: fix compile error

2015-07-01T07:34:39+00:00

Fix these errors when compiling with CONFIG_OPROFILE=y and
CONFIG_PERF_EVENTS=n:
arch/s390/oprofile/init.c: In function ‘oprofile_hwsampler_start’:
arch/s390/oprofile/init.c:93:2: error: implicit declaration of function 'perf_reserve_sampling' [-Werror=implicit-function-declaration]
  retval = perf_reserve_sampling();
  ^
arch/s390/oprofile/init.c:99:3: error: implicit declaration of function 'perf_release_sampling' [-Werror=implicit-function-declaration]
   perf_release_sampling();
   ^

Signed-off-by: Sebastian Ott 
Signed-off-by: Martin Schwidefsky

s390: remove 31 bit support

2015-03-25T10:49:33+00:00

Remove the 31 bit support in order to reduce maintenance cost and
effectively remove dead code. Since a couple of years there is no
distribution left that comes with a 31 bit kernel.

The 31 bit kernel also has been broken since more than a year before
anybody noticed. In addition I added a removal warning to the kernel
shown at ipl for 5 minutes: a960062e5826 ("s390: add 31 bit warning
message") which let everybody know about the plan to remove 31 bit
code. We didn't get any response.

Given that the last 31 bit only machine was introduced in 1999 let's
remove the code.
Anybody with 31 bit user space code can still use the compat mode.

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

s390: Replace __get_cpu_var uses

2014-08-26T17:45:52+00:00

__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&x, this_cpu_ptr(&y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	this_cpu_inc(y)

Cc: Martin Schwidefsky 
CC: linux390@de.ibm.com
Acked-by: Heiko Carstens 
Signed-off-by: Christoph Lameter 
Signed-off-by: Tejun Heo

s390/oprofile: make return of 0 explicit

2014-05-27T08:26:00+00:00

Delete unnecessary local variable whose value is always 0 and that hides
the fact that the result is always 0.

A simplified version of the semantic patch that fixes this problem is as
follows: (http://coccinelle.lip6.fr/)

// 
@r exists@
local idexpression ret;
expression e;
position p;
@@

-ret = 0;
... when != ret = e
return
- ret
+ 0
  ;
// 

[heiko.carstens: turn prepare_cpu_buffers into a void returning function]
Signed-off-by: Julia Lawall 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky