As Colin Cross ported my x86 change to ARM, he also pointed out that
powerpc is also behind in this fix.

The commit 722b3c74 "ftrace/graph: Trace function entry before
updating index" fixes an issue with function graph tracing for x86,
where if the called entry function decides not to trace interrupts, it
can fail the check if an interrupt comes in just after the
curr_ret_stack is updated.

The solution is to call the entry function first, then update the
curr_ret_stack if the entry function wants to be traced.

Cc: Colin Cross <ccross@android.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Just like the module loader, ftrace needs to be updated to use r12
instead of r11 with newer gcc's.
Signed-off-by: NRoger Blofeld <blofeldus@yahoo.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
CC: stable@vger.kernel.org

The patch_instruction() interface is made to modify kernel text. It is
safer to use that then the probe_kernel_write() when modifying kernel
code.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

PowerPC does not have the synchronization issues that x86 has with
modifying code on one CPU while another CPU is executing it.
The other CPU will either see the old or new code without any
issues, unlike x86 which may issue a GPF.

Instead of calling the heavy stop_machine, just update the code.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This patch implements the raw syscall tracepoints on PowerPC and exports
them for ftrace syscalls to use.

To minimise reworking existing code, I slightly re-ordered the thread
info flags such that the new TIF_SYSCALL_TRACEPOINT bit would still fit
within the 16 bits of the andi. instruction's UI field. The instructions
in question are in /arch/powerpc/kernel/entry_{32,64}.S to and the
_TIF_SYSCALL_T_OR_A with the thread flags to see if system call tracing
is enabled.

In the case of 64bit PowerPC, arch_syscall_addr and
arch_syscall_match_sym_name are overridden to allow ftrace syscalls to
work given the unusual system call table structure and symbol names that
start with a period.
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

In case gcc does something funny with the stack frames, or the return
from function code, we would like to detect that.

An arch may implement passing of a variable that is unique to the
function and can be saved on entering a function and can be tested
when exiting the function. Usually the frame pointer can be used for
this purpose.

This patch also implements this for x86. Where it passes in the stack
frame of the parent function, and will test that frame on exit.

There was a case in x86_32 with optimize for size (-Os) where, for a
few functions, gcc would align the stack frame and place a copy of the
return address into it. The function graph tracer modified the copy and
not the actual return address. On return from the funtion, it did not go
to the tracer hook, but returned to the parent. This broke the function
graph tracer, because the return of the parent (where gcc did not do
this funky manipulation) returned to the location that the child function
was suppose to. This caused strange kernel crashes.

This test detected the problem and pointed out where the issue was.

This modifies the parameters of one of the functions that the arch
specific code calls, so it includes changes to arch code to accommodate
the new prototype.

Note, I notice that the parsic arch implements its own push_return_trace.
This is now a generic function and the ftrace_push_return_trace should be
used instead. This patch does not touch that code.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

There's no need to wrap PPC_INST_NOP in a static inline.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

These macros were used in the original port, but since commit
e4486fe3 (ftrace, use probe_kernel API to modify code) they
are unused.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Use ppc_function_entry() from code-patching.h.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

After upgrading my distcc boxes from gcc 4.2.2 to 4.4.0, the function
graph tracer broke. This was discovered on my x86 boxes.

The issue is that gcc used the same register for an output as it did for
an input in an asm statement. I first thought this was a bug in gcc and
reported it. I was notified that gcc was correct and that the output had
to be flagged as an "early clobber".

I noticed that powerpc had the same issue and this patch fixes it.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

pr_debug() can now result in code being generated even when #DEBUG
is not defined. That's not really desirable in the ftrace code
which we want to be snappy.

With CONFIG_DYNAMIC_DEBUG=y:

size before:
   text	   data	    bss	    dec	    hex	filename
   3334	    672	      4	   4010	    faa	arch/powerpc/kernel/ftrace.o

size after:
   text	   data	    bss	    dec	    hex	filename
   2616	    360	      4	   2980	    ba4	arch/powerpc/kernel/ftrace.o
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

'tramp' is an unsigned long, so print it with %lx.

Fixes the following build warning:
arch/powerpc/kernel/ftrace.c:291: error: format ‘%x’ expects type ‘unsigned int’, but argument 2 has type ‘long unsigned int’
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Commit bb725340 ("powerpc64,
ftrace: save toc only on modules for function graph"), added an
#if CONFIG_PPC64.  This changes it to #ifdef.

Fixes the following warning on 32-bit builds:
 arch/powerpc/kernel/ftrace.c:562:5: error: "CONFIG_PPC64" is not defined
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Today's linux-next build (powerpc allyesconfig) failed like this:

arch/powerpc/kernel/ftrace.c: In function 'prepare_ftrace_return':
arch/powerpc/kernel/ftrace.c:612: warning: passing argument 3 of 'ftrace_push_return_trace' makes pointer from integer without a cast
arch/powerpc/kernel/ftrace.c:612: error: too many arguments to function 'ftrace_push_return_trace'

Caused by commit 5d1a03dc
("function-graph: moved the timestamp from arch to generic code") from
the tracing tree which (removed an argument from
ftrace_push_return_trace()) interacting with commit
6794c782 ("powerpc64: port of the
function graph tracer") from the powerpc tree.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: <linuxppc-dev@ozlabs.org>
LKML-Reference: <20090327230834.93d0221d.sfr@canb.auug.org.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Create a new header that becomes a single location for defining PowerPC
opcodes used by code that is either generationg instructions
at runtime (fixups, debug, etc.), emulating instructions, or just
compiling instructions old assemblers don't know about.

We currently don't handle the floating point emulation or alignment decode
as both are better handled by the specific decode support they already
have.

Added support for the new dcbzl, dcbal, msgsnd, tlbilx, & wait instructions
since older assemblers don't know about them.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Impact: clean up, remove duplicate code

When ftrace was first ported to PowerPC, there existed a
create_function_call that would create the instruction to make a call
to a given address. Unfortunately, this call expected to write to
the address it was given, and since it used the address to calculate
the offset, it could not be faked.

ftrace needed a way to create the instruction without actually writing
that instruction to the text section. So ftrace had to implement its
own code.

Now we have create_branch in the code patching library, which does
exactly what ftrace needs. This patch replaces ftrace's implementation
with the library function.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The original port of ftrace to PowerPC kept a lot of the code used
by x86. Some of this code was to handle x86's 5 byte instruction.
This was handled by using character arrays to manipulate the
code.

PowerPC has a consistent 4 byte instruction. Using unsigned ints
makes the code more efficient as well as more readable.
By converting to use unsigned ints to represent instructions,
I was able to remove the side effects that were needed for
manipulating character strings.

  i.e. memcpy and memcmp
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This patch ports the function graph tracer for PowerPC, but only
for static function tracing.
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The TOCS used by modules are different than the one used by
the core kernel code. The function graph tracer must save and
restore the TOC whenever it traces a module call. But this
is an added overhead to burden the majority of core kernel
code being traced.

Benjamin Herrenschmidt suggested in testing the entry of
the call to tell if it is a core kernel function or a module.
He recommended using the REGION_ID() macro to perform this test.

This patch implements Benjamin's idea, and uses a different
return_to_handler routine dependent on if the entry is a core
kernel function or not. The module version saves the TOC, where as
the core kernel version does not.

Geoff Lavand tested on PS3.
Tested-by: NGeoff Levand <geoffrey.levand@am.sony.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This is the port of the function graph tracer to PowerPC with
dynamic tracing.

Geoff Lavand tested on PS3.
Tested-by: NGeoff Levand <geoffrey.levand@am.sony.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This is a port of the function graph tracer that was written by
Frederic Weisbecker for the x86.

This only works for PPC64 at the moment and only for static tracing.
PPC32 and dynamic function graph tracing support will come later.

The trace produces a visual calling of functions:

 # tracer: function_graph
 #
 # CPU  DURATION                  FUNCTION CALLS
 # |     |   |                     |   |   |   |
  0)   2.224 us    |                        }
  0) ! 271.024 us  |                      }
  0) ! 320.080 us  |                    }
  0) ! 324.656 us  |                  }
  0) ! 329.136 us  |                }
  0)               |                .put_prev_task_fair() {
  0)               |                  .update_curr() {
  0)   2.240 us    |                    .update_min_vruntime();
  0)   6.512 us    |                  }
  0)   2.528 us    |                  .__enqueue_entity();
  0) + 15.536 us   |                }
  0)               |                .pick_next_task_fair() {
  0)   2.032 us    |                  .__pick_next_entity();
  0)   2.064 us    |                  .__clear_buddies();
  0)               |                  .set_next_entity() {
  0)   2.672 us    |                    .__dequeue_entity();
  0)   6.864 us    |                  }

Geoff Lavand tested on PS3.
Tested-by: NGeoff Levand <geoffrey.levand@am.sony.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Michael Neuling reported a compile bug when dynamic ftrace was
configured in and modules were not. This was due to the ftrace
code referencing module specific structures.
Reported-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Impact: cleanup

The PowerPC ftrace code uses a hacked up DEBUGP macro for prints.
This patch converts it to the standard pr_debug.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Impact: fix dynamic ftrace with large modules in PPC64

The math to calculate the offset into the TOC that is taken from reading
the trampoline is incorrect. The bottom half of the offset is a signed
extended short. The current code was using an OR to create the offset
when it should have been using an addition.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Acked-by: NGeoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Impact: clean up

Paul Mackerras pointed out that the code to determine if the branch
can reach the destination is incorrect. Michael Ellerman suggested
to pull out the code from create_branch and use that.

Simply using create_branch is probably the best.
Reported-by: NMichael Ellerman <michael@ellerman.id.au>
Reported-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix to PowerPC code modification

After modifying code it is essential to flush the icache. This patch
adds the missing flush.
Reported-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up and robustness addition

This patch addresses the comments made by Paul Mackerras.
It removes the type casting between unsigned int and unsigned char
pointers, and replaces them with a use of all unsigned int.

Verification that the jump is indeed made to a trampoline has also
been added.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add ability to trace modules on 32 bit PowerPC

This patch performs the necessary trampoline calls to handle
modules with dynamic ftrace on 32 bit PowerPC.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: Allow 64 bit PowerPC to trace modules with dynamic ftrace

This adds code to handle the PPC64 module trampolines, and allows for
PPC64 to use dynamic ftrace.

Thanks to Paul Mackerras for these updates:

  - fix the mod and rec->arch.mod NULL checks.
  - fix to is_bl_op compare.

Thanks to Milton Miller for:

  - finding the nasty race with using two nops, and recommending
    instead that I use a branch 8 forward.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: use cleaner probe_kernel API over assembly

Using probe_kernel_read/write interface is a much cleaner approach
than the current assembly version.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: update to PowerPC ftrace arch API

This patch converts PowerPC to use the new dynamic ftrace arch API.

Thanks to Paul Mackennas for pointing out the mistakes of my original
test_24bit_addr function.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

The entire file of ftrace.c in the arch code needs to be marked
as notrace. It is much cleaner to do this from the Makefile with
CFLAGS_REMOVE_ftrace.o.

[ powerpc already had this in its Makefile. ]
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The arch dependent function ftrace_mcount_set was only used by the daemon
start up code. This patch removes it.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Record the address of the mcount call-site. Currently all archs except sparc64
record the address of the instruction following the mcount call-site. Some
general cleanups are entailed. Storing mcount addresses in rec->ip enables
looking them up in the kprobe hash table later on to check if they're kprobe'd.
Signed-off-by: NAbhishek Sagar <sagar.abhishek@gmail.com>
Cc: davem@davemloft.net
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Remove the unneeded function ftrace_ip_converted().
Signed-off-by: NAbhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch cleans up the ftrace code in PowerPC based on the comments from
Michael Ellerman.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: proski@gnu.org
Cc: a.p.zijlstra@chello.nl
Cc: Pekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linuxppc-dev@ozlabs.org
Cc: Soeren Sandmann Pedersen <sandmann@redhat.com>
Cc: paulus@samba.org
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch adds full support for ftrace for PowerPC (both 64 and 32 bit).
This includes dynamic tracing and function filtering.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The fault label to jump to on fault of updating the code was misplaced
preventing the fault from being recorded.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch replaces the indirect call to the mcount function
pointer with a direct call that will be patched by the
dynamic ftrace routines.

On boot up, the mcount function calls the ftace_stub function.
When the dynamic ftrace code is initialized, the ftrace_stub
is replaced with a call to the ftrace_record_ip, which records
the instruction pointers of the locations that call it.

Later, the ftraced daemon will call kstop_machine and patch all
the locations to nops.

When a ftrace is enabled, the original calls to mcount will now
be set top call ftrace_caller, which will do a direct call
to the registered ftrace function. This direct call is also patched
when the function that should be called is updated.

All patching is performed by a kstop_machine routine to prevent any
type of race conditions that is associated with modifying code
on the fly.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch moves the memory management of the ftrace
records out of the arch code and into the generic code
making the arch code simpler.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>