Merge tag 'trace-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "This pull request has a lot of work done.  The main thing is the
  changes to the ftrace function callback infrastructure.  It's
  introducing a way to allow different functions to call directly
  different trampolines instead of all calling the same "mcount" one.

  The only user of this for now is the function graph tracer, which
  always had a different trampoline, but the function tracer trampoline
  was called and did basically nothing, and then the function graph
  tracer trampoline was called.  The difference now, is that the
  function graph tracer trampoline can be called directly if a function
  is only being traced by the function graph trampoline.  If function
  tracing is also happening on the same function, the old way is still
  done.

  The accounting for this takes up more memory when function graph
  tracing is activated, as it needs to keep track of which functions it
  uses.  I have a new way that wont take as much memory, but it's not
  ready yet for this merge window, and will have to wait for the next
  one.

  Another big change was the removal of the ftrace_start/stop() calls
  that were used by the suspend/resume code that stopped function
  tracing when entering into suspend and resume paths.  The stop of
  ftrace was done because there was some function that would crash the
  system if one called smp_processor_id()! The stop/start was a big
  hammer to solve the issue at the time, which was when ftrace was first
  introduced into Linux.  Now ftrace has better infrastructure to debug
  such issues, and I found the problem function and labeled it with
  "notrace" and function tracing can now safely be activated all the way
  down into the guts of suspend and resume

  Other changes include clean ups of uprobe code, clean up of the
  trace_seq() code, and other various small fixes and clean ups to
  ftrace and tracing"

* tag 'trace-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (57 commits)
  ftrace: Add warning if tramp hash does not match nr_trampolines
  ftrace: Fix trampoline hash update check on rec->flags
  ring-buffer: Use rb_page_size() instead of open coded head_page size
  ftrace: Rename ftrace_ops field from trampolines to nr_trampolines
  tracing: Convert local function_graph functions to static
  ftrace: Do not copy old hash when resetting
  tracing: let user specify tracing_thresh after selecting function_graph
  ring-buffer: Always run per-cpu ring buffer resize with schedule_work_on()
  tracing: Remove function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST
  s390/ftrace: remove check of obsolete variable function_trace_stop
  arm64, ftrace: Remove check of obsolete variable function_trace_stop
  Blackfin: ftrace: Remove check of obsolete variable function_trace_stop
  metag: ftrace: Remove check of obsolete variable function_trace_stop
  microblaze: ftrace: Remove check of obsolete variable function_trace_stop
  MIPS: ftrace: Remove check of obsolete variable function_trace_stop
  parisc: ftrace: Remove check of obsolete variable function_trace_stop
  sh: ftrace: Remove check of obsolete variable function_trace_stop
  sparc64,ftrace: Remove check of obsolete variable function_trace_stop
  tile: ftrace: Remove check of obsolete variable function_trace_stop
  ftrace: x86: Remove check of obsolete variable function_trace_stop
  ...

3 files changed, 4 insertions, 21 deletions

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 0d0c9d4ab6d5..47c410d99f5d 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1059,9 +1059,6 @@ ENTRY(mcount)
 END(mcount)
 
 ENTRY(ftrace_caller)
-        cmpl $0, function_trace_stop
-        jne  ftrace_stub
-
         pushl %eax
         pushl %ecx
         pushl %edx
@@ -1093,8 +1090,6 @@ END(ftrace_caller)
 
 ENTRY(ftrace_regs_caller)
         pushf   /* push flags before compare (in cs location) */
-        cmpl $0, function_trace_stop
-        jne ftrace_restore_flags
 
         /*
          * i386 does not save SS and ESP when coming from kernel.
@@ -1153,7 +1148,6 @@ GLOBAL(ftrace_regs_call)
         popf                    /* Pop flags at end (no addl to corrupt flags) */
         jmp ftrace_ret
 
-ftrace_restore_flags:
         popf
         jmp  ftrace_stub
 #else /* ! CONFIG_DYNAMIC_FTRACE */
@@ -1162,9 +1156,6 @@ ENTRY(mcount)
         cmpl $__PAGE_OFFSET, %esp
         jb ftrace_stub          /* Paging not enabled yet? */
 
-        cmpl $0, function_trace_stop
-        jne  ftrace_stub
-
         cmpl $ftrace_stub, ftrace_trace_function
         jnz trace
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index cbc4a91b131e..3386dc9aa333 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -703,6 +703,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
         unsigned long return_hooker = (unsigned long)
                                 &return_to_handler;
 
+        if (unlikely(ftrace_graph_is_dead()))
+                return;
+
         if (unlikely(atomic_read(&current->tracing_graph_pause)))
                 return;
 
diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index c050a0153168..c73aecf10d34 100644
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -46,10 +46,6 @@ END(function_hook)
 .endm
 
 ENTRY(ftrace_caller)
-        /* Check if tracing was disabled (quick check) */
-        cmpl $0, function_trace_stop
-        jne  ftrace_stub
-
         ftrace_caller_setup
         /* regs go into 4th parameter (but make it NULL) */
         movq $0, %rcx
@@ -73,10 +69,6 @@ ENTRY(ftrace_regs_caller)
         /* Save the current flags before compare (in SS location)*/
         pushfq
 
-        /* Check if tracing was disabled (quick check) */
-        cmpl $0, function_trace_stop
-        jne  ftrace_restore_flags
-
         /* skip=8 to skip flags saved in SS */
         ftrace_caller_setup 8
 
@@ -131,7 +123,7 @@ GLOBAL(ftrace_regs_call)
         popfq
 
         jmp ftrace_return
-ftrace_restore_flags:
+
         popfq
         jmp  ftrace_stub
 
@@ -141,9 +133,6 @@ END(ftrace_regs_caller)
 #else /* ! CONFIG_DYNAMIC_FTRACE */
 
 ENTRY(function_hook)
-        cmpl $0, function_trace_stop
-        jne  ftrace_stub
-
         cmpq $ftrace_stub, ftrace_trace_function
         jnz trace