[PATCH v22 01/20] fgraph: Get ftrace recursion lock in function_graph_enter

[Masami Hiramatsu (Google)]

From: Masami Hiramatsu (Google) <mhira...@kernel.org>

Get the ftrace recursion lock in the generic function_graph_enter()
instead of each architecture code.
This changes all function_graph tracer callbacks running in
non-preemptive state. On x86 and powerpc, this is by default, but
on the other architecutres, this will be new.

Signed-off-by: Masami Hiramatsu (Google) <mhira...@kernel.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Nicholas Piggin <npig...@gmail.com>
Cc: Christophe Leroy <christophe.le...@csgroup.eu>
Cc: Naveen N Rao <nav...@kernel.org>
Cc: Madhavan Srinivasan <ma...@linux.ibm.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: x...@kernel.org
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
---
 Changes in v21:
  - Newly added.
---
 arch/powerpc/kernel/trace/ftrace.c       |    6 ------
 arch/powerpc/kernel/trace/ftrace_64_pg.c |    6 ------
 arch/x86/kernel/ftrace.c                 |    7 -------
 kernel/trace/fgraph.c                    |    8 +++++++-
 4 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/kernel/trace/ftrace.c 
b/arch/powerpc/kernel/trace/ftrace.c
index 5ccd791761e8..e41daf2c4a31 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -658,7 +658,6 @@ void ftrace_graph_func(unsigned long ip, unsigned long 
parent_ip,
                       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
        unsigned long sp = arch_ftrace_regs(fregs)->regs.gpr[1];
-       int bit;
 
        if (unlikely(ftrace_graph_is_dead()))
                goto out;
@@ -666,14 +665,9 @@ void ftrace_graph_func(unsigned long ip, unsigned long 
parent_ip,
        if (unlikely(atomic_read(&current->tracing_graph_pause)))
                goto out;
 
-       bit = ftrace_test_recursion_trylock(ip, parent_ip);
-       if (bit < 0)
-               goto out;
-
        if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
                parent_ip = ppc_function_entry(return_to_handler);
 
-       ftrace_test_recursion_unlock(bit);
 out:
        arch_ftrace_regs(fregs)->regs.link = parent_ip;
 }
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c 
b/arch/powerpc/kernel/trace/ftrace_64_pg.c
index 98787376eb87..8fb860b90ae1 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.c
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c
@@ -790,7 +790,6 @@ static unsigned long
 __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long 
sp)
 {
        unsigned long return_hooker;
-       int bit;
 
        if (unlikely(ftrace_graph_is_dead()))
                goto out;
@@ -798,16 +797,11 @@ __prepare_ftrace_return(unsigned long parent, unsigned 
long ip, unsigned long sp
        if (unlikely(atomic_read(&current->tracing_graph_pause)))
                goto out;
 
-       bit = ftrace_test_recursion_trylock(ip, parent);
-       if (bit < 0)
-               goto out;
-
        return_hooker = ppc_function_entry(return_to_handler);
 
        if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
                parent = return_hooker;
 
-       ftrace_test_recursion_unlock(bit);
 out:
        return parent;
 }
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 4dd0ad6c94d6..33f50c80f481 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -615,7 +615,6 @@ void prepare_ftrace_return(unsigned long ip, unsigned long 
*parent,
                           unsigned long frame_pointer)
 {
        unsigned long return_hooker = (unsigned long)&return_to_handler;
-       int bit;
 
        /*
         * When resuming from suspend-to-ram, this function can be indirectly
@@ -635,14 +634,8 @@ void prepare_ftrace_return(unsigned long ip, unsigned long 
*parent,
        if (unlikely(atomic_read(&current->tracing_graph_pause)))
                return;
 
-       bit = ftrace_test_recursion_trylock(ip, *parent);
-       if (bit < 0)
-               return;
-
        if (!function_graph_enter(*parent, ip, frame_pointer, parent))
                *parent = return_hooker;
-
-       ftrace_test_recursion_unlock(bit);
 }
 
 #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index ddedcb50917f..5c68d6109119 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -650,8 +650,13 @@ int function_graph_enter(unsigned long ret, unsigned long 
func,
        struct ftrace_graph_ent trace;
        unsigned long bitmap = 0;
        int offset;
+       int bit;
        int i;
 
+       bit = ftrace_test_recursion_trylock(func, ret);
+       if (bit < 0)
+               return -EBUSY;
+
        trace.func = func;
        trace.depth = ++current->curr_ret_depth;
 
@@ -697,12 +702,13 @@ int function_graph_enter(unsigned long ret, unsigned long 
func,
         * flag, set that bit always.
         */
        set_bitmap(current, offset, bitmap | BIT(0));
-
+       ftrace_test_recursion_unlock(bit);
        return 0;
  out_ret:
        current->curr_ret_stack -= FGRAPH_FRAME_OFFSET + 1;
  out:
        current->curr_ret_depth--;
+       ftrace_test_recursion_unlock(bit);
        return -EBUSY;
 }