Message-ID: <173379653720.973433.18438622234884980494.stgit@devnote2>
Date: Tue, 10 Dec 2024 11:08:57 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Florent Revest <revest@...omium.org>
Cc: linux-trace-kernel@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	bpf <bpf@...r.kernel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Jiri Olsa <jolsa@...nel.org>,
	Alan Maguire <alan.maguire@...cle.com>,
	Mark Rutland <mark.rutland@....com>,
	linux-arch@...r.kernel.org,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: [PATCH v21 01/20] fgraph: Get ftrace recursion lock in function_graph_enter

From: Masami Hiramatsu (Google) <mhiramat@...nel.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) <mhiramat@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Naveen N Rao <naveen@...nel.org>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: x86@...nel.org
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.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 0bf78517b5d4..c57540ad384d 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;
 }
 

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