Re: powerpc ftrace broken due to "manual merge of the ftrace tree with the arm64 tree"

From: Steven Rostedt <rostedt@goodmis.org>
To: Qian Cai <cai@lca.pw>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: powerpc ftrace broken due to "manual merge of the ftrace tree with the arm64 tree"
Date: Mon, 18 Nov 2019 10:16:45 -0500	[thread overview]
Message-ID: <20191118101645.2f68c521@oasis.local.home> (raw)
In-Reply-To: <20191118095842.546b38d8@oasis.local.home>

On Mon, 18 Nov 2019 09:58:42 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 18 Nov 2019 09:51:04 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > > > Test this commit please: b83b43ffc6e4b514ca034a0fbdee01322e2f7022      
> > > 
> > > # git reset --hard b83b43ffc6e4b514ca034a0fbdee01322e2f7022
> > > 
> > > Yes, that one is bad.    
> > 
> > Can you see if this patch fixes the issue for you?  
> 
> Don't bother. This isn't the right fix, I know see the real issue.
> 
> New fix coming shortly.
> 

Can you try this?

It appears that I picked a name "ftrace_graph_stub", that was already in
use by powerpc. This just renames the function stub I used.

-- Steve

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 0f358be551cd..996db32c491b 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -112,7 +112,7 @@
 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 #ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
 /*
- * Need to also make ftrace_graph_stub point to ftrace_stub
+ * Need to also make ftrace_stub_graph point to ftrace_stub
  * so that the same stub location may have different protocols
  * and not mess up with C verifiers.
  */
@@ -120,17 +120,17 @@
 			__start_mcount_loc = .;			\
 			KEEP(*(__patchable_function_entries))	\
 			__stop_mcount_loc = .;			\
-			ftrace_graph_stub = ftrace_stub;
+			ftrace_stub_graph = ftrace_stub;
 #else
 #define MCOUNT_REC()	. = ALIGN(8);				\
 			__start_mcount_loc = .;			\
 			KEEP(*(__mcount_loc))			\
 			__stop_mcount_loc = .;			\
-			ftrace_graph_stub = ftrace_stub;
+			ftrace_stub_graph = ftrace_stub;
 #endif
 #else
 # ifdef CONFIG_FUNCTION_TRACER
-#  define MCOUNT_REC()	ftrace_graph_stub = ftrace_stub;
+#  define MCOUNT_REC()	ftrace_stub_graph = ftrace_stub;
 # else
 #  define MCOUNT_REC()
 # endif
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index fa3ce10d0405..67e0c462b059 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -336,10 +336,10 @@ int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
  * Simply points to ftrace_stub, but with the proper protocol.
  * Defined by the linker script in linux/vmlinux.lds.h
  */
-extern void ftrace_graph_stub(struct ftrace_graph_ret *);
+extern void ftrace_stub_graph(struct ftrace_graph_ret *);
 
 /* The callbacks that hook a function */
-trace_func_graph_ret_t ftrace_graph_return = ftrace_graph_stub;
+trace_func_graph_ret_t ftrace_graph_return = ftrace_stub_graph;
 trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
 static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
 
@@ -619,7 +619,7 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
 		goto out;
 
 	ftrace_graph_active--;
-	ftrace_graph_return = ftrace_graph_stub;
+	ftrace_graph_return = ftrace_stub_graph;
 	ftrace_graph_entry = ftrace_graph_entry_stub;
 	__ftrace_graph_entry = ftrace_graph_entry_stub;
 	ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
