From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Mon, 18 Feb 2019 16:51:28 +0100
Subject: s390/ftrace: use HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
Git-commit: ec7bf4789d95a0053bac0dfa36fbefd8cc584eea
Patch-mainline: v5.2-rc1
References: jsc#SLE-11178

Make the call chain more reliable by tagging the ftrace stack entries
with the stack pointer that is associated with the return address.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
 arch/s390/include/asm/ftrace.h |    2 ++
 arch/s390/kernel/entry.h       |    2 +-
 arch/s390/kernel/ftrace.c      |   11 ++++++-----
 arch/s390/kernel/mcount.S      |    4 ++--
 arch/s390/kernel/unwind_bc.c   |    2 +-
 5 files changed, 12 insertions(+), 9 deletions(-)

--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -10,6 +10,8 @@
 #define MCOUNT_RETURN_FIXUP	18
 #endif
 
+#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
+
 #ifndef __ASSEMBLY__
 
 #define ftrace_return_address(n) __builtin_return_address(n)
--- a/arch/s390/kernel/entry.h
+++ b/arch/s390/kernel/entry.h
@@ -63,7 +63,7 @@ int setup_profiling_timer(unsigned int m
 void __init time_init(void);
 int pfn_is_nosave(unsigned long);
 void s390_early_resume(void);
-unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip);
+unsigned long prepare_ftrace_return(unsigned long parent, unsigned long sp, unsigned long ip);
 
 struct s390_mmap_arg_struct;
 struct fadvise64_64_args;
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -200,7 +200,8 @@ device_initcall(ftrace_plt_init);
  * Hook the return address and push it in the stack of return addresses
  * in current thread info.
  */
-unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
+unsigned long prepare_ftrace_return(unsigned long ra, unsigned long sp,
+				    unsigned long ip)
 {
 	struct ftrace_graph_ent trace;
 
@@ -214,12 +215,12 @@ unsigned long prepare_ftrace_return(unsi
 	/* Only trace if the calling function expects to. */
 	if (!ftrace_graph_entry(&trace))
 		goto out;
-	if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
-				     NULL) == -EBUSY)
+	if (ftrace_push_return_trace(ra, ip, &trace.depth, 0,
+				     (void *) sp) == -EBUSY)
 		goto out;
-	parent = (unsigned long) return_to_handler;
+	ra = (unsigned long) return_to_handler;
 out:
-	return parent;
+	return ra;
 }
 NOKPROBE_SYMBOL(prepare_ftrace_return);
 
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -62,8 +62,8 @@ ENTRY(ftrace_caller)
 # See ftrace_enable_ftrace_graph_caller.
 ENTRY(ftrace_graph_caller)
 	j	ftrace_graph_caller_end
-	lg	%r2,(STACK_PTREGS_GPRS+14*8)(%r15)
-	lg	%r3,(STACK_PTREGS_PSW+8)(%r15)
+	lmg	%r2,%r3,(STACK_PTREGS_GPRS+14*8)(%r15)
+	lg	%r4,(STACK_PTREGS_PSW+8)(%r15)
 	brasl	%r14,prepare_ftrace_return
 	stg	%r2,(STACK_PTREGS_GPRS+14*8)(%r15)
 ftrace_graph_caller_end:
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -84,7 +84,7 @@ bool unwind_next_frame(struct unwind_sta
 	/* Decode any ftrace redirection */
 	if (ip == (unsigned long) return_to_handler)
 		ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					   ip, NULL);
+					   ip, (void *) sp);
 #endif
 
 	/* Update unwind state */