s390/ftrace: use HAVE_FUNCTION_GRAPH_RET_ADDR_PTR

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>

5 files changed, 11 insertions, 8 deletions

diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index 6e0ed0338785..68d362f8d6c1 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -11,6 +11,8 @@
 #define MCOUNT_RETURN_FIXUP     18
 #endif
 
+#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
+
 #ifndef __ASSEMBLY__
 
 #ifdef CONFIG_CC_IS_CLANG
diff --git a/arch/s390/kernel/entry.h b/arch/s390/kernel/entry.h
index c3816ae108b0..20420c2b8a14 100644
--- a/arch/s390/kernel/entry.h
+++ b/arch/s390/kernel/entry.h
@@ -65,7 +65,7 @@ int setup_profiling_timer(unsigned int multiplier);
 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;
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 39b13d71a8fe..1bb85f60c0dd 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -201,17 +201,18 @@ 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)
 {
         if (unlikely(ftrace_graph_is_dead()))
                 goto out;
         if (unlikely(atomic_read(&current->tracing_graph_pause)))
                 goto out;
         ip -= MCOUNT_INSN_SIZE;
-        if (!function_graph_enter(parent, ip, 0, NULL))
-                parent = (unsigned long) return_to_handler;
+        if (!function_graph_enter(ra, ip, 0, (void *) sp))
+                ra = (unsigned long) return_to_handler;
 out:
-        return parent;
+        return ra;
 }
 NOKPROBE_SYMBOL(prepare_ftrace_return);
 
diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 09ae6da0aaa5..9e1660a6b9db 100644
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -65,8 +65,8 @@ ENTRY(ftrace_caller)
         .globl ftrace_graph_caller
 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:
diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index cf5a630f3aa9..57fd4e902f1f 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -84,7 +84,7 @@ bool unwind_next_frame(struct unwind_state *state)
         /* 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 */