1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Code for tracing calls in Linux kernel.
4 * Copyright (C) 2009-2016 Helge Deller <deller@gmx.de>
5 *
6 * based on code for x86 which is:
7 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
8 *
9 * future possible enhancements:
10 * - add CONFIG_DYNAMIC_FTRACE
11 * - add CONFIG_STACK_TRACER
12 */
13
14 #include <linux/init.h>
15 #include <linux/ftrace.h>
16
17 #include <asm/assembly.h>
18 #include <asm/sections.h>
19 #include <asm/ftrace.h>
20
21
22 #define __hot __attribute__ ((__section__ (".text.hot")))
23
24 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
25 /*
26 * Hook the return address and push it in the stack of return addrs
27 * in current thread info.
28 */
prepare_ftrace_return(unsigned long * parent,unsigned long self_addr)29 static void __hot prepare_ftrace_return(unsigned long *parent,
30 unsigned long self_addr)
31 {
32 unsigned long old;
33 struct ftrace_graph_ent trace;
34 extern int parisc_return_to_handler;
35
36 if (unlikely(ftrace_graph_is_dead()))
37 return;
38
39 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
40 return;
41
42 old = *parent;
43
44 trace.func = self_addr;
45 trace.depth = current->curr_ret_stack + 1;
46
47 /* Only trace if the calling function expects to */
48 if (!ftrace_graph_entry(&trace))
49 return;
50
51 if (ftrace_push_return_trace(old, self_addr, &trace.depth,
52 0, NULL) == -EBUSY)
53 return;
54
55 /* activate parisc_return_to_handler() as return point */
56 *parent = (unsigned long) &parisc_return_to_handler;
57 }
58 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
59
ftrace_function_trampoline(unsigned long parent,unsigned long self_addr,unsigned long org_sp_gr3)60 void notrace __hot ftrace_function_trampoline(unsigned long parent,
61 unsigned long self_addr,
62 unsigned long org_sp_gr3)
63 {
64 extern ftrace_func_t ftrace_trace_function; /* depends on CONFIG_DYNAMIC_FTRACE */
65 extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
66
67 if (ftrace_trace_function != ftrace_stub) {
68 /* struct ftrace_ops *op, struct pt_regs *regs); */
69 ftrace_trace_function(parent, self_addr, NULL, NULL);
70 return;
71 }
72
73 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
74 if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub ||
75 ftrace_graph_entry != ftrace_graph_entry_stub) {
76 unsigned long *parent_rp;
77
78 /* calculate pointer to %rp in stack */
79 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET);
80 /* sanity check: parent_rp should hold parent */
81 if (*parent_rp != parent)
82 return;
83
84 prepare_ftrace_return(parent_rp, self_addr);
85 return;
86 }
87 #endif
88 }
89
90
