arch/parisc/kernel/ftrace.c

   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  */
  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(&current->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
  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