arch/parisc/kernel/ftrace.c

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