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         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         if (!function_graph_enter(old, self_addr, 0, NULL))
  44                 /* activate parisc_return_to_handler() as return point */
  45                 *parent = (unsigned long) &parisc_return_to_handler;
  46 }
  47 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
  48
  49 void notrace __hot ftrace_function_trampoline(unsigned long parent,
  50                                 unsigned long self_addr,
  51                                 unsigned long org_sp_gr3)
  52 {
  53         extern ftrace_func_t ftrace_trace_function;  /* depends on CONFIG_DYNAMIC_FTRACE */
  54         extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
  55
  56         if (ftrace_trace_function != ftrace_stub) {
  57                 /* struct ftrace_ops *op, struct pt_regs *regs); */
  58                 ftrace_trace_function(parent, self_addr, NULL, NULL);
  59                 return;
  60         }
  61
  62 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  63         if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub ||
  64                 ftrace_graph_entry != ftrace_graph_entry_stub) {
  65                 unsigned long *parent_rp;
  66
  67                 /* calculate pointer to %rp in stack */
  68                 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET);
  69                 /* sanity check: parent_rp should hold parent */
  70                 if (*parent_rp != parent)
  71                         return;
  72
  73                 prepare_ftrace_return(parent_rp, self_addr);
  74                 return;
  75         }
  76 #endif
  77 }
  78