arch/sh/oprofile/backtrace.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * SH specific backtracing code for oprofile
   4  *
   5  * Copyright 2007 STMicroelectronics Ltd.
   6  *
   7  * Author: Dave Peverley <dpeverley@mpc-data.co.uk>
   8  *
   9  * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
  10  * oprofile backtrace code by John Levon, David Smith
  11  */
  12 #include <linux/oprofile.h>
  13 #include <linux/sched.h>
  14 #include <linux/kallsyms.h>
  15 #include <linux/mm.h>
  16 #include <asm/unwinder.h>
  17 #include <asm/ptrace.h>
  18 #include <linux/uaccess.h>
  19 #include <asm/sections.h>
  20 #include <asm/stacktrace.h>
  21
  22 static int backtrace_stack(void *data, char *name)
  23 {
  24         /* Yes, we want all stacks */
  25         return 0;
  26 }
  27
  28 static void backtrace_address(void *data, unsigned long addr, int reliable)
  29 {
  30         unsigned int *depth = data;
  31
  32         if ((*depth)--)
  33                 oprofile_add_trace(addr);
  34 }
  35
  36 static struct stacktrace_ops backtrace_ops = {
  37         .stack = backtrace_stack,
  38         .address = backtrace_address,
  39 };
  40
  41 /* Limit to stop backtracing too far. */
  42 static int backtrace_limit = 20;
  43
  44 static unsigned long *
  45 user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
  46 {
  47         unsigned long buf_stack;
  48
  49         /* Also check accessibility of address */
  50         if (!access_ok(stackaddr, sizeof(unsigned long)))
  51                 return NULL;
  52
  53         if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
  54                 return NULL;
  55
  56         /* Quick paranoia check */
  57         if (buf_stack & 3)
  58                 return NULL;
  59
  60         oprofile_add_trace(buf_stack);
  61
  62         stackaddr++;
  63
  64         return stackaddr;
  65 }
  66
  67 void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
  68 {
  69         unsigned long *stackaddr;
  70
  71         /*
  72          * Paranoia - clip max depth as we could get lost in the weeds.
  73          */
  74         if (depth > backtrace_limit)
  75                 depth = backtrace_limit;
  76
  77         stackaddr = (unsigned long *)kernel_stack_pointer(regs);
  78         if (!user_mode(regs)) {
  79                 if (depth)
  80                         unwind_stack(NULL, regs, stackaddr,
  81                                      &backtrace_ops, &depth);
  82                 return;
  83         }
  84
  85         while (depth-- && (stackaddr != NULL))
  86                 stackaddr = user_backtrace(stackaddr, regs);
  87 }