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 void backtrace_address(void *data, unsigned long addr, int reliable)
  23 {
  24         unsigned int *depth = data;
  25
  26         if ((*depth)--)
  27                 oprofile_add_trace(addr);
  28 }
  29
  30 static struct stacktrace_ops backtrace_ops = {
  31         .address = backtrace_address,
  32 };
  33
  34 /* Limit to stop backtracing too far. */
  35 static int backtrace_limit = 20;
  36
  37 static unsigned long *
  38 user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
  39 {
  40         unsigned long buf_stack;
  41
  42         /* Also check accessibility of address */
  43         if (!access_ok(stackaddr, sizeof(unsigned long)))
  44                 return NULL;
  45
  46         if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
  47                 return NULL;
  48
  49         /* Quick paranoia check */
  50         if (buf_stack & 3)
  51                 return NULL;
  52
  53         oprofile_add_trace(buf_stack);
  54
  55         stackaddr++;
  56
  57         return stackaddr;
  58 }
  59
  60 void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
  61 {
  62         unsigned long *stackaddr;
  63
  64         /*
  65          * Paranoia - clip max depth as we could get lost in the weeds.
  66          */
  67         if (depth > backtrace_limit)
  68                 depth = backtrace_limit;
  69
  70         stackaddr = (unsigned long *)kernel_stack_pointer(regs);
  71         if (!user_mode(regs)) {
  72                 if (depth)
  73                         unwind_stack(NULL, regs, stackaddr,
  74                                      &backtrace_ops, &depth);
  75                 return;
  76         }
  77
  78         while (depth-- && (stackaddr != NULL))
  79                 stackaddr = user_backtrace(stackaddr, regs);
  80 }