arch/metag/oprofile/backtrace.c

   1 /*
   2  * Copyright (C) 2010-2013 Imagination Technologies Ltd.
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  */
   8
   9 #include <linux/oprofile.h>
  10 #include <linux/uaccess.h>
  11 #include <asm/processor.h>
  12 #include <asm/stacktrace.h>
  13
  14 #include "backtrace.h"
  15
  16 static void user_backtrace_fp(unsigned long __user *fp, unsigned int depth)
  17 {
  18         while (depth-- && access_ok(VERIFY_READ, fp, 8)) {
  19                 unsigned long addr;
  20                 unsigned long __user *fpnew;
  21                 if (__copy_from_user_inatomic(&addr, fp + 1, sizeof(addr)))
  22                         break;
  23                 addr -= 4;
  24
  25                 oprofile_add_trace(addr);
  26
  27                 /* stack grows up, so frame pointers must decrease */
  28                 if (__copy_from_user_inatomic(&fpnew, fp + 0, sizeof(fpnew)))
  29                         break;
  30                 if (fpnew >= fp)
  31                         break;
  32                 fp = fpnew;
  33         }
  34 }
  35
  36 static int kernel_backtrace_frame(struct stackframe *frame, void *data)
  37 {
  38         unsigned int *depth = data;
  39
  40         oprofile_add_trace(frame->pc);
  41
  42         /* decrement depth and stop if we reach 0 */
  43         if ((*depth)-- == 0)
  44                 return 1;
  45
  46         /* otherwise onto the next frame */
  47         return 0;
  48 }
  49
  50 void metag_backtrace(struct pt_regs * const regs, unsigned int depth)
  51 {
  52         if (user_mode(regs)) {
  53                 unsigned long *fp = (unsigned long *)regs->ctx.AX[1].U0;
  54                 user_backtrace_fp((unsigned long __user __force *)fp, depth);
  55         } else {
  56                 struct stackframe frame;
  57                 frame.fp = regs->ctx.AX[1].U0;          /* A0FrP */
  58                 frame.sp = user_stack_pointer(regs);    /* A0StP */
  59                 frame.lr = 0;                           /* from stack */
  60                 frame.pc = regs->ctx.CurrPC;            /* PC */
  61                 walk_stackframe(&frame, &kernel_backtrace_frame, &depth);
  62         }
  63 }