arch/powerpc/oprofile/backtrace.c

   1 /**
   2  * Copyright (C) 2005 Brian Rogan <bcr6@cornell.edu>, IBM
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8 **/
   9
  10 #include <linux/time.h>
  11 #include <linux/oprofile.h>
  12 #include <linux/sched.h>
  13 #include <asm/processor.h>
  14 #include <linux/uaccess.h>
  15 #include <asm/compat.h>
  16 #include <asm/oprofile_impl.h>
  17
  18 #define STACK_SP(STACK)         *(STACK)
  19
  20 #define STACK_LR64(STACK)       *((unsigned long *)(STACK) + 2)
  21 #define STACK_LR32(STACK)       *((unsigned int *)(STACK) + 1)
  22
  23 #ifdef CONFIG_PPC64
  24 #define STACK_LR(STACK)         STACK_LR64(STACK)
  25 #else
  26 #define STACK_LR(STACK)         STACK_LR32(STACK)
  27 #endif
  28
  29 static unsigned int user_getsp32(unsigned int sp, int is_first)
  30 {
  31         unsigned int stack_frame[2];
  32         void __user *p = compat_ptr(sp);
  33
  34         if (!access_ok(p, sizeof(stack_frame)))
  35                 return 0;
  36
  37         /*
  38          * The most likely reason for this is that we returned -EFAULT,
  39          * which means that we've done all that we can do from
  40          * interrupt context.
  41          */
  42         if (__copy_from_user_inatomic(stack_frame, p, sizeof(stack_frame)))
  43                 return 0;
  44
  45         if (!is_first)
  46                 oprofile_add_trace(STACK_LR32(stack_frame));
  47
  48         /*
  49          * We do not enforce increasing stack addresses here because
  50          * we may transition to a different stack, eg a signal handler.
  51          */
  52         return STACK_SP(stack_frame);
  53 }
  54
  55 #ifdef CONFIG_PPC64
  56 static unsigned long user_getsp64(unsigned long sp, int is_first)
  57 {
  58         unsigned long stack_frame[3];
  59
  60         if (!access_ok((void __user *)sp, sizeof(stack_frame)))
  61                 return 0;
  62
  63         if (__copy_from_user_inatomic(stack_frame, (void __user *)sp,
  64                                         sizeof(stack_frame)))
  65                 return 0;
  66
  67         if (!is_first)
  68                 oprofile_add_trace(STACK_LR64(stack_frame));
  69
  70         return STACK_SP(stack_frame);
  71 }
  72 #endif
  73
  74 static unsigned long kernel_getsp(unsigned long sp, int is_first)
  75 {
  76         unsigned long *stack_frame = (unsigned long *)sp;
  77
  78         if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
  79                 return 0;
  80
  81         if (!is_first)
  82                 oprofile_add_trace(STACK_LR(stack_frame));
  83
  84         /*
  85          * We do not enforce increasing stack addresses here because
  86          * we might be transitioning from an interrupt stack to a kernel
  87          * stack. validate_sp() is designed to understand this, so just
  88          * use it.
  89          */
  90         return STACK_SP(stack_frame);
  91 }
  92
  93 void op_powerpc_backtrace(struct pt_regs * const regs, unsigned int depth)
  94 {
  95         unsigned long sp = regs->gpr[1];
  96         int first_frame = 1;
  97
  98         /* We ditch the top stackframe so need to loop through an extra time */
  99         depth += 1;
 100
 101         if (!user_mode(regs)) {
 102                 while (depth--) {
 103                         sp = kernel_getsp(sp, first_frame);
 104                         if (!sp)
 105                                 break;
 106                         first_frame = 0;
 107                 }
 108         } else {
 109                 pagefault_disable();
 110 #ifdef CONFIG_PPC64
 111                 if (!is_32bit_task()) {
 112                         while (depth--) {
 113                                 sp = user_getsp64(sp, first_frame);
 114                                 if (!sp)
 115                                         break;
 116                                 first_frame = 0;
 117                         }
 118                         pagefault_enable();
 119                         return;
 120                 }
 121 #endif
 122
 123                 while (depth--) {
 124                         sp = user_getsp32(sp, first_frame);
 125                         if (!sp)
 126                                 break;
 127                         first_frame = 0;
 128                 }
 129                 pagefault_enable();
 130         }
 131 }