arch/powerpc/oprofile/backtrace.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /**
   3  * Copyright (C) 2005 Brian Rogan <bcr6@cornell.edu>, IBM
   4  *
   5 **/
   6
   7 #include <linux/time.h>
   8 #include <linux/oprofile.h>
   9 #include <linux/sched.h>
  10 #include <asm/processor.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/compat.h>
  13 #include <asm/oprofile_impl.h>
  14
  15 #define STACK_SP(STACK)         *(STACK)
  16
  17 #define STACK_LR64(STACK)       *((unsigned long *)(STACK) + 2)
  18 #define STACK_LR32(STACK)       *((unsigned int *)(STACK) + 1)
  19
  20 #ifdef CONFIG_PPC64
  21 #define STACK_LR(STACK)         STACK_LR64(STACK)
  22 #else
  23 #define STACK_LR(STACK)         STACK_LR32(STACK)
  24 #endif
  25
  26 static unsigned int user_getsp32(unsigned int sp, int is_first)
  27 {
  28         unsigned int stack_frame[2];
  29         void __user *p = compat_ptr(sp);
  30
  31         /*
  32          * The most likely reason for this is that we returned -EFAULT,
  33          * which means that we've done all that we can do from
  34          * interrupt context.
  35          */
  36         if (copy_from_user_nofault(stack_frame, (void __user *)p,
  37                         sizeof(stack_frame)))
  38                 return 0;
  39
  40         if (!is_first)
  41                 oprofile_add_trace(STACK_LR32(stack_frame));
  42
  43         /*
  44          * We do not enforce increasing stack addresses here because
  45          * we may transition to a different stack, eg a signal handler.
  46          */
  47         return STACK_SP(stack_frame);
  48 }
  49
  50 #ifdef CONFIG_PPC64
  51 static unsigned long user_getsp64(unsigned long sp, int is_first)
  52 {
  53         unsigned long stack_frame[3];
  54
  55         if (copy_from_user_nofault(stack_frame, (void __user *)sp,
  56                         sizeof(stack_frame)))
  57                 return 0;
  58
  59         if (!is_first)
  60                 oprofile_add_trace(STACK_LR64(stack_frame));
  61
  62         return STACK_SP(stack_frame);
  63 }
  64 #endif
  65
  66 static unsigned long kernel_getsp(unsigned long sp, int is_first)
  67 {
  68         unsigned long *stack_frame = (unsigned long *)sp;
  69
  70         if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
  71                 return 0;
  72
  73         if (!is_first)
  74                 oprofile_add_trace(STACK_LR(stack_frame));
  75
  76         /*
  77          * We do not enforce increasing stack addresses here because
  78          * we might be transitioning from an interrupt stack to a kernel
  79          * stack. validate_sp() is designed to understand this, so just
  80          * use it.
  81          */
  82         return STACK_SP(stack_frame);
  83 }
  84
  85 void op_powerpc_backtrace(struct pt_regs * const regs, unsigned int depth)
  86 {
  87         unsigned long sp = regs->gpr[1];
  88         int first_frame = 1;
  89
  90         /* We ditch the top stackframe so need to loop through an extra time */
  91         depth += 1;
  92
  93         if (!user_mode(regs)) {
  94                 while (depth--) {
  95                         sp = kernel_getsp(sp, first_frame);
  96                         if (!sp)
  97                                 break;
  98                         first_frame = 0;
  99                 }
 100         } else {
 101 #ifdef CONFIG_PPC64
 102                 if (!is_32bit_task()) {
 103                         while (depth--) {
 104                                 sp = user_getsp64(sp, first_frame);
 105                                 if (!sp)
 106                                         break;
 107                                 first_frame = 0;
 108                         }
 109                         return;
 110                 }
 111 #endif
 112
 113                 while (depth--) {
 114                         sp = user_getsp32(sp, first_frame);
 115                         if (!sp)
 116                                 break;
 117                         first_frame = 0;
 118                 }
 119         }
 120 }