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 <asm/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
 26static 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	if (!access_ok(p, sizeof(stack_frame)))
 32		return 0;
 33
 34	/*
 35	 * The most likely reason for this is that we returned -EFAULT,
 36	 * which means that we've done all that we can do from
 37	 * interrupt context.
 38	 */
 39	if (__copy_from_user_inatomic(stack_frame, p, sizeof(stack_frame)))
 40		return 0;
 41
 42	if (!is_first)
 43		oprofile_add_trace(STACK_LR32(stack_frame));
 44
 45	/*
 46	 * We do not enforce increasing stack addresses here because
 47	 * we may transition to a different stack, eg a signal handler.
 48	 */
 49	return STACK_SP(stack_frame);
 50}
 51
 52#ifdef CONFIG_PPC64
 53static unsigned long user_getsp64(unsigned long sp, int is_first)
 54{
 55	unsigned long stack_frame[3];
 56
 57	if (!access_ok((void __user *)sp, sizeof(stack_frame)))
 58		return 0;
 59
 60	if (__copy_from_user_inatomic(stack_frame, (void __user *)sp,
 61					sizeof(stack_frame)))
 62		return 0;
 63
 64	if (!is_first)
 65		oprofile_add_trace(STACK_LR64(stack_frame));
 66
 67	return STACK_SP(stack_frame);
 68}
 69#endif
 70
 71static unsigned long kernel_getsp(unsigned long sp, int is_first)
 72{
 73	unsigned long *stack_frame = (unsigned long *)sp;
 74
 75	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
 76		return 0;
 77
 78	if (!is_first)
 79		oprofile_add_trace(STACK_LR(stack_frame));
 80
 81	/*
 82	 * We do not enforce increasing stack addresses here because
 83	 * we might be transitioning from an interrupt stack to a kernel
 84	 * stack. validate_sp() is designed to understand this, so just
 85	 * use it.
 86	 */
 87	return STACK_SP(stack_frame);
 88}
 89
 90void op_powerpc_backtrace(struct pt_regs * const regs, unsigned int depth)
 91{
 92	unsigned long sp = regs->gpr[1];
 93	int first_frame = 1;
 94
 95	/* We ditch the top stackframe so need to loop through an extra time */
 96	depth += 1;
 97
 98	if (!user_mode(regs)) {
 99		while (depth--) {
100			sp = kernel_getsp(sp, first_frame);
101			if (!sp)
102				break;
103			first_frame = 0;
104		}
105	} else {
106		pagefault_disable();
107#ifdef CONFIG_PPC64
108		if (!is_32bit_task()) {
109			while (depth--) {
110				sp = user_getsp64(sp, first_frame);
111				if (!sp)
112					break;
113				first_frame = 0;
114			}
115			pagefault_enable();
116			return;
117		}
118#endif
119
120		while (depth--) {
121			sp = user_getsp32(sp, first_frame);
122			if (!sp)
123				break;
124			first_frame = 0;
125		}
126		pagefault_enable();
127	}
128}