| Dave Peverley | 40a8b42 | 2008-12-16 09:35:40 +0900 | [diff] [blame] | 1 | /* |
| 2 | * SH specific backtracing code for oprofile |
| 3 | * |
| 4 | * Copyright 2007 STMicroelectronics Ltd. |
| 5 | * |
| 6 | * Author: Dave Peverley <dpeverley@mpc-data.co.uk> |
| 7 | * |
| 8 | * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386 |
| 9 | * oprofile backtrace code by John Levon, David Smith |
| 10 | * |
| 11 | * This program is free software; you can redistribute it and/or modify |
| 12 | * it under the terms of the GNU General Public License version 2 as |
| 13 | * published by the Free Software Foundation. |
| 14 | * |
| 15 | */ |
| 16 | #include <linux/oprofile.h> |
| 17 | #include <linux/sched.h> |
| 18 | #include <linux/kallsyms.h> |
| 19 | #include <linux/mm.h> |
| 20 | #include <asm/ptrace.h> |
| 21 | #include <asm/uaccess.h> |
| 22 | #include <asm/sections.h> |
| 23 | |
| 24 | /* Limit to stop backtracing too far. */ |
| 25 | static int backtrace_limit = 20; |
| 26 | |
| 27 | static unsigned long * |
| 28 | user_backtrace(unsigned long *stackaddr, struct pt_regs *regs) |
| 29 | { |
| 30 | unsigned long buf_stack; |
| 31 | |
| 32 | /* Also check accessibility of address */ |
| 33 | if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long))) |
| 34 | return NULL; |
| 35 | |
| 36 | if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long))) |
| 37 | return NULL; |
| 38 | |
| 39 | /* Quick paranoia check */ |
| 40 | if (buf_stack & 3) |
| 41 | return NULL; |
| 42 | |
| 43 | oprofile_add_trace(buf_stack); |
| 44 | |
| 45 | stackaddr++; |
| 46 | |
| 47 | return stackaddr; |
| 48 | } |
| 49 | |
| 50 | /* |
| 51 | * | | /\ Higher addresses |
| 52 | * | | |
| 53 | * --------------- stack base (address of current_thread_info) |
| 54 | * | thread info | |
| 55 | * . . |
| 56 | * | stack | |
| 57 | * --------------- saved regs->regs[15] value if valid |
| 58 | * . . |
| 59 | * --------------- struct pt_regs stored on stack (struct pt_regs *) |
| 60 | * | | |
| 61 | * . . |
| 62 | * | | |
| 63 | * --------------- ??? |
| 64 | * | | |
| 65 | * | | \/ Lower addresses |
| 66 | * |
| 67 | * Thus, &pt_regs <-> stack base restricts the valid(ish) fp values |
| 68 | */ |
| 69 | static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs) |
| 70 | { |
| 71 | unsigned long stack = (unsigned long)regs; |
| 72 | unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE; |
| 73 | |
| 74 | return ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base); |
| 75 | } |
| 76 | |
| 77 | static unsigned long * |
| 78 | kernel_backtrace(unsigned long *stackaddr, struct pt_regs *regs) |
| 79 | { |
| 80 | unsigned long addr; |
| 81 | |
| 82 | /* |
| 83 | * If not a valid kernel address, keep going till we find one |
| 84 | * or the SP stops being a valid address. |
| 85 | */ |
| 86 | do { |
| 87 | addr = *stackaddr++; |
| Paul Mundt | 59de580 | 2008-12-22 19:32:27 +0900 | [diff] [blame] | 88 | oprofile_add_trace(addr); |
| Dave Peverley | 40a8b42 | 2008-12-16 09:35:40 +0900 | [diff] [blame] | 89 | } while (valid_kernel_stack(stackaddr, regs)); |
| 90 | |
| 91 | return stackaddr; |
| 92 | } |
| 93 | |
| 94 | void sh_backtrace(struct pt_regs * const regs, unsigned int depth) |
| 95 | { |
| 96 | unsigned long *stackaddr; |
| 97 | |
| 98 | /* |
| 99 | * Paranoia - clip max depth as we could get lost in the weeds. |
| 100 | */ |
| 101 | if (depth > backtrace_limit) |
| 102 | depth = backtrace_limit; |
| 103 | |
| 104 | stackaddr = (unsigned long *)regs->regs[15]; |
| 105 | if (!user_mode(regs)) { |
| 106 | while (depth-- && valid_kernel_stack(stackaddr, regs)) |
| 107 | stackaddr = kernel_backtrace(stackaddr, regs); |
| 108 | |
| 109 | return; |
| 110 | } |
| 111 | |
| 112 | while (depth-- && (stackaddr != NULL)) |
| 113 | stackaddr = user_backtrace(stackaddr, regs); |
| 114 | } |