/* * Arm specific backtracing code for oprofile * * Copyright 2005 Openedhand Ltd. * * Author: Richard Purdie <rpurdie@openedhand.com> * * Based on i386 oprofile backtrace code by John Levon, David Smith * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #include <linux/oprofile.h> #include <linux/sched.h> #include <linux/mm.h> #include <asm/ptrace.h> #include <asm/uaccess.h> #include "../kernel/stacktrace.h" static int report_trace(struct stackframe *frame, void *d) { unsigned int *depth = d; if (*depth) { oprofile_add_trace(frame->lr); (*depth)--; } return *depth == 0; } /* * The registers we're interested in are at the end of the variable * length saved register structure. The fp points at the end of this * structure so the address of this struct is: * (struct frame_tail *)(xxx->fp)-1 */ struct frame_tail { struct frame_tail *fp; unsigned long sp; unsigned long lr; } __attribute__((packed)); static struct frame_tail* user_backtrace(struct frame_tail *tail) { struct frame_tail buftail[2]; /* Also check accessibility of one struct frame_tail beyond */ if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) return NULL; if (__copy_from_user_inatomic(buftail, tail, sizeof(buftail))) return NULL; oprofile_add_trace(buftail[0].lr); /* frame pointers should strictly progress back up the stack * (towards higher addresses) */ if (tail >= buftail[0].fp) return NULL; return buftail[0].fp-1; } void arm_backtrace(struct pt_regs * const regs, unsigned int depth) { struct frame_tail *tail = ((struct frame_tail *) regs->ARM_fp) - 1; if (!user_mode(regs)) { unsigned long base = ((unsigned long)regs) & ~(THREAD_SIZE - 1); walk_stackframe(regs->ARM_fp, base, base + THREAD_SIZE, report_trace, &depth); return; } while (depth-- && tail && !((unsigned long) tail & 3)) tail = user_backtrace(tail); }