112 lines
2.5 KiB
C
112 lines
2.5 KiB
C
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/**
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* @file backtrace.c
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*
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* @remark Copyright 2002 OProfile authors
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* @remark Read the file COPYING
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*
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* @author John Levon
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* @author David Smith
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*/
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#include <linux/oprofile.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <asm/ptrace.h>
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struct frame_head {
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struct frame_head * ebp;
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unsigned long ret;
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} __attribute__((packed));
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static struct frame_head *
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dump_backtrace(struct frame_head * head)
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{
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oprofile_add_trace(head->ret);
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/* frame pointers should strictly progress back up the stack
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* (towards higher addresses) */
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if (head >= head->ebp)
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return NULL;
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return head->ebp;
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}
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/* check that the page(s) containing the frame head are present */
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static int pages_present(struct frame_head * head)
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{
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struct mm_struct * mm = current->mm;
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/* FIXME: only necessary once per page */
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if (!check_user_page_readable(mm, (unsigned long)head))
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return 0;
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return check_user_page_readable(mm, (unsigned long)(head + 1));
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}
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/*
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* | | /\ Higher addresses
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* | |
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* --------------- stack base (address of current_thread_info)
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* | thread info |
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* . .
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* | stack |
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* --------------- saved regs->ebp value if valid (frame_head address)
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* . .
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* --------------- struct pt_regs stored on stack (struct pt_regs *)
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* | |
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* . .
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* | |
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* --------------- %esp
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* | |
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* | | \/ Lower addresses
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*
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* Thus, &pt_regs <-> stack base restricts the valid(ish) ebp values
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*/
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#ifdef CONFIG_FRAME_POINTER
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static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
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{
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unsigned long headaddr = (unsigned long)head;
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unsigned long stack = (unsigned long)regs;
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unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
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return headaddr > stack && headaddr < stack_base;
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}
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#else
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/* without fp, it's just junk */
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static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
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{
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return 0;
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}
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#endif
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void
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x86_backtrace(struct pt_regs * const regs, unsigned int depth)
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{
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struct frame_head *head;
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#ifdef CONFIG_X86_64
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head = (struct frame_head *)regs->rbp;
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#else
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head = (struct frame_head *)regs->ebp;
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#endif
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if (!user_mode(regs)) {
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while (depth-- && valid_kernel_stack(head, regs))
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head = dump_backtrace(head);
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return;
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}
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#ifdef CONFIG_SMP
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if (!spin_trylock(¤t->mm->page_table_lock))
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return;
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#endif
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while (depth-- && head && pages_present(head))
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head = dump_backtrace(head);
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#ifdef CONFIG_SMP
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spin_unlock(¤t->mm->page_table_lock);
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#endif
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}
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