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127 lines
3.2 KiB
127 lines
3.2 KiB
/**
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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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#include <asm/uaccess.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_kernel_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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static struct frame_head *
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dump_user_backtrace(struct frame_head * head)
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{
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struct frame_head bufhead[2];
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/* Also check accessibility of one struct frame_head beyond */
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if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
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return NULL;
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if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
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return NULL;
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oprofile_add_trace(bufhead[0].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 >= bufhead[0].ebp)
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return NULL;
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return bufhead[0].ebp;
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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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* --------------- saved regs->rsp value if x86_64
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* | |
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* --------------- struct pt_regs * stored on stack if 32-bit
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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, regs (or regs->rsp for x86_64) <-> stack base restricts the
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* valid(ish) ebp values. Note: (1) for x86_64, NMI and several other
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* exceptions use special stacks, maintained by the interrupt stack table
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* (IST). These stacks are set up in trap_init() in
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* arch/x86_64/kernel/traps.c. Thus, for x86_64, regs now does not point
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* to the kernel stack; instead, it points to some location on the NMI
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* stack. On the other hand, regs->rsp is the stack pointer saved when the
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* NMI occurred. (2) For 32-bit, regs->esp is not valid because the
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* processor does not save %esp on the kernel stack when interrupts occur
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* in the kernel mode.
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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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#ifdef CONFIG_X86_64
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unsigned long stack = (unsigned long)regs->rsp;
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#else
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unsigned long stack = (unsigned long)regs;
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#endif
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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_vm(regs)) {
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while (depth-- && valid_kernel_stack(head, regs))
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head = dump_kernel_backtrace(head);
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return;
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}
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while (depth-- && head)
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head = dump_user_backtrace(head);
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}
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