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115 lines
2.8 KiB
C
115 lines
2.8 KiB
C
/*
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* SH specific backtracing code for oprofile
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*
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* Copyright 2007 STMicroelectronics Ltd.
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*
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* Author: Dave Peverley <dpeverley@mpc-data.co.uk>
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*
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* Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
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* oprofile backtrace code by John Levon, David Smith
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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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/kallsyms.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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#include <asm/sections.h>
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/* Limit to stop backtracing too far. */
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static int backtrace_limit = 20;
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static unsigned long *
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user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
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{
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unsigned long buf_stack;
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/* Also check accessibility of address */
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if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
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return NULL;
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if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
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return NULL;
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/* Quick paranoia check */
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if (buf_stack & 3)
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return NULL;
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oprofile_add_trace(buf_stack);
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stackaddr++;
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return stackaddr;
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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->regs[15] value if valid
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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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* --------------- ???
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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) fp values
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*/
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static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs)
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{
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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 ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base);
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}
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static unsigned long *
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kernel_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
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{
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unsigned long addr;
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/*
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* If not a valid kernel address, keep going till we find one
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* or the SP stops being a valid address.
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*/
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do {
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addr = *stackaddr++;
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oprofile_add_trace(addr);
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} while (valid_kernel_stack(stackaddr, regs));
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return stackaddr;
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}
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void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
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{
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unsigned long *stackaddr;
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/*
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* Paranoia - clip max depth as we could get lost in the weeds.
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*/
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if (depth > backtrace_limit)
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depth = backtrace_limit;
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stackaddr = (unsigned long *)regs->regs[15];
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if (!user_mode(regs)) {
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while (depth-- && valid_kernel_stack(stackaddr, regs))
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stackaddr = kernel_backtrace(stackaddr, regs);
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return;
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}
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while (depth-- && (stackaddr != NULL))
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stackaddr = user_backtrace(stackaddr, regs);
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}
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