Commit 40a8b421 authored by Dave Peverley's avatar Dave Peverley Committed by Paul Mundt
Browse files

sh: oprofile: Backtrace support. 



This patch improves the oprofile support on sh and adds backtrace
support.

Signed-off-by: default avatarDave Peverley <dpeverley@mpc-data.co.uk>
Signed-off-by: default avatarChris Smith <chris.smith@st.com>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 60a51fbe

arch/sh/oprofile/backtrace.c

0 → 100644
+118 −0
Original line number Diff line number Diff line 
/*

 * SH specific backtracing code for oprofile

 *

 * Copyright 2007 STMicroelectronics Ltd.

 *

 * Author: Dave Peverley <dpeverley@mpc-data.co.uk>

 *

 * Based on ARM oprofile backtrace code by Richard Purdie and in turn, 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/kallsyms.h>

#include <linux/mm.h>

#include <asm/ptrace.h>

#include <asm/uaccess.h>

#include <asm/sections.h>



/* Limit to stop backtracing too far. */

static int backtrace_limit = 20;



static unsigned long *

user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)

{

	unsigned long buf_stack;



	/* Also check accessibility of address */

	if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))

		return NULL;



	if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))

		return NULL;



	/* Quick paranoia check */

	if (buf_stack & 3)

		return NULL;



	oprofile_add_trace(buf_stack);



	stackaddr++;



	return stackaddr;

}



/*

 * |             | /\ Higher addresses

 * |             |

 * --------------- stack base (address of current_thread_info)

 * | thread info |

 * .             .

 * |    stack    |

 * --------------- saved regs->regs[15] value if valid

 * .             .

 * --------------- struct pt_regs stored on stack (struct pt_regs *)

 * |             |

 * .             .

 * |             |

 * --------------- ???

 * |             |

 * |             | \/ Lower addresses

 *

 * Thus, &pt_regs <-> stack base restricts the valid(ish) fp values

 */

static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs)

{

	unsigned long stack = (unsigned long)regs;

	unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;



	return ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base);

}



static unsigned long *

kernel_backtrace(unsigned long *stackaddr, struct pt_regs *regs)

{

	unsigned long addr;



	/*

	 * If not a valid kernel address, keep going till we find one

	 * or the SP stops being a valid address.

	 */

	do {

		addr = *stackaddr++;



		if (__kernel_text_address(addr)) {

			oprofile_add_trace(addr);

			break;

		}

	} while (valid_kernel_stack(stackaddr, regs));



	return stackaddr;

}



void sh_backtrace(struct pt_regs * const regs, unsigned int depth)

{

	unsigned long *stackaddr;



	/*

	 * Paranoia - clip max depth as we could get lost in the weeds.

	 */

	if (depth > backtrace_limit)

		depth = backtrace_limit;



	stackaddr = (unsigned long *)regs->regs[15];

	if (!user_mode(regs)) {

		while (depth-- && valid_kernel_stack(stackaddr, regs))

			stackaddr = kernel_backtrace(stackaddr, regs);



		return;

	}



	while (depth-- && (stackaddr != NULL))

		stackaddr = user_backtrace(stackaddr, regs);

}

arch/sh/oprofile/common.c

+9 −0
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ static struct op_sh_model *model; 


static struct op_counter_config ctr[20];



extern void sh_backtrace(struct pt_regs * const regs, unsigned int depth);



static int op_sh_setup(void)

{

	/* Pre-compute the values to stuff in the hardware registers.  */
@@ -85,6 +87,13 @@ int __init oprofile_arch_init(struct oprofile_operations *ops) 
	struct op_sh_model *lmodel = NULL;

	int ret;



	/*

	 * Always assign the backtrace op. If the counter initialization

	 * fails, we fall back to the timer which will still make use of

	 * this.

	 */

	ops->backtrace = sh_backtrace;



	switch (current_cpu_data.type) {

	/* SH-4 types */

	case CPU_SH7750: