diff options
| -rw-r--r-- | arch/sh/oprofile/backtrace.c | 118 | ||||
| -rw-r--r-- | arch/sh/oprofile/common.c | 9 |
2 files changed, 127 insertions, 0 deletions
diff --git a/arch/sh/oprofile/backtrace.c b/arch/sh/oprofile/backtrace.c new file mode 100644 index 000000000000..418e834654c1 --- /dev/null +++ b/arch/sh/oprofile/backtrace.c @@ -0,0 +1,118 @@ +/* + * 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); +} diff --git a/arch/sh/oprofile/common.c b/arch/sh/oprofile/common.c index a4d8c0c9a63c..1d97d64cb95f 100644 --- a/arch/sh/oprofile/common.c +++ b/arch/sh/oprofile/common.c @@ -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: |