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/*
* arch/arm/kernel/kprobes-common.c
*
* Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
*
* Some contents moved here from arch/arm/include/asm/kprobes-arm.c which is
* Copyright (C) 2006, 2007 Motorola Inc.
*
* 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/kernel.h>
#include <linux/kprobes.h>
#include "kprobes.h"
/*
* For STR and STM instructions, an ARM core may choose to use either
* a +8 or a +12 displacement from the current instruction's address.
* Whichever value is chosen for a given core, it must be the same for
* both instructions and may not change. This function measures it.
*/
int str_pc_offset;
void __init find_str_pc_offset(void)
{
int addr, scratch, ret;
__asm__ (
"sub %[ret], pc, #4 \n\t"
"str pc, %[addr] \n\t"
"ldr %[scr], %[addr] \n\t"
"sub %[ret], %[scr], %[ret] \n\t"
: [ret] "=r" (ret), [scr] "=r" (scratch), [addr] "+m" (addr));
str_pc_offset = ret;
}
void __init arm_kprobe_decode_init(void)
{
find_str_pc_offset();
}
static unsigned long __kprobes __check_eq(unsigned long cpsr)
{
return cpsr & PSR_Z_BIT;
}
static unsigned long __kprobes __check_ne(unsigned long cpsr)
{
return (~cpsr) & PSR_Z_BIT;
}
static unsigned long __kprobes __check_cs(unsigned long cpsr)
{
return cpsr & PSR_C_BIT;
}
static unsigned long __kprobes __check_cc(unsigned long cpsr)
{
return (~cpsr) & PSR_C_BIT;
}
static unsigned long __kprobes __check_mi(unsigned long cpsr)
{
return cpsr & PSR_N_BIT;
}
static unsigned long __kprobes __check_pl(unsigned long cpsr)
{
return (~cpsr) & PSR_N_BIT;
}
static unsigned long __kprobes __check_vs(unsigned long cpsr)
{
return cpsr & PSR_V_BIT;
}
static unsigned long __kprobes __check_vc(unsigned long cpsr)
{
return (~cpsr) & PSR_V_BIT;
}
static unsigned long __kprobes __check_hi(unsigned long cpsr)
{
cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
return cpsr & PSR_C_BIT;
}
static unsigned long __kprobes __check_ls(unsigned long cpsr)
{
cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
return (~cpsr) & PSR_C_BIT;
}
static unsigned long __kprobes __check_ge(unsigned long cpsr)
{
cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
return (~cpsr) & PSR_N_BIT;
}
static unsigned long __kprobes __check_lt(unsigned long cpsr)
{
cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
return cpsr & PSR_N_BIT;
}
static unsigned long __kprobes __check_gt(unsigned long cpsr)
{
unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
temp |= (cpsr << 1); /* PSR_N_BIT |= PSR_Z_BIT */
return (~temp) & PSR_N_BIT;
}
static unsigned long __kprobes __check_le(unsigned long cpsr)
{
unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
temp |= (cpsr << 1); /* PSR_N_BIT |= PSR_Z_BIT */
return temp & PSR_N_BIT;
}
static unsigned long __kprobes __check_al(unsigned long cpsr)
{
return true;
}
kprobe_check_cc * const kprobe_condition_checks[16] = {
&__check_eq, &__check_ne, &__check_cs, &__check_cc,
&__check_mi, &__check_pl, &__check_vs, &__check_vc,
&__check_hi, &__check_ls, &__check_ge, &__check_lt,
&__check_gt, &__check_le, &__check_al, &__check_al
};
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