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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"
static void __kprobes simulate_ldm1stm1(probes_opcode_t insn,
struct arch_specific_insn *asi,
struct pt_regs *regs)
{
int rn = (insn >> 16) & 0xf;
int lbit = insn & (1 << 20);
int wbit = insn & (1 << 21);
int ubit = insn & (1 << 23);
int pbit = insn & (1 << 24);
long *addr = (long *)regs->uregs[rn];
int reg_bit_vector;
int reg_count;
reg_count = 0;
reg_bit_vector = insn & 0xffff;
while (reg_bit_vector) {
reg_bit_vector &= (reg_bit_vector - 1);
++reg_count;
}
if (!ubit)
addr -= reg_count;
addr += (!pbit == !ubit);
reg_bit_vector = insn & 0xffff;
while (reg_bit_vector) {
int reg = __ffs(reg_bit_vector);
reg_bit_vector &= (reg_bit_vector - 1);
if (lbit)
regs->uregs[reg] = *addr++;
else
*addr++ = regs->uregs[reg];
}
if (wbit) {
if (!ubit)
addr -= reg_count;
addr -= (!pbit == !ubit);
regs->uregs[rn] = (long)addr;
}
}
static void __kprobes simulate_stm1_pc(probes_opcode_t insn,
struct arch_specific_insn *asi,
struct pt_regs *regs)
{
unsigned long addr = regs->ARM_pc - 4;
regs->ARM_pc = (long)addr + str_pc_offset;
simulate_ldm1stm1(insn, asi, regs);
regs->ARM_pc = (long)addr + 4;
}
static void __kprobes simulate_ldm1_pc(probes_opcode_t insn,
struct arch_specific_insn *asi,
struct pt_regs *regs)
{
simulate_ldm1stm1(insn, asi, regs);
load_write_pc(regs->ARM_pc, regs);
}
static void __kprobes
emulate_generic_r0_12_noflags(probes_opcode_t insn,
struct arch_specific_insn *asi, struct pt_regs *regs)
{
register void *rregs asm("r1") = regs;
register void *rfn asm("lr") = asi->insn_fn;
__asm__ __volatile__ (
"stmdb sp!, {%[regs], r11} \n\t"
"ldmia %[regs], {r0-r12} \n\t"
#if __LINUX_ARM_ARCH__ >= 6
"blx %[fn] \n\t"
#else
"str %[fn], [sp, #-4]! \n\t"
"adr lr, 1f \n\t"
"ldr pc, [sp], #4 \n\t"
"1: \n\t"
#endif
"ldr lr, [sp], #4 \n\t" /* lr = regs */
"stmia lr, {r0-r12} \n\t"
"ldr r11, [sp], #4 \n\t"
: [regs] "=r" (rregs), [fn] "=r" (rfn)
: "0" (rregs), "1" (rfn)
: "r0", "r2", "r3", "r4", "r5", "r6", "r7",
"r8", "r9", "r10", "r12", "memory", "cc"
);
}
static void __kprobes
emulate_generic_r2_14_noflags(probes_opcode_t insn,
struct arch_specific_insn *asi, struct pt_regs *regs)
{
emulate_generic_r0_12_noflags(insn, asi,
(struct pt_regs *)(regs->uregs+2));
}
static void __kprobes
emulate_ldm_r3_15(probes_opcode_t insn,
struct arch_specific_insn *asi, struct pt_regs *regs)
{
emulate_generic_r0_12_noflags(insn, asi,
(struct pt_regs *)(regs->uregs+3));
load_write_pc(regs->ARM_pc, regs);
}
enum probes_insn __kprobes
kprobe_decode_ldmstm(probes_opcode_t insn, struct arch_specific_insn *asi,
const struct decode_header *h)
{
kprobe_insn_handler_t *handler = 0;
unsigned reglist = insn & 0xffff;
int is_ldm = insn & 0x100000;
int rn = (insn >> 16) & 0xf;
if (rn <= 12 && (reglist & 0xe000) == 0) {
/* Instruction only uses registers in the range R0..R12 */
handler = emulate_generic_r0_12_noflags;
} else if (rn >= 2 && (reglist & 0x8003) == 0) {
/* Instruction only uses registers in the range R2..R14 */
rn -= 2;
reglist >>= 2;
handler = emulate_generic_r2_14_noflags;
} else if (rn >= 3 && (reglist & 0x0007) == 0) {
/* Instruction only uses registers in the range R3..R15 */
if (is_ldm && (reglist & 0x8000)) {
rn -= 3;
reglist >>= 3;
handler = emulate_ldm_r3_15;
}
}
if (handler) {
/* We can emulate the instruction in (possibly) modified form */
asi->insn[0] = (insn & 0xfff00000) | (rn << 16) | reglist;
asi->insn_handler = handler;
return INSN_GOOD;
}
/* Fallback to slower simulation... */
if (reglist & 0x8000)
handler = is_ldm ? simulate_ldm1_pc : simulate_stm1_pc;
else
handler = simulate_ldm1stm1;
asi->insn_handler = handler;
return INSN_GOOD_NO_SLOT;
}
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