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linux/arch/arm/kernel/kprobes-thumb.c

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ARM: kprobes: Add Thumb instruction decoding stubs Extend arch_prepare_kprobe to support probing of Thumb code. For the actual decoding of Thumb instructions, stub functions are added which currently just reject the probe. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-19 18:56:58 +02:00
/*
* arch/arm/kernel/kprobes-thumb.c
*
* Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
*
* 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"
ARM: kprobes: Add condition code checking to Thumb emulation Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-20 20:29:52 +02:00
/*
* True if current instruction is in an IT block.
*/
#define in_it_block(cpsr) ((cpsr & 0x06000c00) != 0x00000000)
/*
* Return the condition code to check for the currently executing instruction.
* This is in ITSTATE<7:4> which is in CPSR<15:12> but is only valid if
* in_it_block returns true.
*/
#define current_cond(cpsr) ((cpsr >> 12) & 0xf)
ARM: kprobes: Decode 16-bit Thumb BX and BLX instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:51:03 +02:00
/*
* Return the PC value for a probe in thumb code.
* This is the address of the probed instruction plus 4.
* We subtract one because the address will have bit zero set to indicate
* a pointer to thumb code.
*/
static inline unsigned long __kprobes thumb_probe_pc(struct kprobe *p)
{
return (unsigned long)p->addr - 1 + 4;
}
ARM: kprobes: Decode 32-bit Thumb table branch instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:26:16 +02:00
static void __kprobes
t32_simulate_table_branch(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p);
int rn = (insn >> 16) & 0xf;
int rm = insn & 0xf;
unsigned long rnv = (rn == 15) ? pc : regs->uregs[rn];
unsigned long rmv = regs->uregs[rm];
unsigned int halfwords;
if (insn & 0x10)
halfwords = ((u16 *)rnv)[rmv];
else
halfwords = ((u8 *)rnv)[rmv];
regs->ARM_pc = pc + 2 * halfwords;
}
ARM: kprobes: Decode 32-bit Thumb load/store multiple instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-07 09:59:32 +02:00
static enum kprobe_insn __kprobes
t32_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
enum kprobe_insn ret = kprobe_decode_ldmstm(insn, asi);
/* Fixup modified instruction to have halfwords in correct order...*/
insn = asi->insn[0];
((u16 *)asi->insn)[0] = insn >> 16;
((u16 *)asi->insn)[1] = insn & 0xffff;
return ret;
}
ARM: kprobes: Decode 32-bit Thumb load/store dual and load/store exclusive instructions We reject probing of load/store exclusive instructions because any emulation routine could never succeed in gaining exclusive access as the exception framework clears the exclusivity monitor when a probes breakpoint is hit. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:23:21 +02:00
static void __kprobes
t32_emulate_ldrdstrd(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p) & ~3;
int rt1 = (insn >> 12) & 0xf;
int rt2 = (insn >> 8) & 0xf;
int rn = (insn >> 16) & 0xf;
register unsigned long rt1v asm("r0") = regs->uregs[rt1];
register unsigned long rt2v asm("r1") = regs->uregs[rt2];
register unsigned long rnv asm("r2") = (rn == 15) ? pc
: regs->uregs[rn];
__asm__ __volatile__ (
"blx %[fn]"
: "=r" (rt1v), "=r" (rt2v), "=r" (rnv)
: "0" (rt1v), "1" (rt2v), "2" (rnv), [fn] "r" (p->ainsn.insn_fn)
: "lr", "memory", "cc"
);
if (rn != 15)
regs->uregs[rn] = rnv; /* Writeback base register */
regs->uregs[rt1] = rt1v;
regs->uregs[rt2] = rt2v;
}
ARM: kprobes: Decode 32-bit Thumb data-processing (shifted register) instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:31:58 +02:00
static void __kprobes
t32_emulate_rd8rn16rm0_rwflags(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
int rd = (insn >> 8) & 0xf;
int rn = (insn >> 16) & 0xf;
int rm = insn & 0xf;
register unsigned long rdv asm("r1") = regs->uregs[rd];
register unsigned long rnv asm("r2") = regs->uregs[rn];
register unsigned long rmv asm("r3") = regs->uregs[rm];
unsigned long cpsr = regs->ARM_cpsr;
__asm__ __volatile__ (
"msr cpsr_fs, %[cpsr] \n\t"
"blx %[fn] \n\t"
"mrs %[cpsr], cpsr \n\t"
: "=r" (rdv), [cpsr] "=r" (cpsr)
: "0" (rdv), "r" (rnv), "r" (rmv),
"1" (cpsr), [fn] "r" (p->ainsn.insn_fn)
: "lr", "memory", "cc"
);
regs->uregs[rd] = rdv;
regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
}
ARM: kprobes: Decode 32-bit Thumb load/store multiple instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-07 09:59:32 +02:00
static const union decode_item t32_table_1110_100x_x0xx[] = {
/* Load/store multiple instructions */
/* Rn is PC 1110 100x x0xx 1111 xxxx xxxx xxxx xxxx */
DECODE_REJECT (0xfe4f0000, 0xe80f0000),
/* SRS 1110 1000 00x0 xxxx xxxx xxxx xxxx xxxx */
/* RFE 1110 1000 00x1 xxxx xxxx xxxx xxxx xxxx */
DECODE_REJECT (0xffc00000, 0xe8000000),
/* SRS 1110 1001 10x0 xxxx xxxx xxxx xxxx xxxx */
/* RFE 1110 1001 10x1 xxxx xxxx xxxx xxxx xxxx */
DECODE_REJECT (0xffc00000, 0xe9800000),
/* STM Rn, {...pc} 1110 100x x0x0 xxxx 1xxx xxxx xxxx xxxx */
DECODE_REJECT (0xfe508000, 0xe8008000),
/* LDM Rn, {...lr,pc} 1110 100x x0x1 xxxx 11xx xxxx xxxx xxxx */
DECODE_REJECT (0xfe50c000, 0xe810c000),
/* LDM/STM Rn, {...sp} 1110 100x x0xx xxxx xx1x xxxx xxxx xxxx */
DECODE_REJECT (0xfe402000, 0xe8002000),
/* STMIA 1110 1000 10x0 xxxx xxxx xxxx xxxx xxxx */
/* LDMIA 1110 1000 10x1 xxxx xxxx xxxx xxxx xxxx */
/* STMDB 1110 1001 00x0 xxxx xxxx xxxx xxxx xxxx */
/* LDMDB 1110 1001 00x1 xxxx xxxx xxxx xxxx xxxx */
DECODE_CUSTOM (0xfe400000, 0xe8000000, t32_decode_ldmstm),
DECODE_END
};
ARM: kprobes: Decode 32-bit Thumb load/store dual and load/store exclusive instructions We reject probing of load/store exclusive instructions because any emulation routine could never succeed in gaining exclusive access as the exception framework clears the exclusivity monitor when a probes breakpoint is hit. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:23:21 +02:00
static const union decode_item t32_table_1110_100x_x1xx[] = {
/* Load/store dual, load/store exclusive, table branch */
/* STRD (immediate) 1110 1000 x110 xxxx xxxx xxxx xxxx xxxx */
/* LDRD (immediate) 1110 1000 x111 xxxx xxxx xxxx xxxx xxxx */
DECODE_OR (0xff600000, 0xe8600000),
/* STRD (immediate) 1110 1001 x1x0 xxxx xxxx xxxx xxxx xxxx */
/* LDRD (immediate) 1110 1001 x1x1 xxxx xxxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xff400000, 0xe9400000, t32_emulate_ldrdstrd,
REGS(NOPCWB, NOSPPC, NOSPPC, 0, 0)),
ARM: kprobes: Decode 32-bit Thumb table branch instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:26:16 +02:00
/* TBB 1110 1000 1101 xxxx xxxx xxxx 0000 xxxx */
/* TBH 1110 1000 1101 xxxx xxxx xxxx 0001 xxxx */
DECODE_SIMULATEX(0xfff000e0, 0xe8d00000, t32_simulate_table_branch,
REGS(NOSP, 0, 0, 0, NOSPPC)),
ARM: kprobes: Decode 32-bit Thumb load/store dual and load/store exclusive instructions We reject probing of load/store exclusive instructions because any emulation routine could never succeed in gaining exclusive access as the exception framework clears the exclusivity monitor when a probes breakpoint is hit. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:23:21 +02:00
/* STREX 1110 1000 0100 xxxx xxxx xxxx xxxx xxxx */
/* LDREX 1110 1000 0101 xxxx xxxx xxxx xxxx xxxx */
/* STREXB 1110 1000 1100 xxxx xxxx xxxx 0100 xxxx */
/* STREXH 1110 1000 1100 xxxx xxxx xxxx 0101 xxxx */
/* STREXD 1110 1000 1100 xxxx xxxx xxxx 0111 xxxx */
/* LDREXB 1110 1000 1101 xxxx xxxx xxxx 0100 xxxx */
/* LDREXH 1110 1000 1101 xxxx xxxx xxxx 0101 xxxx */
/* LDREXD 1110 1000 1101 xxxx xxxx xxxx 0111 xxxx */
/* And unallocated instructions... */
DECODE_END
};
ARM: kprobes: Decode 32-bit Thumb data-processing (shifted register) instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:31:58 +02:00
static const union decode_item t32_table_1110_101x[] = {
/* Data-processing (shifted register) */
/* TST 1110 1010 0001 xxxx xxxx 1111 xxxx xxxx */
/* TEQ 1110 1010 1001 xxxx xxxx 1111 xxxx xxxx */
DECODE_EMULATEX (0xff700f00, 0xea100f00, t32_emulate_rd8rn16rm0_rwflags,
REGS(NOSPPC, 0, 0, 0, NOSPPC)),
/* CMN 1110 1011 0001 xxxx xxxx 1111 xxxx xxxx */
DECODE_OR (0xfff00f00, 0xeb100f00),
/* CMP 1110 1011 1011 xxxx xxxx 1111 xxxx xxxx */
DECODE_EMULATEX (0xfff00f00, 0xebb00f00, t32_emulate_rd8rn16rm0_rwflags,
REGS(NOPC, 0, 0, 0, NOSPPC)),
/* MOV 1110 1010 010x 1111 xxxx xxxx xxxx xxxx */
/* MVN 1110 1010 011x 1111 xxxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xffcf0000, 0xea4f0000, t32_emulate_rd8rn16rm0_rwflags,
REGS(0, 0, NOSPPC, 0, NOSPPC)),
/* ??? 1110 1010 101x xxxx xxxx xxxx xxxx xxxx */
/* ??? 1110 1010 111x xxxx xxxx xxxx xxxx xxxx */
DECODE_REJECT (0xffa00000, 0xeaa00000),
/* ??? 1110 1011 001x xxxx xxxx xxxx xxxx xxxx */
DECODE_REJECT (0xffe00000, 0xeb200000),
/* ??? 1110 1011 100x xxxx xxxx xxxx xxxx xxxx */
DECODE_REJECT (0xffe00000, 0xeb800000),
/* ??? 1110 1011 111x xxxx xxxx xxxx xxxx xxxx */
DECODE_REJECT (0xffe00000, 0xebe00000),
/* ADD/SUB SP, SP, Rm, LSL #0..3 */
/* 1110 1011 x0xx 1101 x000 1101 xx00 xxxx */
DECODE_EMULATEX (0xff4f7f30, 0xeb0d0d00, t32_emulate_rd8rn16rm0_rwflags,
REGS(SP, 0, SP, 0, NOSPPC)),
/* ADD/SUB SP, SP, Rm, shift */
/* 1110 1011 x0xx 1101 xxxx 1101 xxxx xxxx */
DECODE_REJECT (0xff4f0f00, 0xeb0d0d00),
/* ADD/SUB Rd, SP, Rm, shift */
/* 1110 1011 x0xx 1101 xxxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xff4f0000, 0xeb0d0000, t32_emulate_rd8rn16rm0_rwflags,
REGS(SP, 0, NOPC, 0, NOSPPC)),
/* AND 1110 1010 000x xxxx xxxx xxxx xxxx xxxx */
/* BIC 1110 1010 001x xxxx xxxx xxxx xxxx xxxx */
/* ORR 1110 1010 010x xxxx xxxx xxxx xxxx xxxx */
/* ORN 1110 1010 011x xxxx xxxx xxxx xxxx xxxx */
/* EOR 1110 1010 100x xxxx xxxx xxxx xxxx xxxx */
/* PKH 1110 1010 110x xxxx xxxx xxxx xxxx xxxx */
/* ADD 1110 1011 000x xxxx xxxx xxxx xxxx xxxx */
/* ADC 1110 1011 010x xxxx xxxx xxxx xxxx xxxx */
/* SBC 1110 1011 011x xxxx xxxx xxxx xxxx xxxx */
/* SUB 1110 1011 101x xxxx xxxx xxxx xxxx xxxx */
/* RSB 1110 1011 110x xxxx xxxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xfe000000, 0xea000000, t32_emulate_rd8rn16rm0_rwflags,
REGS(NOSPPC, 0, NOSPPC, 0, NOSPPC)),
DECODE_END
};
ARM: kprobes: Decode 32-bit Thumb data-processing (modified immediate) instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:36:35 +02:00
static const union decode_item t32_table_1111_0x0x___0[] = {
/* Data-processing (modified immediate) */
/* TST 1111 0x00 0001 xxxx 0xxx 1111 xxxx xxxx */
/* TEQ 1111 0x00 1001 xxxx 0xxx 1111 xxxx xxxx */
DECODE_EMULATEX (0xfb708f00, 0xf0100f00, t32_emulate_rd8rn16rm0_rwflags,
REGS(NOSPPC, 0, 0, 0, 0)),
/* CMN 1111 0x01 0001 xxxx 0xxx 1111 xxxx xxxx */
DECODE_OR (0xfbf08f00, 0xf1100f00),
/* CMP 1111 0x01 1011 xxxx 0xxx 1111 xxxx xxxx */
DECODE_EMULATEX (0xfbf08f00, 0xf1b00f00, t32_emulate_rd8rn16rm0_rwflags,
REGS(NOPC, 0, 0, 0, 0)),
/* MOV 1111 0x00 010x 1111 0xxx xxxx xxxx xxxx */
/* MVN 1111 0x00 011x 1111 0xxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xfbcf8000, 0xf04f0000, t32_emulate_rd8rn16rm0_rwflags,
REGS(0, 0, NOSPPC, 0, 0)),
/* ??? 1111 0x00 101x xxxx 0xxx xxxx xxxx xxxx */
DECODE_REJECT (0xfbe08000, 0xf0a00000),
/* ??? 1111 0x00 110x xxxx 0xxx xxxx xxxx xxxx */
/* ??? 1111 0x00 111x xxxx 0xxx xxxx xxxx xxxx */
DECODE_REJECT (0xfbc08000, 0xf0c00000),
/* ??? 1111 0x01 001x xxxx 0xxx xxxx xxxx xxxx */
DECODE_REJECT (0xfbe08000, 0xf1200000),
/* ??? 1111 0x01 100x xxxx 0xxx xxxx xxxx xxxx */
DECODE_REJECT (0xfbe08000, 0xf1800000),
/* ??? 1111 0x01 111x xxxx 0xxx xxxx xxxx xxxx */
DECODE_REJECT (0xfbe08000, 0xf1e00000),
/* ADD Rd, SP, #imm 1111 0x01 000x 1101 0xxx xxxx xxxx xxxx */
/* SUB Rd, SP, #imm 1111 0x01 101x 1101 0xxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xfb4f8000, 0xf10d0000, t32_emulate_rd8rn16rm0_rwflags,
REGS(SP, 0, NOPC, 0, 0)),
/* AND 1111 0x00 000x xxxx 0xxx xxxx xxxx xxxx */
/* BIC 1111 0x00 001x xxxx 0xxx xxxx xxxx xxxx */
/* ORR 1111 0x00 010x xxxx 0xxx xxxx xxxx xxxx */
/* ORN 1111 0x00 011x xxxx 0xxx xxxx xxxx xxxx */
/* EOR 1111 0x00 100x xxxx 0xxx xxxx xxxx xxxx */
/* ADD 1111 0x01 000x xxxx 0xxx xxxx xxxx xxxx */
/* ADC 1111 0x01 010x xxxx 0xxx xxxx xxxx xxxx */
/* SBC 1111 0x01 011x xxxx 0xxx xxxx xxxx xxxx */
/* SUB 1111 0x01 101x xxxx 0xxx xxxx xxxx xxxx */
/* RSB 1111 0x01 110x xxxx 0xxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xfa008000, 0xf0000000, t32_emulate_rd8rn16rm0_rwflags,
REGS(NOSPPC, 0, NOSPPC, 0, 0)),
DECODE_END
};
ARM: kprobes: Decode 32-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 14:55:47 +02:00
static const union decode_item t32_table_1111_0xxx___1[] = {
/* Branches and miscellaneous control */
/* YIELD 1111 0011 1010 xxxx 10x0 x000 0000 0001 */
DECODE_OR (0xfff0d7ff, 0xf3a08001),
/* SEV 1111 0011 1010 xxxx 10x0 x000 0000 0100 */
DECODE_EMULATE (0xfff0d7ff, 0xf3a08004, kprobe_emulate_none),
/* NOP 1111 0011 1010 xxxx 10x0 x000 0000 0000 */
/* WFE 1111 0011 1010 xxxx 10x0 x000 0000 0010 */
/* WFI 1111 0011 1010 xxxx 10x0 x000 0000 0011 */
DECODE_SIMULATE (0xfff0d7fc, 0xf3a08000, kprobe_simulate_nop),
DECODE_END
};
const union decode_item kprobe_decode_thumb32_table[] = {
ARM: kprobes: Decode 32-bit Thumb load/store multiple instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-07 09:59:32 +02:00
/*
* Load/store multiple instructions
* 1110 100x x0xx xxxx xxxx xxxx xxxx xxxx
*/
DECODE_TABLE (0xfe400000, 0xe8000000, t32_table_1110_100x_x0xx),
ARM: kprobes: Decode 32-bit Thumb load/store dual and load/store exclusive instructions We reject probing of load/store exclusive instructions because any emulation routine could never succeed in gaining exclusive access as the exception framework clears the exclusivity monitor when a probes breakpoint is hit. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:23:21 +02:00
/*
* Load/store dual, load/store exclusive, table branch
* 1110 100x x1xx xxxx xxxx xxxx xxxx xxxx
*/
DECODE_TABLE (0xfe400000, 0xe8400000, t32_table_1110_100x_x1xx),
ARM: kprobes: Decode 32-bit Thumb data-processing (shifted register) instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:31:58 +02:00
/*
* Data-processing (shifted register)
* 1110 101x xxxx xxxx xxxx xxxx xxxx xxxx
*/
DECODE_TABLE (0xfe000000, 0xea000000, t32_table_1110_101x),
ARM: kprobes: Decode 32-bit Thumb data-processing (modified immediate) instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 15:36:35 +02:00
/*
* Data-processing (modified immediate)
* 1111 0x0x xxxx xxxx 0xxx xxxx xxxx xxxx
*/
DECODE_TABLE (0xfa008000, 0xf0000000, t32_table_1111_0x0x___0),
ARM: kprobes: Decode 32-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 14:55:47 +02:00
/*
* Branches and miscellaneous control
* 1111 0xxx xxxx xxxx 1xxx xxxx xxxx xxxx
*/
DECODE_TABLE (0xf8008000, 0xf0008000, t32_table_1111_0xxx___1),
DECODE_END
};
ARM: kprobes: Decode 16-bit Thumb BX and BLX instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:51:03 +02:00
static void __kprobes
t16_simulate_bxblx(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p);
int rm = (insn >> 3) & 0xf;
unsigned long rmv = (rm == 15) ? pc : regs->uregs[rm];
if (insn & (1 << 7)) /* BLX ? */
regs->ARM_lr = (unsigned long)p->addr + 2;
bx_write_pc(rmv, regs);
}
ARM: kprobes: Decode 16-bit Thumb load and store instructions Most of these instructions only operate on the low registers R0-R7 so they can make use of t16_emulate_loregs_rwflags. The instructions which use SP or PC for addressing have their own simulation functions. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:00:09 +02:00
static void __kprobes
t16_simulate_ldr_literal(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long* base = (unsigned long *)(thumb_probe_pc(p) & ~3);
long index = insn & 0xff;
int rt = (insn >> 8) & 0x7;
regs->uregs[rt] = base[index];
}
static void __kprobes
t16_simulate_ldrstr_sp_relative(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long* base = (unsigned long *)regs->ARM_sp;
long index = insn & 0xff;
int rt = (insn >> 8) & 0x7;
if (insn & 0x800) /* LDR */
regs->uregs[rt] = base[index];
else /* STR */
base[index] = regs->uregs[rt];
}
ARM: kprobes: Decode 16-bit Thumb PC- and SP-relative address instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:05:53 +02:00
static void __kprobes
t16_simulate_reladr(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long base = (insn & 0x800) ? regs->ARM_sp
: (thumb_probe_pc(p) & ~3);
long offset = insn & 0xff;
int rt = (insn >> 8) & 0x7;
regs->uregs[rt] = base + offset * 4;
}
static void __kprobes
t16_simulate_add_sp_imm(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
long imm = insn & 0x7f;
if (insn & 0x80) /* SUB */
regs->ARM_sp -= imm * 4;
else /* ADD */
regs->ARM_sp += imm * 4;
}
ARM: kprobes: Decode 16-bit Thumb CBZ and bit manipulation instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:10:44 +02:00
static void __kprobes
t16_simulate_cbz(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
int rn = insn & 0x7;
kprobe_opcode_t nonzero = regs->uregs[rn] ? insn : ~insn;
if (nonzero & 0x800) {
long i = insn & 0x200;
long imm5 = insn & 0xf8;
unsigned long pc = thumb_probe_pc(p);
regs->ARM_pc = pc + (i >> 3) + (imm5 >> 2);
}
}
ARM: kprobes: Decode 16-bit Thumb IT instruction The normal Thumb singlestepping routine updates the IT state after calling the instruction handler. We don't what this to happen after the IT instruction simulation sets the IT state, therefore we need to provide a custom singlestep routine. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:16:05 +02:00
static void __kprobes
t16_simulate_it(struct kprobe *p, struct pt_regs *regs)
{
/*
* The 8 IT state bits are split into two parts in CPSR:
* ITSTATE<1:0> are in CPSR<26:25>
* ITSTATE<7:2> are in CPSR<15:10>
* The new IT state is in the lower byte of insn.
*/
kprobe_opcode_t insn = p->opcode;
unsigned long cpsr = regs->ARM_cpsr;
cpsr &= ~PSR_IT_MASK;
cpsr |= (insn & 0xfc) << 8;
cpsr |= (insn & 0x03) << 25;
regs->ARM_cpsr = cpsr;
}
static void __kprobes
t16_singlestep_it(struct kprobe *p, struct pt_regs *regs)
{
regs->ARM_pc += 2;
t16_simulate_it(p, regs);
}
static enum kprobe_insn __kprobes
t16_decode_it(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
asi->insn_singlestep = t16_singlestep_it;
return INSN_GOOD_NO_SLOT;
}
ARM: kprobes: Decode 16-bit Thumb branch instructions We previously changed the behaviour of probes so that conditional instructions don't fire when the condition isn't met. For ARM branches, and Thumb branches in IT blocks, this means they don't fire if the branch isn't taken. For consistency, we implement the same for Thumb conditional branch instructions. This involves setting up insn_check_cc to point to the relevant condition checking function. As the emulation routine is only called when this condition passes, it doesn't need to check again and can unconditionally update PC. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:30:43 +02:00
static void __kprobes
t16_simulate_cond_branch(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p);
long offset = insn & 0x7f;
offset -= insn & 0x80; /* Apply sign bit */
regs->ARM_pc = pc + (offset * 2);
}
static enum kprobe_insn __kprobes
t16_decode_cond_branch(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
int cc = (insn >> 8) & 0xf;
asi->insn_check_cc = kprobe_condition_checks[cc];
asi->insn_handler = t16_simulate_cond_branch;
return INSN_GOOD_NO_SLOT;
}
static void __kprobes
t16_simulate_branch(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p);
long offset = insn & 0x3ff;
offset -= insn & 0x400; /* Apply sign bit */
regs->ARM_pc = pc + (offset * 2);
}
ARM: kprobes: Decode 16-bit Thumb data-processing instructions These instructions only operate on the low registers R0-R7, therefore it is possible to emulate them by executing the original instruction unaltered if we restore and save these registers. This is what t16_emulate_loregs does. Some of these instructions don't update the PSR when they execute in an IT block, so there are two flavours of emulation functions: t16_emulate_loregs_{noit}rwflags Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:46:05 +02:00
static unsigned long __kprobes
t16_emulate_loregs(struct kprobe *p, struct pt_regs *regs)
{
unsigned long oldcpsr = regs->ARM_cpsr;
unsigned long newcpsr;
__asm__ __volatile__ (
"msr cpsr_fs, %[oldcpsr] \n\t"
"ldmia %[regs], {r0-r7} \n\t"
"blx %[fn] \n\t"
"stmia %[regs], {r0-r7} \n\t"
"mrs %[newcpsr], cpsr \n\t"
: [newcpsr] "=r" (newcpsr)
: [oldcpsr] "r" (oldcpsr), [regs] "r" (regs),
[fn] "r" (p->ainsn.insn_fn)
: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
"lr", "memory", "cc"
);
return (oldcpsr & ~APSR_MASK) | (newcpsr & APSR_MASK);
}
static void __kprobes
t16_emulate_loregs_rwflags(struct kprobe *p, struct pt_regs *regs)
{
regs->ARM_cpsr = t16_emulate_loregs(p, regs);
}
static void __kprobes
t16_emulate_loregs_noitrwflags(struct kprobe *p, struct pt_regs *regs)
{
unsigned long cpsr = t16_emulate_loregs(p, regs);
if (!in_it_block(cpsr))
regs->ARM_cpsr = cpsr;
}
ARM: kprobes: Decode 16-bit Thumb special data instructions These data-processing instructions operate on the full range of CPU registers, so to simulate them we have to modify the registers used by the instruction. We can't make use of the decoding table framework to do this because the registers aren't encoded cleanly in separate nibbles, therefore we need a custom decode function. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:54:57 +02:00
static void __kprobes
t16_emulate_hiregs(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p);
int rdn = (insn & 0x7) | ((insn & 0x80) >> 4);
int rm = (insn >> 3) & 0xf;
register unsigned long rdnv asm("r1");
register unsigned long rmv asm("r0");
unsigned long cpsr = regs->ARM_cpsr;
rdnv = (rdn == 15) ? pc : regs->uregs[rdn];
rmv = (rm == 15) ? pc : regs->uregs[rm];
__asm__ __volatile__ (
"msr cpsr_fs, %[cpsr] \n\t"
"blx %[fn] \n\t"
"mrs %[cpsr], cpsr \n\t"
: "=r" (rdnv), [cpsr] "=r" (cpsr)
: "0" (rdnv), "r" (rmv), "1" (cpsr), [fn] "r" (p->ainsn.insn_fn)
: "lr", "memory", "cc"
);
if (rdn == 15)
rdnv &= ~1;
regs->uregs[rdn] = rdnv;
regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
}
static enum kprobe_insn __kprobes
t16_decode_hiregs(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
insn &= ~0x00ff;
insn |= 0x001; /* Set Rdn = R1 and Rm = R0 */
((u16 *)asi->insn)[0] = insn;
asi->insn_handler = t16_emulate_hiregs;
return INSN_GOOD;
}
ARM: kprobes: Decode 16-bit Thumb PUSH and POP instructions These instructions are equivalent to stmdb sp!,{r0-r7,lr} ldmdb sp!,{r0-r7,pc} and we emulate them by transforming them into the 32-bit Thumb instructions stmdb r9!,{r0-r7,r8} ldmdb r9!,{r0-r7,r8} This is simpler, and almost certainly executes faster, than writing simulation functions. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:13:29 +02:00
static void __kprobes
t16_emulate_push(struct kprobe *p, struct pt_regs *regs)
{
__asm__ __volatile__ (
"ldr r9, [%[regs], #13*4] \n\t"
"ldr r8, [%[regs], #14*4] \n\t"
"ldmia %[regs], {r0-r7} \n\t"
"blx %[fn] \n\t"
"str r9, [%[regs], #13*4] \n\t"
:
: [regs] "r" (regs), [fn] "r" (p->ainsn.insn_fn)
: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9",
"lr", "memory", "cc"
);
}
static enum kprobe_insn __kprobes
t16_decode_push(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
/*
* To simulate a PUSH we use a Thumb-2 "STMDB R9!, {registers}"
* and call it with R9=SP and LR in the register list represented
* by R8.
*/
((u16 *)asi->insn)[0] = 0xe929; /* 1st half STMDB R9!,{} */
((u16 *)asi->insn)[1] = insn & 0x1ff; /* 2nd half (register list) */
asi->insn_handler = t16_emulate_push;
return INSN_GOOD;
}
static void __kprobes
t16_emulate_pop_nopc(struct kprobe *p, struct pt_regs *regs)
{
__asm__ __volatile__ (
"ldr r9, [%[regs], #13*4] \n\t"
"ldmia %[regs], {r0-r7} \n\t"
"blx %[fn] \n\t"
"stmia %[regs], {r0-r7} \n\t"
"str r9, [%[regs], #13*4] \n\t"
:
: [regs] "r" (regs), [fn] "r" (p->ainsn.insn_fn)
: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r9",
"lr", "memory", "cc"
);
}
static void __kprobes
t16_emulate_pop_pc(struct kprobe *p, struct pt_regs *regs)
{
register unsigned long pc asm("r8");
__asm__ __volatile__ (
"ldr r9, [%[regs], #13*4] \n\t"
"ldmia %[regs], {r0-r7} \n\t"
"blx %[fn] \n\t"
"stmia %[regs], {r0-r7} \n\t"
"str r9, [%[regs], #13*4] \n\t"
: "=r" (pc)
: [regs] "r" (regs), [fn] "r" (p->ainsn.insn_fn)
: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r9",
"lr", "memory", "cc"
);
bx_write_pc(pc, regs);
}
static enum kprobe_insn __kprobes
t16_decode_pop(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
/*
* To simulate a POP we use a Thumb-2 "LDMDB R9!, {registers}"
* and call it with R9=SP and PC in the register list represented
* by R8.
*/
((u16 *)asi->insn)[0] = 0xe8b9; /* 1st half LDMIA R9!,{} */
((u16 *)asi->insn)[1] = insn & 0x1ff; /* 2nd half (register list) */
asi->insn_handler = insn & 0x100 ? t16_emulate_pop_pc
: t16_emulate_pop_nopc;
return INSN_GOOD;
}
ARM: kprobes: Decode 16-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:36:32 +02:00
static const union decode_item t16_table_1011[] = {
/* Miscellaneous 16-bit instructions */
ARM: kprobes: Decode 16-bit Thumb PC- and SP-relative address instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:05:53 +02:00
/* ADD (SP plus immediate) 1011 0000 0xxx xxxx */
/* SUB (SP minus immediate) 1011 0000 1xxx xxxx */
DECODE_SIMULATE (0xff00, 0xb000, t16_simulate_add_sp_imm),
ARM: kprobes: Decode 16-bit Thumb CBZ and bit manipulation instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:10:44 +02:00
/* CBZ 1011 00x1 xxxx xxxx */
/* CBNZ 1011 10x1 xxxx xxxx */
DECODE_SIMULATE (0xf500, 0xb100, t16_simulate_cbz),
/* SXTH 1011 0010 00xx xxxx */
/* SXTB 1011 0010 01xx xxxx */
/* UXTH 1011 0010 10xx xxxx */
/* UXTB 1011 0010 11xx xxxx */
/* REV 1011 1010 00xx xxxx */
/* REV16 1011 1010 01xx xxxx */
/* ??? 1011 1010 10xx xxxx */
/* REVSH 1011 1010 11xx xxxx */
DECODE_REJECT (0xffc0, 0xba80),
DECODE_EMULATE (0xf500, 0xb000, t16_emulate_loregs_rwflags),
ARM: kprobes: Decode 16-bit Thumb PUSH and POP instructions These instructions are equivalent to stmdb sp!,{r0-r7,lr} ldmdb sp!,{r0-r7,pc} and we emulate them by transforming them into the 32-bit Thumb instructions stmdb r9!,{r0-r7,r8} ldmdb r9!,{r0-r7,r8} This is simpler, and almost certainly executes faster, than writing simulation functions. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:13:29 +02:00
/* PUSH 1011 010x xxxx xxxx */
DECODE_CUSTOM (0xfe00, 0xb400, t16_decode_push),
/* POP 1011 110x xxxx xxxx */
DECODE_CUSTOM (0xfe00, 0xbc00, t16_decode_pop),
ARM: kprobes: Decode 16-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:36:32 +02:00
/*
* If-Then, and hints
* 1011 1111 xxxx xxxx
*/
/* YIELD 1011 1111 0001 0000 */
DECODE_OR (0xffff, 0xbf10),
/* SEV 1011 1111 0100 0000 */
DECODE_EMULATE (0xffff, 0xbf40, kprobe_emulate_none),
/* NOP 1011 1111 0000 0000 */
/* WFE 1011 1111 0010 0000 */
/* WFI 1011 1111 0011 0000 */
DECODE_SIMULATE (0xffcf, 0xbf00, kprobe_simulate_nop),
/* Unassigned hints 1011 1111 xxxx 0000 */
DECODE_REJECT (0xff0f, 0xbf00),
ARM: kprobes: Decode 16-bit Thumb IT instruction The normal Thumb singlestepping routine updates the IT state after calling the instruction handler. We don't what this to happen after the IT instruction simulation sets the IT state, therefore we need to provide a custom singlestep routine. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:16:05 +02:00
/* IT 1011 1111 xxxx xxxx */
DECODE_CUSTOM (0xff00, 0xbf00, t16_decode_it),
ARM: kprobes: Decode 16-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:36:32 +02:00
ARM: kprobes: Reject 16-bit Thumb SETEND, CPS and BKPT instructions These are very rare and/or problematic to emulate so we will take the easy option and disallow probing them (as does the existing ARM implementation). Rejecting these instructions doesn't actually require any entries in the decoding table as it is the default case for instructions which aren't found. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:39:07 +02:00
/* SETEND 1011 0110 010x xxxx */
/* CPS 1011 0110 011x xxxx */
/* BKPT 1011 1110 xxxx xxxx */
/* And unallocated instructions... */
ARM: kprobes: Decode 16-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:36:32 +02:00
DECODE_END
};
const union decode_item kprobe_decode_thumb16_table[] = {
ARM: kprobes: Decode 16-bit Thumb data-processing instructions These instructions only operate on the low registers R0-R7, therefore it is possible to emulate them by executing the original instruction unaltered if we restore and save these registers. This is what t16_emulate_loregs does. Some of these instructions don't update the PSR when they execute in an IT block, so there are two flavours of emulation functions: t16_emulate_loregs_{noit}rwflags Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:46:05 +02:00
/*
* Shift (immediate), add, subtract, move, and compare
* 00xx xxxx xxxx xxxx
*/
/* CMP (immediate) 0010 1xxx xxxx xxxx */
DECODE_EMULATE (0xf800, 0x2800, t16_emulate_loregs_rwflags),
/* ADD (register) 0001 100x xxxx xxxx */
/* SUB (register) 0001 101x xxxx xxxx */
/* LSL (immediate) 0000 0xxx xxxx xxxx */
/* LSR (immediate) 0000 1xxx xxxx xxxx */
/* ASR (immediate) 0001 0xxx xxxx xxxx */
/* ADD (immediate, Thumb) 0001 110x xxxx xxxx */
/* SUB (immediate, Thumb) 0001 111x xxxx xxxx */
/* MOV (immediate) 0010 0xxx xxxx xxxx */
/* ADD (immediate, Thumb) 0011 0xxx xxxx xxxx */
/* SUB (immediate, Thumb) 0011 1xxx xxxx xxxx */
DECODE_EMULATE (0xc000, 0x0000, t16_emulate_loregs_noitrwflags),
/*
* 16-bit Thumb data-processing instructions
* 0100 00xx xxxx xxxx
*/
/* TST (register) 0100 0010 00xx xxxx */
DECODE_EMULATE (0xffc0, 0x4200, t16_emulate_loregs_rwflags),
/* CMP (register) 0100 0010 10xx xxxx */
/* CMN (register) 0100 0010 11xx xxxx */
DECODE_EMULATE (0xff80, 0x4280, t16_emulate_loregs_rwflags),
/* AND (register) 0100 0000 00xx xxxx */
/* EOR (register) 0100 0000 01xx xxxx */
/* LSL (register) 0100 0000 10xx xxxx */
/* LSR (register) 0100 0000 11xx xxxx */
/* ASR (register) 0100 0001 00xx xxxx */
/* ADC (register) 0100 0001 01xx xxxx */
/* SBC (register) 0100 0001 10xx xxxx */
/* ROR (register) 0100 0001 11xx xxxx */
/* RSB (immediate) 0100 0010 01xx xxxx */
/* ORR (register) 0100 0011 00xx xxxx */
/* MUL 0100 0011 00xx xxxx */
/* BIC (register) 0100 0011 10xx xxxx */
/* MVN (register) 0100 0011 10xx xxxx */
DECODE_EMULATE (0xfc00, 0x4000, t16_emulate_loregs_noitrwflags),
ARM: kprobes: Decode 16-bit Thumb BX and BLX instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:51:03 +02:00
/*
* Special data instructions and branch and exchange
* 0100 01xx xxxx xxxx
*/
/* BLX pc 0100 0111 1111 1xxx */
DECODE_REJECT (0xfff8, 0x47f8),
/* BX (register) 0100 0111 0xxx xxxx */
/* BLX (register) 0100 0111 1xxx xxxx */
DECODE_SIMULATE (0xff00, 0x4700, t16_simulate_bxblx),
ARM: kprobes: Decode 16-bit Thumb special data instructions These data-processing instructions operate on the full range of CPU registers, so to simulate them we have to modify the registers used by the instruction. We can't make use of the decoding table framework to do this because the registers aren't encoded cleanly in separate nibbles, therefore we need a custom decode function. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:54:57 +02:00
/* ADD pc, pc 0100 0100 1111 1111 */
DECODE_REJECT (0xffff, 0x44ff),
/* ADD (register) 0100 0100 xxxx xxxx */
/* CMP (register) 0100 0101 xxxx xxxx */
/* MOV (register) 0100 0110 xxxx xxxx */
DECODE_CUSTOM (0xfc00, 0x4400, t16_decode_hiregs),
ARM: kprobes: Decode 16-bit Thumb load and store instructions Most of these instructions only operate on the low registers R0-R7 so they can make use of t16_emulate_loregs_rwflags. The instructions which use SP or PC for addressing have their own simulation functions. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:00:09 +02:00
/*
* Load from Literal Pool
* LDR (literal) 0100 1xxx xxxx xxxx
*/
DECODE_SIMULATE (0xf800, 0x4800, t16_simulate_ldr_literal),
/*
* 16-bit Thumb Load/store instructions
* 0101 xxxx xxxx xxxx
* 011x xxxx xxxx xxxx
* 100x xxxx xxxx xxxx
*/
/* STR (register) 0101 000x xxxx xxxx */
/* STRH (register) 0101 001x xxxx xxxx */
/* STRB (register) 0101 010x xxxx xxxx */
/* LDRSB (register) 0101 011x xxxx xxxx */
/* LDR (register) 0101 100x xxxx xxxx */
/* LDRH (register) 0101 101x xxxx xxxx */
/* LDRB (register) 0101 110x xxxx xxxx */
/* LDRSH (register) 0101 111x xxxx xxxx */
/* STR (immediate, Thumb) 0110 0xxx xxxx xxxx */
/* LDR (immediate, Thumb) 0110 1xxx xxxx xxxx */
/* STRB (immediate, Thumb) 0111 0xxx xxxx xxxx */
/* LDRB (immediate, Thumb) 0111 1xxx xxxx xxxx */
DECODE_EMULATE (0xc000, 0x4000, t16_emulate_loregs_rwflags),
/* STRH (immediate, Thumb) 1000 0xxx xxxx xxxx */
/* LDRH (immediate, Thumb) 1000 1xxx xxxx xxxx */
DECODE_EMULATE (0xf000, 0x8000, t16_emulate_loregs_rwflags),
/* STR (immediate, Thumb) 1001 0xxx xxxx xxxx */
/* LDR (immediate, Thumb) 1001 1xxx xxxx xxxx */
DECODE_SIMULATE (0xf000, 0x9000, t16_simulate_ldrstr_sp_relative),
ARM: kprobes: Decode 16-bit Thumb PC- and SP-relative address instructions Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:05:53 +02:00
/*
* Generate PC-/SP-relative address
* ADR (literal) 1010 0xxx xxxx xxxx
* ADD (SP plus immediate) 1010 1xxx xxxx xxxx
*/
DECODE_SIMULATE (0xf000, 0xa000, t16_simulate_reladr),
ARM: kprobes: Decode 16-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:36:32 +02:00
/*
* Miscellaneous 16-bit instructions
* 1011 xxxx xxxx xxxx
*/
DECODE_TABLE (0xf000, 0xb000, t16_table_1011),
ARM: kprobes: Decode 16-bit Thumb load and store instructions Most of these instructions only operate on the low registers R0-R7 so they can make use of t16_emulate_loregs_rwflags. The instructions which use SP or PC for addressing have their own simulation functions. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:00:09 +02:00
/* STM 1100 0xxx xxxx xxxx */
/* LDM 1100 1xxx xxxx xxxx */
DECODE_EMULATE (0xf000, 0xc000, t16_emulate_loregs_rwflags),
ARM: kprobes: Reject 16-bit Thumb SVC and UNDEFINED instructions SVC (SWI) instructions shouldn't occur in kernel code so we don't need to be able to probe them. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:25:47 +02:00
/*
* Conditional branch, and Supervisor Call
*/
/* Permanently UNDEFINED 1101 1110 xxxx xxxx */
/* SVC 1101 1111 xxxx xxxx */
DECODE_REJECT (0xfe00, 0xde00),
ARM: kprobes: Decode 16-bit Thumb branch instructions We previously changed the behaviour of probes so that conditional instructions don't fire when the condition isn't met. For ARM branches, and Thumb branches in IT blocks, this means they don't fire if the branch isn't taken. For consistency, we implement the same for Thumb conditional branch instructions. This involves setting up insn_check_cc to point to the relevant condition checking function. As the emulation routine is only called when this condition passes, it doesn't need to check again and can unconditionally update PC. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 17:30:43 +02:00
/* Conditional branch 1101 xxxx xxxx xxxx */
DECODE_CUSTOM (0xf000, 0xd000, t16_decode_cond_branch),
/*
* Unconditional branch
* B 1110 0xxx xxxx xxxx
*/
DECODE_SIMULATE (0xf800, 0xe000, t16_simulate_branch),
ARM: kprobes: Decode 16-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:36:32 +02:00
DECODE_END
};
ARM: kprobes: Add condition code checking to Thumb emulation Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-20 20:29:52 +02:00
static unsigned long __kprobes thumb_check_cc(unsigned long cpsr)
{
if (unlikely(in_it_block(cpsr)))
return kprobe_condition_checks[current_cond(cpsr)](cpsr);
return true;
}
ARM: kprobes: Add hooks to override singlestep() When a probe fires we must single-step the instruction which was replaced by a breakpoint. As the steps to do this vary between ARM and Thumb instructions we need a way to customise single-stepping. This is done by adding a new hook called insn_singlestep to arch_specific_insn which is initialised by the instruction decoding functions. These single-step hooks must update PC and call the instruction handler. For Thumb instructions an additional step of updating ITSTATE is needed. We do this after calling the handler because some handlers will need to test if they are running in an IT block. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-06-09 13:11:27 +02:00
static void __kprobes thumb16_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->ARM_pc += 2;
p->ainsn.insn_handler(p, regs);
regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
}
static void __kprobes thumb32_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->ARM_pc += 4;
p->ainsn.insn_handler(p, regs);
regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
}
ARM: kprobes: Add Thumb instruction decoding stubs Extend arch_prepare_kprobe to support probing of Thumb code. For the actual decoding of Thumb instructions, stub functions are added which currently just reject the probe. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-19 18:56:58 +02:00
enum kprobe_insn __kprobes
thumb16_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
ARM: kprobes: Add hooks to override singlestep() When a probe fires we must single-step the instruction which was replaced by a breakpoint. As the steps to do this vary between ARM and Thumb instructions we need a way to customise single-stepping. This is done by adding a new hook called insn_singlestep to arch_specific_insn which is initialised by the instruction decoding functions. These single-step hooks must update PC and call the instruction handler. For Thumb instructions an additional step of updating ITSTATE is needed. We do this after calling the handler because some handlers will need to test if they are running in an IT block. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-06-09 13:11:27 +02:00
asi->insn_singlestep = thumb16_singlestep;
ARM: kprobes: Add condition code checking to Thumb emulation Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-20 20:29:52 +02:00
asi->insn_check_cc = thumb_check_cc;
ARM: kprobes: Decode 16-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-02 16:36:32 +02:00
return kprobe_decode_insn(insn, asi, kprobe_decode_thumb16_table, true);
ARM: kprobes: Add Thumb instruction decoding stubs Extend arch_prepare_kprobe to support probing of Thumb code. For the actual decoding of Thumb instructions, stub functions are added which currently just reject the probe. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-19 18:56:58 +02:00
}
enum kprobe_insn __kprobes
thumb32_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
ARM: kprobes: Add hooks to override singlestep() When a probe fires we must single-step the instruction which was replaced by a breakpoint. As the steps to do this vary between ARM and Thumb instructions we need a way to customise single-stepping. This is done by adding a new hook called insn_singlestep to arch_specific_insn which is initialised by the instruction decoding functions. These single-step hooks must update PC and call the instruction handler. For Thumb instructions an additional step of updating ITSTATE is needed. We do this after calling the handler because some handlers will need to test if they are running in an IT block. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-06-09 13:11:27 +02:00
asi->insn_singlestep = thumb32_singlestep;
ARM: kprobes: Add condition code checking to Thumb emulation Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-20 20:29:52 +02:00
asi->insn_check_cc = thumb_check_cc;
ARM: kprobes: Decode 32-bit Thumb hint instructions For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-03 14:55:47 +02:00
return kprobe_decode_insn(insn, asi, kprobe_decode_thumb32_table, true);
ARM: kprobes: Add Thumb instruction decoding stubs Extend arch_prepare_kprobe to support probing of Thumb code. For the actual decoding of Thumb instructions, stub functions are added which currently just reject the probe. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-04-19 18:56:58 +02:00
}