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ARM: kprobes: Fix emulation of CMP, CMN, TST and TEQ instructions.

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Probing these instructions was corrupting R0 because the emulation code
didn't account for the fact that they don't write a result to a
register.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
This commit is contained in:
Jon Medhurst 2011-04-06 11:17:11 +01:00 committed by Nicolas Pitre
parent a539f5d46c
commit ad111ce466
1 changed files with 53 additions and 2 deletions
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55
arch/arm/kernel/kprobes-decode.c
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@ -807,6 +807,17 @@ emulate_alu_imm_rwflags(struct kprobe *p, struct pt_regs *regs)
regs->uregs[rd] = insnslot_1arg_rwflags(rnv, &regs->ARM_cpsr, i_fn);
}
static void __kprobes
emulate_alu_tests_imm(struct kprobe *p, struct pt_regs *regs)
{
insn_1arg_fn_t *i_fn = (insn_1arg_fn_t *)&p->ainsn.insn[0];
kprobe_opcode_t insn = p->opcode;
int rn = (insn >> 16) & 0xf;
long rnv = (rn == 15) ? (long)p->addr + 8 : regs->uregs[rn];
insnslot_1arg_rwflags(rnv, &regs->ARM_cpsr, i_fn);
}
static void __kprobes
emulate_alu_rflags(struct kprobe *p, struct pt_regs *regs)
{
@ -843,6 +854,22 @@ emulate_alu_rwflags(struct kprobe *p, struct pt_regs *regs)
insnslot_3arg_rwflags(rnv, rmv, rsv, &regs->ARM_cpsr, i_fn);
}
static void __kprobes
emulate_alu_tests(struct kprobe *p, struct pt_regs *regs)
{
insn_3arg_fn_t *i_fn = (insn_3arg_fn_t *)&p->ainsn.insn[0];
kprobe_opcode_t insn = p->opcode;
long ppc = (long)p->addr + 8;
int rn = (insn >> 16) & 0xf;
int rs = (insn >> 8) & 0xf; /* rs/rsv may be invalid, don't care. */
int rm = insn & 0xf;
long rnv = (rn == 15) ? ppc : regs->uregs[rn];
long rmv = (rm == 15) ? ppc : regs->uregs[rm];
long rsv = regs->uregs[rs];
insnslot_3arg_rwflags(rnv, rmv, rsv, &regs->ARM_cpsr, i_fn);
}
static enum kprobe_insn __kprobes
prep_emulate_ldr_str(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
@ -1142,8 +1169,20 @@ space_cccc_000x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
insn |= 0x00000200; /* Rs = r2 */
}
asi->insn[0] = insn;
asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
if ((insn & 0x0f900000) == 0x01100000) {
/*
* TST : cccc 0001 0001 xxxx xxxx xxxx xxxx xxxx
* TEQ : cccc 0001 0011 xxxx xxxx xxxx xxxx xxxx
* CMP : cccc 0001 0101 xxxx xxxx xxxx xxxx xxxx
* CMN : cccc 0001 0111 xxxx xxxx xxxx xxxx xxxx
*/
asi->insn_handler = emulate_alu_tests;
} else {
/* ALU ops which write to Rd */
asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
emulate_alu_rwflags : emulate_alu_rflags;
}
return INSN_GOOD;
}
@ -1170,8 +1209,20 @@ space_cccc_001x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
*/
insn &= 0xffff0fff; /* Rd = r0 */
asi->insn[0] = insn;
asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
if ((insn & 0x0f900000) == 0x03100000) {
/*
* TST : cccc 0011 0001 xxxx xxxx xxxx xxxx xxxx
* TEQ : cccc 0011 0011 xxxx xxxx xxxx xxxx xxxx
* CMP : cccc 0011 0101 xxxx xxxx xxxx xxxx xxxx
* CMN : cccc 0011 0111 xxxx xxxx xxxx xxxx xxxx
*/
asi->insn_handler = emulate_alu_tests_imm;
} else {
/* ALU ops which write to Rd */
asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
emulate_alu_imm_rwflags : emulate_alu_imm_rflags;
}
return INSN_GOOD;
}