ARM: kprobes: Fix emulation of MRS instruction
The MRS instruction should set mode and interrupt bits in the read value
so it is simpler to use a new simulation routine (simulate_mrs) rather
than some modified emulation.
prep_emulate_rd12 is now unused and removed.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c
index e5bc576..4ab83f4 100644
--- a/arch/arm/kernel/kprobes-decode.c
+++ b/arch/arm/kernel/kprobes-decode.c
@@ -451,6 +451,14 @@
regs->ARM_cpsr |= PSR_T_BIT;
}
+static void __kprobes simulate_mrs(struct kprobe *p, struct pt_regs *regs)
+{
+ kprobe_opcode_t insn = p->opcode;
+ int rd = (insn >> 12) & 0xf;
+ unsigned long mask = 0xf8ff03df; /* Mask out execution state */
+ regs->uregs[rd] = regs->ARM_cpsr & mask;
+}
+
static void __kprobes simulate_ldm1stm1(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
@@ -896,15 +904,6 @@
}
static enum kprobe_insn __kprobes
-prep_emulate_rd12(kprobe_opcode_t insn, struct arch_specific_insn *asi)
-{
- insn &= 0xffff0fff; /* Rd = r0 */
- asi->insn[0] = insn;
- asi->insn_handler = emulate_rd12;
- return INSN_GOOD;
-}
-
-static enum kprobe_insn __kprobes
prep_emulate_rd12rn16rm0_wflags(kprobe_opcode_t insn,
struct arch_specific_insn *asi)
{
@@ -1035,8 +1034,10 @@
return INSN_REJECTED;
/* MRS cpsr : cccc 0001 0000 xxxx xxxx xxxx 0000 xxxx */
- if ((insn & 0x0ff000f0) == 0x01000000)
- return prep_emulate_rd12(insn, asi);
+ if ((insn & 0x0ff000f0) == 0x01000000) {
+ asi->insn_handler = simulate_mrs;
+ return INSN_GOOD_NO_SLOT;
+ }
/* SMLALxy : cccc 0001 0100 xxxx xxxx xxxx 1xx0 xxxx */
if ((insn & 0x0ff00090) == 0x01400080)