ARM: kprobes: Extend arch_specific_insn to add pointer to emulated instruction
When we come to emulating Thumb instructions then, to interwork
correctly, the code on in the instruction slot must be invoked with a
function pointer which has the least significant bit set. Rather that
set this by hand in every Thumb emulation function we will add a new
field for this purpose to arch_specific_insn, called insn_fn.
This also enables us to seamlessly share emulation functions between ARM
and Thumb code.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index 77b7c69..129c116 100644
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -51,6 +51,7 @@
kprobe_opcode_t insn;
kprobe_opcode_t tmp_insn[MAX_INSN_SIZE];
unsigned long addr = (unsigned long)p->addr;
+ bool thumb;
kprobe_decode_insn_t *decode_insn;
int is;
@@ -58,6 +59,7 @@
return -EINVAL;
#ifdef CONFIG_THUMB2_KERNEL
+ thumb = true;
addr &= ~1; /* Bit 0 would normally be set to indicate Thumb code */
insn = ((u16 *)addr)[0];
if (is_wide_instruction(insn)) {
@@ -67,6 +69,7 @@
} else
decode_insn = thumb16_kprobe_decode_insn;
#else /* !CONFIG_THUMB2_KERNEL */
+ thumb = false;
if (addr & 0x3)
return -EINVAL;
insn = *p->addr;
@@ -88,6 +91,8 @@
p->ainsn.insn[is] = tmp_insn[is];
flush_insns(p->ainsn.insn,
sizeof(p->ainsn.insn[0]) * MAX_INSN_SIZE);
+ p->ainsn.insn_fn = (kprobe_insn_fn_t *)
+ ((uintptr_t)p->ainsn.insn | thumb);
break;
case INSN_GOOD_NO_SLOT: /* instruction doesn't need insn slot */