Commit e2960317 authored by Jon Medhurst's avatar Jon Medhurst Committed by Tixy
Browse files

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: default avatarJon Medhurst <tixy@yxit.co.uk>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent c6a7d97d

arch/arm/include/asm/kprobes.h

+2 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ struct kprobe; 
typedef void (kprobe_insn_handler_t)(struct kprobe *, struct pt_regs *);

typedef unsigned long (kprobe_check_cc)(unsigned long);

typedef void (kprobe_insn_singlestep_t)(struct kprobe *, struct pt_regs *);

typedef void (kprobe_insn_fn_t)(void);



/* Architecture specific copy of original instruction. */

struct arch_specific_insn {
@@ -41,6 +42,7 @@ struct arch_specific_insn { 
	kprobe_insn_handler_t		*insn_handler;

	kprobe_check_cc			*insn_check_cc;

	kprobe_insn_singlestep_t	*insn_singlestep;

	kprobe_insn_fn_t		*insn_fn;

};



struct prev_kprobe {

arch/arm/kernel/kprobes.c

+5 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) 
	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 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) 
		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 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) 
	} 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 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) 
			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 */

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