Commit b4657f76 authored by Jordan Niethe's avatar Jordan Niethe Committed by Michael Ellerman
Browse files

powerpc/kprobes: Don't allow breakpoints on suffixes 



Do not allow inserting breakpoints on the suffix of a prefix instruction
in kprobes.

Signed-off-by: default avatarJordan Niethe <jniethe5@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-28-jniethe5@gmail.com
parent c9c831ae

arch/powerpc/kernel/kprobes.c

+13 −0
Original line number Diff line number Diff line
@@ -106,7 +106,9 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) 
int arch_prepare_kprobe(struct kprobe *p)

{

	int ret = 0;

	struct kprobe *prev;

	struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr);

	struct ppc_inst prefix = ppc_inst_read((struct ppc_inst *)(p->addr - 1));



	if ((unsigned long)p->addr & 0x03) {

		printk("Attempt to register kprobe at an unaligned address\n");
@@ -114,6 +116,17 @@ int arch_prepare_kprobe(struct kprobe *p) 
	} else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) {

		printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n");

		ret = -EINVAL;

	} else if (ppc_inst_prefixed(prefix)) {

		printk("Cannot register a kprobe on the second word of prefixed instruction\n");

		ret = -EINVAL;

	}

	preempt_disable();

	prev = get_kprobe(p->addr - 1);

	preempt_enable_no_resched();

	if (prev &&

	    ppc_inst_prefixed(ppc_inst_read((struct ppc_inst *)prev->ainsn.insn))) {

		printk("Cannot register a kprobe on the second word of prefixed instruction\n");

		ret = -EINVAL;

	}



	/* insn must be on a special executable page on ppc64.  This is