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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: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-28-jniethe5@gmail.com
This commit is contained in:
Jordan Niethe 2020-05-06 13:40:47 +10:00 committed by Michael Ellerman
parent c9c831aebd
commit b4657f7650
1 changed files with 13 additions and 0 deletions
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13
arch/powerpc/kernel/kprobes.c
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@ -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