@@ -105,56 +105,54 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
int arch_prepare_kprobe(struct kprobe *p)
{
- int ret = 0;
+ struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr);
+ struct instruction_op op;
struct kprobe *prev;
struct pt_regs regs;
- struct instruction_op op;
- struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr);
+ int ret = 0;
if ((unsigned long)p->addr & 0x03) {
- printk("Attempt to register kprobe at an unaligned address\n");
- ret = -EINVAL;
+ pr_info("Attempt to register kprobe at an unaligned address\n");
+ return -EINVAL;
} else if (IS_MTMSRD(insn) || IS_RFID(insn)) {
- printk("Cannot register a kprobe on mtmsr[d]/rfi[d]\n");
- ret = -EINVAL;
+ pr_info("Cannot register a kprobe on mtmsr[d]/rfi[d]\n");
+ return -EINVAL;
} else if ((unsigned long)p->addr & ~PAGE_MASK &&
ppc_inst_prefixed(ppc_inst_read((struct ppc_inst *)(p->addr - 1)))) {
- printk("Cannot register a kprobe on the second word of prefixed instruction\n");
- ret = -EINVAL;
+ pr_info("Cannot register a kprobe on the second word of prefixed instruction\n");
+ return -EINVAL;
}
+
+ /* Check if the previous instruction is a prefix instruction with an active kprobe */
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;
+ if (prev && ppc_inst_prefixed(ppc_inst_read((struct ppc_inst *)prev->ainsn.insn))) {
+ pr_info("Cannot register a kprobe on the second word of prefixed instruction\n");
+ return -EINVAL;
}
/* insn must be on a special executable page on ppc64. This is
* not explicitly required on ppc32 (right now), but it doesn't hurt */
- if (!ret) {
- p->ainsn.insn = get_insn_slot();
- if (!p->ainsn.insn)
- ret = -ENOMEM;
- }
+ p->ainsn.insn = get_insn_slot();
+ if (!p->ainsn.insn)
+ return -ENOMEM;
- if (!ret) {
- patch_instruction((struct ppc_inst *)p->ainsn.insn, insn);
- p->opcode = ppc_inst_val(insn);
-
- /* Check if this is an instruction we recognise */
- p->ainsn.boostable = 0;
- memset(®s, 0, sizeof(struct pt_regs));
- regs.nip = (unsigned long)p->addr;
- regs.msr = MSR_KERNEL;
- ret = analyse_instr(&op, ®s, insn);
- if (ret == 1 || (ret == 0 && GETTYPE(op.type) != UNKNOWN))
- p->ainsn.boostable = 1;
- ret = 0;
- }
+ if (patch_instruction((struct ppc_inst *)p->ainsn.insn, insn))
+ return -EFAULT;
- return ret;
+ p->opcode = ppc_inst_val(insn);
+
+ /* Check if this is an instruction we recognise */
+ p->ainsn.boostable = 0;
+ memset(®s, 0, sizeof(struct pt_regs));
+ regs.nip = (unsigned long)p->addr;
+ regs.msr = MSR_KERNEL;
+ ret = analyse_instr(&op, ®s, insn);
+ if (ret == 1 || (ret == 0 && GETTYPE(op.type) != UNKNOWN))
+ p->ainsn.boostable = 1;
+
+ return 0;
}
NOKPROBE_SYMBOL(arch_prepare_kprobe);
Clean up the function to look sane: - return immediately on error, rather than pointlessly setting the return value - pr_info() instead of printk() - check return value of patch_instruction() - and to top it all of: a reverse christmas tree! Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- arch/powerpc/kernel/kprobes.c | 64 +++++++++++++++++------------------ 1 file changed, 31 insertions(+), 33 deletions(-)