From 9ec4b1f356b3bad928ae8e2aa9caebfa737d52df Mon Sep 17 00:00:00 2001 From: Ananth N Mavinakayanahalli Date: Mon, 27 Jun 2005 15:17:01 -0700 Subject: [PATCH] kprobes: fix single-step out of line - take2 Now that PPC64 has no-execute support, here is a second try to fix the single step out of line during kprobe execution. Kprobes on x86_64 already solved this problem by allocating an executable page and using it as the scratch area for stepping out of line. Reuse that. Signed-off-by: Ananth N Mavinakayanahalli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/ppc64/kernel/kprobes.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) (limited to 'arch/ppc64/kernel') diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c index 782ce3efa2c1..86cc5496db9f 100644 --- a/arch/ppc64/kernel/kprobes.c +++ b/arch/ppc64/kernel/kprobes.c @@ -36,6 +36,8 @@ #include #include +static DECLARE_MUTEX(kprobe_mutex); + static struct kprobe *current_kprobe; static unsigned long kprobe_status, kprobe_saved_msr; static struct kprobe *kprobe_prev; @@ -54,6 +56,15 @@ int arch_prepare_kprobe(struct kprobe *p) printk("Cannot register a kprobe on rfid or mtmsrd\n"); ret = -EINVAL; } + + /* insn must be on a special executable page on ppc64 */ + if (!ret) { + up(&kprobe_mutex); + p->ainsn.insn = get_insn_slot(); + down(&kprobe_mutex); + if (!p->ainsn.insn) + ret = -ENOMEM; + } return ret; } @@ -79,16 +90,22 @@ void arch_disarm_kprobe(struct kprobe *p) void arch_remove_kprobe(struct kprobe *p) { + up(&kprobe_mutex); + free_insn_slot(p->ainsn.insn); + down(&kprobe_mutex); } static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) { + kprobe_opcode_t insn = *p->ainsn.insn; + regs->msr |= MSR_SE; - /*single step inline if it a breakpoint instruction*/ - if (p->opcode == BREAKPOINT_INSTRUCTION) + + /* single step inline if it is a trap variant */ + if (IS_TW(insn) || IS_TD(insn) || IS_TWI(insn) || IS_TDI(insn)) regs->nip = (unsigned long)p->addr; else - regs->nip = (unsigned long)&p->ainsn.insn; + regs->nip = (unsigned long)p->ainsn.insn; } static inline void save_previous_kprobe(void) @@ -205,9 +222,10 @@ no_kprobe: static void resume_execution(struct kprobe *p, struct pt_regs *regs) { int ret; + unsigned int insn = *p->ainsn.insn; regs->nip = (unsigned long)p->addr; - ret = emulate_step(regs, p->ainsn.insn[0]); + ret = emulate_step(regs, insn); if (ret == 0) regs->nip = (unsigned long)p->addr + 4; } -- cgit v1.2.2