Commit ba090f9c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Catalin Marinas
Browse files

arm64: kprobes: Remove redundant kprobe_step_ctx 



The kprobe_step_ctx (kcb->ss_ctx) has ss_pending and match_addr, but
those are redundant because those can be replaced by KPROBE_HIT_SS and
&cur_kprobe->ainsn.api.insn[1] respectively.
To simplify the code, remove the kprobe_step_ctx.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: default avatarJean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201103134900.337243-2-jean-philippe@linaro.org


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent f8394f23

arch/arm64/include/asm/kprobes.h

+0 −7
Original line number Diff line number Diff line
@@ -28,18 +28,11 @@ struct prev_kprobe { 
	unsigned int status;

};



/* Single step context for kprobe */

struct kprobe_step_ctx {

	unsigned long ss_pending;

	unsigned long match_addr;

};



/* per-cpu kprobe control block */

struct kprobe_ctlblk {

	unsigned int kprobe_status;

	unsigned long saved_irqflag;

	struct prev_kprobe prev_kprobe;

	struct kprobe_step_ctx ss_ctx;

};



void arch_remove_kprobe(struct kprobe *);

arch/arm64/kernel/probes/kprobes.c

+12 −41
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; 
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);



static void __kprobes

post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);

post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *);



static void __kprobes arch_prepare_ss_slot(struct kprobe *p)

{
@@ -68,7 +68,7 @@ static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) 
		p->ainsn.api.handler((u32)p->opcode, (long)p->addr, regs);



	/* single step simulated, now go for post processing */

	post_kprobe_handler(kcb, regs);

	post_kprobe_handler(p, kcb, regs);

}



int __kprobes arch_prepare_kprobe(struct kprobe *p)
@@ -177,19 +177,6 @@ static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, 
	regs->pstate |= kcb->saved_irqflag;

}



static void __kprobes

set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr)

{

	kcb->ss_ctx.ss_pending = true;

	kcb->ss_ctx.match_addr = addr + sizeof(kprobe_opcode_t);

}



static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb)

{

	kcb->ss_ctx.ss_pending = false;

	kcb->ss_ctx.match_addr = 0;

}



static void __kprobes setup_singlestep(struct kprobe *p,

				       struct pt_regs *regs,

				       struct kprobe_ctlblk *kcb, int reenter)
@@ -209,7 +196,6 @@ static void __kprobes setup_singlestep(struct kprobe *p, 
		/* prepare for single stepping */

		slot = (unsigned long)p->ainsn.api.insn;



		set_ss_context(kcb, slot);	/* mark pending ss */

		kprobes_save_local_irqflag(kcb, regs);

		instruction_pointer_set(regs, slot);

	} else {
@@ -243,13 +229,8 @@ static int __kprobes reenter_kprobe(struct kprobe *p, 
}



static void __kprobes

post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs)

post_kprobe_handler(struct kprobe *cur, struct kprobe_ctlblk *kcb, struct pt_regs *regs)

{

	struct kprobe *cur = kprobe_running();



	if (!cur)

		return;



	/* return addr restore if non-branching insn */

	if (cur->ainsn.api.restore != 0)

		instruction_pointer_set(regs, cur->ainsn.api.restore);
@@ -364,33 +345,23 @@ static void __kprobes kprobe_handler(struct pt_regs *regs) 
	 */

}



static int __kprobes

kprobe_ss_hit(struct kprobe_ctlblk *kcb, unsigned long addr)

{

	if ((kcb->ss_ctx.ss_pending)

	    && (kcb->ss_ctx.match_addr == addr)) {

		clear_ss_context(kcb);	/* clear pending ss */

		return DBG_HOOK_HANDLED;

	}

	/* not ours, kprobes should ignore it */

	return DBG_HOOK_ERROR;

}



static int __kprobes

kprobe_breakpoint_ss_handler(struct pt_regs *regs, unsigned int esr)

{

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

	int retval;



	/* return error if this is not our step */

	retval = kprobe_ss_hit(kcb, instruction_pointer(regs));

	unsigned long addr = instruction_pointer(regs);

	struct kprobe *cur = kprobe_running();



	if (retval == DBG_HOOK_HANDLED) {

	if (cur && (kcb->kprobe_status == KPROBE_HIT_SS)

	    && ((unsigned long)&cur->ainsn.api.insn[1] == addr)) {

		kprobes_restore_local_irqflag(kcb, regs);

		post_kprobe_handler(kcb, regs);

		post_kprobe_handler(cur, kcb, regs);



		return DBG_HOOK_HANDLED;

	}



	return retval;

	/* not ours, kprobes should ignore it */

	return DBG_HOOK_ERROR;

}



static struct break_hook kprobes_break_ss_hook = {