Commit fc0a1fea authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Martin Schwidefsky
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[S390] kprobes: single step cleanup 



The saved interrupt mask and the saved control registers are only
relevant while single stepping is set up. A secondary kprobe while
kprobe single stepping is active may not occur. That makes is safe
to remove the save and restore of kprobe_saved_imask / kprobe_save_ctl
from save_previous_kprobe and restore_previous_kprobe.
Move all single step related code to two functions, enable_singlestep
and disable_singlestep.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 35f2aaa7

arch/s390/include/asm/kprobes.h

+0 −3
Original line number Diff line number Diff line
@@ -72,9 +72,6 @@ struct ins_replace_args { 
struct prev_kprobe {

	struct kprobe *kp;

	unsigned long status;

	unsigned long saved_psw;

	unsigned long kprobe_saved_imask;

	unsigned long kprobe_saved_ctl[3];

};



/* per-cpu kprobe control block */

arch/s390/kernel/kprobes.c

+36 −41
Original line number Diff line number Diff line
@@ -198,51 +198,58 @@ void __kprobes arch_remove_kprobe(struct kprobe *p) 
	}

}



static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)

static void __kprobes enable_singlestep(struct kprobe_ctlblk *kcb,

					struct pt_regs *regs,

					unsigned long ip)

{

	per_cr_bits kprobe_per_regs[1];



	memset(kprobe_per_regs, 0, sizeof(per_cr_bits));

	regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;



	/* Set up the per control reg info, will pass to lctl */

	memset(kprobe_per_regs, 0, sizeof(per_cr_bits));

	kprobe_per_regs[0].em_instruction_fetch = 1;

	kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;

	kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;

	kprobe_per_regs[0].starting_addr = ip;

	kprobe_per_regs[0].ending_addr = ip;



	/* Save control regs and psw mask */

	__ctl_store(kcb->kprobe_saved_ctl, 9, 11);

	kcb->kprobe_saved_imask = regs->psw.mask &

		(PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);



	/* Set the PER control regs, turns on single step for this address */

	/* Set PER control regs, turns on single step for the given address */

	__ctl_load(kprobe_per_regs, 9, 11);

	regs->psw.mask |= PSW_MASK_PER;

	regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);

	regs->psw.addr = ip | PSW_ADDR_AMODE;

}



static void __kprobes disable_singlestep(struct kprobe_ctlblk *kcb,

					 struct pt_regs *regs,

					 unsigned long ip)

{

	/* Restore control regs and psw mask, set new psw address */

	__ctl_load(kcb->kprobe_saved_ctl, 9, 11);

	regs->psw.mask &= ~PSW_MASK_PER;

	regs->psw.mask |= kcb->kprobe_saved_imask;

	regs->psw.addr = ip | PSW_ADDR_AMODE;

}





static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)

{

	kcb->prev_kprobe.kp = kprobe_running();

	kcb->prev_kprobe.status = kcb->kprobe_status;

	kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;

	memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,

					sizeof(kcb->kprobe_saved_ctl));

}



static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)

{

	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;

	kcb->kprobe_status = kcb->prev_kprobe.status;

	kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;

	memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,

					sizeof(kcb->kprobe_saved_ctl));

}



static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,

						struct kprobe_ctlblk *kcb)

{

	__get_cpu_var(current_kprobe) = p;

	/* Save the interrupt and per flags */

	kcb->kprobe_saved_imask = regs->psw.mask &

		(PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);

	/* Save the control regs that govern PER */

	__ctl_store(kcb->kprobe_saved_ctl, 9, 11);

}



void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
@@ -282,7 +289,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) 
			save_previous_kprobe(kcb);

			set_current_kprobe(p, regs, kcb);

			kprobes_inc_nmissed_count(p);

			prepare_singlestep(p, regs);

			enable_singlestep(kcb, regs,

					  (unsigned long) p->ainsn.insn);

			kcb->kprobe_status = KPROBE_REENTER;

			return 1;

		} else {
@@ -311,7 +319,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) 
		return 1;



ss_probe:

	prepare_singlestep(p, regs);

	enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);

	kcb->kprobe_status = KPROBE_HIT_SS;

	return 1;
@@ -433,31 +441,20 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p, 
static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)

{

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();



	regs->psw.addr &= PSW_ADDR_INSN;

	unsigned long ip = regs->psw.addr & PSW_ADDR_INSN;



	if (p->ainsn.fixup & FIXUP_PSW_NORMAL)

		regs->psw.addr = (unsigned long)p->addr +

				((unsigned long)regs->psw.addr -

				 (unsigned long)p->ainsn.insn);

		ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;



	if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)

		if ((unsigned long)regs->psw.addr -

		    (unsigned long)p->ainsn.insn == p->ainsn.ilen)

			regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;

		if (ip - (unsigned long) p->ainsn.insn == p->ainsn.ilen)

			ip = (unsigned long) p->addr + p->ainsn.ilen;



	if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)

		regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +

						(regs->gprs[p->ainsn.reg] -

						(unsigned long)p->ainsn.insn))

						| PSW_ADDR_AMODE;

		regs->gprs[p->ainsn.reg] += (unsigned long) p->addr -

					    (unsigned long) p->ainsn.insn;



	regs->psw.addr |= PSW_ADDR_AMODE;

	/* turn off PER mode */

	regs->psw.mask &= ~PSW_MASK_PER;

	/* Restore the original per control regs */

	__ctl_load(kcb->kprobe_saved_ctl, 9, 11);

	regs->psw.mask |= kcb->kprobe_saved_imask;

	disable_singlestep(kcb, regs, ip);

}



static int __kprobes post_kprobe_handler(struct pt_regs *regs)
@@ -515,9 +512,7 @@ static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr) 
		 * and allow the page fault handler to continue as a

		 * normal page fault.

		 */

		regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;

		regs->psw.mask &= ~PSW_MASK_PER;

		regs->psw.mask |= kcb->kprobe_saved_imask;

		disable_singlestep(kcb, regs, (unsigned long) cur->addr);

		if (kcb->kprobe_status == KPROBE_REENTER)

			restore_previous_kprobe(kcb);

		else {

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