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Commit adb45839 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Martin Schwidefsky
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[S390] kprobes: disable interrupts throughout 



Execute the kprobe exception and fault handler with interrupts disabled.
To disable the interrupts only while a single step is in progress is not
good enough, a kprobe from interrupt context while another kprobe is
handled can confuse the internal house keeping.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent becf91f1

arch/s390/kernel/kprobes.c

+27 −14
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <asm/sections.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/hardirq.h>



DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;

DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
@@ -212,7 +213,7 @@ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) 
	/* Set the PER control regs, turns on single step for this address */

	__ctl_load(kprobe_per_regs, 9, 11);

	regs->psw.mask |= PSW_MASK_PER;

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

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

}



static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
@@ -239,7 +240,7 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, 
	__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 | PSW_MASK_MCHECK);

		(PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);

	/* Save the control regs that govern PER */

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

}
@@ -316,8 +317,6 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) 
		return 1;



ss_probe:

	if (regs->psw.mask & (PSW_MASK_PER | PSW_MASK_IO))

		local_irq_disable();

	prepare_singlestep(p, regs);

	kcb->kprobe_status = KPROBE_HIT_SS;

	return 1;
@@ -465,8 +464,6 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs) 
		goto out;

	}

	reset_current_kprobe();

	if (regs->psw.mask & (PSW_MASK_PER | PSW_MASK_IO))

		local_irq_enable();

out:

	preempt_enable_no_resched();
@@ -482,7 +479,7 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs) 
	return 1;

}



int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)

static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr)

{

	struct kprobe *cur = kprobe_running();

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -508,8 +505,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) 
			restore_previous_kprobe(kcb);

		else {

			reset_current_kprobe();

			if (regs->psw.mask & (PSW_MASK_PER | PSW_MASK_IO))

				local_irq_enable();

		}

		preempt_enable_no_resched();

		break;
@@ -553,6 +548,18 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) 
	return 0;

}



int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)

{

	int ret;



	if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))

		local_irq_disable();

	ret = kprobe_trap_handler(regs, trapnr);

	if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))

		local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);

	return ret;

}



/*

 * Wrapper routine to for handling exceptions.

 */
@@ -560,8 +567,12 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, 
				       unsigned long val, void *data)

{

	struct die_args *args = (struct die_args *)data;

	struct pt_regs *regs = args->regs;

	int ret = NOTIFY_DONE;



	if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))

		local_irq_disable();



	switch (val) {

	case DIE_BPT:

		if (kprobe_handler(args->regs))
@@ -572,16 +583,17 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, 
			ret = NOTIFY_STOP;

		break;

	case DIE_TRAP:

		/* kprobe_running() needs smp_processor_id() */

		preempt_disable();

		if (kprobe_running() &&

		    kprobe_fault_handler(args->regs, args->trapnr))

		if (!preemptible() && kprobe_running() &&

		    kprobe_trap_handler(args->regs, args->trapnr))

			ret = NOTIFY_STOP;

		preempt_enable();

		break;

	default:

		break;

	}



	if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))

		local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);



	return ret;

}
@@ -595,6 +607,7 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) 


	/* setup return addr to the jprobe handler routine */

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

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



	/* r14 is the function return address */

	kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];