Commit c536aa1c authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

kprobes/ftrace: Add recursion protection to the ftrace callback 

If a ftrace callback does not supply its own recursion protection and
does not set the RECURSION_SAFE flag in its ftrace_ops, then ftrace will
make a helper trampoline to do so before calling the callback instead of
just calling the callback directly.

The default for ftrace_ops is going to change. It will expect that handlers
provide their own recursion protection, unless its ftrace_ops states
otherwise.

Link: https://lkml.kernel.org/r/20201028115613.140212174@goodmis.org
Link: https://lkml.kernel.org/r/20201106023546.944907560@goodmis.org



Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh  Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-csky@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 6cdf9418

arch/csky/kernel/probes/ftrace.c

+10 −2
Original line number Diff line number Diff line
@@ -13,16 +13,21 @@ int arch_check_ftrace_location(struct kprobe *p) 
void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,

			   struct ftrace_ops *ops, struct pt_regs *regs)

{

	int bit;

	bool lr_saver = false;

	struct kprobe *p;

	struct kprobe_ctlblk *kcb;



	/* Preempt is disabled by ftrace */

	bit = ftrace_test_recursion_trylock();

	if (bit < 0)

		return;



	preempt_disable_notrace();

	p = get_kprobe((kprobe_opcode_t *)ip);

	if (!p) {

		p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));

		if (unlikely(!p) || kprobe_disabled(p))

			return;

			goto out;

		lr_saver = true;

	}
@@ -56,6 +61,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
		 */

		__this_cpu_write(current_kprobe, NULL);

	}

out:

	preempt_enable_notrace();

	ftrace_test_recursion_unlock(bit);

}

NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/parisc/kernel/ftrace.c

+13 −3
Original line number Diff line number Diff line
@@ -207,14 +207,21 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
			   struct ftrace_ops *ops, struct pt_regs *regs)

{

	struct kprobe_ctlblk *kcb;

	struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip);

	struct kprobe *p;

	int bit;



	if (unlikely(!p) || kprobe_disabled(p))

	bit = ftrace_test_recursion_trylock();

	if (bit < 0)

		return;



	preempt_disable_notrace();

	p = get_kprobe((kprobe_opcode_t *)ip);

	if (unlikely(!p) || kprobe_disabled(p))

		goto out;



	if (kprobe_running()) {

		kprobes_inc_nmissed_count(p);

		return;

		goto out;

	}



	__this_cpu_write(current_kprobe, p);
@@ -235,6 +242,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
		}

	}

	__this_cpu_write(current_kprobe, NULL);

out:

	preempt_enable_notrace();

	ftrace_test_recursion_unlock(bit);

}

NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/powerpc/kernel/kprobes-ftrace.c

+10 −1
Original line number Diff line number Diff line
@@ -18,10 +18,16 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, 
{

	struct kprobe *p;

	struct kprobe_ctlblk *kcb;

	int bit;



	bit = ftrace_test_recursion_trylock();

	if (bit < 0)

		return;



	preempt_disable_notrace();

	p = get_kprobe((kprobe_opcode_t *)nip);

	if (unlikely(!p) || kprobe_disabled(p))

		return;

		goto out;



	kcb = get_kprobe_ctlblk();

	if (kprobe_running()) {
@@ -52,6 +58,9 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, 
		 */

		__this_cpu_write(current_kprobe, NULL);

	}

out:

	preempt_enable_notrace();

	ftrace_test_recursion_unlock(bit);

}

NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/s390/kernel/ftrace.c

+13 −3
Original line number Diff line number Diff line
@@ -201,14 +201,21 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
		struct ftrace_ops *ops, struct pt_regs *regs)

{

	struct kprobe_ctlblk *kcb;

	struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip);

	struct kprobe *p;

	int bit;



	if (unlikely(!p) || kprobe_disabled(p))

	bit = ftrace_test_recursion_trylock();

	if (bit < 0)

		return;



	preempt_disable_notrace();

	p = get_kprobe((kprobe_opcode_t *)ip);

	if (unlikely(!p) || kprobe_disabled(p))

		goto out;



	if (kprobe_running()) {

		kprobes_inc_nmissed_count(p);

		return;

		goto out;

	}



	__this_cpu_write(current_kprobe, p);
@@ -228,6 +235,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
		}

	}

	__this_cpu_write(current_kprobe, NULL);

out:

	preempt_enable_notrace();

	ftrace_test_recursion_unlock(bit);

}

NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/x86/kernel/kprobes/ftrace.c

+10 −2
Original line number Diff line number Diff line
@@ -18,11 +18,16 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
{

	struct kprobe *p;

	struct kprobe_ctlblk *kcb;

	int bit;



	/* Preempt is disabled by ftrace */

	bit = ftrace_test_recursion_trylock();

	if (bit < 0)

		return;



	preempt_disable_notrace();

	p = get_kprobe((kprobe_opcode_t *)ip);

	if (unlikely(!p) || kprobe_disabled(p))

		return;

		goto out;



	kcb = get_kprobe_ctlblk();

	if (kprobe_running()) {
@@ -52,6 +57,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
		 */

		__this_cpu_write(current_kprobe, NULL);

	}

out:

	preempt_enable_notrace();

	ftrace_test_recursion_unlock(bit);

}

NOKPROBE_SYMBOL(kprobe_ftrace_handler);

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