From c536aa1c5b17fac1ee395932031ff7d82827f2c5 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Date: Thu, 5 Nov 2020 21:32:40 -0500
Subject: [PATCH] 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: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
arch/csky/kernel/probes/ftrace.c | 12 ++++++++++--
arch/parisc/kernel/ftrace.c | 16 +++++++++++++---
arch/powerpc/kernel/kprobes-ftrace.c | 11 ++++++++++-
arch/s390/kernel/ftrace.c | 16 +++++++++++++---
arch/x86/kernel/kprobes/ftrace.c | 12 ++++++++++--
5 files changed, 56 insertions(+), 11 deletions(-)
diff --git a/arch/csky/kernel/probes/ftrace.c b/arch/csky/kernel/probes/ftrace.c
index 5264763d05bef..5eb2604fdf712 100644
--- a/arch/csky/kernel/probes/ftrace.c
+++ b/arch/csky/kernel/probes/ftrace.c
@@ -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);
diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index 63e3ecb9da812..13d85042810aa 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -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);
diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c
index 972cb28174b20..5df8d50c65ae2 100644
--- a/arch/powerpc/kernel/kprobes-ftrace.c
+++ b/arch/powerpc/kernel/kprobes-ftrace.c
@@ -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);
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index b388e87a08bf9..8f31c726537ad 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -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);
diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c
index 681a4b36e9bbe..a40a6cdfcca3b 100644
--- a/arch/x86/kernel/kprobes/ftrace.c
+++ b/arch/x86/kernel/kprobes/ftrace.c
@@ -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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