On Thu, 05 Nov 2020 21:32:40 -0500 Steven Rostedt (VMware) <rost...@goodmis.org> wrote:
> From: "Steven Rostedt (VMware)" <rost...@goodmis.org> > > 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/20201028115613.140212...@goodmis.org > Looks good to me. Acked-by: Masami Hiramatsu <mhira...@kernel.org> Thank you! > Cc: Andrew Morton <a...@linux-foundation.org> > Cc: Masami Hiramatsu <mhira...@kernel.org> > Cc: Guo Ren <guo...@kernel.org> > Cc: "James E.J. Bottomley" <james.bottom...@hansenpartnership.com> > Cc: Helge Deller <del...@gmx.de> > Cc: Michael Ellerman <m...@ellerman.id.au> > Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> > Cc: Paul Mackerras <pau...@samba.org> > Cc: Heiko Carstens <h...@linux.ibm.com> > Cc: Vasily Gorbik <g...@linux.ibm.com> > Cc: Christian Borntraeger <borntrae...@de.ibm.com> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Borislav Petkov <b...@alien8.de> > Cc: x...@kernel.org > Cc: "H. Peter Anvin" <h...@zytor.com> > Cc: "Naveen N. Rao" <naveen.n....@linux.ibm.com> > Cc: Anil S Keshavamurthy <anil.s.keshavamur...@intel.com> > Cc: "David S. Miller" <da...@davemloft.net> > Cc: linux-c...@vger.kernel.org > Cc: linux-par...@vger.kernel.org > Cc: linuxppc-...@lists.ozlabs.org > Cc: linux-s...@vger.kernel.org > Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org> > --- > > Changes since v2: > > - Move get_kprobe() into preempt disabled sections for various archs > > > 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 5264763d05be..5eb2604fdf71 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 63e3ecb9da81..13d85042810a 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 972cb28174b2..5df8d50c65ae 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 b388e87a08bf..8f31c726537a 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 681a4b36e9bb..a40a6cdfcca3 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); > > -- > 2.28.0 > > -- Masami Hiramatsu <mhira...@kernel.org>
