From c536aa1c5b17fac1ee395932031ff7d82827f2c5 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 5 Nov 2020 21:32:40 -0500 Subject: 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 Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Miroslav Benes Cc: Petr Mladek Cc: Andrew Morton Cc: Guo Ren Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Cc: Thomas Gleixner Cc: Borislav Petkov Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: "Naveen N. Rao" Cc: Anil S Keshavamurthy Cc: "David S. Miller" 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 Signed-off-by: Steven Rostedt (VMware) --- arch/parisc/kernel/ftrace.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'arch/parisc/kernel') 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); -- cgit v1.2.3 From 773c16705058e9be7b0f4ce124e89cd231c120a2 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 5 Nov 2020 21:32:46 -0500 Subject: ftrace: Add recording of functions that caused recursion This adds CONFIG_FTRACE_RECORD_RECURSION that will record to a file "recursed_functions" all the functions that caused recursion while a callback to the function tracer was running. Link: https://lkml.kernel.org/r/20201106023548.102375687@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Guo Ren Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Cc: Thomas Gleixner Cc: Borislav Petkov Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: Kees Cook Cc: Anton Vorontsov Cc: Colin Cross Cc: Tony Luck Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Miroslav Benes Cc: Petr Mladek Cc: Joe Lawrence Cc: Kamalesh Babulal Cc: Mauro Carvalho Chehab Cc: Sebastian Andrzej Siewior Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-csky@vger.kernel.org Cc: linux-parisc@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: live-patching@vger.kernel.org Signed-off-by: Steven Rostedt (VMware) --- arch/parisc/kernel/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/parisc/kernel') diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c index 13d85042810a..1c5d3732bda2 100644 --- a/arch/parisc/kernel/ftrace.c +++ b/arch/parisc/kernel/ftrace.c @@ -210,7 +210,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct kprobe *p; int bit; - bit = ftrace_test_recursion_trylock(); + bit = ftrace_test_recursion_trylock(ip, parent_ip); if (bit < 0) return; -- cgit v1.2.3 From d19ad0775dcd64b49eecf4fa79c17959ebfbd26b Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Wed, 28 Oct 2020 17:42:17 -0400 Subject: ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs In preparation to have arguments of a function passed to callbacks attached to functions as default, change the default callback prototype to receive a struct ftrace_regs as the forth parameter instead of a pt_regs. For callbacks that set the FL_SAVE_REGS flag in their ftrace_ops flags, they will now need to get the pt_regs via a ftrace_get_regs() helper call. If this is called by a callback that their ftrace_ops did not have a FL_SAVE_REGS flag set, it that helper function will return NULL. This will allow the ftrace_regs to hold enough just to get the parameters and stack pointer, but without the worry that callbacks may have a pt_regs that is not completely filled. Acked-by: Peter Zijlstra (Intel) Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- arch/parisc/kernel/ftrace.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'arch/parisc/kernel') diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c index 1c5d3732bda2..0a1e75af5382 100644 --- a/arch/parisc/kernel/ftrace.c +++ b/arch/parisc/kernel/ftrace.c @@ -51,7 +51,7 @@ static void __hot prepare_ftrace_return(unsigned long *parent, void notrace __hot ftrace_function_trampoline(unsigned long parent, unsigned long self_addr, unsigned long org_sp_gr3, - struct pt_regs *regs) + struct ftrace_regs *fregs) { #ifndef CONFIG_DYNAMIC_FTRACE extern ftrace_func_t ftrace_trace_function; @@ -61,7 +61,7 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent, if (function_trace_op->flags & FTRACE_OPS_FL_ENABLED && ftrace_trace_function != ftrace_stub) ftrace_trace_function(self_addr, parent, - function_trace_op, regs); + function_trace_op, fregs); #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (dereference_function_descriptor(ftrace_graph_return) != @@ -204,9 +204,10 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, #ifdef CONFIG_KPROBES_ON_FTRACE void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, - struct ftrace_ops *ops, struct pt_regs *regs) + struct ftrace_ops *ops, struct ftrace_regs *fregs) { struct kprobe_ctlblk *kcb; + struct pt_regs *regs; struct kprobe *p; int bit; @@ -214,6 +215,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, if (bit < 0) return; + regs = ftrace_get_regs(fregs); preempt_disable_notrace(); p = get_kprobe((kprobe_opcode_t *)ip); if (unlikely(!p) || kprobe_disabled(p)) -- cgit v1.2.3