From 6cdf941871ec9cb1cf03227038a45a73afd8dc9a Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 5 Nov 2020 21:32:39 -0500 Subject: pstore/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/20201028115612.990886844@goodmis.org Link: https://lkml.kernel.org/r/20201106023546.720372267@goodmis.org Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Miroslav Benes Cc: Petr Mladek Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Thomas Meyer Reviewed-by: Kees Cook Signed-off-by: Steven Rostedt (VMware) --- fs/pstore/ftrace.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'fs') diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c index 5c0450701293..816210fc5d3a 100644 --- a/fs/pstore/ftrace.c +++ b/fs/pstore/ftrace.c @@ -28,6 +28,7 @@ static void notrace pstore_ftrace_call(unsigned long ip, struct ftrace_ops *op, struct pt_regs *regs) { + int bit; unsigned long flags; struct pstore_ftrace_record rec = {}; struct pstore_record record = { @@ -40,6 +41,10 @@ static void notrace pstore_ftrace_call(unsigned long ip, if (unlikely(oops_in_progress)) return; + bit = ftrace_test_recursion_trylock(); + if (bit < 0) + return; + local_irq_save(flags); rec.ip = ip; @@ -49,6 +54,7 @@ static void notrace pstore_ftrace_call(unsigned long ip, psinfo->write(&record); local_irq_restore(flags); + ftrace_test_recursion_unlock(bit); } static struct ftrace_ops pstore_ftrace_ops __read_mostly = { -- 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) --- fs/pstore/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c index 816210fc5d3a..adb0935eb062 100644 --- a/fs/pstore/ftrace.c +++ b/fs/pstore/ftrace.c @@ -41,7 +41,7 @@ static void notrace pstore_ftrace_call(unsigned long ip, if (unlikely(oops_in_progress)) return; - 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) --- fs/pstore/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c index adb0935eb062..5939595f0115 100644 --- a/fs/pstore/ftrace.c +++ b/fs/pstore/ftrace.c @@ -26,7 +26,7 @@ static u64 pstore_ftrace_stamp; static void notrace pstore_ftrace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, - struct pt_regs *regs) + struct ftrace_regs *fregs) { int bit; unsigned long flags; -- cgit v1.2.3