From: Steven Rostedt (VMware) <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
Petr Mladek <pmladek@suse.com>, Thomas Meyer <thomas@m3y3r.de>,
Kees Cook <keescook@chromium.org>
Subject: [PATCH 04/11 v3] pstore/ftrace: Add recursion protection to the ftrace callback
Date: Thu, 05 Nov 2020 21:32:39 -0500 [thread overview]
Message-ID: <20201106023546.720372267@goodmis.org> (raw)
In-Reply-To: 20201106023235.367190737@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@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/20201028115612.990886844@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Meyer <thomas@m3y3r.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
fs/pstore/ftrace.c | 6 ++++++
1 file changed, 6 insertions(+)
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 = {
--
2.28.0
next prev parent reply other threads:[~2020-11-06 2:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 2:32 [PATCH 00/11 v3] ftrace: Have callbacks handle their own recursion Steven Rostedt
2020-11-06 2:32 ` [PATCH 01/11 v3] ftrace: Move the recursion testing into global headers Steven Rostedt
2020-11-06 2:32 ` [PATCH 02/11 v3] ftrace: Add ftrace_test_recursion_trylock() helper function Steven Rostedt
2020-11-06 2:32 ` [PATCH 03/11 v3] ftrace: Optimize testing what context current is in Steven Rostedt
2020-11-09 12:17 ` Peter Zijlstra
2020-11-09 16:51 ` Steven Rostedt
2020-11-06 2:32 ` Steven Rostedt [this message]
2020-11-06 2:32 ` [PATCH 05/11 v3] kprobes/ftrace: Add recursion protection to the ftrace callback Steven Rostedt
2020-11-06 10:25 ` Masami Hiramatsu
2020-11-06 2:32 ` [PATCH 06/11 v3] livepatch/ftrace: " Steven Rostedt
2020-11-06 10:05 ` Miroslav Benes
2020-11-06 2:32 ` [PATCH 07/11 v3] livepatch: Trigger WARNING if livepatch function fails due to recursion Steven Rostedt
2020-11-06 10:07 ` Miroslav Benes
2020-11-06 2:32 ` [PATCH 08/11 v3] perf/ftrace: Add recursion protection to the ftrace callback Steven Rostedt
2020-11-06 2:32 ` [PATCH 09/11 v3] perf/ftrace: Check for rcu_is_watching() in callback function Steven Rostedt
2020-11-06 2:32 ` [PATCH 10/11 v3] ftrace: Reverse what the RECURSION flag means in the ftrace_ops Steven Rostedt
2020-11-06 2:32 ` [PATCH 11/11 v3] ftrace: Add recording of functions that caused recursion Steven Rostedt
2020-11-06 13:13 ` Petr Mladek
2020-11-06 13:41 ` Steven Rostedt
2020-11-06 14:27 ` Petr Mladek
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