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Message-ID: <20231222195144.24532-6-graf@amazon.com>
Date: Fri, 22 Dec 2023 19:51:38 +0000
From: Alexander Graf <graf@...zon.com>
To: <linux-kernel@...r.kernel.org>
CC: <linux-trace-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
<devicetree@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
<kexec@...ts.infradead.org>, <linux-doc@...r.kernel.org>, <x86@...nel.org>,
Eric Biederman <ebiederm@...ssion.com>, "H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
"Rob Herring" <robh+dt@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
"Andrew Morton" <akpm@...ux-foundation.org>, Mark Rutland
<mark.rutland@....com>, "Tom Lendacky" <thomas.lendacky@....com>, Ashish
Kalra <ashish.kalra@....com>, James Gowans <jgowans@...zon.com>, Stanislav
Kinsburskii <skinsburskii@...ux.microsoft.com>, <arnd@...db.de>,
<pbonzini@...hat.com>, <madvenka@...ux.microsoft.com>, Anthony Yznaga
<anthony.yznaga@...cle.com>, Usama Arif <usama.arif@...edance.com>, David
Woodhouse <dwmw@...zon.co.uk>, Benjamin Herrenschmidt
<benh@...nel.crashing.org>
Subject: [PATCH v2 11/17] tracing: Introduce kho serialization
We want to be able to transfer ftrace state from one kernel to the next.
To start off with, let's establish all the boiler plate to get a write
hook when KHO wants to serialize and fill out basic data.
Follow-up patches will fill in serialization of ring buffers and events.
Signed-off-by: Alexander Graf <graf@...zon.com>
---
v1 -> v2:
- Remove ifdefs
---
kernel/trace/trace.c | 47 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 199df497db07..6ec31879b4eb 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -32,6 +32,7 @@
#include <linux/percpu.h>
#include <linux/splice.h>
#include <linux/kdebug.h>
+#include <linux/kexec.h>
#include <linux/string.h>
#include <linux/mount.h>
#include <linux/rwsem.h>
@@ -866,6 +867,8 @@ static struct tracer *trace_types __read_mostly;
*/
DEFINE_MUTEX(trace_types_lock);
+static bool trace_in_kho;
+
/*
* serialize the access of the ring buffer
*
@@ -10560,12 +10563,56 @@ void __init early_trace_init(void)
init_events();
}
+static int trace_kho_notifier(struct notifier_block *self,
+ unsigned long cmd,
+ void *v)
+{
+ const char compatible[] = "ftrace-v1";
+ void *fdt = v;
+ int err = 0;
+
+ switch (cmd) {
+ case KEXEC_KHO_ABORT:
+ if (trace_in_kho)
+ mutex_unlock(&trace_types_lock);
+ trace_in_kho = false;
+ return NOTIFY_DONE;
+ case KEXEC_KHO_DUMP:
+ /* Handled below */
+ break;
+ default:
+ return NOTIFY_BAD;
+ }
+
+ if (unlikely(tracing_disabled))
+ return NOTIFY_DONE;
+
+ err |= fdt_begin_node(fdt, "ftrace");
+ err |= fdt_property(fdt, "compatible", compatible, sizeof(compatible));
+ err |= fdt_end_node(fdt);
+
+ if (!err) {
+ /* Hold all future allocations */
+ mutex_lock(&trace_types_lock);
+ trace_in_kho = true;
+ }
+
+ return err ? NOTIFY_BAD : NOTIFY_DONE;
+}
+
+static struct notifier_block trace_kho_nb = {
+ .notifier_call = trace_kho_notifier,
+};
+
void __init trace_init(void)
{
trace_event_init();
if (boot_instance_index)
enable_instances();
+
+ if (IS_ENABLED(CONFIG_FTRACE_KHO))
+ register_kho_notifier(&trace_kho_nb);
}
__init static void clear_boot_tracer(void)
--
2.40.1
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
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