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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , "Rob Herring" , Steven Rostedt , "Andrew Morton" , Mark Rutland , "Tom Lendacky" , Ashish Kalra , James Gowans , Stanislav Kinsburskii , , , , Anthony Yznaga , Usama Arif , David Woodhouse , Benjamin Herrenschmidt Subject: [PATCH v2 11/17] tracing: Introduce kho serialization Date: Fri, 22 Dec 2023 19:36:01 +0000 Message-ID: <20231222193607.15474-12-graf@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231222193607.15474-1-graf@amazon.com> References: <20231222193607.15474-1-graf@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.253.83.51] X-ClientProxiedBy: EX19D041UWA004.ant.amazon.com (10.13.139.9) To EX19D020UWC004.ant.amazon.com (10.13.138.149) X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: A48D1C0019 X-Stat-Signature: 15jusgwjeq5qubzmwe3p6rnzsw5kc6yj X-HE-Tag: 1703273891-699006 X-HE-Meta: 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 rKS+jIwo 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 --- 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 #include #include +#include #include #include #include @@ -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)