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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 19:51:38 +0000 Message-ID: <20231222195144.24532-6-graf@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231222195144.24532-1-graf@amazon.com> References: <20231222193607.15474-1-graf@amazon.com> <20231222195144.24532-1-graf@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.253.83.51] X-ClientProxiedBy: EX19D042UWA003.ant.amazon.com (10.13.139.44) To EX19D020UWC004.ant.amazon.com (10.13.138.149) X-Rspam-User: X-Stat-Signature: 15jusgwjeq5qubzmwe3p6rnzsw5kc6yj X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 9B676120017 X-HE-Tag: 1703274759-23084 X-HE-Meta: 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 82mxOU25 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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)