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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Steven Rostedt , Andrew Morton , Mark Rutland , "Tom Lendacky" , Ashish Kalra , James Gowans , Stanislav Kinsburskii , , , , Anthony Yznaga , Usama Arif , David Woodhouse , Benjamin Herrenschmidt , Rob Herring , Krzysztof Kozlowski Subject: [PATCH v3 11/17] tracing: Introduce kho serialization Date: Wed, 17 Jan 2024 14:46:58 +0000 Message-ID: <20240117144704.602-12-graf@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240117144704.602-1-graf@amazon.com> References: <20240117144704.602-1-graf@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.253.83.51] X-ClientProxiedBy: EX19D043UWA002.ant.amazon.com (10.13.139.53) To EX19D020UWC004.ant.amazon.com (10.13.138.149) X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6792C40010 X-Stat-Signature: hip977e59jkatfbyppmw6rubpqd1ef87 X-HE-Tag: 1705502949-99545 X-HE-Meta: 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 weLG87w8 9MZzh/qD8Xev07r0eoQvJP+ptMr2jFC6QEdcTejktiV8Nuh74vsLhTZjIWk8Mf9gQ1J60dqV3DbLSQxPYhj1uHo0UwrZVolNKhbCu7CHt3+r8vi/LTitrtoOpV2f6wDTA3GBXJ7brLrrXHjwtvaER8SLqd4hK2nuF2k7DshHivUYcwfXjLq5m9JqdpysrYXYWBfy9bfD1KAPGsF/clTn3yssDsQXSGN/c05V5LecG/4mpg/aayAcmgqqp4TwzOz2ijNIrcrk9PQBz2HXlm+D8UqKh5gNMH1dENF0Heo2PXdeZ2WE9s2VG2+tUXY/FMfpPZkHJc4SHstBEln6f5yWysuwnkMWEj25Bclj8rMNVzypoMRhDhfU852RAnNGvNC0xkv8v 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 a0defe156b57..9a0d96975c9c 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 * @@ -10574,12 +10577,56 @@ 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)