ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 98 insertions, 0 deletions

diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c
new file mode 100644
index 000000000..bdee057db
--- /dev/null
+++ b/drivers/firmware/smccc/smccc.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Arm Limited
+ */
+
+#define pr_fmt(fmt) "smccc: " fmt
+
+#include <linux/cache.h>
+#include <linux/init.h>
+#include <linux/arm-smccc.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <asm/archrandom.h>
+
+static u32 smccc_version = ARM_SMCCC_VERSION_1_0;
+static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE;
+
+bool __ro_after_init smccc_trng_available = false;
+s32 __ro_after_init smccc_soc_id_version = SMCCC_RET_NOT_SUPPORTED;
+s32 __ro_after_init smccc_soc_id_revision = SMCCC_RET_NOT_SUPPORTED;
+
+void __init arm_smccc_version_init(u32 version, enum arm_smccc_conduit conduit)
+{
+	struct arm_smccc_res res;
+
+	smccc_version = version;
+	smccc_conduit = conduit;
+
+	smccc_trng_available = smccc_probe_trng();
+
+	if ((smccc_version >= ARM_SMCCC_VERSION_1_2) &&
+	    (smccc_conduit != SMCCC_CONDUIT_NONE)) {
+		arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
+				     ARM_SMCCC_ARCH_SOC_ID, &res);
+		if ((s32)res.a0 >= 0) {
+			arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_SOC_ID, 0, &res);
+			smccc_soc_id_version = (s32)res.a0;
+			arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_SOC_ID, 1, &res);
+			smccc_soc_id_revision = (s32)res.a0;
+		}
+	}
+}
+
+enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void)
+{
+	if (smccc_version < ARM_SMCCC_VERSION_1_1)
+		return SMCCC_CONDUIT_NONE;
+
+	return smccc_conduit;
+}
+EXPORT_SYMBOL_GPL(arm_smccc_1_1_get_conduit);
+
+u32 arm_smccc_get_version(void)
+{
+	return smccc_version;
+}
+EXPORT_SYMBOL_GPL(arm_smccc_get_version);
+
+s32 arm_smccc_get_soc_id_version(void)
+{
+	return smccc_soc_id_version;
+}
+
+s32 arm_smccc_get_soc_id_revision(void)
+{
+	return smccc_soc_id_revision;
+}
+EXPORT_SYMBOL_GPL(arm_smccc_get_soc_id_revision);
+
+bool arm_smccc_hypervisor_has_uuid(const uuid_t *hyp_uuid)
+{
+	struct arm_smccc_res res = {};
+	uuid_t uuid;
+
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res);
+	if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
+		return false;
+
+	uuid = smccc_res_to_uuid(res.a0, res.a1, res.a2, res.a3);
+	return uuid_equal(&uuid, hyp_uuid);
+}
+EXPORT_SYMBOL_GPL(arm_smccc_hypervisor_has_uuid);
+
+static int __init smccc_devices_init(void)
+{
+	struct platform_device *pdev;
+
+	if (smccc_trng_available) {
+		pdev = platform_device_register_simple("smccc_trng", -1,
+						       NULL, 0);
+		if (IS_ERR(pdev))
+			pr_err("smccc_trng: could not register device: %ld\n",
+			       PTR_ERR(pdev));
+	}
+
+	return 0;
+}
+device_initcall(smccc_devices_init);