kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 460 insertions, 0 deletions

diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c
new file mode 100644
index 000000000..b0ed4cb49
--- /dev/null
+++ b/drivers/tee/optee/rpc.c
@@ -0,0 +1,460 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2015-2021, Linaro Limited
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/rpmb.h>
+#include <linux/slab.h>
+#include <linux/tee_core.h>
+#include "optee_private.h"
+#include "optee_rpc_cmd.h"
+
+static void handle_rpc_func_cmd_get_time(struct optee_msg_arg *arg)
+{
+	struct timespec64 ts;
+
+	if (arg->num_params != 1)
+		goto bad;
+	if ((arg->params[0].attr & OPTEE_MSG_ATTR_TYPE_MASK) !=
+			OPTEE_MSG_ATTR_TYPE_VALUE_OUTPUT)
+		goto bad;
+
+	ktime_get_real_ts64(&ts);
+	arg->params[0].u.value.a = ts.tv_sec;
+	arg->params[0].u.value.b = ts.tv_nsec;
+
+	arg->ret = TEEC_SUCCESS;
+	return;
+bad:
+	arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+}
+
+#if IS_REACHABLE(CONFIG_I2C)
+static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
+					     struct optee_msg_arg *arg)
+{
+	struct optee *optee = tee_get_drvdata(ctx->teedev);
+	struct tee_param *params;
+	struct i2c_adapter *adapter;
+	struct i2c_msg msg = { };
+	size_t i;
+	int ret = -EOPNOTSUPP;
+	static const u8 attr[] = {
+		TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
+		TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
+		TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
+		TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT,
+	};
+
+	if (arg->num_params != ARRAY_SIZE(attr)) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		return;
+	}
+
+	params = kmalloc_objs(struct tee_param, arg->num_params);
+	if (!params) {
+		arg->ret = TEEC_ERROR_OUT_OF_MEMORY;
+		return;
+	}
+
+	if (optee->ops->from_msg_param(optee, params, arg->num_params,
+				       arg->params))
+		goto bad;
+
+	for (i = 0; i < arg->num_params; i++) {
+		if (params[i].attr != attr[i])
+			goto bad;
+	}
+
+	adapter = i2c_get_adapter(params[0].u.value.b);
+	if (!adapter)
+		goto bad;
+
+	if (params[1].u.value.a & OPTEE_RPC_I2C_FLAGS_TEN_BIT) {
+		if (!i2c_check_functionality(adapter,
+					     I2C_FUNC_10BIT_ADDR)) {
+			i2c_put_adapter(adapter);
+			goto bad;
+		}
+
+		msg.flags = I2C_M_TEN;
+	}
+
+	msg.addr = params[0].u.value.c;
+	msg.buf  = params[2].u.memref.shm->kaddr;
+	msg.len  = params[2].u.memref.size;
+
+	switch (params[0].u.value.a) {
+	case OPTEE_RPC_I2C_TRANSFER_RD:
+		msg.flags |= I2C_M_RD;
+		break;
+	case OPTEE_RPC_I2C_TRANSFER_WR:
+		break;
+	default:
+		i2c_put_adapter(adapter);
+		goto bad;
+	}
+
+	ret = i2c_transfer(adapter, &msg, 1);
+
+	if (ret < 0) {
+		arg->ret = TEEC_ERROR_COMMUNICATION;
+	} else {
+		params[3].u.value.a = msg.len;
+		if (optee->ops->to_msg_param(optee, arg->params,
+					     arg->num_params, params))
+			arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		else
+			arg->ret = TEEC_SUCCESS;
+	}
+
+	i2c_put_adapter(adapter);
+	kfree(params);
+	return;
+bad:
+	kfree(params);
+	arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+}
+#else
+static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
+					     struct optee_msg_arg *arg)
+{
+	arg->ret = TEEC_ERROR_NOT_SUPPORTED;
+}
+#endif
+
+static void handle_rpc_func_cmd_wq(struct optee *optee,
+				   struct optee_msg_arg *arg)
+{
+	int rc = 0;
+
+	if (arg->num_params != 1)
+		goto bad;
+
+	if ((arg->params[0].attr & OPTEE_MSG_ATTR_TYPE_MASK) !=
+			OPTEE_MSG_ATTR_TYPE_VALUE_INPUT)
+		goto bad;
+
+	switch (arg->params[0].u.value.a) {
+	case OPTEE_RPC_NOTIFICATION_WAIT:
+		rc = optee_notif_wait(optee, arg->params[0].u.value.b, arg->params[0].u.value.c);
+		if (rc)
+			goto bad;
+		break;
+	case OPTEE_RPC_NOTIFICATION_SEND:
+		if (optee_notif_send(optee, arg->params[0].u.value.b))
+			goto bad;
+		break;
+	default:
+		goto bad;
+	}
+
+	arg->ret = TEEC_SUCCESS;
+	return;
+bad:
+	if (rc == -ETIMEDOUT)
+		arg->ret = TEE_ERROR_TIMEOUT;
+	else
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+}
+
+static void handle_rpc_func_cmd_wait(struct optee_msg_arg *arg)
+{
+	u32 msec_to_wait;
+
+	if (arg->num_params != 1)
+		goto bad;
+
+	if ((arg->params[0].attr & OPTEE_MSG_ATTR_TYPE_MASK) !=
+			OPTEE_MSG_ATTR_TYPE_VALUE_INPUT)
+		goto bad;
+
+	msec_to_wait = arg->params[0].u.value.a;
+
+	/* Go to interruptible sleep */
+	msleep_interruptible(msec_to_wait);
+
+	arg->ret = TEEC_SUCCESS;
+	return;
+bad:
+	arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+}
+
+static void handle_rpc_supp_cmd(struct tee_context *ctx, struct optee *optee,
+				struct optee_msg_arg *arg)
+{
+	struct tee_param *params;
+
+	arg->ret_origin = TEEC_ORIGIN_COMMS;
+
+	params = kmalloc_objs(struct tee_param, arg->num_params);
+	if (!params) {
+		arg->ret = TEEC_ERROR_OUT_OF_MEMORY;
+		return;
+	}
+
+	if (optee->ops->from_msg_param(optee, params, arg->num_params,
+				       arg->params)) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		goto out;
+	}
+
+	arg->ret = optee_supp_thrd_req(ctx, arg->cmd, arg->num_params, params);
+
+	if (optee->ops->to_msg_param(optee, arg->params, arg->num_params,
+				     params))
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+out:
+	kfree(params);
+}
+
+struct tee_shm *optee_rpc_cmd_alloc_suppl(struct tee_context *ctx, size_t sz)
+{
+	u32 ret;
+	struct tee_param param;
+	struct optee *optee = tee_get_drvdata(ctx->teedev);
+	struct tee_shm *shm;
+
+	param.attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT;
+	param.u.value.a = OPTEE_RPC_SHM_TYPE_APPL;
+	param.u.value.b = sz;
+	param.u.value.c = 0;
+
+	ret = optee_supp_thrd_req(ctx, OPTEE_RPC_CMD_SHM_ALLOC, 1, &param);
+	if (ret)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_lock(&optee->supp.mutex);
+	/* Increases count as secure world doesn't have a reference */
+	shm = tee_shm_get_from_id(optee->supp.ctx, param.u.value.c);
+	mutex_unlock(&optee->supp.mutex);
+	return shm;
+}
+
+void optee_rpc_cmd_free_suppl(struct tee_context *ctx, struct tee_shm *shm)
+{
+	struct tee_param param;
+
+	param.attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT;
+	param.u.value.a = OPTEE_RPC_SHM_TYPE_APPL;
+	param.u.value.b = tee_shm_get_id(shm);
+	param.u.value.c = 0;
+
+	/*
+	 * Match the tee_shm_get_from_id() in optee_rpc_cmd_alloc_suppl()
+	 * as secure world has released its reference.
+	 *
+	 * It's better to do this before sending the request to supplicant
+	 * as we'd like to let the process doing the initial allocation to
+	 * do release the last reference too in order to avoid stacking
+	 * many pending fput() on the client process. This could otherwise
+	 * happen if secure world does many allocate and free in a single
+	 * invoke.
+	 */
+	tee_shm_put(shm);
+
+	optee_supp_thrd_req(ctx, OPTEE_RPC_CMD_SHM_FREE, 1, &param);
+}
+
+static void handle_rpc_func_rpmb_probe_reset(struct tee_context *ctx,
+					     struct optee *optee,
+					     struct optee_msg_arg *arg)
+{
+	struct tee_param params[1];
+
+	if (arg->num_params != ARRAY_SIZE(params) ||
+	    optee->ops->from_msg_param(optee, params, arg->num_params,
+				       arg->params) ||
+	    params[0].attr != TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		return;
+	}
+
+	params[0].u.value.a = OPTEE_RPC_SHM_TYPE_KERNEL;
+	params[0].u.value.b = 0;
+	params[0].u.value.c = 0;
+	if (optee->ops->to_msg_param(optee, arg->params,
+				     arg->num_params, params)) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		return;
+	}
+
+	mutex_lock(&optee->rpmb_dev_mutex);
+	rpmb_dev_put(optee->rpmb_dev);
+	optee->rpmb_dev = NULL;
+	mutex_unlock(&optee->rpmb_dev_mutex);
+
+	arg->ret = TEEC_SUCCESS;
+}
+
+static int rpmb_type_to_rpc_type(enum rpmb_type rtype)
+{
+	switch (rtype) {
+	case RPMB_TYPE_EMMC:
+		return OPTEE_RPC_RPMB_EMMC;
+	case RPMB_TYPE_UFS:
+		return OPTEE_RPC_RPMB_UFS;
+	case RPMB_TYPE_NVME:
+		return OPTEE_RPC_RPMB_NVME;
+	default:
+		return -1;
+	}
+}
+
+static int rpc_rpmb_match(struct device *dev, const void *data)
+{
+	struct rpmb_dev *rdev = to_rpmb_dev(dev);
+
+	return rpmb_type_to_rpc_type(rdev->descr.type) >= 0;
+}
+
+static void handle_rpc_func_rpmb_probe_next(struct tee_context *ctx,
+					    struct optee *optee,
+					    struct optee_msg_arg *arg)
+{
+	struct rpmb_dev *rdev;
+	struct tee_param params[2];
+	void *buf;
+
+	if (arg->num_params != ARRAY_SIZE(params) ||
+	    optee->ops->from_msg_param(optee, params, arg->num_params,
+				       arg->params) ||
+	    params[0].attr != TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT ||
+	    params[1].attr != TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		return;
+	}
+	buf = tee_shm_get_va(params[1].u.memref.shm,
+			     params[1].u.memref.shm_offs);
+	if (IS_ERR(buf)) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		return;
+	}
+
+	mutex_lock(&optee->rpmb_dev_mutex);
+	rdev = rpmb_dev_find_device(NULL, optee->rpmb_dev, rpc_rpmb_match);
+	rpmb_dev_put(optee->rpmb_dev);
+	optee->rpmb_dev = rdev;
+	mutex_unlock(&optee->rpmb_dev_mutex);
+
+	if (!rdev) {
+		arg->ret = TEEC_ERROR_ITEM_NOT_FOUND;
+		return;
+	}
+
+	if (params[1].u.memref.size < rdev->descr.dev_id_len) {
+		arg->ret = TEEC_ERROR_SHORT_BUFFER;
+		return;
+	}
+	memcpy(buf, rdev->descr.dev_id, rdev->descr.dev_id_len);
+	params[1].u.memref.size = rdev->descr.dev_id_len;
+	params[0].u.value.a = rpmb_type_to_rpc_type(rdev->descr.type);
+	params[0].u.value.b = rdev->descr.capacity;
+	params[0].u.value.c = rdev->descr.reliable_wr_count;
+	if (optee->ops->to_msg_param(optee, arg->params,
+				     arg->num_params, params)) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		return;
+	}
+
+	arg->ret = TEEC_SUCCESS;
+}
+
+static void handle_rpc_func_rpmb_frames(struct tee_context *ctx,
+					struct optee *optee,
+					struct optee_msg_arg *arg)
+{
+	struct tee_param params[2];
+	struct rpmb_dev *rdev;
+	void *p0, *p1;
+
+	mutex_lock(&optee->rpmb_dev_mutex);
+	rdev = rpmb_dev_get(optee->rpmb_dev);
+	mutex_unlock(&optee->rpmb_dev_mutex);
+	if (!rdev) {
+		arg->ret = TEEC_ERROR_ITEM_NOT_FOUND;
+		return;
+	}
+
+	if (arg->num_params != ARRAY_SIZE(params) ||
+	    optee->ops->from_msg_param(optee, params, arg->num_params,
+				       arg->params) ||
+	    params[0].attr != TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT ||
+	    params[1].attr != TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		goto out;
+	}
+
+	p0 = tee_shm_get_va(params[0].u.memref.shm,
+			    params[0].u.memref.shm_offs);
+	p1 = tee_shm_get_va(params[1].u.memref.shm,
+			    params[1].u.memref.shm_offs);
+	if (rpmb_route_frames(rdev, p0, params[0].u.memref.size, p1,
+			      params[1].u.memref.size)) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		goto out;
+	}
+	if (optee->ops->to_msg_param(optee, arg->params,
+				     arg->num_params, params)) {
+		arg->ret = TEEC_ERROR_BAD_PARAMETERS;
+		goto out;
+	}
+	arg->ret = TEEC_SUCCESS;
+out:
+	rpmb_dev_put(rdev);
+}
+
+void optee_rpc_cmd(struct tee_context *ctx, struct optee *optee,
+		   struct optee_msg_arg *arg)
+{
+	switch (arg->cmd) {
+	case OPTEE_RPC_CMD_GET_TIME:
+		handle_rpc_func_cmd_get_time(arg);
+		break;
+	case OPTEE_RPC_CMD_NOTIFICATION:
+		handle_rpc_func_cmd_wq(optee, arg);
+		break;
+	case OPTEE_RPC_CMD_SUSPEND:
+		handle_rpc_func_cmd_wait(arg);
+		break;
+	case OPTEE_RPC_CMD_I2C_TRANSFER:
+		handle_rpc_func_cmd_i2c_transfer(ctx, arg);
+		break;
+	/*
+	 * optee->in_kernel_rpmb_routing true means that OP-TEE supports
+	 * in-kernel RPMB routing _and_ that the RPMB subsystem is
+	 * reachable. This is reported to user space with
+	 * rpmb_routing_model=kernel in sysfs.
+	 *
+	 * rpmb_routing_model=kernel is also a promise to user space that
+	 * RPMB access will not require supplicant support, hence the
+	 * checks below.
+	 */
+	case OPTEE_RPC_CMD_RPMB_PROBE_RESET:
+		if (optee->in_kernel_rpmb_routing)
+			handle_rpc_func_rpmb_probe_reset(ctx, optee, arg);
+		else
+			handle_rpc_supp_cmd(ctx, optee, arg);
+		break;
+	case OPTEE_RPC_CMD_RPMB_PROBE_NEXT:
+		if (optee->in_kernel_rpmb_routing)
+			handle_rpc_func_rpmb_probe_next(ctx, optee, arg);
+		else
+			handle_rpc_supp_cmd(ctx, optee, arg);
+		break;
+	case OPTEE_RPC_CMD_RPMB_FRAMES:
+		if (optee->in_kernel_rpmb_routing)
+			handle_rpc_func_rpmb_frames(ctx, optee, arg);
+		else
+			handle_rpc_supp_cmd(ctx, optee, arg);
+		break;
+	default:
+		handle_rpc_supp_cmd(ctx, optee, arg);
+	}
+}
+
+