/*
 * Copyright (c) 2015, Linaro Limited
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */
#include <linux/arm-smccc.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/tee_drv.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include "optee_private.h"
#include "optee_smc.h"

struct optee_call_waiter {
        struct list_head list_node;
        struct completion c;
};

static void optee_cq_wait_init(struct optee_call_queue *cq,
                               struct optee_call_waiter *w)
{
        /*
         * We're preparing to make a call to secure world. In case we can't
         * allocate a thread in secure world we'll end up waiting in
         * optee_cq_wait_for_completion().
         *
         * Normally if there's no contention in secure world the call will
         * complete and we can cleanup directly with optee_cq_wait_final().
         */
        mutex_lock(&cq->mutex);

        /*
         * We add ourselves to the queue, but we don't wait. This
         * guarantees that we don't lose a completion if secure world
         * returns busy and another thread just exited and try to complete
         * someone.
         */
        init_completion(&w->c);
        list_add_tail(&w->list_node, &cq->waiters);

        mutex_unlock(&cq->mutex);
}

static void optee_cq_wait_for_completion(struct optee_call_queue *cq,
                                         struct optee_call_waiter *w)
{
        wait_for_completion(&w->c);

        mutex_lock(&cq->mutex);

        /* Move to end of list to get out of the way for other waiters */
        list_del(&w->list_node);
        reinit_completion(&w->c);
        list_add_tail(&w->list_node, &cq->waiters);

        mutex_unlock(&cq->mutex);
}

static void optee_cq_complete_one(struct optee_call_queue *cq)
{
        struct optee_call_waiter *w;

        list_for_each_entry(w, &cq->waiters, list_node) {
                if (!completion_done(&w->c)) {
                        complete(&w->c);
                        break;
                }
        }
}

static void optee_cq_wait_final(struct optee_call_queue *cq,
                                struct optee_call_waiter *w)
{
        /*
         * We're done with the call to secure world. The thread in secure
         * world that was used for this call is now available for some
         * other task to use.
         */
        mutex_lock(&cq->mutex);

        /* Get out of the list */
        list_del(&w->list_node);

        /* Wake up one eventual waiting task */
        optee_cq_complete_one(cq);

        /*
         * If we're completed we've got a completion from another task that
         * was just done with its call to secure world. Since yet another
         * thread now is available in secure world wake up another eventual
         * waiting task.
         */
        if (completion_done(&w->c))
                optee_cq_complete_one(cq);

        mutex_unlock(&cq->mutex);
}

/* Requires the filpstate mutex to be held */
static struct optee_session *find_session(struct optee_context_data *ctxdata,
                                          u32 session_id)
{
        struct optee_session *sess;

        list_for_each_entry(sess, &ctxdata->sess_list, list_node)
                if (sess->session_id == session_id)
                        return sess;

        return NULL;
}

/**
 * optee_do_call_with_arg() - Do an SMC to OP-TEE in secure world
 * @ctx:        calling context
 * @parg:       physical address of message to pass to secure world
 *
 * Does and SMC to OP-TEE in secure world and handles eventual resulting
 * Remote Procedure Calls (RPC) from OP-TEE.
 *
 * Returns return code from secure world, 0 is OK
 */
u32 optee_do_call_with_arg(struct tee_context *ctx, phys_addr_t parg)
{
        struct optee *optee = tee_get_drvdata(ctx->teedev);
        struct optee_call_waiter w;
        struct optee_rpc_param param = { };
        struct optee_call_ctx call_ctx = { };
        u32 ret;

        param.a0 = OPTEE_SMC_CALL_WITH_ARG;
        reg_pair_from_64(&param.a1, &param.a2, parg);
        /* Initialize waiter */
        optee_cq_wait_init(&optee->call_queue, &w);
        while (true) {
                struct arm_smccc_res res;

                optee->invoke_fn(param.a0, param.a1, param.a2, param.a3,
                                 param.a4, param.a5, param.a6, param.a7,
                                 &res);

                if (res.a0 == OPTEE_SMC_RETURN_ETHREAD_LIMIT) {
                        /*
                         * Out of threads in secure world, wait for a thread
                         * become available.
                         */
                        optee_cq_wait_for_completion(&optee->call_queue, &w);
                } else if (OPTEE_SMC_RETURN_IS_RPC(res.a0)) {
                        param.a0 = res.a0;
                        param.a1 = res.a1;
                        param.a2 = res.a2;
                        param.a3 = res.a3;
                        optee_handle_rpc(ctx, &param, &call_ctx);
                } else {
                        ret = res.a0;
                        break;
                }
        }

        optee_rpc_finalize_call(&call_ctx);
        /*
         * We're done with our thread in secure world, if there's any
         * thread waiters wake up one.
         */
        optee_cq_wait_final(&optee->call_queue, &w);

        return ret;
}

static struct tee_shm *get_msg_arg(struct tee_context *ctx, size_t num_params,
                                   struct optee_msg_arg **msg_arg,
                                   phys_addr_t *msg_parg)
{
        int rc;
        struct tee_shm *shm;
        struct optee_msg_arg *ma;

        shm = tee_shm_alloc(ctx, OPTEE_MSG_GET_ARG_SIZE(num_params),
                            TEE_SHM_MAPPED);
        if (IS_ERR(shm))
                return shm;

        ma = tee_shm_get_va(shm, 0);
        if (IS_ERR(ma)) {
                rc = PTR_ERR(ma);
                goto out;
        }

        rc = tee_shm_get_pa(shm, 0, msg_parg);
        if (rc)
                goto out;

        memset(ma, 0, OPTEE_MSG_GET_ARG_SIZE(num_params));
        ma->num_params = num_params;
        *msg_arg = ma;
out:
        if (rc) {
                tee_shm_free(shm);
                return ERR_PTR(rc);
        }

        return shm;
}

int optee_open_session(struct tee_context *ctx,
                       struct tee_ioctl_open_session_arg *arg,
                       struct tee_param *param)
{
        struct optee_context_data *ctxdata = ctx->data;
        int rc;
        struct tee_shm *shm;
        struct optee_msg_arg *msg_arg;
        phys_addr_t msg_parg;
        struct optee_session *sess = NULL;

        /* +2 for the meta parameters added below */
        shm = get_msg_arg(ctx, arg->num_params + 2, &msg_arg, &msg_parg);
        if (IS_ERR(shm))
                return PTR_ERR(shm);

        msg_arg->cmd = OPTEE_MSG_CMD_OPEN_SESSION;
        msg_arg->cancel_id = arg->cancel_id;

        /*
         * Initialize and add the meta parameters needed when opening a
         * session.
         */
        msg_arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_VALUE_INPUT |
                                  OPTEE_MSG_ATTR_META;
        msg_arg->params[1].attr = OPTEE_MSG_ATTR_TYPE_VALUE_INPUT |
                                  OPTEE_MSG_ATTR_META;
        memcpy(&msg_arg->params[0].u.value, arg->uuid, sizeof(arg->uuid));
        memcpy(&msg_arg->params[1].u.value, arg->uuid, sizeof(arg->clnt_uuid));
        msg_arg->params[1].u.value.c = arg->clnt_login;

        rc = optee_to_msg_param(msg_arg->params + 2, arg->num_params, param);
        if (rc)
                goto out;

        sess = kzalloc(sizeof(*sess), GFP_KERNEL);
        if (!sess) {
                rc = -ENOMEM;
                goto out;
        }

        if (optee_do_call_with_arg(ctx, msg_parg)) {
                msg_arg->ret = TEEC_ERROR_COMMUNICATION;
                msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
        }

        if (msg_arg->ret == TEEC_SUCCESS) {
                /* A new session has been created, add it to the list. */
                sess->session_id = msg_arg->session;
                mutex_lock(&ctxdata->mutex);
                list_add(&sess->list_node, &ctxdata->sess_list);
                mutex_unlock(&ctxdata->mutex);
        } else {
                kfree(sess);
        }

        if (optee_from_msg_param(param, arg->num_params, msg_arg->params + 2)) {
                arg->ret = TEEC_ERROR_COMMUNICATION;
                arg->ret_origin = TEEC_ORIGIN_COMMS;
                /* Close session again to avoid leakage */
                optee_close_session(ctx, msg_arg->session);
        } else {
                arg->session = msg_arg->session;
                arg->ret = msg_arg->ret;
                arg->ret_origin = msg_arg->ret_origin;
        }
out:
        tee_shm_free(shm);

        return rc;
}

int optee_close_session(struct tee_context *ctx, u32 session)
{
        struct optee_context_data *ctxdata = ctx->data;
        struct tee_shm *shm;
        struct optee_msg_arg *msg_arg;
        phys_addr_t msg_parg;
        struct optee_session *sess;

        /* Check that the session is valid and remove it from the list */
        mutex_lock(&ctxdata->mutex);
        sess = find_session(ctxdata, session);
        if (sess)
                list_del(&sess->list_node);
        mutex_unlock(&ctxdata->mutex);
        if (!sess)
                return -EINVAL;
        kfree(sess);

        shm = get_msg_arg(ctx, 0, &msg_arg, &msg_parg);
        if (IS_ERR(shm))
                return PTR_ERR(shm);

        msg_arg->cmd = OPTEE_MSG_CMD_CLOSE_SESSION;
        msg_arg->session = session;
        optee_do_call_with_arg(ctx, msg_parg);

        tee_shm_free(shm);
        return 0;
}

int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
                      struct tee_param *param)
{
        struct optee_context_data *ctxdata = ctx->data;
        struct tee_shm *shm;
        struct optee_msg_arg *msg_arg;
        phys_addr_t msg_parg;
        struct optee_session *sess;
        int rc;

        /* Check that the session is valid */
        mutex_lock(&ctxdata->mutex);
        sess = find_session(ctxdata, arg->session);
        mutex_unlock(&ctxdata->mutex);
        if (!sess)
                return -EINVAL;

        shm = get_msg_arg(ctx, arg->num_params, &msg_arg, &msg_parg);
        if (IS_ERR(shm))
                return PTR_ERR(shm);
        msg_arg->cmd = OPTEE_MSG_CMD_INVOKE_COMMAND;
        msg_arg->func = arg->func;
        msg_arg->session = arg->session;
        msg_arg->cancel_id = arg->cancel_id;

        rc = optee_to_msg_param(msg_arg->params, arg->num_params, param);
        if (rc)
                goto out;

        if (optee_do_call_with_arg(ctx, msg_parg)) {
                msg_arg->ret = TEEC_ERROR_COMMUNICATION;
                msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
        }

        if (optee_from_msg_param(param, arg->num_params, msg_arg->params)) {
                msg_arg->ret = TEEC_ERROR_COMMUNICATION;
                msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
        }

        arg->ret = msg_arg->ret;
        arg->ret_origin = msg_arg->ret_origin;
out:
        tee_shm_free(shm);
        return rc;
}

int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session)
{
        struct optee_context_data *ctxdata = ctx->data;
        struct tee_shm *shm;
        struct optee_msg_arg *msg_arg;
        phys_addr_t msg_parg;
        struct optee_session *sess;

        /* Check that the session is valid */
        mutex_lock(&ctxdata->mutex);
        sess = find_session(ctxdata, session);
        mutex_unlock(&ctxdata->mutex);
        if (!sess)
                return -EINVAL;

        shm = get_msg_arg(ctx, 0, &msg_arg, &msg_parg);
        if (IS_ERR(shm))
                return PTR_ERR(shm);

        msg_arg->cmd = OPTEE_MSG_CMD_CANCEL;
        msg_arg->session = session;
        msg_arg->cancel_id = cancel_id;
        optee_do_call_with_arg(ctx, msg_parg);

        tee_shm_free(shm);
        return 0;
}

/**
 * optee_enable_shm_cache() - Enables caching of some shared memory allocation
 *                            in OP-TEE
 * @optee:      main service struct
 */
void optee_enable_shm_cache(struct optee *optee)
{
        struct optee_call_waiter w;

        /* We need to retry until secure world isn't busy. */
        optee_cq_wait_init(&optee->call_queue, &w);
        while (true) {
                struct arm_smccc_res res;

                optee->invoke_fn(OPTEE_SMC_ENABLE_SHM_CACHE, 0, 0, 0, 0, 0, 0,
                                 0, &res);
                if (res.a0 == OPTEE_SMC_RETURN_OK)
                        break;
                optee_cq_wait_for_completion(&optee->call_queue, &w);
        }
        optee_cq_wait_final(&optee->call_queue, &w);
}

/**
 * optee_disable_shm_cache() - Disables caching of some shared memory allocation
 *                            in OP-TEE
 * @optee:      main service struct
 */
void optee_disable_shm_cache(struct optee *optee)
{
        struct optee_call_waiter w;

        /* We need to retry until secure world isn't busy. */
        optee_cq_wait_init(&optee->call_queue, &w);
        while (true) {
                union {
                        struct arm_smccc_res smccc;
                        struct optee_smc_disable_shm_cache_result result;
                } res;

                optee->invoke_fn(OPTEE_SMC_DISABLE_SHM_CACHE, 0, 0, 0, 0, 0, 0,
                                 0, &res.smccc);
                if (res.result.status == OPTEE_SMC_RETURN_ENOTAVAIL)
                        break; /* All shm's freed */
                if (res.result.status == OPTEE_SMC_RETURN_OK) {
                        struct tee_shm *shm;

                        shm = reg_pair_to_ptr(res.result.shm_upper32,
                                              res.result.shm_lower32);
                        tee_shm_free(shm);
                } else {
                        optee_cq_wait_for_completion(&optee->call_queue, &w);
                }
        }
        optee_cq_wait_final(&optee->call_queue, &w);
}

#define PAGELIST_ENTRIES_PER_PAGE                               \
        ((OPTEE_MSG_NONCONTIG_PAGE_SIZE / sizeof(u64)) - 1)

/**
 * optee_fill_pages_list() - write list of user pages to given shared
 * buffer.
 *
 * @dst: page-aligned buffer where list of pages will be stored
 * @pages: array of pages that represents shared buffer
 * @num_pages: number of entries in @pages
 * @page_offset: offset of user buffer from page start
 *
 * @dst should be big enough to hold list of user page addresses and
 *      links to the next pages of buffer
 */
void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,
                           size_t page_offset)
{
        int n = 0;
        phys_addr_t optee_page;
        /*
         * Refer to OPTEE_MSG_ATTR_NONCONTIG description in optee_msg.h
         * for details.
         */
        struct {
                u64 pages_list[PAGELIST_ENTRIES_PER_PAGE];
                u64 next_page_data;
        } *pages_data;

        /*
         * Currently OP-TEE uses 4k page size and it does not looks
         * like this will change in the future.  On other hand, there are
         * no know ARM architectures with page size < 4k.
         * Thus the next built assert looks redundant. But the following
         * code heavily relies on this assumption, so it is better be
         * safe than sorry.
         */
        BUILD_BUG_ON(PAGE_SIZE < OPTEE_MSG_NONCONTIG_PAGE_SIZE);

        pages_data = (void *)dst;
        /*
         * If linux page is bigger than 4k, and user buffer offset is
         * larger than 4k/8k/12k/etc this will skip first 4k pages,
         * because they bear no value data for OP-TEE.
         */
        optee_page = page_to_phys(*pages) +
                round_down(page_offset, OPTEE_MSG_NONCONTIG_PAGE_SIZE);

        while (true) {
                pages_data->pages_list[n++] = optee_page;

                if (n == PAGELIST_ENTRIES_PER_PAGE) {
                        pages_data->next_page_data =
                                virt_to_phys(pages_data + 1);
                        pages_data++;
                        n = 0;
                }

                optee_page += OPTEE_MSG_NONCONTIG_PAGE_SIZE;
                if (!(optee_page & ~PAGE_MASK)) {
                        if (!--num_pages)
                                break;
                        pages++;
                        optee_page = page_to_phys(*pages);
                }
        }
}

/*
 * The final entry in each pagelist page is a pointer to the next
 * pagelist page.
 */
static size_t get_pages_list_size(size_t num_entries)
{
        int pages = DIV_ROUND_UP(num_entries, PAGELIST_ENTRIES_PER_PAGE);

        return pages * OPTEE_MSG_NONCONTIG_PAGE_SIZE;
}

u64 *optee_allocate_pages_list(size_t num_entries)
{
        return alloc_pages_exact(get_pages_list_size(num_entries), GFP_KERNEL);
}

void optee_free_pages_list(void *list, size_t num_entries)
{
        free_pages_exact(list, get_pages_list_size(num_entries));
}

static bool is_normal_memory(pgprot_t p)
{
#if defined(CONFIG_ARM)
        return (pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEALLOC;
#elif defined(CONFIG_ARM64)
        return (pgprot_val(p) & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL);
#else
#error "Unuspported architecture"
#endif
}

static int __check_mem_type(struct vm_area_struct *vma, unsigned long end)
{
        while (vma && is_normal_memory(vma->vm_page_prot)) {
                if (vma->vm_end >= end)
                        return 0;
                vma = vma->vm_next;
        }

        return -EINVAL;
}

static int check_mem_type(unsigned long start, size_t num_pages)
{
        struct mm_struct *mm = current->mm;
        int rc;

        down_read(&mm->mmap_sem);
        rc = __check_mem_type(find_vma(mm, start),
                              start + num_pages * PAGE_SIZE);
        up_read(&mm->mmap_sem);

        return rc;
}

int optee_shm_register(struct tee_context *ctx, struct tee_shm *shm,
                       struct page **pages, size_t num_pages,
                       unsigned long start)
{
        struct tee_shm *shm_arg = NULL;
        struct optee_msg_arg *msg_arg;
        u64 *pages_list;
        phys_addr_t msg_parg;
        int rc;

        if (!num_pages)
                return -EINVAL;

        rc = check_mem_type(start, num_pages);
        if (rc)
                return rc;

        pages_list = optee_allocate_pages_list(num_pages);
        if (!pages_list)
                return -ENOMEM;

        shm_arg = get_msg_arg(ctx, 1, &msg_arg, &msg_parg);
        if (IS_ERR(shm_arg)) {
                rc = PTR_ERR(shm_arg);
                goto out;
        }

        optee_fill_pages_list(pages_list, pages, num_pages,
                              tee_shm_get_page_offset(shm));

        msg_arg->cmd = OPTEE_MSG_CMD_REGISTER_SHM;
        msg_arg->params->attr = OPTEE_MSG_ATTR_TYPE_TMEM_OUTPUT |
                                OPTEE_MSG_ATTR_NONCONTIG;
        msg_arg->params->u.tmem.shm_ref = (unsigned long)shm;
        msg_arg->params->u.tmem.size = tee_shm_get_size(shm);
        /*
         * In the least bits of msg_arg->params->u.tmem.buf_ptr we
         * store buffer offset from 4k page, as described in OP-TEE ABI.
         */
        msg_arg->params->u.tmem.buf_ptr = virt_to_phys(pages_list) |
          (tee_shm_get_page_offset(shm) & (OPTEE_MSG_NONCONTIG_PAGE_SIZE - 1));

        if (optee_do_call_with_arg(ctx, msg_parg) ||
            msg_arg->ret != TEEC_SUCCESS)
                rc = -EINVAL;

        tee_shm_free(shm_arg);
out:
        optee_free_pages_list(pages_list, num_pages);
        return rc;
}

int optee_shm_unregister(struct tee_context *ctx, struct tee_shm *shm)
{
        struct tee_shm *shm_arg;
        struct optee_msg_arg *msg_arg;
        phys_addr_t msg_parg;
        int rc = 0;

        shm_arg = get_msg_arg(ctx, 1, &msg_arg, &msg_parg);
        if (IS_ERR(shm_arg))
                return PTR_ERR(shm_arg);

        msg_arg->cmd = OPTEE_MSG_CMD_UNREGISTER_SHM;

        msg_arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_RMEM_INPUT;
        msg_arg->params[0].u.rmem.shm_ref = (unsigned long)shm;

        if (optee_do_call_with_arg(ctx, msg_parg) ||
            msg_arg->ret != TEEC_SUCCESS)
                rc = -EINVAL;
        tee_shm_free(shm_arg);
        return rc;
}

int optee_shm_register_supp(struct tee_context *ctx, struct tee_shm *shm,
                            struct page **pages, size_t num_pages,
                            unsigned long start)
{
        /*
         * We don't want to register supplicant memory in OP-TEE.
         * Instead information about it will be passed in RPC code.
         */
        return check_mem_type(start, num_pages);
}

int optee_shm_unregister_supp(struct tee_context *ctx, struct tee_shm *shm)
{
        return 0;
}