/*
 * EFI stub implementation that is shared by arm and arm64 architectures.
 * This should be #included by the EFI stub implementation files.
 *
 * Copyright (C) 2013,2014 Linaro Limited
 *     Roy Franz <roy.franz@linaro.org
 * Copyright (C) 2013 Red Hat, Inc.
 *     Mark Salter <msalter@redhat.com>
 *
 * This file is part of the Linux kernel, and is made available under the
 * terms of the GNU General Public License version 2.
 *
 */

#include <linux/efi.h>
#include <linux/sort.h>
#include <asm/efi.h>

#include "efistub.h"

/*
 * This is the base address at which to start allocating virtual memory ranges
 * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
 * any allocation we choose, and eliminate the risk of a conflict after kexec.
 * The value chosen is the largest non-zero power of 2 suitable for this purpose
 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
 * be mapped efficiently.
 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
 * entire footprint of the UEFI runtime services memory regions)
 */
#define EFI_RT_VIRTUAL_BASE     SZ_512M
#define EFI_RT_VIRTUAL_SIZE     SZ_512M

#ifdef CONFIG_ARM64
# define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE_64
#else
# define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE
#endif

static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;

efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
                             void *__image, void **__fh)
{
        efi_file_io_interface_t *io;
        efi_loaded_image_t *image = __image;
        efi_file_handle_t *fh;
        efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
        efi_status_t status;
        void *handle = (void *)(unsigned long)image->device_handle;

        status = sys_table_arg->boottime->handle_protocol(handle,
                                 &fs_proto, (void **)&io);
        if (status != EFI_SUCCESS) {
                efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
                return status;
        }

        status = io->open_volume(io, &fh);
        if (status != EFI_SUCCESS)
                efi_printk(sys_table_arg, "Failed to open volume\n");

        *__fh = fh;
        return status;
}

void efi_char16_printk(efi_system_table_t *sys_table_arg,
                              efi_char16_t *str)
{
        struct efi_simple_text_output_protocol *out;

        out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
        out->output_string(out, str);
}

static struct screen_info *setup_graphics(efi_system_table_t *sys_table_arg)
{
        efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
        efi_status_t status;
        unsigned long size;
        void **gop_handle = NULL;
        struct screen_info *si = NULL;

        size = 0;
        status = efi_call_early(locate_handle, EFI_LOCATE_BY_PROTOCOL,
                                &gop_proto, NULL, &size, gop_handle);
        if (status == EFI_BUFFER_TOO_SMALL) {
                si = alloc_screen_info(sys_table_arg);
                if (!si)
                        return NULL;
                efi_setup_gop(sys_table_arg, si, &gop_proto, size);
        }
        return si;
}

/*
 * This function handles the architcture specific differences between arm and
 * arm64 regarding where the kernel image must be loaded and any memory that
 * must be reserved. On failure it is required to free all
 * all allocations it has made.
 */
efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
                                 unsigned long *image_addr,
                                 unsigned long *image_size,
                                 unsigned long *reserve_addr,
                                 unsigned long *reserve_size,
                                 unsigned long dram_base,
                                 efi_loaded_image_t *image);
/*
 * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 * that is described in the PE/COFF header.  Most of the code is the same
 * for both archictectures, with the arch-specific code provided in the
 * handle_kernel_image() function.
 */
unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
                               unsigned long *image_addr)
{
        efi_loaded_image_t *image;
        efi_status_t status;
        unsigned long image_size = 0;
        unsigned long dram_base;
        /* addr/point and size pairs for memory management*/
        unsigned long initrd_addr;
        u64 initrd_size = 0;
        unsigned long fdt_addr = 0;  /* Original DTB */
        unsigned long fdt_size = 0;
        char *cmdline_ptr = NULL;
        int cmdline_size = 0;
        unsigned long new_fdt_addr;
        efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
        unsigned long reserve_addr = 0;
        unsigned long reserve_size = 0;
        enum efi_secureboot_mode secure_boot;
        struct screen_info *si;

        /* Check if we were booted by the EFI firmware */
        if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
                goto fail;

        status = check_platform_features(sys_table);
        if (status != EFI_SUCCESS)
                goto fail;

        /*
         * Get a handle to the loaded image protocol.  This is used to get
         * information about the running image, such as size and the command
         * line.
         */
        status = sys_table->boottime->handle_protocol(handle,
                                        &loaded_image_proto, (void *)&image);
        if (status != EFI_SUCCESS) {
                pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
                goto fail;
        }

        dram_base = get_dram_base(sys_table);
        if (dram_base == EFI_ERROR) {
                pr_efi_err(sys_table, "Failed to find DRAM base\n");
                goto fail;
        }

        /*
         * Get the command line from EFI, using the LOADED_IMAGE
         * protocol. We are going to copy the command line into the
         * device tree, so this can be allocated anywhere.
         */
        cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
        if (!cmdline_ptr) {
                pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
                goto fail;
        }

        if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
            IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
            cmdline_size == 0)
                efi_parse_options(CONFIG_CMDLINE);

        if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
                efi_parse_options(cmdline_ptr);

        pr_efi(sys_table, "Booting Linux Kernel...\n");

        si = setup_graphics(sys_table);

        status = handle_kernel_image(sys_table, image_addr, &image_size,
                                     &reserve_addr,
                                     &reserve_size,
                                     dram_base, image);
        if (status != EFI_SUCCESS) {
                pr_efi_err(sys_table, "Failed to relocate kernel\n");
                goto fail_free_cmdline;
        }

        /* Ask the firmware to clear memory on unclean shutdown */
        efi_enable_reset_attack_mitigation(sys_table);

        secure_boot = efi_get_secureboot(sys_table);

        /*
         * Unauthenticated device tree data is a security hazard, so ignore
         * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
         * boot is enabled if we can't determine its state.
         */
        if (secure_boot != efi_secureboot_mode_disabled &&
            strstr(cmdline_ptr, "dtb=")) {
                pr_efi(sys_table, "Ignoring DTB from command line.\n");
        } else {
                status = handle_cmdline_files(sys_table, image, cmdline_ptr,
                                              "dtb=",
                                              ~0UL, &fdt_addr, &fdt_size);

                if (status != EFI_SUCCESS) {
                        pr_efi_err(sys_table, "Failed to load device tree!\n");
                        goto fail_free_image;
                }
        }

        if (fdt_addr) {
                pr_efi(sys_table, "Using DTB from command line\n");
        } else {
                /* Look for a device tree configuration table entry. */
                fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
                if (fdt_addr)
                        pr_efi(sys_table, "Using DTB from configuration table\n");
        }

        if (!fdt_addr)
                pr_efi(sys_table, "Generating empty DTB\n");

        status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=",
                                      efi_get_max_initrd_addr(dram_base,
                                                              *image_addr),
                                      (unsigned long *)&initrd_addr,
                                      (unsigned long *)&initrd_size);
        if (status != EFI_SUCCESS)
                pr_efi_err(sys_table, "Failed initrd from command line!\n");

        efi_random_get_seed(sys_table);

        /* hibernation expects the runtime regions to stay in the same place */
        if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr()) {
                /*
                 * Randomize the base of the UEFI runtime services region.
                 * Preserve the 2 MB alignment of the region by taking a
                 * shift of 21 bit positions into account when scaling
                 * the headroom value using a 32-bit random value.
                 */
                static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
                                            EFI_RT_VIRTUAL_BASE -
                                            EFI_RT_VIRTUAL_SIZE;
                u32 rnd;

                status = efi_get_random_bytes(sys_table, sizeof(rnd),
                                              (u8 *)&rnd);
                if (status == EFI_SUCCESS) {
                        virtmap_base = EFI_RT_VIRTUAL_BASE +
                                       (((headroom >> 21) * rnd) >> (32 - 21));
                }
        }

        new_fdt_addr = fdt_addr;
        status = allocate_new_fdt_and_exit_boot(sys_table, handle,
                                &new_fdt_addr, efi_get_max_fdt_addr(dram_base),
                                initrd_addr, initrd_size, cmdline_ptr,
                                fdt_addr, fdt_size);

        /*
         * If all went well, we need to return the FDT address to the
         * calling function so it can be passed to kernel as part of
         * the kernel boot protocol.
         */
        if (status == EFI_SUCCESS)
                return new_fdt_addr;

        pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");

        efi_free(sys_table, initrd_size, initrd_addr);
        efi_free(sys_table, fdt_size, fdt_addr);

fail_free_image:
        efi_free(sys_table, image_size, *image_addr);
        efi_free(sys_table, reserve_size, reserve_addr);
fail_free_cmdline:
        free_screen_info(sys_table, si);
        efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
fail:
        return EFI_ERROR;
}

static int cmp_mem_desc(const void *l, const void *r)
{
        const efi_memory_desc_t *left = l, *right = r;

        return (left->phys_addr > right->phys_addr) ? 1 : -1;
}

/*
 * Returns whether region @left ends exactly where region @right starts,
 * or false if either argument is NULL.
 */
static bool regions_are_adjacent(efi_memory_desc_t *left,
                                 efi_memory_desc_t *right)
{
        u64 left_end;

        if (left == NULL || right == NULL)
                return false;

        left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;

        return left_end == right->phys_addr;
}

/*
 * Returns whether region @left and region @right have compatible memory type
 * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
 */
static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
                                                      efi_memory_desc_t *right)
{
        static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
                                         EFI_MEMORY_WC | EFI_MEMORY_UC |
                                         EFI_MEMORY_RUNTIME;

        return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
}

/*
 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 *
 * This function populates the virt_addr fields of all memory region descriptors
 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 * are also copied to @runtime_map, and their total count is returned in @count.
 */
void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
                     unsigned long desc_size, efi_memory_desc_t *runtime_map,
                     int *count)
{
        u64 efi_virt_base = virtmap_base;
        efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
        int l;

        /*
         * To work around potential issues with the Properties Table feature
         * introduced in UEFI 2.5, which may split PE/COFF executable images
         * in memory into several RuntimeServicesCode and RuntimeServicesData
         * regions, we need to preserve the relative offsets between adjacent
         * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
         * The easiest way to find adjacent regions is to sort the memory map
         * before traversing it.
         */
        if (IS_ENABLED(CONFIG_ARM64))
                sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc,
                     NULL);

        for (l = 0; l < map_size; l += desc_size, prev = in) {
                u64 paddr, size;

                in = (void *)memory_map + l;
                if (!(in->attribute & EFI_MEMORY_RUNTIME))
                        continue;

                paddr = in->phys_addr;
                size = in->num_pages * EFI_PAGE_SIZE;

                /*
                 * Make the mapping compatible with 64k pages: this allows
                 * a 4k page size kernel to kexec a 64k page size kernel and
                 * vice versa.
                 */
                if ((IS_ENABLED(CONFIG_ARM64) &&
                     !regions_are_adjacent(prev, in)) ||
                    !regions_have_compatible_memory_type_attrs(prev, in)) {

                        paddr = round_down(in->phys_addr, SZ_64K);
                        size += in->phys_addr - paddr;

                        /*
                         * Avoid wasting memory on PTEs by choosing a virtual
                         * base that is compatible with section mappings if this
                         * region has the appropriate size and physical
                         * alignment. (Sections are 2 MB on 4k granule kernels)
                         */
                        if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
                                efi_virt_base = round_up(efi_virt_base, SZ_2M);
                        else
                                efi_virt_base = round_up(efi_virt_base, SZ_64K);
                }

                in->virt_addr = efi_virt_base + in->phys_addr - paddr;
                efi_virt_base += size;

                memcpy(out, in, desc_size);
                out = (void *)out + desc_size;
                ++*count;
        }
}