// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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>
 */

#include <linux/efi.h>
#include <linux/libfdt.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.
 *
 * For ARM/ARM64:
 * 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)
 *
 * For RISC-V:
 * There is no specific reason for which, this address (512MB) can't be used
 * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
 * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
 * as well to minimize the code churn.
 */
#define EFI_RT_VIRTUAL_BASE     SZ_512M
#define EFI_RT_VIRTUAL_SIZE     SZ_512M

#ifdef CONFIG_ARM64
# define EFI_RT_VIRTUAL_LIMIT   DEFAULT_MAP_WINDOW_64
#else
# define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE
#endif

static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
static bool flat_va_mapping;

const efi_system_table_t *efi_system_table;

static struct screen_info *setup_graphics(void)
{
        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_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
                             &gop_proto, NULL, &size, gop_handle);
        if (status == EFI_BUFFER_TOO_SMALL) {
                si = alloc_screen_info();
                if (!si)
                        return NULL;
                status = efi_setup_gop(si, &gop_proto, size);
                if (status != EFI_SUCCESS) {
                        free_screen_info(si);
                        return NULL;
                }
        }
        return si;
}

static void install_memreserve_table(void)
{
        struct linux_efi_memreserve *rsv;
        efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
        efi_status_t status;

        status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
                             (void **)&rsv);
        if (status != EFI_SUCCESS) {
                efi_err("Failed to allocate memreserve entry!\n");
                return;
        }

        rsv->next = 0;
        rsv->size = 0;
        atomic_set(&rsv->count, 0);

        status = efi_bs_call(install_configuration_table,
                             &memreserve_table_guid, rsv);
        if (status != EFI_SUCCESS)
                efi_err("Failed to install memreserve config table!\n");
}

/*
 * 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.
 */
efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
                                   efi_system_table_t *sys_table_arg)
{
        efi_loaded_image_t *image;
        efi_status_t status;
        unsigned long image_addr;
        unsigned long image_size = 0;
        /* addr/point and size pairs for memory management*/
        unsigned long initrd_addr = 0;
        unsigned long initrd_size = 0;
        unsigned long fdt_addr = 0;  /* Original DTB */
        unsigned long fdt_size = 0;
        char *cmdline_ptr = NULL;
        int cmdline_size = 0;
        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;
        efi_properties_table_t *prop_tbl;
        unsigned long max_addr;

        efi_system_table = sys_table_arg;

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

        status = check_platform_features();
        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 = efi_system_table->boottime->handle_protocol(handle,
                                        &loaded_image_proto, (void *)&image);
        if (status != EFI_SUCCESS) {
                efi_err("Failed to get loaded image protocol\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(image, &cmdline_size);
        if (!cmdline_ptr) {
                efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
                status = EFI_OUT_OF_RESOURCES;
                goto fail;
        }

        if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
            IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
            cmdline_size == 0) {
                status = efi_parse_options(CONFIG_CMDLINE);
                if (status != EFI_SUCCESS) {
                        efi_err("Failed to parse options\n");
                        goto fail_free_cmdline;
                }
        }

        if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
                status = efi_parse_options(cmdline_ptr);
                if (status != EFI_SUCCESS) {
                        efi_err("Failed to parse options\n");
                        goto fail_free_cmdline;
                }
        }

        efi_info("Booting Linux Kernel...\n");

        si = setup_graphics();

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

        efi_retrieve_tpm2_eventlog();

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

        secure_boot = efi_get_secureboot();

        /*
         * 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 (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
             secure_boot != efi_secureboot_mode_disabled) {
                if (strstr(cmdline_ptr, "dtb="))
                        efi_err("Ignoring DTB from command line.\n");
        } else {
                status = efi_load_dtb(image, &fdt_addr, &fdt_size);

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

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

        if (!fdt_addr)
                efi_info("Generating empty DTB\n");

        if (!efi_noinitrd) {
                max_addr = efi_get_max_initrd_addr(image_addr);
                status = efi_load_initrd(image, &initrd_addr, &initrd_size,
                                         ULONG_MAX, max_addr);
                if (status != EFI_SUCCESS)
                        efi_err("Failed to load initrd!\n");
        }

        efi_random_get_seed();

        /*
         * If the NX PE data feature is enabled in the properties table, we
         * should take care not to create a virtual mapping that changes the
         * relative placement of runtime services code and data regions, as
         * they may belong to the same PE/COFF executable image in memory.
         * The easiest way to achieve that is to simply use a 1:1 mapping.
         */
        prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
        flat_va_mapping = prop_tbl &&
                          (prop_tbl->memory_protection_attribute &
                           EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);

        /* hibernation expects the runtime regions to stay in the same place */
        if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
                /*
                 * 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(sizeof(rnd), (u8 *)&rnd);
                if (status == EFI_SUCCESS) {
                        virtmap_base = EFI_RT_VIRTUAL_BASE +
                                       (((headroom >> 21) * rnd) >> (32 - 21));
                }
        }

        install_memreserve_table();

        status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
                                                efi_get_max_fdt_addr(image_addr),
                                                initrd_addr, initrd_size,
                                                cmdline_ptr, fdt_addr, fdt_size);
        if (status != EFI_SUCCESS)
                goto fail_free_initrd;

        if (IS_ENABLED(CONFIG_ARM))
                efi_handle_post_ebs_state();

        efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
        /* not reached */

fail_free_initrd:
        efi_err("Failed to update FDT and exit boot services\n");

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

fail_free_image:
        efi_free(image_size, image_addr);
        efi_free(reserve_size, reserve_addr);
fail_free_screeninfo:
        free_screen_info(si);
fail_free_cmdline:
        efi_bs_call(free_pool, cmdline_ptr);
fail:
        return status;
}

/*
 * 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, *out = runtime_map;
        int l;

        for (l = 0; l < map_size; l += desc_size) {
                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;

                in->virt_addr = in->phys_addr;
                if (efi_novamap) {
                        continue;
                }

                /*
                 * 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 (!flat_va_mapping) {

                        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 - paddr;
                        efi_virt_base += size;
                }

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