// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) Paul Mackerras 1997.
 *
 * Updates for PPC64 by Todd Inglett, Dave Engebretsen & Peter Bergner.
 */
#include <stdarg.h>
#include <stddef.h>
#include "elf.h"
#include "page.h"
#include "string.h"
#include "stdio.h"
#include "ops.h"
#include "reg.h"

struct addr_range {
        void *addr;
        unsigned long size;
};

#undef DEBUG

static struct addr_range prep_kernel(void)
{
        char elfheader[256];
        unsigned char *vmlinuz_addr = (unsigned char *)_vmlinux_start;
        unsigned long vmlinuz_size = _vmlinux_end - _vmlinux_start;
        void *addr = 0;
        struct elf_info ei;
        long len;
        int uncompressed_image = 0;

        len = partial_decompress(vmlinuz_addr, vmlinuz_size,
                elfheader, sizeof(elfheader), 0);
        /* assume uncompressed data if -1 is returned */
        if (len == -1) {
                uncompressed_image = 1;
                memcpy(elfheader, vmlinuz_addr, sizeof(elfheader));
                printf("No valid compressed data found, assume uncompressed data\n\r");
        }

        if (!parse_elf64(elfheader, &ei) && !parse_elf32(elfheader, &ei))
                fatal("Error: not a valid PPC32 or PPC64 ELF file!\n\r");

        if (platform_ops.image_hdr)
                platform_ops.image_hdr(elfheader);

        /* We need to alloc the memsize: gzip will expand the kernel
         * text/data, then possible rubbish we don't care about. But
         * the kernel bss must be claimed (it will be zero'd by the
         * kernel itself)
         */
        printf("Allocating 0x%lx bytes for kernel...\n\r", ei.memsize);

        if (platform_ops.vmlinux_alloc) {
                addr = platform_ops.vmlinux_alloc(ei.memsize);
        } else {
                /*
                 * Check if the kernel image (without bss) would overwrite the
                 * bootwrapper. The device tree has been moved in fdt_init()
                 * to an area allocated with malloc() (somewhere past _end).
                 */
                if ((unsigned long)_start < ei.loadsize)
                        fatal("Insufficient memory for kernel at address 0!"
                               " (_start=%p, uncompressed size=%08lx)\n\r",
                               _start, ei.loadsize);

                if ((unsigned long)_end < ei.memsize)
                        fatal("The final kernel image would overwrite the "
                                        "device tree\n\r");
        }

        if (uncompressed_image) {
                memcpy(addr, vmlinuz_addr + ei.elfoffset, ei.loadsize);
                printf("0x%lx bytes of uncompressed data copied\n\r",
                       ei.loadsize);
                goto out;
        }

        /* Finally, decompress the kernel */
        printf("Decompressing (0x%p <- 0x%p:0x%p)...\n\r", addr,
               vmlinuz_addr, vmlinuz_addr+vmlinuz_size);

        len = partial_decompress(vmlinuz_addr, vmlinuz_size,
                addr, ei.loadsize, ei.elfoffset);

        if (len < 0)
                fatal("Decompression failed with error code %ld\n\r", len);

        if (len != ei.loadsize)
                 fatal("Decompression error: got 0x%lx bytes, expected 0x%lx.\n\r",
                         len, ei.loadsize);

        printf("Done! Decompressed 0x%lx bytes\n\r", len);
out:
        flush_cache(addr, ei.loadsize);

        return (struct addr_range){addr, ei.memsize};
}

static struct addr_range prep_initrd(struct addr_range vmlinux, void *chosen,
                                     unsigned long initrd_addr,
                                     unsigned long initrd_size)
{
        /* If we have an image attached to us, it overrides anything
         * supplied by the loader. */
        if (_initrd_end > _initrd_start) {
                printf("Attached initrd image at 0x%p-0x%p\n\r",
                       _initrd_start, _initrd_end);
                initrd_addr = (unsigned long)_initrd_start;
                initrd_size = _initrd_end - _initrd_start;
        } else if (initrd_size > 0) {
                printf("Using loader supplied ramdisk at 0x%lx-0x%lx\n\r",
                       initrd_addr, initrd_addr + initrd_size);
        }

        /* If there's no initrd at all, we're done */
        if (! initrd_size)
                return (struct addr_range){0, 0};

        /*
         * If the initrd is too low it will be clobbered when the
         * kernel relocates to its final location.  In this case,
         * allocate a safer place and move it.
         */
        if (initrd_addr < vmlinux.size) {
                void *old_addr = (void *)initrd_addr;

                printf("Allocating 0x%lx bytes for initrd ...\n\r",
                       initrd_size);
                initrd_addr = (unsigned long)malloc(initrd_size);
                if (! initrd_addr)
                        fatal("Can't allocate memory for initial "
                               "ramdisk !\n\r");
                printf("Relocating initrd 0x%lx <- 0x%p (0x%lx bytes)\n\r",
                       initrd_addr, old_addr, initrd_size);
                memmove((void *)initrd_addr, old_addr, initrd_size);
        }

        printf("initrd head: 0x%lx\n\r", *((unsigned long *)initrd_addr));

        /* Tell the kernel initrd address via device tree */
        setprop_val(chosen, "linux,initrd-start", (u32)(initrd_addr));
        setprop_val(chosen, "linux,initrd-end", (u32)(initrd_addr+initrd_size));

        return (struct addr_range){(void *)initrd_addr, initrd_size};
}

/* A buffer that may be edited by tools operating on a zImage binary so as to
 * edit the command line passed to vmlinux (by setting /chosen/bootargs).
 * The buffer is put in it's own section so that tools may locate it easier.
 */
static char cmdline[BOOT_COMMAND_LINE_SIZE]
        __attribute__((__section__("__builtin_cmdline")));

static void prep_cmdline(void *chosen)
{
        unsigned int getline_timeout = 5000;
        int v;
        int n;

        /* Wait-for-input time */
        n = getprop(chosen, "linux,cmdline-timeout", &v, sizeof(v));
        if (n == sizeof(v))
                getline_timeout = v;

        if (cmdline[0] == '\0')
                getprop(chosen, "bootargs", cmdline, BOOT_COMMAND_LINE_SIZE-1);

        printf("\n\rLinux/PowerPC load: %s", cmdline);

        /* If possible, edit the command line */
        if (console_ops.edit_cmdline && getline_timeout)
                console_ops.edit_cmdline(cmdline, BOOT_COMMAND_LINE_SIZE, getline_timeout);

        printf("\n\r");

        /* Put the command line back into the devtree for the kernel */
        setprop_str(chosen, "bootargs", cmdline);
}

struct platform_ops platform_ops;
struct dt_ops dt_ops;
struct console_ops console_ops;
struct loader_info loader_info;

void start(void)
{
        struct addr_range vmlinux, initrd;
        kernel_entry_t kentry;
        unsigned long ft_addr = 0;
        void *chosen;

        /* Do this first, because malloc() could clobber the loader's
         * command line.  Only use the loader command line if a
         * built-in command line wasn't set by an external tool */
        if ((loader_info.cmdline_len > 0) && (cmdline[0] == '\0'))
                memmove(cmdline, loader_info.cmdline,
                        min(loader_info.cmdline_len, BOOT_COMMAND_LINE_SIZE-1));

        if (console_ops.open && (console_ops.open() < 0))
                exit();
        if (platform_ops.fixups)
                platform_ops.fixups();

        printf("\n\rzImage starting: loaded at 0x%p (sp: 0x%p)\n\r",
               _start, get_sp());

        /* Ensure that the device tree has a /chosen node */
        chosen = finddevice("/chosen");
        if (!chosen)
                chosen = create_node(NULL, "chosen");

        vmlinux = prep_kernel();
        initrd = prep_initrd(vmlinux, chosen,
                             loader_info.initrd_addr, loader_info.initrd_size);
        prep_cmdline(chosen);

        printf("Finalizing device tree...");
        if (dt_ops.finalize)
                ft_addr = dt_ops.finalize();
        if (ft_addr)
                printf(" flat tree at 0x%lx\n\r", ft_addr);
        else
                printf(" using OF tree (promptr=%p)\n\r", loader_info.promptr);

        if (console_ops.close)
                console_ops.close();

        kentry = (kernel_entry_t) vmlinux.addr;
        if (ft_addr) {
                if(platform_ops.kentry)
                        platform_ops.kentry(ft_addr, vmlinux.addr);
                else
                        kentry(ft_addr, 0, NULL);
        }
        else
                kentry((unsigned long)initrd.addr, initrd.size,
                       loader_info.promptr);

        /* console closed so printf in fatal below may not work */
        fatal("Error: Linux kernel returned to zImage boot wrapper!\n\r");
}