// SPDX-License-Identifier: GPL-2.0
/*
 * misc.c
 *
 * This is a collection of several routines used to extract the kernel
 * which includes KASLR relocation, decompression, ELF parsing, and
 * relocation processing. Additionally included are the screen and serial
 * output functions and related debugging support functions.
 *
 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
 * puts by Nick Holloway 1993, better puts by Martin Mares 1995
 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
 */

#include "misc.h"
#include "error.h"
#include "pgtable.h"
#include "../string.h"
#include "../voffset.h"

/*
 * WARNING!!
 * This code is compiled with -fPIC and it is relocated dynamically at
 * run time, but no relocation processing is performed. This means that
 * it is not safe to place pointers in static structures.
 */

/* Macros used by the included decompressor code below. */
#define STATIC          static

/*
 * Use normal definitions of mem*() from string.c. There are already
 * included header files which expect a definition of memset() and by
 * the time we define memset macro, it is too late.
 */
#undef memcpy
#undef memset
#define memzero(s, n)   memset((s), 0, (n))
#define memmove         memmove

/* Functions used by the included decompressor code below. */
void *memmove(void *dest, const void *src, size_t n);

/*
 * This is set up by the setup-routine at boot-time
 */
struct boot_params *boot_params;

memptr free_mem_ptr;
memptr free_mem_end_ptr;

static char *vidmem;
static int vidport;
static int lines, cols;

#ifdef CONFIG_KERNEL_GZIP
#include "../../../../lib/decompress_inflate.c"
#endif

#ifdef CONFIG_KERNEL_BZIP2
#include "../../../../lib/decompress_bunzip2.c"
#endif

#ifdef CONFIG_KERNEL_LZMA
#include "../../../../lib/decompress_unlzma.c"
#endif

#ifdef CONFIG_KERNEL_XZ
#include "../../../../lib/decompress_unxz.c"
#endif

#ifdef CONFIG_KERNEL_LZO
#include "../../../../lib/decompress_unlzo.c"
#endif

#ifdef CONFIG_KERNEL_LZ4
#include "../../../../lib/decompress_unlz4.c"
#endif
/*
 * NOTE: When adding a new decompressor, please update the analysis in
 * ../header.S.
 */

static void scroll(void)
{
        int i;

        memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
        for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
                vidmem[i] = ' ';
}

#define XMTRDY          0x20

#define TXR             0       /*  Transmit register (WRITE) */
#define LSR             5       /*  Line Status               */
static void serial_putchar(int ch)
{
        unsigned timeout = 0xffff;

        while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
                cpu_relax();

        outb(ch, early_serial_base + TXR);
}

void __putstr(const char *s)
{
        int x, y, pos;
        char c;

        if (early_serial_base) {
                const char *str = s;
                while (*str) {
                        if (*str == '\n')
                                serial_putchar('\r');
                        serial_putchar(*str++);
                }
        }

        if (lines == 0 || cols == 0)
                return;

        x = boot_params->screen_info.orig_x;
        y = boot_params->screen_info.orig_y;

        while ((c = *s++) != '\0') {
                if (c == '\n') {
                        x = 0;
                        if (++y >= lines) {
                                scroll();
                                y--;
                        }
                } else {
                        vidmem[(x + cols * y) * 2] = c;
                        if (++x >= cols) {
                                x = 0;
                                if (++y >= lines) {
                                        scroll();
                                        y--;
                                }
                        }
                }
        }

        boot_params->screen_info.orig_x = x;
        boot_params->screen_info.orig_y = y;

        pos = (x + cols * y) * 2;       /* Update cursor position */
        outb(14, vidport);
        outb(0xff & (pos >> 9), vidport+1);
        outb(15, vidport);
        outb(0xff & (pos >> 1), vidport+1);
}

void __puthex(unsigned long value)
{
        char alpha[2] = "0";
        int bits;

        for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
                unsigned long digit = (value >> bits) & 0xf;

                if (digit < 0xA)
                        alpha[0] = '0' + digit;
                else
                        alpha[0] = 'a' + (digit - 0xA);

                __putstr(alpha);
        }
}

#if CONFIG_X86_NEED_RELOCS
static void handle_relocations(void *output, unsigned long output_len,
                               unsigned long virt_addr)
{
        int *reloc;
        unsigned long delta, map, ptr;
        unsigned long min_addr = (unsigned long)output;
        unsigned long max_addr = min_addr + (VO___bss_start - VO__text);

        /*
         * Calculate the delta between where vmlinux was linked to load
         * and where it was actually loaded.
         */
        delta = min_addr - LOAD_PHYSICAL_ADDR;

        /*
         * The kernel contains a table of relocation addresses. Those
         * addresses have the final load address of the kernel in virtual
         * memory. We are currently working in the self map. So we need to
         * create an adjustment for kernel memory addresses to the self map.
         * This will involve subtracting out the base address of the kernel.
         */
        map = delta - __START_KERNEL_map;

        /*
         * 32-bit always performs relocations. 64-bit relocations are only
         * needed if KASLR has chosen a different starting address offset
         * from __START_KERNEL_map.
         */
        if (IS_ENABLED(CONFIG_X86_64))
                delta = virt_addr - LOAD_PHYSICAL_ADDR;

        if (!delta) {
                debug_putstr("No relocation needed... ");
                return;
        }
        debug_putstr("Performing relocations... ");

        /*
         * Process relocations: 32 bit relocations first then 64 bit after.
         * Three sets of binary relocations are added to the end of the kernel
         * before compression. Each relocation table entry is the kernel
         * address of the location which needs to be updated stored as a
         * 32-bit value which is sign extended to 64 bits.
         *
         * Format is:
         *
         * kernel bits...
         * 0 - zero terminator for 64 bit relocations
         * 64 bit relocation repeated
         * 0 - zero terminator for inverse 32 bit relocations
         * 32 bit inverse relocation repeated
         * 0 - zero terminator for 32 bit relocations
         * 32 bit relocation repeated
         *
         * So we work backwards from the end of the decompressed image.
         */
        for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
                long extended = *reloc;
                extended += map;

                ptr = (unsigned long)extended;
                if (ptr < min_addr || ptr > max_addr)
                        error("32-bit relocation outside of kernel!\n");

                *(uint32_t *)ptr += delta;
        }
#ifdef CONFIG_X86_64
        while (*--reloc) {
                long extended = *reloc;
                extended += map;

                ptr = (unsigned long)extended;
                if (ptr < min_addr || ptr > max_addr)
                        error("inverse 32-bit relocation outside of kernel!\n");

                *(int32_t *)ptr -= delta;
        }
        for (reloc--; *reloc; reloc--) {
                long extended = *reloc;
                extended += map;

                ptr = (unsigned long)extended;
                if (ptr < min_addr || ptr > max_addr)
                        error("64-bit relocation outside of kernel!\n");

                *(uint64_t *)ptr += delta;
        }
#endif
}
#else
static inline void handle_relocations(void *output, unsigned long output_len,
                                      unsigned long virt_addr)
{ }
#endif

static void parse_elf(void *output)
{
#ifdef CONFIG_X86_64
        Elf64_Ehdr ehdr;
        Elf64_Phdr *phdrs, *phdr;
#else
        Elf32_Ehdr ehdr;
        Elf32_Phdr *phdrs, *phdr;
#endif
        void *dest;
        int i;

        memcpy(&ehdr, output, sizeof(ehdr));
        if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
           ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
           ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
           ehdr.e_ident[EI_MAG3] != ELFMAG3) {
                error("Kernel is not a valid ELF file");
                return;
        }

        debug_putstr("Parsing ELF... ");

        phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
        if (!phdrs)
                error("Failed to allocate space for phdrs");

        memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);

        for (i = 0; i < ehdr.e_phnum; i++) {
                phdr = &phdrs[i];

                switch (phdr->p_type) {
                case PT_LOAD:
#ifdef CONFIG_X86_64
                        if ((phdr->p_align % 0x200000) != 0)
                                error("Alignment of LOAD segment isn't multiple of 2MB");
#endif
#ifdef CONFIG_RELOCATABLE
                        dest = output;
                        dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
#else
                        dest = (void *)(phdr->p_paddr);
#endif
                        memmove(dest, output + phdr->p_offset, phdr->p_filesz);
                        break;
                default: /* Ignore other PT_* */ break;
                }
        }

        free(phdrs);
}

/*
 * The compressed kernel image (ZO), has been moved so that its position
 * is against the end of the buffer used to hold the uncompressed kernel
 * image (VO) and the execution environment (.bss, .brk), which makes sure
 * there is room to do the in-place decompression. (See header.S for the
 * calculations.)
 *
 *                             |-----compressed kernel image------|
 *                             V                                  V
 * 0                       extract_offset                      +INIT_SIZE
 * |-----------|---------------|-------------------------|--------|
 *             |               |                         |        |
 *           VO__text      startup_32 of ZO          VO__end    ZO__end
 *             ^                                         ^
 *             |-------uncompressed kernel image---------|
 *
 */
asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
                                  unsigned char *input_data,
                                  unsigned long input_len,
                                  unsigned char *output,
                                  unsigned long output_len)
{
        const unsigned long kernel_total_size = VO__end - VO__text;
        unsigned long virt_addr = LOAD_PHYSICAL_ADDR;

        /* Retain x86 boot parameters pointer passed from startup_32/64. */
        boot_params = rmode;

        /* Clear flags intended for solely in-kernel use. */
        boot_params->hdr.loadflags &= ~KASLR_FLAG;

        sanitize_boot_params(boot_params);

        if (boot_params->screen_info.orig_video_mode == 7) {
                vidmem = (char *) 0xb0000;
                vidport = 0x3b4;
        } else {
                vidmem = (char *) 0xb8000;
                vidport = 0x3d4;
        }

        lines = boot_params->screen_info.orig_video_lines;
        cols = boot_params->screen_info.orig_video_cols;

        console_init();
        debug_putstr("early console in extract_kernel\n");

        free_mem_ptr     = heap;        /* Heap */
        free_mem_end_ptr = heap + BOOT_HEAP_SIZE;

        /* Report initial kernel position details. */
        debug_putaddr(input_data);
        debug_putaddr(input_len);
        debug_putaddr(output);
        debug_putaddr(output_len);
        debug_putaddr(kernel_total_size);

#ifdef CONFIG_X86_64
        /* Report address of 32-bit trampoline */
        debug_putaddr(trampoline_32bit);
#endif

        /*
         * The memory hole needed for the kernel is the larger of either
         * the entire decompressed kernel plus relocation table, or the
         * entire decompressed kernel plus .bss and .brk sections.
         */
        choose_random_location((unsigned long)input_data, input_len,
                                (unsigned long *)&output,
                                max(output_len, kernel_total_size),
                                &virt_addr);

        /* Validate memory location choices. */
        if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
                error("Destination physical address inappropriately aligned");
        if (virt_addr & (MIN_KERNEL_ALIGN - 1))
                error("Destination virtual address inappropriately aligned");
#ifdef CONFIG_X86_64
        if (heap > 0x3fffffffffffUL)
                error("Destination address too large");
        if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
                error("Destination virtual address is beyond the kernel mapping area");
#else
        if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
                error("Destination address too large");
#endif
#ifndef CONFIG_RELOCATABLE
        if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
                error("Destination address does not match LOAD_PHYSICAL_ADDR");
        if (virt_addr != LOAD_PHYSICAL_ADDR)
                error("Destination virtual address changed when not relocatable");
#endif

        debug_putstr("\nDecompressing Linux... ");
        __decompress(input_data, input_len, NULL, NULL, output, output_len,
                        NULL, error);
        parse_elf(output);
        handle_relocations(output, output_len, virt_addr);
        debug_putstr("done.\nBooting the kernel.\n");
        return output;
}

void fortify_panic(const char *name)
{
        error("detected buffer overflow");
}