// 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");
}
