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// 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) *
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