430 lines
11 KiB
C
430 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* misc.c
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*
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* This is a collection of several routines used to extract the kernel
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* which includes KASLR relocation, decompression, ELF parsing, and
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* relocation processing. Additionally included are the screen and serial
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* output functions and related debugging support functions.
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*
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* malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
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* puts by Nick Holloway 1993, better puts by Martin Mares 1995
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* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
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*/
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#include "misc.h"
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#include "error.h"
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#include "pgtable.h"
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#include "../string.h"
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#include "../voffset.h"
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#include <asm/bootparam_utils.h>
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/*
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* WARNING!!
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* This code is compiled with -fPIC and it is relocated dynamically at
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* run time, but no relocation processing is performed. This means that
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* it is not safe to place pointers in static structures.
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*/
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/* Macros used by the included decompressor code below. */
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#define STATIC static
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/*
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* Use normal definitions of mem*() from string.c. There are already
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* included header files which expect a definition of memset() and by
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* the time we define memset macro, it is too late.
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*/
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#undef memcpy
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#undef memset
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#define memzero(s, n) memset((s), 0, (n))
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#define memmove memmove
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/* Functions used by the included decompressor code below. */
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void *memmove(void *dest, const void *src, size_t n);
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/*
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* This is set up by the setup-routine at boot-time
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*/
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struct boot_params *boot_params;
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memptr free_mem_ptr;
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memptr free_mem_end_ptr;
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static char *vidmem;
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static int vidport;
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static int lines, cols;
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#ifdef CONFIG_KERNEL_GZIP
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#include "../../../../lib/decompress_inflate.c"
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#endif
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#ifdef CONFIG_KERNEL_BZIP2
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#include "../../../../lib/decompress_bunzip2.c"
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#endif
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#ifdef CONFIG_KERNEL_LZMA
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#include "../../../../lib/decompress_unlzma.c"
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#endif
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#ifdef CONFIG_KERNEL_XZ
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#include "../../../../lib/decompress_unxz.c"
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#endif
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#ifdef CONFIG_KERNEL_LZO
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#include "../../../../lib/decompress_unlzo.c"
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#endif
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#ifdef CONFIG_KERNEL_LZ4
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#include "../../../../lib/decompress_unlz4.c"
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#endif
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/*
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* NOTE: When adding a new decompressor, please update the analysis in
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* ../header.S.
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*/
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static void scroll(void)
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{
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int i;
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memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
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for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
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vidmem[i] = ' ';
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}
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#define XMTRDY 0x20
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#define TXR 0 /* Transmit register (WRITE) */
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#define LSR 5 /* Line Status */
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static void serial_putchar(int ch)
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{
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unsigned timeout = 0xffff;
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while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
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cpu_relax();
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outb(ch, early_serial_base + TXR);
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}
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void __putstr(const char *s)
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{
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int x, y, pos;
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char c;
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if (early_serial_base) {
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const char *str = s;
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while (*str) {
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if (*str == '\n')
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serial_putchar('\r');
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serial_putchar(*str++);
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}
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}
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if (lines == 0 || cols == 0)
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return;
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x = boot_params->screen_info.orig_x;
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y = boot_params->screen_info.orig_y;
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while ((c = *s++) != '\0') {
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if (c == '\n') {
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x = 0;
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if (++y >= lines) {
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scroll();
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y--;
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}
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} else {
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vidmem[(x + cols * y) * 2] = c;
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if (++x >= cols) {
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x = 0;
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if (++y >= lines) {
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scroll();
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y--;
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}
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}
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}
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}
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boot_params->screen_info.orig_x = x;
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boot_params->screen_info.orig_y = y;
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pos = (x + cols * y) * 2; /* Update cursor position */
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outb(14, vidport);
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outb(0xff & (pos >> 9), vidport+1);
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outb(15, vidport);
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outb(0xff & (pos >> 1), vidport+1);
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}
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void __puthex(unsigned long value)
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{
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char alpha[2] = "0";
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int bits;
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for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
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unsigned long digit = (value >> bits) & 0xf;
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if (digit < 0xA)
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alpha[0] = '0' + digit;
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else
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alpha[0] = 'a' + (digit - 0xA);
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__putstr(alpha);
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}
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}
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#if CONFIG_X86_NEED_RELOCS
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static void handle_relocations(void *output, unsigned long output_len,
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unsigned long virt_addr)
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{
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int *reloc;
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unsigned long delta, map, ptr;
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unsigned long min_addr = (unsigned long)output;
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unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
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/*
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* Calculate the delta between where vmlinux was linked to load
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* and where it was actually loaded.
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*/
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delta = min_addr - LOAD_PHYSICAL_ADDR;
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/*
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* The kernel contains a table of relocation addresses. Those
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* addresses have the final load address of the kernel in virtual
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* memory. We are currently working in the self map. So we need to
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* create an adjustment for kernel memory addresses to the self map.
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* This will involve subtracting out the base address of the kernel.
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*/
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map = delta - __START_KERNEL_map;
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/*
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* 32-bit always performs relocations. 64-bit relocations are only
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* needed if KASLR has chosen a different starting address offset
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* from __START_KERNEL_map.
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*/
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if (IS_ENABLED(CONFIG_X86_64))
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delta = virt_addr - LOAD_PHYSICAL_ADDR;
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if (!delta) {
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debug_putstr("No relocation needed... ");
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return;
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}
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debug_putstr("Performing relocations... ");
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/*
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* Process relocations: 32 bit relocations first then 64 bit after.
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* Three sets of binary relocations are added to the end of the kernel
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* before compression. Each relocation table entry is the kernel
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* address of the location which needs to be updated stored as a
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* 32-bit value which is sign extended to 64 bits.
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*
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* Format is:
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*
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* kernel bits...
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* 0 - zero terminator for 64 bit relocations
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* 64 bit relocation repeated
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* 0 - zero terminator for inverse 32 bit relocations
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* 32 bit inverse relocation repeated
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* 0 - zero terminator for 32 bit relocations
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* 32 bit relocation repeated
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*
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* So we work backwards from the end of the decompressed image.
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*/
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for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
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long extended = *reloc;
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extended += map;
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ptr = (unsigned long)extended;
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if (ptr < min_addr || ptr > max_addr)
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error("32-bit relocation outside of kernel!\n");
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*(uint32_t *)ptr += delta;
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}
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#ifdef CONFIG_X86_64
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while (*--reloc) {
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long extended = *reloc;
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extended += map;
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ptr = (unsigned long)extended;
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if (ptr < min_addr || ptr > max_addr)
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error("inverse 32-bit relocation outside of kernel!\n");
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*(int32_t *)ptr -= delta;
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}
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for (reloc--; *reloc; reloc--) {
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long extended = *reloc;
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extended += map;
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ptr = (unsigned long)extended;
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if (ptr < min_addr || ptr > max_addr)
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error("64-bit relocation outside of kernel!\n");
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*(uint64_t *)ptr += delta;
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}
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#endif
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}
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#else
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static inline void handle_relocations(void *output, unsigned long output_len,
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unsigned long virt_addr)
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{ }
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#endif
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static void parse_elf(void *output)
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{
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#ifdef CONFIG_X86_64
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Elf64_Ehdr ehdr;
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Elf64_Phdr *phdrs, *phdr;
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#else
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Elf32_Ehdr ehdr;
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Elf32_Phdr *phdrs, *phdr;
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#endif
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void *dest;
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int i;
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memcpy(&ehdr, output, sizeof(ehdr));
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if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
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ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
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ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
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ehdr.e_ident[EI_MAG3] != ELFMAG3) {
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error("Kernel is not a valid ELF file");
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return;
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}
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debug_putstr("Parsing ELF... ");
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phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
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if (!phdrs)
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error("Failed to allocate space for phdrs");
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memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
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for (i = 0; i < ehdr.e_phnum; i++) {
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phdr = &phdrs[i];
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switch (phdr->p_type) {
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case PT_LOAD:
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#ifdef CONFIG_X86_64
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if ((phdr->p_align % 0x200000) != 0)
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error("Alignment of LOAD segment isn't multiple of 2MB");
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#endif
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#ifdef CONFIG_RELOCATABLE
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dest = output;
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dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
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#else
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dest = (void *)(phdr->p_paddr);
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#endif
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memmove(dest, output + phdr->p_offset, phdr->p_filesz);
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break;
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default: /* Ignore other PT_* */ break;
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}
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}
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free(phdrs);
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}
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/*
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* The compressed kernel image (ZO), has been moved so that its position
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* is against the end of the buffer used to hold the uncompressed kernel
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* image (VO) and the execution environment (.bss, .brk), which makes sure
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* there is room to do the in-place decompression. (See header.S for the
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* calculations.)
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*
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* |-----compressed kernel image------|
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* V V
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* 0 extract_offset +INIT_SIZE
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* |-----------|---------------|-------------------------|--------|
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* | | | |
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* VO__text startup_32 of ZO VO__end ZO__end
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* ^ ^
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* |-------uncompressed kernel image---------|
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*
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*/
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asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
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unsigned char *input_data,
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unsigned long input_len,
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unsigned char *output,
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unsigned long output_len)
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{
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const unsigned long kernel_total_size = VO__end - VO__text;
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unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
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/* Retain x86 boot parameters pointer passed from startup_32/64. */
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boot_params = rmode;
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/* Clear flags intended for solely in-kernel use. */
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boot_params->hdr.loadflags &= ~KASLR_FLAG;
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sanitize_boot_params(boot_params);
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if (boot_params->screen_info.orig_video_mode == 7) {
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vidmem = (char *) 0xb0000;
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vidport = 0x3b4;
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} else {
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vidmem = (char *) 0xb8000;
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vidport = 0x3d4;
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}
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lines = boot_params->screen_info.orig_video_lines;
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cols = boot_params->screen_info.orig_video_cols;
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console_init();
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debug_putstr("early console in extract_kernel\n");
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free_mem_ptr = heap; /* Heap */
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free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
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/* Report initial kernel position details. */
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debug_putaddr(input_data);
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debug_putaddr(input_len);
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debug_putaddr(output);
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debug_putaddr(output_len);
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debug_putaddr(kernel_total_size);
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#ifdef CONFIG_X86_64
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/* Report address of 32-bit trampoline */
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debug_putaddr(trampoline_32bit);
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#endif
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/*
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* The memory hole needed for the kernel is the larger of either
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* the entire decompressed kernel plus relocation table, or the
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* entire decompressed kernel plus .bss and .brk sections.
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*/
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choose_random_location((unsigned long)input_data, input_len,
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(unsigned long *)&output,
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max(output_len, kernel_total_size),
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&virt_addr);
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/* Validate memory location choices. */
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if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
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error("Destination physical address inappropriately aligned");
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if (virt_addr & (MIN_KERNEL_ALIGN - 1))
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error("Destination virtual address inappropriately aligned");
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#ifdef CONFIG_X86_64
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if (heap > 0x3fffffffffffUL)
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error("Destination address too large");
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if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
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error("Destination virtual address is beyond the kernel mapping area");
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#else
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if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
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error("Destination address too large");
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#endif
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#ifndef CONFIG_RELOCATABLE
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if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
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error("Destination address does not match LOAD_PHYSICAL_ADDR");
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if (virt_addr != LOAD_PHYSICAL_ADDR)
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error("Destination virtual address changed when not relocatable");
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#endif
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debug_putstr("\nDecompressing Linux... ");
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__decompress(input_data, input_len, NULL, NULL, output, output_len,
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NULL, error);
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parse_elf(output);
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handle_relocations(output, output_len, virt_addr);
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debug_putstr("done.\nBooting the kernel.\n");
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return output;
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}
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void fortify_panic(const char *name)
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{
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error("detected buffer overflow");
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}
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