arch/x86/boot/compressed/misc.c - linux - Git at Google

 /*
  * misc.c
  *
  * This is a collection of several routines from gzip-1.0.3
  * adapted for Linux.
  *
  * 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"

 /* 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.
  */

 /*
  * Getting to provable safe in place decompression is hard.
  * Worst case behaviours need to be analyzed.
  * Background information:
  *
  * The file layout is:
  *    magic[2]
  *    method[1]
  *    flags[1]
  *    timestamp[4]
  *    extraflags[1]
  *    os[1]
  *    compressed data blocks[N]
  *    crc[4] orig_len[4]
  *
  * resulting in 18 bytes of non compressed data overhead.
  *
  * Files divided into blocks
  * 1 bit (last block flag)
  * 2 bits (block type)
  *
  * 1 block occurs every 32K -1 bytes or when there 50% compression
  * has been achieved. The smallest block type encoding is always used.
  *
  * stored:
  *    32 bits length in bytes.
  *
  * fixed:
  *    magic fixed tree.
  *    symbols.
  *
  * dynamic:
  *    dynamic tree encoding.
  *    symbols.
  *
  *
  * The buffer for decompression in place is the length of the
  * uncompressed data, plus a small amount extra to keep the algorithm safe.
  * The compressed data is placed at the end of the buffer.  The output
  * pointer is placed at the start of the buffer and the input pointer
  * is placed where the compressed data starts.  Problems will occur
  * when the output pointer overruns the input pointer.
  *
  * The output pointer can only overrun the input pointer if the input
  * pointer is moving faster than the output pointer.  A condition only
  * triggered by data whose compressed form is larger than the uncompressed
  * form.
  *
  * The worst case at the block level is a growth of the compressed data
  * of 5 bytes per 32767 bytes.
  *
  * The worst case internal to a compressed block is very hard to figure.
  * The worst case can at least be boundined by having one bit that represents
  * 32764 bytes and then all of the rest of the bytes representing the very
  * very last byte.
  *
  * All of which is enough to compute an amount of extra data that is required
  * to be safe.  To avoid problems at the block level allocating 5 extra bytes
  * per 32767 bytes of data is sufficient.  To avoind problems internal to a
  * block adding an extra 32767 bytes (the worst case uncompressed block size)
  * is sufficient, to ensure that in the worst case the decompressed data for
  * block will stop the byte before the compressed data for a block begins.
  * To avoid problems with the compressed data's meta information an extra 18
  * bytes are needed.  Leading to the formula:
  *
  * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
  *
  * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
  * Adding 32768 instead of 32767 just makes for round numbers.
  * Adding the decompressor_size is necessary as it musht live after all
  * of the data as well.  Last I measured the decompressor is about 14K.
  * 10K of actual data and 4K of bss.
  *
  */

 /*
  * gzip declarations
  */
 #define STATIC		static

 #undef memset
 #undef memcpy
 #define memzero(s, n)	memset((s), 0, (n))


 static void error(char *m);

 /*
  * This is set up by the setup-routine at boot-time
  */
 struct boot_params *real_mode;		/* Pointer to real-mode data */
 static int quiet;
 static int debug;

 void *memset(void *s, int c, size_t n);
 void *memcpy(void *dest, const void *src, size_t n);

 #ifdef CONFIG_X86_64
 #define memptr long
 #else
 #define memptr unsigned
 #endif

 static memptr free_mem_ptr;
 static 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_LZO
 #include "../../../../lib/decompress_unlzo.c"
 #endif

 static void scroll(void)
 {
 	int i;

 	memcpy(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(int error, const char *s)
 {
 	int x, y, pos;
 	char c;

 #ifndef CONFIG_X86_VERBOSE_BOOTUP
 	if (!error)
 		return;
 #endif
 	if (early_serial_base) {
 		const char *str = s;
 		while (*str) {
 			if (*str == '\n')
 				serial_putchar('\r');
 			serial_putchar(*str++);
 		}
 	}

 	if (real_mode->screen_info.orig_video_mode == 0 &&
 	    lines == 0 && cols == 0)
 		return;

 	x = real_mode->screen_info.orig_x;
 	y = real_mode->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--;
 				}
 			}
 		}
 	}

 	real_mode->screen_info.orig_x = x;
 	real_mode->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 *memset(void *s, int c, size_t n)
 {
 	int i;
 	char *ss = s;

 	for (i = 0; i < n; i++)
 		ss[i] = c;
 	return s;
 }
 #ifdef CONFIG_X86_32
 void *memcpy(void *dest, const void *src, size_t n)
 {
 	int d0, d1, d2;
 	asm volatile(
 		"rep ; movsl\n\t"
 		"movl %4,%%ecx\n\t"
 		"rep ; movsb\n\t"
 		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
 		: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
 		: "memory");

 	return dest;
 }
 #else
 void *memcpy(void *dest, const void *src, size_t n)
 {
 	long d0, d1, d2;
 	asm volatile(
 		"rep ; movsq\n\t"
 		"movq %4,%%rcx\n\t"
 		"rep ; movsb\n\t"
 		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
 		: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
 		: "memory");

 	return dest;
 }
 #endif

 static void error(char *x)
 {
 	__putstr(1, "\n\n");
 	__putstr(1, x);
 	__putstr(1, "\n\n -- System halted");

 	while (1)
 		asm("hlt");
 }

 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;
 	}

 	if (!quiet)
 		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_RELOCATABLE
 			dest = output;
 			dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 #else
 			dest = (void *)(phdr->p_paddr);
 #endif
 			memcpy(dest,
 			       output + phdr->p_offset,
 			       phdr->p_filesz);
 			break;
 		default: /* Ignore other PT_* */ break;
 		}
 	}
 }

 asmlinkage void decompress_kernel(void *rmode, memptr heap,
 				  unsigned char *input_data,
 				  unsigned long input_len,
 				  unsigned char *output)
 {
 	real_mode = rmode;

 	if (cmdline_find_option_bool("quiet"))
 		quiet = 1;
 	if (cmdline_find_option_bool("debug"))
 		debug = 1;

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

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

 	console_init();
 	if (debug)
 		putstr("early console in decompress_kernel\n");

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

 	if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 		error("Destination address inappropriately aligned");
 #ifdef CONFIG_X86_64
 	if (heap > 0x3fffffffffffUL)
 		error("Destination address too large");
 #else
 	if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
 		error("Destination address too large");
 #endif
 #ifndef CONFIG_RELOCATABLE
 	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 		error("Wrong destination address");
 #endif

 	if (!quiet)
 		putstr("\nDecompressing Linux... ");
 	decompress(input_data, input_len, NULL, NULL, output, NULL, error);
 	parse_elf(output);
 	if (!quiet)
 		putstr("done.\nBooting the kernel.\n");
 	return;
 }
	/*
	* misc.c
	*
	* This is a collection of several routines from gzip-1.0.3
	* adapted for Linux.
	*
	* 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"

	/* 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.
	*/

	/*
	* Getting to provable safe in place decompression is hard.
	* Worst case behaviours need to be analyzed.
	* Background information:
	*
	* The file layout is:
	* magic[2]
	* method[1]
	* flags[1]
	* timestamp[4]
	* extraflags[1]
	* os[1]
	* compressed data blocks[N]
	* crc[4] orig_len[4]
	*
	* resulting in 18 bytes of non compressed data overhead.
	*
	* Files divided into blocks
	* 1 bit (last block flag)
	* 2 bits (block type)
	*
	* 1 block occurs every 32K -1 bytes or when there 50% compression
	* has been achieved. The smallest block type encoding is always used.
	*
	* stored:
	* 32 bits length in bytes.
	*
	* fixed:
	* magic fixed tree.
	* symbols.
	*
	* dynamic:
	* dynamic tree encoding.
	* symbols.
	*
	*
	* The buffer for decompression in place is the length of the
	* uncompressed data, plus a small amount extra to keep the algorithm safe.
	* The compressed data is placed at the end of the buffer. The output
	* pointer is placed at the start of the buffer and the input pointer
	* is placed where the compressed data starts. Problems will occur
	* when the output pointer overruns the input pointer.
	*
	* The output pointer can only overrun the input pointer if the input
	* pointer is moving faster than the output pointer. A condition only
	* triggered by data whose compressed form is larger than the uncompressed
	* form.
	*
	* The worst case at the block level is a growth of the compressed data
	* of 5 bytes per 32767 bytes.
	*
	* The worst case internal to a compressed block is very hard to figure.
	* The worst case can at least be boundined by having one bit that represents
	* 32764 bytes and then all of the rest of the bytes representing the very
	* very last byte.
	*
	* All of which is enough to compute an amount of extra data that is required
	* to be safe. To avoid problems at the block level allocating 5 extra bytes
	* per 32767 bytes of data is sufficient. To avoind problems internal to a
	* block adding an extra 32767 bytes (the worst case uncompressed block size)
	* is sufficient, to ensure that in the worst case the decompressed data for
	* block will stop the byte before the compressed data for a block begins.
	* To avoid problems with the compressed data's meta information an extra 18
	* bytes are needed. Leading to the formula:
	*
	* extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
	*
	* Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
	* Adding 32768 instead of 32767 just makes for round numbers.
	* Adding the decompressor_size is necessary as it musht live after all
	* of the data as well. Last I measured the decompressor is about 14K.
	* 10K of actual data and 4K of bss.
	*
	*/

	/*
	* gzip declarations
	*/
	#define STATIC static

	#undef memset
	#undef memcpy
	#define memzero(s, n) memset((s), 0, (n))


	static void error(char *m);

	/*
	* This is set up by the setup-routine at boot-time
	*/
	struct boot_params real_mode; / Pointer to real-mode data */
	static int quiet;
	static int debug;

	void memset(void s, int c, size_t n);
	void memcpy(void dest, const void *src, size_t n);

	#ifdef CONFIG_X86_64
	#define memptr long
	#else
	#define memptr unsigned
	#endif

	static memptr free_mem_ptr;
	static 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_LZO
	#include "../../../../lib/decompress_unlzo.c"
	#endif

	static void scroll(void)
	{
	int i;

	memcpy(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(int error, const char *s)
	{
	int x, y, pos;
	char c;

	#ifndef CONFIG_X86_VERBOSE_BOOTUP
	if (!error)
	return;
	#endif
	if (early_serial_base) {
	const char *str = s;
	while (*str) {
	if (*str == '\n')
	serial_putchar('\r');
	serial_putchar(*str++);
	}
	}

	if (real_mode->screen_info.orig_video_mode == 0 &&
	lines == 0 && cols == 0)
	return;

	x = real_mode->screen_info.orig_x;
	y = real_mode->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--;
	}
	}
	}
	}

	real_mode->screen_info.orig_x = x;
	real_mode->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 memset(void s, int c, size_t n)
	{
	int i;
	char *ss = s;

	for (i = 0; i < n; i++)
	ss[i] = c;
	return s;
	}
	#ifdef CONFIG_X86_32
	void memcpy(void dest, const void *src, size_t n)
	{
	int d0, d1, d2;
	asm volatile(
	"rep ; movsl\n\t"
	"movl %4,%%ecx\n\t"
	"rep ; movsb\n\t"
	: "=&c" (d0), "=&D" (d1), "=&S" (d2)
	: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
	: "memory");

	return dest;
	}
	#else
	void memcpy(void dest, const void *src, size_t n)
	{
	long d0, d1, d2;
	asm volatile(
	"rep ; movsq\n\t"
	"movq %4,%%rcx\n\t"
	"rep ; movsb\n\t"
	: "=&c" (d0), "=&D" (d1), "=&S" (d2)
	: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
	: "memory");

	return dest;
	}
	#endif

	static void error(char *x)
	{
	__putstr(1, "\n\n");
	__putstr(1, x);
	__putstr(1, "\n\n -- System halted");

	while (1)
	asm("hlt");
	}

	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;
	}

	if (!quiet)
	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_RELOCATABLE
	dest = output;
	dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
	#else
	dest = (void *)(phdr->p_paddr);
	#endif
	memcpy(dest,
	output + phdr->p_offset,
	phdr->p_filesz);
	break;
	default: /* Ignore other PT_* */ break;
	}
	}
	}

	asmlinkage void decompress_kernel(void *rmode, memptr heap,
	unsigned char *input_data,
	unsigned long input_len,
	unsigned char *output)
	{
	real_mode = rmode;

	if (cmdline_find_option_bool("quiet"))
	quiet = 1;
	if (cmdline_find_option_bool("debug"))
	debug = 1;

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

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

	console_init();
	if (debug)
	putstr("early console in decompress_kernel\n");

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

	if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
	error("Destination address inappropriately aligned");
	#ifdef CONFIG_X86_64
	if (heap > 0x3fffffffffffUL)
	error("Destination address too large");
	#else
	if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
	error("Destination address too large");
	#endif
	#ifndef CONFIG_RELOCATABLE
	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
	error("Wrong destination address");
	#endif

	if (!quiet)
	putstr("\nDecompressing Linux... ");
	decompress(input_data, input_len, NULL, NULL, output, NULL, error);
	parse_elf(output);
	if (!quiet)
	putstr("done.\nBooting the kernel.\n");
	return;
	}