/*
* misc.c
*
- * This is a collection of several routines from gzip-1.0.3
- * adapted for Linux.
+ * 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
*/
#include "misc.h"
+#include "error.h"
#include "../string.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.
- */
+#include "../voffset.h"
/*
- * 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.
- *
+ * 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.
*/
-/*
- * gzip declarations
- */
+/* Macros used by the included decompressor code below. */
#define STATIC static
-#undef memcpy
-
/*
- * Use a normal definition of memset() from string.c. There are already
+ * 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
-
-static void error(char *m);
+/* 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 *real_mode; /* Pointer to real-mode data */
+struct boot_params *boot_params;
memptr free_mem_ptr;
memptr free_mem_end_ptr;
#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;
- memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
+ memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
vidmem[i] = ' ';
}
}
}
- if (real_mode->screen_info.orig_video_mode == 0 &&
+ if (boot_params->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;
+ x = boot_params->screen_info.orig_x;
+ y = boot_params->screen_info.orig_y;
while ((c = *s++) != '\0') {
if (c == '\n') {
}
}
- real_mode->screen_info.orig_x = x;
- real_mode->screen_info.orig_y = 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);
}
}
-static void error(char *x)
-{
- error_putstr("\n\n");
- error_putstr(x);
- error_putstr("\n\n -- System halted");
-
- while (1)
- asm("hlt");
-}
-
#if CONFIG_X86_NEED_RELOCS
static void handle_relocations(void *output, unsigned long output_len)
{
int *reloc;
unsigned long delta, map, ptr;
unsigned long min_addr = (unsigned long)output;
- unsigned long max_addr = min_addr + output_len;
+ unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
/*
* Calculate the delta between where vmlinux was linked to load
* So we work backwards from the end of the decompressed image.
*/
for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
- int extended = *reloc;
+ long extended = *reloc;
extended += map;
ptr = (unsigned long)extended;
#else
dest = (void *)(phdr->p_paddr);
#endif
- memcpy(dest,
- output + phdr->p_offset,
- phdr->p_filesz);
+ memmove(dest, output + phdr->p_offset, phdr->p_filesz);
break;
default: /* Ignore other PT_* */ break;
}
free(phdrs);
}
-asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
+/*
+ * 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,
- unsigned long run_size)
+ unsigned long output_len)
{
+ const unsigned long kernel_total_size = VO__end - VO__text;
unsigned char *output_orig = output;
- real_mode = rmode;
+ /* Retain x86 boot parameters pointer passed from startup_32/64. */
+ boot_params = rmode;
- /* Clear it for solely in-kernel use */
- real_mode->hdr.loadflags &= ~KASLR_FLAG;
+ /* Clear flags intended for solely in-kernel use. */
+ boot_params->hdr.loadflags &= ~KASLR_FLAG;
- sanitize_boot_params(real_mode);
+ sanitize_boot_params(boot_params);
- if (real_mode->screen_info.orig_video_mode == 7) {
+ if (boot_params->screen_info.orig_video_mode == 7) {
vidmem = (char *) 0xb0000;
vidport = 0x3b4;
} else {
vidport = 0x3d4;
}
- lines = real_mode->screen_info.orig_video_lines;
- cols = real_mode->screen_info.orig_video_cols;
+ lines = boot_params->screen_info.orig_video_lines;
+ cols = boot_params->screen_info.orig_video_cols;
console_init();
- debug_putstr("early console in decompress_kernel\n");
+ debug_putstr("early console in extract_kernel\n");
free_mem_ptr = heap; /* Heap */
free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
debug_putaddr(input_len);
debug_putaddr(output);
debug_putaddr(output_len);
- debug_putaddr(run_size);
+ debug_putaddr(kernel_total_size);
/*
* 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.
*/
- output = choose_kernel_location(real_mode, input_data, input_len, output,
- output_len > run_size ? output_len
- : run_size);
+ output = choose_random_location(input_data, input_len, output,
+ max(output_len, kernel_total_size));
/* Validate memory location choices. */
if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
projects / cascardo / linux.git / blobdiff