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linux-sg2042
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[PATCH] i386: Relocatable kernel support 

This patch modifies the i386 kernel so that if CONFIG_RELOCATABLE is
selected it will be able to be loaded at any 4K aligned address below
1G.  The technique used is to compile the decompressor with -fPIC and
modify it so the decompressor is fully relocatable.  For the main
kernel relocations are generated.  Resulting in a kernel that is relocatable
with no runtime overhead and no need to modify the source code.

A reserved 32bit word in the parameters has been assigned
to serve as a stack so we figure out where are running.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Eric W. Biederman 2006-12-07 02:14:04 +01:00 committed by Andi Kleen
parent fd593d1277
commit 968de4f026
10 changed files with 919 additions and 209 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/i386/Kconfig
View File

@ -773,6 +773,18 @@ config CRASH_DUMP
PHYSICAL_START.
For more details see Documentation/kdump/kdump.txt
config RELOCATABLE
bool "Build a relocatable kernel"
help
This build a kernel image that retains relocation information
so it can be loaded someplace besides the default 1MB.
The relocations tend to the kernel binary about 10% larger,
but are discarded at runtime.
One use is for the kexec on panic case where the recovery kernel
must live at a different physical address than the primary
kernel.
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)

4
arch/i386/Makefile
View File

@ -26,7 +26,9 @@ endif
LDFLAGS := -m elf_i386
OBJCOPYFLAGS := -O binary -R .note -R .comment -S
LDFLAGS_vmlinux :=
ifdef CONFIG_RELOCATABLE
LDFLAGS_vmlinux := --emit-relocs
endif
CHECKFLAGS += -D__i386__
CFLAGS += -pipe -msoft-float

28
arch/i386/boot/compressed/Makefile
View File

@ -4,22 +4,42 @@
# create a compressed vmlinux image from the original vmlinux
#
targets := vmlinux vmlinux.bin vmlinux.bin.gz head.o misc.o piggy.o
targets := vmlinux vmlinux.bin vmlinux.bin.gz head.o misc.o piggy.o \
vmlinux.bin.all vmlinux.relocs
EXTRA_AFLAGS := -traditional
LDFLAGS_vmlinux := -Ttext $(IMAGE_OFFSET) -e startup_32
LDFLAGS_vmlinux := -T
CFLAGS_misc.o += -fPIC
hostprogs-y := relocs
$(obj)/vmlinux: $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
$(obj)/vmlinux: $(src)/vmlinux.lds $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
$(call if_changed,ld)
@:
$(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
quiet_cmd_relocs = RELOCS $@
cmd_relocs = $(obj)/relocs $< > $@
$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
$(call if_changed,relocs)
vmlinux.bin.all-y := $(obj)/vmlinux.bin
vmlinux.bin.all-$(CONFIG_RELOCATABLE) += $(obj)/vmlinux.relocs
quiet_cmd_relocbin = BUILD $@
cmd_relocbin = cat $(filter-out FORCE,$^) > $@
$(obj)/vmlinux.bin.all: $(vmlinux.bin.all-y) FORCE
$(call if_changed,relocbin)
ifdef CONFIG_RELOCATABLE
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin.all FORCE
$(call if_changed,gzip)
else
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
$(call if_changed,gzip)
endif
LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T
$(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.gz FORCE
$(obj)/piggy.o: $(src)/vmlinux.scr $(obj)/vmlinux.bin.gz FORCE
$(call if_changed,ld)

182
arch/i386/boot/compressed/head.S
View File

@ -25,9 +25,11 @@
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page.h>
.section ".text.head"
.globl startup_32
startup_32:
cld
cli
@ -36,93 +38,141 @@ startup_32:
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
movl %eax,%ss
lss stack_start,%esp
xorl %eax,%eax
1: incl %eax # check that A20 really IS enabled
movl %eax,0x000000 # loop forever if it isn't
cmpl %eax,0x100000
je 1b
/* Calculate the delta between where we were compiled to run
* at and where we were actually loaded at. This can only be done
* with a short local call on x86. Nothing else will tell us what
* address we are running at. The reserved chunk of the real-mode
* data at 0x34-0x3f are used as the stack for this calculation.
* Only 4 bytes are needed.
*/
leal 0x40(%esi), %esp
call 1f
1: popl %ebp
subl $1b, %ebp
/* Compute the delta between where we were compiled to run at
* and where the code will actually run at.
*/
/* Start with the delta to where the kernel will run at. If we are
* a relocatable kernel this is the delta to our load address otherwise
* this is the delta to CONFIG_PHYSICAL start.
*/
#ifdef CONFIG_RELOCATABLE
movl %ebp, %ebx
#else
movl $(CONFIG_PHYSICAL_START - startup_32), %ebx
#endif
/* Replace the compressed data size with the uncompressed size */
subl input_len(%ebp), %ebx
movl output_len(%ebp), %eax
addl %eax, %ebx
/* Add 8 bytes for every 32K input block */
shrl $12, %eax
addl %eax, %ebx
/* Add 32K + 18 bytes of extra slack */
addl $(32768 + 18), %ebx
/* Align on a 4K boundary */
addl $4095, %ebx
andl $~4095, %ebx
/* Copy the compressed kernel to the end of our buffer
* where decompression in place becomes safe.
*/
pushl %esi
leal _end(%ebp), %esi
leal _end(%ebx), %edi
movl $(_end - startup_32), %ecx
std
rep
movsb
cld
popl %esi
/* Compute the kernel start address.
*/
#ifdef CONFIG_RELOCATABLE
leal startup_32(%ebp), %ebp
#else
movl $CONFIG_PHYSICAL_START, %ebp
#endif
/*
* Initialize eflags. Some BIOS's leave bits like NT set. This would
* confuse the debugger if this code is traced.
* XXX - best to initialize before switching to protected mode.
* Jump to the relocated address.
*/
pushl $0
popfl
leal relocated(%ebx), %eax
jmp *%eax
.section ".text"
relocated:
/*
* Clear BSS
*/
xorl %eax,%eax
movl $_edata,%edi
movl $_end,%ecx
leal _edata(%ebx),%edi
leal _end(%ebx), %ecx
subl %edi,%ecx
cld
rep
stosb
/*
* Setup the stack for the decompressor
*/
leal stack_end(%ebx), %esp
/*
* Do the decompression, and jump to the new kernel..
*/
subl $16,%esp # place for structure on the stack
movl %esp,%eax
movl output_len(%ebx), %eax
pushl %eax
pushl %ebp # output address
movl input_len(%ebx), %eax
pushl %eax # input_len
leal input_data(%ebx), %eax
pushl %eax # input_data
leal _end(%ebx), %eax
pushl %eax # end of the image as third argument
pushl %esi # real mode pointer as second arg
pushl %eax # address of structure as first arg
call decompress_kernel
orl %eax,%eax
jnz 3f
popl %esi # discard address
popl %esi # real mode pointer
xorl %ebx,%ebx
ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
addl $20, %esp
popl %ecx
#if CONFIG_RELOCATABLE
/* Find the address of the relocations.
*/
movl %ebp, %edi
addl %ecx, %edi
/* Calculate the delta between where vmlinux was compiled to run
* and where it was actually loaded.
*/
movl %ebp, %ebx
subl $CONFIG_PHYSICAL_START, %ebx
/*
* We come here, if we were loaded high.
* We need to move the move-in-place routine down to 0x1000
* and then start it with the buffer addresses in registers,
* which we got from the stack.
* Process relocations.
*/
3:
movl $move_routine_start,%esi
movl $0x1000,%edi
movl $move_routine_end,%ecx
subl %esi,%ecx
addl $3,%ecx
shrl $2,%ecx
cld
rep
movsl
popl %esi # discard the address
popl %ebx # real mode pointer
popl %esi # low_buffer_start
popl %ecx # lcount
popl %edx # high_buffer_start
popl %eax # hcount
movl $CONFIG_PHYSICAL_START,%edi
cli # make sure we don't get interrupted
ljmp $(__BOOT_CS), $0x1000 # and jump to the move routine
1: subl $4, %edi
movl 0(%edi), %ecx
testl %ecx, %ecx
jz 2f
addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
jmp 1b
2:
#endif
/*
* Routine (template) for moving the decompressed kernel in place,
* if we were high loaded. This _must_ PIC-code !
* Jump to the decompressed kernel.
*/
move_routine_start:
movl %ecx,%ebp
shrl $2,%ecx
rep
movsl
movl %ebp,%ecx
andl $3,%ecx
rep
movsb
movl %edx,%esi
movl %eax,%ecx # NOTE: rep movsb won't move if %ecx == 0
addl $3,%ecx
shrl $2,%ecx
rep
movsl
movl %ebx,%esi # Restore setup pointer
xorl %ebx,%ebx
ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
move_routine_end:
jmp *%ebp
.bss
.balign 4
stack:
.fill 4096, 1, 0
stack_end:

261
arch/i386/boot/compressed/misc.c
View File

@ -13,6 +13,88 @@
#include <linux/vmalloc.h>
#include <linux/screen_info.h>
#include <asm/io.h>
#include <asm/page.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 analized.
* 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 actuall data and 4K of bss.
*
*/
/*
* gzip declarations
@ -29,15 +111,20 @@ typedef unsigned char uch;
typedef unsigned short ush;
typedef unsigned long ulg;
#define WSIZE 0x8000 /* Window size must be at least 32k, */
/* and a power of two */
#define WSIZE 0x80000000 /* Window size must be at least 32k,
* and a power of two
* We don't actually have a window just
* a huge output buffer so I report
* a 2G windows size, as that should
* always be larger than our output buffer.
*/
static uch *inbuf; /* input buffer */
static uch window[WSIZE]; /* Sliding window buffer */
static uch *inbuf; /* input buffer */
static uch *window; /* Sliding window buffer, (and final output buffer) */
static unsigned insize = 0; /* valid bytes in inbuf */
static unsigned inptr = 0; /* index of next byte to be processed in inbuf */
static unsigned outcnt = 0; /* bytes in output buffer */
static unsigned insize; /* valid bytes in inbuf */
static unsigned inptr; /* index of next byte to be processed in inbuf */
static unsigned outcnt; /* bytes in output buffer */
/* gzip flag byte */
#define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */
@ -88,8 +175,6 @@ extern unsigned char input_data[];
extern int input_len;
static long bytes_out = 0;
static uch *output_data;
static unsigned long output_ptr = 0;
static void *malloc(int size);
static void free(void *where);
@ -99,17 +184,10 @@ static void *memcpy(void *dest, const void *src, unsigned n);
static void putstr(const char *);
extern int end;
static long free_mem_ptr = (long)&end;
static long free_mem_end_ptr;
static unsigned long free_mem_ptr;
static unsigned long free_mem_end_ptr;
#define INPLACE_MOVE_ROUTINE 0x1000
#define LOW_BUFFER_START 0x2000
#define LOW_BUFFER_MAX 0x90000
#define HEAP_SIZE 0x3000
static unsigned int low_buffer_end, low_buffer_size;
static int high_loaded =0;
static uch *high_buffer_start /* = (uch *)(((ulg)&end) + HEAP_SIZE)*/;
static char *vidmem = (char *)0xb8000;
static int vidport;
@ -150,7 +228,7 @@ static void gzip_mark(void **ptr)
static void gzip_release(void **ptr)
{
free_mem_ptr = (long) *ptr;
free_mem_ptr = (unsigned long) *ptr;
}
static void scroll(void)
@ -178,7 +256,7 @@ static void putstr(const char *s)
y--;
}
} else {
vidmem [ ( x + cols * y ) * 2 ] = c;
vidmem [ ( x + cols * y ) * 2 ] = c;
if ( ++x >= cols ) {
x = 0;
if ( ++y >= lines ) {
@ -223,58 +301,31 @@ static void* memcpy(void* dest, const void* src, unsigned n)
*/
static int fill_inbuf(void)
{
if (insize != 0) {
error("ran out of input data");
}
inbuf = input_data;
insize = input_len;
inptr = 1;
return inbuf[0];
error("ran out of input data");
return 0;
}
/* ===========================================================================
* Write the output window window[0..outcnt-1] and update crc and bytes_out.
* (Used for the decompressed data only.)
*/
static void flush_window_low(void)
{
ulg c = crc; /* temporary variable */
unsigned n;
uch *in, *out, ch;
in = window;
out = &output_data[output_ptr];
for (n = 0; n < outcnt; n++) {
ch = *out++ = *in++;
c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
}
crc = c;
bytes_out += (ulg)outcnt;
output_ptr += (ulg)outcnt;
outcnt = 0;
}
static void flush_window_high(void)
{
ulg c = crc; /* temporary variable */
unsigned n;
uch *in, ch;
in = window;
for (n = 0; n < outcnt; n++) {
ch = *output_data++ = *in++;
if ((ulg)output_data == low_buffer_end) output_data=high_buffer_start;
c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
}
crc = c;
bytes_out += (ulg)outcnt;
outcnt = 0;
}
static void flush_window(void)
{
if (high_loaded) flush_window_high();
else flush_window_low();
/* With my window equal to my output buffer
* I only need to compute the crc here.
*/
ulg c = crc; /* temporary variable */
unsigned n;
uch *in, ch;
in = window;
for (n = 0; n < outcnt; n++) {
ch = *in++;
c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
}
crc = c;
bytes_out += (ulg)outcnt;
outcnt = 0;
}
static void error(char *x)
@ -286,66 +337,8 @@ static void error(char *x)
while(1); /* Halt */
}
#define STACK_SIZE (4096)
long user_stack [STACK_SIZE];
struct {
long * a;
short b;
} stack_start = { & user_stack [STACK_SIZE] , __BOOT_DS };
static void setup_normal_output_buffer(void)
{
#ifdef STANDARD_MEMORY_BIOS_CALL
if (RM_EXT_MEM_K < 1024) error("Less than 2MB of memory");
#else
if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < 1024) error("Less than 2MB of memory");
#endif
output_data = (unsigned char *)CONFIG_PHYSICAL_START; /* Normally Points to 1M */
free_mem_end_ptr = (long)real_mode;
}
struct moveparams {
uch *low_buffer_start; int lcount;
uch *high_buffer_start; int hcount;
};
static void setup_output_buffer_if_we_run_high(struct moveparams *mv)
{
high_buffer_start = (uch *)(((ulg)&end) + HEAP_SIZE);
#ifdef STANDARD_MEMORY_BIOS_CALL
if (RM_EXT_MEM_K < (3*1024)) error("Less than 4MB of memory");
#else
if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < (3*1024)) error("Less than 4MB of memory");
#endif
mv->low_buffer_start = output_data = (unsigned char *)LOW_BUFFER_START;
low_buffer_end = ((unsigned int)real_mode > LOW_BUFFER_MAX
? LOW_BUFFER_MAX : (unsigned int)real_mode) & ~0xfff;
low_buffer_size = low_buffer_end - LOW_BUFFER_START;
high_loaded = 1;
free_mem_end_ptr = (long)high_buffer_start;
if ( (CONFIG_PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {
high_buffer_start = (uch *)(CONFIG_PHYSICAL_START + low_buffer_size);
mv->hcount = 0; /* say: we need not to move high_buffer */
}
else mv->hcount = -1;
mv->high_buffer_start = high_buffer_start;
}
static void close_output_buffer_if_we_run_high(struct moveparams *mv)
{
if (bytes_out > low_buffer_size) {
mv->lcount = low_buffer_size;
if (mv->hcount)
mv->hcount = bytes_out - low_buffer_size;
} else {
mv->lcount = bytes_out;
mv->hcount = 0;
}
}
asmlinkage int decompress_kernel(struct moveparams *mv, void *rmode)
asmlinkage void decompress_kernel(void *rmode, unsigned long end,
uch *input_data, unsigned long input_len, uch *output)
{
real_mode = rmode;
@ -360,13 +353,25 @@ asmlinkage int decompress_kernel(struct moveparams *mv, void *rmode)
lines = RM_SCREEN_INFO.orig_video_lines;
cols = RM_SCREEN_INFO.orig_video_cols;
if (free_mem_ptr < 0x100000) setup_normal_output_buffer();
else setup_output_buffer_if_we_run_high(mv);
window = output; /* Output buffer (Normally at 1M) */
free_mem_ptr = end; /* Heap */
free_mem_end_ptr = end + HEAP_SIZE;
inbuf = input_data; /* Input buffer */
insize = input_len;
inptr = 0;
if (((u32)output - CONFIG_PHYSICAL_START) & 0x3fffff)
error("Destination address not 4M aligned");
if (end > ((-__PAGE_OFFSET-(512 <<20)-1) & 0x7fffffff))
error("Destination address too large");
#ifndef CONFIG_RELOCATABLE
if ((u32)output != CONFIG_PHYSICAL_START)
error("Wrong destination address");
#endif
makecrc();
putstr("Uncompressing Linux... ");
gunzip();
putstr("Ok, booting the kernel.\n");
if (high_loaded) close_output_buffer_if_we_run_high(mv);
return high_loaded;
return;
}

563
arch/i386/boot/compressed/relocs.c Normal file
View File

@ -0,0 +1,563 @@
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <elf.h>
#include <byteswap.h>
#define USE_BSD
#include <endian.h>
#define MAX_SHDRS 100
static Elf32_Ehdr ehdr;
static Elf32_Shdr shdr[MAX_SHDRS];
static Elf32_Sym *symtab[MAX_SHDRS];
static Elf32_Rel *reltab[MAX_SHDRS];
static char *strtab[MAX_SHDRS];
static unsigned long reloc_count, reloc_idx;
static unsigned long *relocs;
static void die(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
exit(1);
}
static const char *sym_type(unsigned type)
{
static const char *type_name[] = {
#define SYM_TYPE(X) [X] = #X
SYM_TYPE(STT_NOTYPE),
SYM_TYPE(STT_OBJECT),
SYM_TYPE(STT_FUNC),
SYM_TYPE(STT_SECTION),
SYM_TYPE(STT_FILE),
SYM_TYPE(STT_COMMON),
SYM_TYPE(STT_TLS),
#undef SYM_TYPE
};
const char *name = "unknown sym type name";
if (type < sizeof(type_name)/sizeof(type_name[0])) {
name = type_name[type];
}
return name;
}
static const char *sym_bind(unsigned bind)
{
static const char *bind_name[] = {
#define SYM_BIND(X) [X] = #X
SYM_BIND(STB_LOCAL),
SYM_BIND(STB_GLOBAL),
SYM_BIND(STB_WEAK),
#undef SYM_BIND
};
const char *name = "unknown sym bind name";
if (bind < sizeof(bind_name)/sizeof(bind_name[0])) {
name = bind_name[bind];
}
return name;
}
static const char *sym_visibility(unsigned visibility)
{
static const char *visibility_name[] = {
#define SYM_VISIBILITY(X) [X] = #X
SYM_VISIBILITY(STV_DEFAULT),
SYM_VISIBILITY(STV_INTERNAL),
SYM_VISIBILITY(STV_HIDDEN),
SYM_VISIBILITY(STV_PROTECTED),
#undef SYM_VISIBILITY
};
const char *name = "unknown sym visibility name";
if (visibility < sizeof(visibility_name)/sizeof(visibility_name[0])) {
name = visibility_name[visibility];
}
return name;
}
static const char *rel_type(unsigned type)
{
static const char *type_name[] = {
#define REL_TYPE(X) [X] = #X
REL_TYPE(R_386_NONE),
REL_TYPE(R_386_32),
REL_TYPE(R_386_PC32),
REL_TYPE(R_386_GOT32),
REL_TYPE(R_386_PLT32),
REL_TYPE(R_386_COPY),
REL_TYPE(R_386_GLOB_DAT),
REL_TYPE(R_386_JMP_SLOT),
REL_TYPE(R_386_RELATIVE),
REL_TYPE(R_386_GOTOFF),
REL_TYPE(R_386_GOTPC),
#undef REL_TYPE
};
const char *name = "unknown type rel type name";
if (type < sizeof(type_name)/sizeof(type_name[0])) {
name = type_name[type];
}
return name;
}
static const char *sec_name(unsigned shndx)
{
const char *sec_strtab;
const char *name;
sec_strtab = strtab[ehdr.e_shstrndx];
name = "<noname>";
if (shndx < ehdr.e_shnum) {
name = sec_strtab + shdr[shndx].sh_name;
}
else if (shndx == SHN_ABS) {
name = "ABSOLUTE";
}
else if (shndx == SHN_COMMON) {
name = "COMMON";
}
return name;
}
static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
{
const char *name;
name = "<noname>";
if (sym->st_name) {
name = sym_strtab + sym->st_name;
}
else {
name = sec_name(shdr[sym->st_shndx].sh_name);
}
return name;
}
#if BYTE_ORDER == LITTLE_ENDIAN
#define le16_to_cpu(val) (val)
#define le32_to_cpu(val) (val)
#endif
#if BYTE_ORDER == BIG_ENDIAN
#define le16_to_cpu(val) bswap_16(val)
#define le32_to_cpu(val) bswap_32(val)
#endif
static uint16_t elf16_to_cpu(uint16_t val)
{
return le16_to_cpu(val);
}
static uint32_t elf32_to_cpu(uint32_t val)
{
return le32_to_cpu(val);
}
static void read_ehdr(FILE *fp)
{
if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
die("Cannot read ELF header: %s\n",
strerror(errno));
}
if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
die("No ELF magic\n");
}
if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
die("Not a 32 bit executable\n");
}
if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
die("Not a LSB ELF executable\n");
}
if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
die("Unknown ELF version\n");
}
/* Convert the fields to native endian */
ehdr.e_type = elf16_to_cpu(ehdr.e_type);
ehdr.e_machine = elf16_to_cpu(ehdr.e_machine);
ehdr.e_version = elf32_to_cpu(ehdr.e_version);
ehdr.e_entry = elf32_to_cpu(ehdr.e_entry);
ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff);
ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff);
ehdr.e_flags = elf32_to_cpu(ehdr.e_flags);
ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize);
ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum);
ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum);
ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx);
if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
die("Unsupported ELF header type\n");
}
if (ehdr.e_machine != EM_386) {
die("Not for x86\n");
}
if (ehdr.e_version != EV_CURRENT) {
die("Unknown ELF version\n");
}
if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
die("Bad Elf header size\n");
}
if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
die("Bad program header entry\n");
}
if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
die("Bad section header entry\n");
}
if (ehdr.e_shstrndx >= ehdr.e_shnum) {
die("String table index out of bounds\n");
}
}
static void read_shdrs(FILE *fp)
{
int i;
if (ehdr.e_shnum > MAX_SHDRS) {
die("%d section headers supported: %d\n",
ehdr.e_shnum, MAX_SHDRS);
}
if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
ehdr.e_shoff, strerror(errno));
}
if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
die("Cannot read ELF section headers: %s\n",
strerror(errno));
}
for(i = 0; i < ehdr.e_shnum; i++) {
shdr[i].sh_name = elf32_to_cpu(shdr[i].sh_name);
shdr[i].sh_type = elf32_to_cpu(shdr[i].sh_type);
shdr[i].sh_flags = elf32_to_cpu(shdr[i].sh_flags);
shdr[i].sh_addr = elf32_to_cpu(shdr[i].sh_addr);
shdr[i].sh_offset = elf32_to_cpu(shdr[i].sh_offset);
shdr[i].sh_size = elf32_to_cpu(shdr[i].sh_size);
shdr[i].sh_link = elf32_to_cpu(shdr[i].sh_link);
shdr[i].sh_info = elf32_to_cpu(shdr[i].sh_info);
shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
shdr[i].sh_entsize = elf32_to_cpu(shdr[i].sh_entsize);
}
}
static void read_strtabs(FILE *fp)
{
int i;
for(i = 0; i < ehdr.e_shnum; i++) {
if (shdr[i].sh_type != SHT_STRTAB) {
continue;
}
strtab[i] = malloc(shdr[i].sh_size);
if (!strtab[i]) {
die("malloc of %d bytes for strtab failed\n",
shdr[i].sh_size);
}
if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
shdr[i].sh_offset, strerror(errno));
}
if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
die("Cannot read symbol table: %s\n",
strerror(errno));
}
}
}
static void read_symtabs(FILE *fp)
{
int i,j;
for(i = 0; i < ehdr.e_shnum; i++) {
if (shdr[i].sh_type != SHT_SYMTAB) {
continue;
}
symtab[i] = malloc(shdr[i].sh_size);
if (!symtab[i]) {
die("malloc of %d bytes for symtab failed\n",
shdr[i].sh_size);
}
if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
shdr[i].sh_offset, strerror(errno));
}
if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
die("Cannot read symbol table: %s\n",
strerror(errno));
}
for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
symtab[i][j].st_name = elf32_to_cpu(symtab[i][j].st_name);
symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
symtab[i][j].st_size = elf32_to_cpu(symtab[i][j].st_size);
symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
}
}
}
static void read_relocs(FILE *fp)
{
int i,j;
for(i = 0; i < ehdr.e_shnum; i++) {
if (shdr[i].sh_type != SHT_REL) {
continue;
}
reltab[i] = malloc(shdr[i].sh_size);
if (!reltab[i]) {
die("malloc of %d bytes for relocs failed\n",
shdr[i].sh_size);
}
if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
shdr[i].sh_offset, strerror(errno));
}
if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
die("Cannot read symbol table: %s\n",
strerror(errno));
}
for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
reltab[i][j].r_info = elf32_to_cpu(reltab[i][j].r_info);
}
}
}
static void print_absolute_symbols(void)
{
int i;
printf("Absolute symbols\n");
printf(" Num: Value Size Type Bind Visibility Name\n");
for(i = 0; i < ehdr.e_shnum; i++) {
char *sym_strtab;
Elf32_Sym *sh_symtab;
int j;
if (shdr[i].sh_type != SHT_SYMTAB) {
continue;
}
sh_symtab = symtab[i];
sym_strtab = strtab[shdr[i].sh_link];
for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
Elf32_Sym *sym;
const char *name;
sym = &symtab[i][j];
name = sym_name(sym_strtab, sym);
if (sym->st_shndx != SHN_ABS) {
continue;
}
printf("%5d %08x %5d %10s %10s %12s %s\n",
j, sym->st_value, sym->st_size,
sym_type(ELF32_ST_TYPE(sym->st_info)),
sym_bind(ELF32_ST_BIND(sym->st_info)),
sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
name);
}
}
printf("\n");
}
static void print_absolute_relocs(void)
{
int i;
printf("Absolute relocations\n");
printf("Offset Info Type Sym.Value Sym.Name\n");
for(i = 0; i < ehdr.e_shnum; i++) {
char *sym_strtab;
Elf32_Sym *sh_symtab;
unsigned sec_applies, sec_symtab;
int j;
if (shdr[i].sh_type != SHT_REL) {
continue;
}
sec_symtab = shdr[i].sh_link;
sec_applies = shdr[i].sh_info;
if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
continue;
}
sh_symtab = symtab[sec_symtab];
sym_strtab = strtab[shdr[sec_symtab].sh_link];
for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
Elf32_Rel *rel;
Elf32_Sym *sym;
const char *name;
rel = &reltab[i][j];
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
name = sym_name(sym_strtab, sym);
if (sym->st_shndx != SHN_ABS) {
continue;
}
printf("%08x %08x %10s %08x %s\n",
rel->r_offset,
rel->r_info,
rel_type(ELF32_R_TYPE(rel->r_info)),
sym->st_value,
name);
}
}
printf("\n");
}
static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
{
int i;
/* Walk through the relocations */
for(i = 0; i < ehdr.e_shnum; i++) {
char *sym_strtab;
Elf32_Sym *sh_symtab;
unsigned sec_applies, sec_symtab;
int j;
if (shdr[i].sh_type != SHT_REL) {
continue;
}
sec_symtab = shdr[i].sh_link;
sec_applies = shdr[i].sh_info;
if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
continue;
}
sh_symtab = symtab[sec_symtab];
sym_strtab = strtab[shdr[sec_symtab].sh_link];
for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
Elf32_Rel *rel;
Elf32_Sym *sym;
unsigned r_type;
rel = &reltab[i][j];
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
r_type = ELF32_R_TYPE(rel->r_info);
/* Don't visit relocations to absolute symbols */
if (sym->st_shndx == SHN_ABS) {
continue;
}
if (r_type == R_386_PC32) {
/* PC relative relocations don't need to be adjusted */
}
else if (r_type == R_386_32) {
/* Visit relocations that need to be adjusted */
visit(rel, sym);
}
else {
die("Unsupported relocation type: %d\n", r_type);
}
}
}
}
static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
reloc_count += 1;
}
static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
/* Remember the address that needs to be adjusted. */
relocs[reloc_idx++] = rel->r_offset;
}
static int cmp_relocs(const void *va, const void *vb)
{
const unsigned long *a, *b;
a = va; b = vb;
return (*a == *b)? 0 : (*a > *b)? 1 : -1;
}
static void emit_relocs(int as_text)
{
int i;
/* Count how many relocations I have and allocate space for them. */
reloc_count = 0;
walk_relocs(count_reloc);
relocs = malloc(reloc_count * sizeof(relocs[0]));
if (!relocs) {
die("malloc of %d entries for relocs failed\n",
reloc_count);
}
/* Collect up the relocations */
reloc_idx = 0;
walk_relocs(collect_reloc);
/* Order the relocations for more efficient processing */
qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
/* Print the relocations */
if (as_text) {
/* Print the relocations in a form suitable that
* gas will like.
*/
printf(".section \".data.reloc\",\"a\"\n");
printf(".balign 4\n");
for(i = 0; i < reloc_count; i++) {
printf("\t .long 0x%08lx\n", relocs[i]);
}
printf("\n");
}
else {
unsigned char buf[4];
buf[0] = buf[1] = buf[2] = buf[3] = 0;
/* Print a stop */
printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
/* Now print each relocation */
for(i = 0; i < reloc_count; i++) {
buf[0] = (relocs[i] >> 0) & 0xff;
buf[1] = (relocs[i] >> 8) & 0xff;
buf[2] = (relocs[i] >> 16) & 0xff;
buf[3] = (relocs[i] >> 24) & 0xff;
printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
}
}
}
static void usage(void)
{
die("i386_reloc [--abs | --text] vmlinux\n");
}
int main(int argc, char **argv)
{
int show_absolute;
int as_text;
const char *fname;
FILE *fp;
int i;
show_absolute = 0;
as_text = 0;
fname = NULL;
for(i = 1; i < argc; i++) {
char *arg = argv[i];
if (*arg == '-') {
if (strcmp(argv[1], "--abs") == 0) {
show_absolute = 1;
continue;
}
else if (strcmp(argv[1], "--text") == 0) {
as_text = 1;
continue;
}
}
else if (!fname) {
fname = arg;
continue;
}
usage();
}
if (!fname) {
usage();
}
fp = fopen(fname, "r");
if (!fp) {
die("Cannot open %s: %s\n",
fname, strerror(errno));
}
read_ehdr(fp);
read_shdrs(fp);
read_strtabs(fp);
read_symtabs(fp);
read_relocs(fp);
if (show_absolute) {
print_absolute_symbols();
print_absolute_relocs();
return 0;
}
emit_relocs(as_text);
return 0;
}

43
arch/i386/boot/compressed/vmlinux.lds Normal file
View File

@ -0,0 +1,43 @@
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
OUTPUT_ARCH(i386)
ENTRY(startup_32)
SECTIONS
{
/* Be careful parts of head.S assume startup_32 is at
* address 0.
*/
. = 0 ;
.text.head : {
_head = . ;
*(.text.head)
_ehead = . ;
}
.data.compressed : {
*(.data.compressed)
}
.text : {
_text = .; /* Text */
*(.text)
*(.text.*)
_etext = . ;
}
.rodata : {
_rodata = . ;
*(.rodata) /* read-only data */
*(.rodata.*)
_erodata = . ;
}
.data : {
_data = . ;
*(.data)
*(.data.*)
_edata = . ;
}
.bss : {
_bss = . ;
*(.bss)
*(.bss.*)
*(COMMON)
_end = . ;
}
}

3
arch/i386/boot/compressed/vmlinux.scr
View File

@ -1,9 +1,10 @@
SECTIONS
{
.data : {
.data.compressed : {
input_len = .;
LONG(input_data_end - input_data) input_data = .;
*(.data)
output_len = . - 4;
input_data_end = .;
}
}

29
arch/i386/boot/setup.S
View File

@ -588,11 +588,6 @@ rmodeswtch_normal:
call default_switch
rmodeswtch_end:
# we get the code32 start address and modify the below 'jmpi'
# (loader may have changed it)
movl %cs:code32_start, %eax
movl %eax, %cs:code32
# Now we move the system to its rightful place ... but we check if we have a
# big-kernel. In that case we *must* not move it ...
testb $LOADED_HIGH, %cs:loadflags
@ -788,11 +783,12 @@ a20_err_msg:
a20_done:
#endif /* CONFIG_X86_VOYAGER */
# set up gdt and idt
# set up gdt and idt and 32bit start address
lidt idt_48 # load idt with 0,0
xorl %eax, %eax # Compute gdt_base
movw %ds, %ax # (Convert %ds:gdt to a linear ptr)
shll $4, %eax
addl %eax, code32
addl $gdt, %eax
movl %eax, (gdt_48+2)
lgdt gdt_48 # load gdt with whatever is
@ -851,9 +847,26 @@ flush_instr:
# Manual, Mixing 16-bit and 32-bit code, page 16-6)
.byte 0x66, 0xea # prefix + jmpi-opcode
code32: .long 0x1000 # will be set to 0x100000
# for big kernels
code32: .long startup_32 # will be set to %cs+startup_32
.word __BOOT_CS
.code32
startup_32:
movl $(__BOOT_DS), %eax
movl %eax, %ds
movl %eax, %es
movl %eax, %fs
movl %eax, %gs
movl %eax, %ss
xorl %eax, %eax
1: incl %eax # check that A20 really IS enabled
movl %eax, 0x00000000 # loop forever if it isn't
cmpl %eax, 0x00100000
je 1b
# Jump to the 32bit entry point
jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi)
.code16
# Here's a bunch of information about your current kernel..
kernel_version: .ascii UTS_RELEASE

3
include/linux/screen_info.h
View File

@ -42,7 +42,8 @@ struct screen_info {
u16 pages; /* 0x32 */
u16 vesa_attributes; /* 0x34 */
u32 capabilities; /* 0x36 */
/* 0x3a -- 0x3f reserved for future expansion */
/* 0x3a -- 0x3b reserved for future expansion */
/* 0x3c -- 0x3f micro stack for relocatable kernels */
};
extern struct screen_info screen_info;