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[PATCH] i386: Relocatable kernel support

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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
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12
arch/i386/Kconfig
View File

@ -773,6 +773,18 @@ config CRASH_DUMP
PHYSICAL_START. PHYSICAL_START.
For more details see Documentation/kdump/kdump.txt 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 config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP) 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 LDFLAGS := -m elf_i386
OBJCOPYFLAGS := -O binary -R .note -R .comment -S OBJCOPYFLAGS := -O binary -R .note -R .comment -S
LDFLAGS_vmlinux := ifdef CONFIG_RELOCATABLE
LDFLAGS_vmlinux := --emit-relocs
endif
CHECKFLAGS += -D__i386__ CHECKFLAGS += -D__i386__
CFLAGS += -pipe -msoft-float 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 # 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 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) $(call if_changed,ld)
@: @:
$(obj)/vmlinux.bin: vmlinux FORCE $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy) $(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 $(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
$(call if_changed,gzip) $(call if_changed,gzip)
endif
LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T 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) $(call if_changed,ld)

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

@ -25,9 +25,11 @@
#include <linux/linkage.h> #include <linux/linkage.h>
#include <asm/segment.h> #include <asm/segment.h>
#include <asm/page.h>
.section ".text.head"
.globl startup_32 .globl startup_32
startup_32: startup_32:
cld cld
cli cli
@ -36,93 +38,141 @@ startup_32:
movl %eax,%es movl %eax,%es
movl %eax,%fs movl %eax,%fs
movl %eax,%gs movl %eax,%gs
movl %eax,%ss
lss stack_start,%esp /* Calculate the delta between where we were compiled to run
xorl %eax,%eax * at and where we were actually loaded at. This can only be done
1: incl %eax # check that A20 really IS enabled * with a short local call on x86. Nothing else will tell us what
movl %eax,0x000000 # loop forever if it isn't * address we are running at. The reserved chunk of the real-mode
cmpl %eax,0x100000 * data at 0x34-0x3f are used as the stack for this calculation.
je 1b * 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 * Jump to the relocated address.
* confuse the debugger if this code is traced.
* XXX - best to initialize before switching to protected mode.
*/ */
pushl $0 leal relocated(%ebx), %eax
popfl jmp *%eax
.section ".text"
relocated:
/* /*
* Clear BSS * Clear BSS
*/ */
xorl %eax,%eax xorl %eax,%eax
movl $_edata,%edi leal _edata(%ebx),%edi
movl $_end,%ecx leal _end(%ebx), %ecx
subl %edi,%ecx subl %edi,%ecx
cld cld
rep rep
stosb stosb
/*
* Setup the stack for the decompressor
*/
leal stack_end(%ebx), %esp
/* /*
* Do the decompression, and jump to the new kernel.. * Do the decompression, and jump to the new kernel..
*/ */
subl $16,%esp # place for structure on the stack movl output_len(%ebx), %eax
movl %esp,%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 %esi # real mode pointer as second arg
pushl %eax # address of structure as first arg
call decompress_kernel call decompress_kernel
orl %eax,%eax addl $20, %esp
jnz 3f popl %ecx
popl %esi # discard address
popl %esi # real mode pointer #if CONFIG_RELOCATABLE
xorl %ebx,%ebx /* Find the address of the relocations.
ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START */
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. * Process relocations.
* 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.
*/ */
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 1: subl $4, %edi
popl %ebx # real mode pointer movl 0(%edi), %ecx
popl %esi # low_buffer_start testl %ecx, %ecx
popl %ecx # lcount jz 2f
popl %edx # high_buffer_start addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
popl %eax # hcount jmp 1b
movl $CONFIG_PHYSICAL_START,%edi 2:
cli # make sure we don't get interrupted #endif
ljmp $(__BOOT_CS), $0x1000 # and jump to the move routine
/* /*
* Routine (template) for moving the decompressed kernel in place, * Jump to the decompressed kernel.
* if we were high loaded. This _must_ PIC-code !
*/ */
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 xorl %ebx,%ebx
ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START jmp *%ebp
move_routine_end:
.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/vmalloc.h>
#include <linux/screen_info.h> #include <linux/screen_info.h>
#include <asm/io.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 * gzip declarations
@ -29,15 +111,20 @@ typedef unsigned char uch;
typedef unsigned short ush; typedef unsigned short ush;
typedef unsigned long ulg; typedef unsigned long ulg;
#define WSIZE 0x8000 /* Window size must be at least 32k, */ #define WSIZE 0x80000000 /* Window size must be at least 32k,
/* and a power of two */ * 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 *inbuf; /* input buffer */
static uch window[WSIZE]; /* Sliding window buffer */ static uch *window; /* Sliding window buffer, (and final output buffer) */
static unsigned insize = 0; /* valid bytes in inbuf */ static unsigned insize; /* valid bytes in inbuf */
static unsigned inptr = 0; /* index of next byte to be processed in inbuf */ static unsigned inptr; /* index of next byte to be processed in inbuf */
static unsigned outcnt = 0; /* bytes in output buffer */ static unsigned outcnt; /* bytes in output buffer */
/* gzip flag byte */ /* gzip flag byte */
#define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */ #define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */
@ -88,8 +175,6 @@ extern unsigned char input_data[];
extern int input_len; extern int input_len;
static long bytes_out = 0; static long bytes_out = 0;
static uch *output_data;
static unsigned long output_ptr = 0;
static void *malloc(int size); static void *malloc(int size);
static void free(void *where); static void free(void *where);
@ -99,17 +184,10 @@ static void *memcpy(void *dest, const void *src, unsigned n);
static void putstr(const char *); static void putstr(const char *);
extern int end; static unsigned long free_mem_ptr;
static long free_mem_ptr = (long)&end; static unsigned long free_mem_end_ptr;
static long free_mem_end_ptr;
#define INPLACE_MOVE_ROUTINE 0x1000
#define LOW_BUFFER_START 0x2000
#define LOW_BUFFER_MAX 0x90000
#define HEAP_SIZE 0x3000 #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 char *vidmem = (char *)0xb8000;
static int vidport; static int vidport;
@ -150,7 +228,7 @@ static void gzip_mark(void **ptr)
static void gzip_release(void **ptr) static void gzip_release(void **ptr)
{ {
free_mem_ptr = (long) *ptr; free_mem_ptr = (unsigned long) *ptr;
} }
static void scroll(void) static void scroll(void)
@ -178,7 +256,7 @@ static void putstr(const char *s)
y--; y--;
} }
} else { } else {
vidmem [ ( x + cols * y ) * 2 ] = c; vidmem [ ( x + cols * y ) * 2 ] = c;
if ( ++x >= cols ) { if ( ++x >= cols ) {
x = 0; x = 0;
if ( ++y >= lines ) { if ( ++y >= lines ) {
@ -223,58 +301,31 @@ static void* memcpy(void* dest, const void* src, unsigned n)
*/ */
static int fill_inbuf(void) static int fill_inbuf(void)
{ {
if (insize != 0) { error("ran out of input data");
error("ran out of input data"); return 0;
}
inbuf = input_data;
insize = input_len;
inptr = 1;
return inbuf[0];
} }
/* =========================================================================== /* ===========================================================================
* Write the output window window[0..outcnt-1] and update crc and bytes_out. * Write the output window window[0..outcnt-1] and update crc and bytes_out.
* (Used for the decompressed data only.) * (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) static void flush_window(void)
{ {
if (high_loaded) flush_window_high(); /* With my window equal to my output buffer
else flush_window_low(); * 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) static void error(char *x)
@ -286,66 +337,8 @@ static void error(char *x)
while(1); /* Halt */ while(1); /* Halt */
} }
#define STACK_SIZE (4096) asmlinkage void decompress_kernel(void *rmode, unsigned long end,
uch *input_data, unsigned long input_len, uch *output)
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)
{ {
real_mode = rmode; real_mode = rmode;
@ -360,13 +353,25 @@ asmlinkage int decompress_kernel(struct moveparams *mv, void *rmode)
lines = RM_SCREEN_INFO.orig_video_lines; lines = RM_SCREEN_INFO.orig_video_lines;
cols = RM_SCREEN_INFO.orig_video_cols; cols = RM_SCREEN_INFO.orig_video_cols;
if (free_mem_ptr < 0x100000) setup_normal_output_buffer(); window = output; /* Output buffer (Normally at 1M) */
else setup_output_buffer_if_we_run_high(mv); 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(); makecrc();
putstr("Uncompressing Linux... "); putstr("Uncompressing Linux... ");
gunzip(); gunzip();
putstr("Ok, booting the kernel.\n"); putstr("Ok, booting the kernel.\n");
if (high_loaded) close_output_buffer_if_we_run_high(mv); return;
return high_loaded;
} }

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 SECTIONS
{ {
.data : { .data.compressed : {
input_len = .; input_len = .;
LONG(input_data_end - input_data) input_data = .; LONG(input_data_end - input_data) input_data = .;
*(.data) *(.data)
output_len = . - 4;
input_data_end = .; input_data_end = .;
} }
} }

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

@ -588,11 +588,6 @@ rmodeswtch_normal:
call default_switch call default_switch
rmodeswtch_end: 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 # 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 ... # big-kernel. In that case we *must* not move it ...
testb $LOADED_HIGH, %cs:loadflags testb $LOADED_HIGH, %cs:loadflags
@ -788,11 +783,12 @@ a20_err_msg:
a20_done: a20_done:
#endif /* CONFIG_X86_VOYAGER */ #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 lidt idt_48 # load idt with 0,0
xorl %eax, %eax # Compute gdt_base xorl %eax, %eax # Compute gdt_base
movw %ds, %ax # (Convert %ds:gdt to a linear ptr) movw %ds, %ax # (Convert %ds:gdt to a linear ptr)
shll $4, %eax shll $4, %eax
addl %eax, code32
addl $gdt, %eax addl $gdt, %eax
movl %eax, (gdt_48+2) movl %eax, (gdt_48+2)
lgdt gdt_48 # load gdt with whatever is 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) # Manual, Mixing 16-bit and 32-bit code, page 16-6)
.byte 0x66, 0xea # prefix + jmpi-opcode .byte 0x66, 0xea # prefix + jmpi-opcode
code32: .long 0x1000 # will be set to 0x100000 code32: .long startup_32 # will be set to %cs+startup_32
# for big kernels
.word __BOOT_CS .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.. # Here's a bunch of information about your current kernel..
kernel_version: .ascii UTS_RELEASE kernel_version: .ascii UTS_RELEASE

3
include/linux/screen_info.h
View File

@ -42,7 +42,8 @@ struct screen_info {
u16 pages; /* 0x32 */ u16 pages; /* 0x32 */
u16 vesa_attributes; /* 0x34 */ u16 vesa_attributes; /* 0x34 */
u32 capabilities; /* 0x36 */ 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; extern struct screen_info screen_info;