ELF format in bzImage backport to 2.6.24

["Corey Henderson" <corman@cormander.com>]

[-- Attachment #1: Type: text/plain, Size: 506 bytes --]

Hello,

If anyone is interested in booting a 2.6.24 kernel on both bare-metal and
within xen using the same kernel image, I went ahead and back-ported Ian
Campbell's commit to the 2.6.26 kernel to 2.6.24.7

The patch is attached. I also have Ian's backports to 2.6.25 (which is
what I used to backport to 2.6.24) so if you're interested in obtaining
those as well, let me know.

If you wish to reply to this message, please CC me as I'm not a subscriber
to the LKML.

Have a great day.

--
Corey Henderson

[-- Attachment #2: bzImage-format-2.08.patch --]
[-- Type: application/octet-stream, Size: 12468 bytes --]

diff -ruNp linux-2.6.24.7/arch/x86/boot/compressed/misc_32.c linux-2.6.24.7-new/arch/x86/boot/compressed/misc_32.c
--- linux-2.6.24.7/arch/x86/boot/compressed/misc_32.c	2008-05-06 19:22:34.000000000 -0400
+++ linux-2.6.24.7-new/arch/x86/boot/compressed/misc_32.c	2008-08-12 16:49:46.000000000 -0400
@@ -10,9 +10,12 @@
  */
 
 #undef CONFIG_PARAVIRT
+#define _ASM_DESC_H_ 1
+
 #include <linux/linkage.h>
 #include <linux/vmalloc.h>
 #include <linux/screen_info.h>
+#include <linux/elf.h>
 #include <asm/io.h>
 #include <asm/page.h>
 #include <asm/boot.h>
@@ -342,6 +345,56 @@ static void error(char *x)
 	while(1);	/* Halt */
 }
 
+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;
+		}
+
+	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, unsigned long end,
 			uch *input_data, unsigned long input_len, uch *output)
 {
@@ -377,6 +430,7 @@ asmlinkage void decompress_kernel(void *
 	makecrc();
 	putstr("Uncompressing Linux... ");
 	gunzip();
+	parse_elf(output);
 	putstr("Ok, booting the kernel.\n");
 	return;
 }
diff -ruNp linux-2.6.24.7/arch/x86/boot/header.S linux-2.6.24.7-new/arch/x86/boot/header.S
--- linux-2.6.24.7/arch/x86/boot/header.S	2008-05-06 19:22:34.000000000 -0400
+++ linux-2.6.24.7-new/arch/x86/boot/header.S	2008-08-12 16:51:15.000000000 -0400
@@ -22,6 +22,7 @@
 #include <asm/page.h>
 #include <asm/setup.h>
 #include "boot.h"
+#include "offsets.h"
 
 SETUPSECTS	= 4			/* default nr of setup-sectors */
 BOOTSEG		= 0x07C0		/* original address of boot-sector */
@@ -119,7 +120,7 @@ _start:
 	# Part 2 of the header, from the old setup.S
 
 		.ascii	"HdrS"		# header signature
-		.word	0x0207		# header version number (>= 0x0105)
+		.word	0x0208		# header version number (>= 0x0105)
 					# or else old loadlin-1.5 will fail)
 		.globl realmode_swtch
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
@@ -220,6 +221,9 @@ hardware_subarch:	.long 0			# subarchite
 
 hardware_subarch_data:	.quad 0
 
+payload_offset:		.long input_data
+payload_length:		.long input_data_end-input_data
+
 # End of setup header #####################################################
 
 	.section ".inittext", "ax"
diff -ruNp linux-2.6.24.7/arch/x86/boot/Makefile linux-2.6.24.7-new/arch/x86/boot/Makefile
--- linux-2.6.24.7/arch/x86/boot/Makefile	2008-05-06 19:22:34.000000000 -0400
+++ linux-2.6.24.7-new/arch/x86/boot/Makefile	2008-08-12 16:41:32.000000000 -0400
@@ -85,6 +85,20 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vm
 
 SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
 
+sed-offsets := -e 's/^00*/0/' \
+        -e 's/^\([0-9a-fA-F]*\) . \(input_data\|input_data_end\)$$/\#define \2 0x\1/p'
+
+quiet_cmd_offsets = OFFSETS $@
+      cmd_offsets = $(NM) $< | sed -n $(sed-offsets) > $@
+
+$(obj)/offsets.h: $(obj)/compressed/vmlinux FORCE
+	$(call if_changed,offsets)
+
+targets += offsets.h
+
+AFLAGS_header.o += -I$(obj)
+$(obj)/header.o: $(obj)/offsets.h
+
 LDFLAGS_setup.elf	:= -T
 $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE
 	$(call if_changed,ld)
diff -ruNp linux-2.6.24.7/arch/x86/boot/tools/build.c linux-2.6.24.7-new/arch/x86/boot/tools/build.c
--- linux-2.6.24.7/arch/x86/boot/tools/build.c	2008-05-06 19:22:34.000000000 -0400
+++ linux-2.6.24.7-new/arch/x86/boot/tools/build.c	2008-08-12 16:50:54.000000000 -0400
@@ -50,6 +50,75 @@ typedef unsigned long  u32;
 u8 buf[SETUP_SECT_MAX*512];
 int is_big_kernel;
 
+/*----------------------------------------------------------------------*/
+
+static const u32 crctab32[] = {
+	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
+	0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
+	0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
+	0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
+	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
+	0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+	0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
+	0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
+	0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
+	0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
+	0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
+	0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
+	0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
+	0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
+	0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
+	0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
+	0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
+	0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
+	0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
+	0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
+	0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
+	0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
+	0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
+	0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
+	0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
+	0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
+	0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
+	0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
+	0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
+	0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
+	0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
+	0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
+	0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
+	0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
+	0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
+	0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
+	0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
+	0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
+	0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
+	0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
+	0x2d02ef8d
+};
+
+static u32 partial_crc32_one(u8 c, u32 crc)
+{
+	return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
+}
+
+static u32 partial_crc32(const u8 *s, int len, u32 crc)
+{
+	while (len--)
+		crc = partial_crc32_one(*s++, crc);
+	return crc;
+}
+
 static void die(const char * str, ...)
 {
 	va_list args;
@@ -74,6 +143,7 @@ int main(int argc, char ** argv)
 	FILE *file;
 	int fd;
 	void *kernel;
+	u32 crc = 0xffffffffUL;
 
 	if (argc > 2 && !strcmp(argv[1], "-b"))
 	  {
@@ -144,7 +214,8 @@ int main(int argc, char ** argv)
 	kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
 	if (kernel == MAP_FAILED)
 		die("Unable to mmap '%s': %m", argv[2]);
-	sys_size = (sz + 15) / 16;
+	/* Number of 16-byte paragraphs, including space for a 4-byte CRC */
+	sys_size = (sz + 15 + 4) / 16;
 	if (!is_big_kernel && sys_size > DEF_SYSSIZE)
 		die("System is too big. Try using bzImage or modules.");
 
@@ -155,12 +226,27 @@ int main(int argc, char ** argv)
 	buf[0x1f6] = sys_size >> 16;
 	buf[0x1f7] = sys_size >> 24;
 
+	crc = partial_crc32(buf, i, crc);
 	if (fwrite(buf, 1, i, stdout) != i)
 		die("Writing setup failed");
 
 	/* Copy the kernel code */
+	crc = partial_crc32(kernel, sz, crc);
 	if (fwrite(kernel, 1, sz, stdout) != sz)
 		die("Writing kernel failed");
+
+	/* Add padding leaving 4 bytes for the checksum */
+	while (sz++ < (sys_size*16) - 4) {
+		crc = partial_crc32_one('\0', crc);
+		if (fwrite("\0", 1, 1, stdout) != 1)
+			die("Writing padding failed");
+	}
+
+	/* Write the CRC */
+	fprintf(stderr, "CRC %lx\n", crc);
+	if (fwrite(&crc, 1, 4, stdout) != 4)
+		die("Writing CRC failed");
+
 	close(fd);
 
 	/* Everything is OK */
diff -ruNp linux-2.6.24.7/Documentation/i386/boot.txt linux-2.6.24.7-new/Documentation/i386/boot.txt
--- linux-2.6.24.7/Documentation/i386/boot.txt	2008-05-06 19:22:34.000000000 -0400
+++ linux-2.6.24.7-new/Documentation/i386/boot.txt	2008-08-12 16:51:15.000000000 -0400
@@ -170,6 +170,8 @@ Offset	Proto	Name		Meaning
 0238/4	2.06+	cmdline_size	Maximum size of the kernel command line
 023C/4	2.07+	hardware_subarch Hardware subarchitecture
 0240/8	2.07+	hardware_subarch_data Subarchitecture-specific data
+0248/4	2.08+	payload_offset	Offset of kernel payload
+024C/4	2.08+	payload_length	Length of kernel payload
 
 (1) For backwards compatibility, if the setup_sects field contains 0, the
     real value is 4.
@@ -512,6 +514,32 @@ Protocol:	2.07+
 
   A pointer to data that is specific to hardware subarch
 
+Field name:	payload_offset
+Type:		read
+Offset/size:	0x248/4
+Protocol:	2.08+
+
+  If non-zero then this field contains the offset from the end of the
+  real-mode code to the payload.
+
+  The payload may be compressed. The format of both the compressed and
+  uncompressed data should be determined using the standard magic
+  numbers. Currently only gzip compressed ELF is used.
+  
+Field name:	payload_length
+Type:		read
+Offset/size:	0x24c/4
+Protocol:	2.08+
+
+  The length of the payload.
+
+**** THE IMAGE CHECKSUM
+
+From boot protocol version 2.08 onwards the CRC-32 is calculated over
+the entire file using the characteristic polynomial 0x04C11DB7 and an
+initial remainder of 0xffffffff.  The checksum is appended to the
+file; therefore the CRC of the file up to the limit specified in the
+syssize field of the header is always 0.
 
 **** THE KERNEL COMMAND LINE
 
--- a/arch/x86/Makefile_32	2008-05-06 19:22:34.000000000 -0400
+++ b/arch/x86/Makefile_32	2008-08-12 17:57:15.000000000 -0400
@@ -31,7 +31,6 @@
 endif
 
 LDFLAGS		:= -m elf_i386
-OBJCOPYFLAGS	:= -O binary -R .note -R .comment -S
 ifdef CONFIG_RELOCATABLE
 LDFLAGS_vmlinux := --emit-relocs
 endif
--- a/arch/x86/boot/Makefile	2008-08-13 00:57:46.000000000 -0400
+++ b/arch/x86/boot/Makefile	2008-08-12 17:58:34.000000000 -0400
@@ -80,6 +80,7 @@
 	$(call if_changed,image)
 	@echo 'Kernel: $@ is ready' ' (#'`cat .version`')'
 
+OBJCOPYFLAGS_vmlinux.bin := -O binary -R .note -R .comment -S
 $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
 	$(call if_changed,objcopy)
 
@@ -104,7 +105,6 @@
 	$(call if_changed,ld)
 
 OBJCOPYFLAGS_setup.bin	:= -O binary
-
 $(obj)/setup.bin: $(obj)/setup.elf FORCE
 	$(call if_changed,objcopy)
 
--- a/arch/x86/boot/compressed/Makefile_32	2008-05-06 19:22:34.000000000 -0400
+++ b/arch/x86/boot/compressed/Makefile_32	2008-08-12 18:01:58.000000000 -0400
@@ -11,7 +11,7 @@
 LDFLAGS_vmlinux := -T
 hostprogs-y	:= relocs
 
-KBUILD_CFLAGS  := -m32 -D__KERNEL__ $(LINUX_INCLUDE) -O2 \
+KBUILD_CFLAGS  := -m32 -D__KERNEL__ $(LINUX_INCLUDE) -Iinclude/asm/mach-generic/ -O2 \
 	   -fno-strict-aliasing -fPIC \
 	   $(call cc-option,-ffreestanding) \
 	   $(call cc-option,-fno-stack-protector)
@@ -21,6 +21,7 @@
 	$(call if_changed,ld)
 	@:
 
+OBJCOPYFLAGS_vmlinux.bin := -R .comment -S
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)