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Commit 02a884c0 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86, boot: determine compressed code offset at compile time 



Determine the compressed code offset (from the kernel runtime address)
at compile time.  This allows some minor optimizations in
arch/x86/boot/compressed/head_*.S, but more importantly it makes this
value available to the build process, which will enable a future patch
to export the necessary linear memory footprint into the bzImage
header.

[ Impact: cleanup, future patch enabling ]

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 36d3793c

arch/x86/boot/compressed/Makefile

+8 −3
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__ 
LDFLAGS := -m elf_$(UTS_MACHINE)

LDFLAGS_vmlinux := -T



hostprogs-y	:= mkpiggy



$(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o $(obj)/piggy.o FORCE

	$(call if_changed,ld)

	@:
@@ -50,6 +52,9 @@ suffix-$(CONFIG_KERNEL_GZIP) := gz 
suffix-$(CONFIG_KERNEL_BZIP2)	:= bz2

suffix-$(CONFIG_KERNEL_LZMA)	:= lzma



LDFLAGS_piggy.o := -r --format binary --oformat $(CONFIG_OUTPUT_FORMAT) -T

$(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.$(suffix-y) FORCE

	$(call if_changed,ld)
 
quiet_cmd_mkpiggy = MKPIGGY $@

      cmd_mkpiggy = $(obj)/mkpiggy $< > $@ || ( rm -f $@ ; false )



targets += piggy.S

$(obj)/piggy.S: $(obj)/vmlinux.bin.$(suffix-y) $(obj)/mkpiggy FORCE

	$(call if_changed,mkpiggy)

arch/x86/boot/compressed/head_32.S

+5 −19
Original line number Diff line number Diff line
@@ -75,18 +75,8 @@ ENTRY(startup_32) 
	movl	$LOAD_PHYSICAL_ADDR, %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

	/* Target address to relocate to for decompression */

	addl	$z_extract_offset, %ebx



	/* Set up the stack */

	leal	boot_stack_end(%ebx), %esp
@@ -142,12 +132,10 @@ relocated: 
/*

 * Do the decompression, and jump to the new kernel..

 */

	movl	output_len(%ebx), %eax

	pushl	%eax

	leal	z_extract_offset_negative(%ebx), %ebp

				/* push arguments for decompress_kernel: */

	pushl	%ebp		/* output address */

	movl	input_len(%ebx), %eax

	pushl	%eax		/* input_len */

	pushl	$z_input_len	/* input_len */

	leal	input_data(%ebx), %eax

	pushl	%eax		/* input_data */

	leal	boot_heap(%ebx), %eax
@@ -155,14 +143,12 @@ relocated: 
	pushl	%esi		/* real mode pointer */

	call	decompress_kernel

	addl	$20, %esp

	popl	%ecx



#if CONFIG_RELOCATABLE

/*

 * Find the address of the relocations.

 */

	movl	%ebp, %edi

	addl	%ecx, %edi

	leal	z_output_len(%ebp), %edi



/*

 * Calculate the delta between where vmlinux was compiled to run

arch/x86/boot/compressed/head_64.S

+13 −28
Original line number Diff line number Diff line
@@ -90,16 +90,8 @@ ENTRY(startup_32) 
	movl	$CONFIG_PHYSICAL_START, %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 and align on a 4K boundary */

	addl	$(32768 + 18 + 4095), %ebx

	andl	$~4095, %ebx

	/* Target address to relocate to for decompression */

	addl	$z_extract_offset, %ebx



/*

 * Prepare for entering 64 bit mode
@@ -224,6 +216,9 @@ ENTRY(startup_64) 
	 * If it is a relocatable kernel then decompress and run the kernel

	 * from load address aligned to 2MB addr, otherwise decompress and

	 * run the kernel from CONFIG_PHYSICAL_START

	 *

	 * We cannot rely on the calculation done in 32-bit mode, since we

	 * may have been invoked via the 64-bit entry point.

	 */



	/* Start with the delta to where the kernel will run at. */
@@ -237,17 +232,8 @@ ENTRY(startup_64) 
	movq	%rbp, %rbx

#endif



	/* Replace the compressed data size with the uncompressed size */

	movl	input_len(%rip), %eax

	subq	%rax, %rbx

	movl	output_len(%rip), %eax

	addq	%rax, %rbx

	/* Add 8 bytes for every 32K input block */

	shrq	$12, %rax

	addq	%rax, %rbx

	/* Add 32K + 18 bytes of extra slack and align on a 4K boundary */

	addq	$(32768 + 18 + 4095), %rbx

	andq	$~4095, %rbx

	/* Target address to relocate to for decompression */

	leaq	z_extract_offset(%rbp), %rbx



	/* Set up the stack */

	leaq	boot_stack_end(%rbx), %rsp
@@ -292,13 +278,12 @@ relocated: 
/*

 * Do the decompression, and jump to the new kernel..

 */

	pushq	%rsi			# Save the real mode argument

	movq	%rsi, %rdi		# real mode address

	leaq	boot_heap(%rip), %rsi	# malloc area for uncompression

	leaq	input_data(%rip), %rdx  # input_data

	movl	input_len(%rip), %eax

	movq	%rax, %rcx		# input_len

	movq	%rbp, %r8		# output

	pushq	%rsi			/* Save the real mode argument */

	movq	%rsi, %rdi		/* real mode address */

	leaq	boot_heap(%rip), %rsi	/* malloc area for uncompression */

	leaq	input_data(%rip), %rdx  /* input_data */

	movl	$z_input_len, %ecx	/* input_len */

	movq	%rbp, %r8		/* output target address */

	call	decompress_kernel

	popq	%rsi

arch/x86/boot/compressed/mkpiggy.c

0 → 100644
+97 −0
Original line number Diff line number Diff line 
/* ----------------------------------------------------------------------- *

 *

 *  Copyright (C) 2009 Intel Corporation. All rights reserved.

 *

 *  This program is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU General Public License version

 *  2 as published by the Free Software Foundation.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 *  02110-1301, USA.

 *

 *  H. Peter Anvin <hpa@linux.intel.com>

 *

 * ----------------------------------------------------------------------- */



/*

 * Compute the desired load offset from a compressed program; outputs

 * a small assembly wrapper with the appropriate symbols defined.

 */



#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <inttypes.h>



static uint32_t getle32(const void *p)

{

	const uint8_t *cp = p;



	return (uint32_t)cp[0] + ((uint32_t)cp[1] << 8) +

		((uint32_t)cp[2] << 16) + ((uint32_t)cp[3] << 24);

}



int main(int argc, char *argv[])

{

	uint32_t olen;

	long ilen;

	unsigned long offs;

	FILE *f;



	if (argc < 2) {

		fprintf(stderr, "Usage: %s compressed_file\n", argv[0]);

		return 1;

	}



	/* Get the information for the compressed kernel image first */



	f = fopen(argv[1], "r");

	if (!f) {

		perror(argv[1]);

		return 1;

	}





	if (fseek(f, -4L, SEEK_END)) {

		perror(argv[1]);

	}

	fread(&olen, sizeof olen, 1, f);

	ilen = ftell(f);

	olen = getle32(&olen);

	fclose(f);



	/*

	 * Now we have the input (compressed) and output (uncompressed)

	 * sizes, compute the necessary decompression offset...

	 */



	offs = (olen > ilen) ? olen - ilen : 0;

	offs += olen >> 12;	/* Add 8 bytes for each 32K block */

	offs += 32*1024 + 18;	/* Add 32K + 18 bytes slack */

	offs = (offs+4095) & ~4095; /* Round to a 4K boundary */



	printf(".section \".rodata.compressed\",\"a\",@progbits\n");

	printf(".globl z_input_len\n");

	printf("z_input_len = %lu\n", ilen);

	printf(".globl z_output_len\n");

	printf("z_output_len = %lu\n", (unsigned long)olen);

	printf(".globl z_extract_offset\n");

	printf("z_extract_offset = 0x%lx\n", offs);

	/* z_extract_offset_negative allows simplification of head_32.S */

	printf(".globl z_extract_offset_negative\n");

	printf("z_extract_offset_negative = -0x%lx\n", offs);



	printf(".globl input_data, input_data_end\n");

	printf("input_data:\n");

	printf(".incbin \"%s\"\n", argv[1]);

	printf("input_data_end:\n");



	return 0;

}

arch/x86/boot/compressed/vmlinux.scr

deleted100644 → 0
+0 −10
Original line number Diff line number Diff line 
SECTIONS

{

  .rodata.compressed : {

	input_len = .;

	LONG(input_data_end - input_data) input_data = .;

	*(.data)

	output_len = . - 4;

	input_data_end = .;

	}

}