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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: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2009-05-08 17:42:16 -07:00
parent 36d3793c94
commit 02a884c0fe
5 changed files with 123 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
arch/x86/boot/compressed/Makefile
View File

@ -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)

24
arch/x86/boot/compressed/head_32.S
View File

@ -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

41
arch/x86/boot/compressed/head_64.S
View File

@ -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

97
arch/x86/boot/compressed/mkpiggy.c Normal file
View File

@ -0,0 +1,97 @@
/* ----------------------------------------------------------------------- *
*
* 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;
}

10
arch/x86/boot/compressed/vmlinux.scr
View File

@ -1,10 +0,0 @@
SECTIONS
{
.rodata.compressed : {
input_len = .;
LONG(input_data_end - input_data) input_data = .;
*(.data)
output_len = . - 4;
input_data_end = .;
}
}