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Enhance documentation for process flow and testing.

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Include some notes for compressing kernels from Linux 2.4.x.

committer: jreiser <jreiser> 1103513947 +0000
This commit is contained in:
John Reiser 2004-12-20 03:39:07 +00:00
parent 0516d8260c
commit f0c21c7203
1 changed files with 65 additions and 6 deletions
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71
src/p_vmlinx.cpp
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@ -482,12 +482,16 @@ void PackVmlinuxI386::unpack(OutputFile *fo)
// @:
//
//$(obj)/upx-piggy.o: vmlinux FORCE
// rm -f $(obj)/upx-piggy.o
// upx -o $(obj)/upx-piggy.o $<
// rm -f $@
// upx --best -o $@ $<
//-----
//
//----- arch/i386/boot/compressed/upx-head.S
//#include <asm/segment.h>
//#ifndef __BOOT_CS /* Linux 2.4.x */
//#define __BOOT_CS __KERNEL_CS
//#define __BOOT_DS __KERNEL_DS
//#endif
//
// .text
//startup_32: .globl startup_32 # In: %esi=0x90000 setup data "real_mode pointer"
@ -518,11 +522,65 @@ void PackVmlinuxI386::unpack(OutputFile *fo)
///* Fall into .text of upx-compressed vmlinux. */
//-----
// Approximate translation for Linux 2.4.x:
// - - -
// arch/i386/Makefile: LD_FLAGS=-e startup_32
//----- arch/i386/boot/compressed/Makefile
//# linux/arch/i386/boot/compressed/Makefile
//#
//# create a compressed vmlinux image from the original vmlinux
//#
//
//HEAD = upx-head.o
//SYSTEM = $(TOPDIR)/vmlinux
//
//OBJECTS = $(HEAD)
//
//ZLDFLAGS = -e startup_32
//
//#
//# ZIMAGE_OFFSET is the load offset of the compression loader
//# BZIMAGE_OFFSET is the load offset of the high loaded compression loader
//#
//ZIMAGE_OFFSET = 0x1000
//BZIMAGE_OFFSET = 0x100000
//
//ZLINKFLAGS = -Ttext $(ZIMAGE_OFFSET) $(ZLDFLAGS)
//BZLINKFLAGS = -Ttext $(BZIMAGE_OFFSET) $(ZLDFLAGS)
//
//all: vmlinux
//
//vmlinux: upx-piggy.o $(OBJECTS)
// $(LD) $(ZLINKFLAGS) -o vmlinux $(OBJECTS) upx-piggy.o
//
//bvmlinux: upx-piggy.o $(OBJECTS)
// $(LD) $(BZLINKFLAGS) -o bvmlinux $(OBJECTS) upx-piggy.o
//
//upx-piggy.o: $(SYSTEM)
// $(RM) -f $@
// upx --best -o $@ $<
//
//clean:
// rm -f vmlinux bvmlinux _tmp_*
//-----
//
// Example test jig:
// gcc -o test-piggy -nostartfiles -nostdlib test-piggy.o piggy.o
// gdb test-piggy
// $ gcc -o test-piggy -nostartfiles -nostdlib test-piggy.o piggy.o
// $ gdb test-piggy
// (gdb) run >dumped
// (gdb) /* Execute [single step, etc.; the decompressor+unfilter moves!]
// * until reaching the 'lret' at the end of unfilter.
// */
// (gdb) set $pc= &dump
// (gdb) stepi
// (gdb) set $edx=<actual_uncompressed_length>
// (gdb) continue
// (gdb) q
// $ # Compare file 'dumped' with the portion of vmlinux that made piggy.o.
// $ dd if=vmlinux bs=<leader_size> skip=1 | cmp - dumped
// cmp: EOF on dumped
// $
//----- test-piggy.S
//#include <asm/mman.h>
//#include <asm/unistd.h>
@ -550,9 +608,10 @@ void PackVmlinuxI386::unpack(OutputFile *fo)
// pushl $0
// pushl $ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED
// pushl $ PROT_EXEC | PROT_WRITE | PROT_READ
// pushl $0x600000 # 6MB
// pushl $0x100000 # 1MB
// pushl $0x600000 # 6MB length
// pushl $0x100000 # 1MB address
// call mmap
// leal -0x9000(%esp),%esi # expect "lea 0x9000(%esi),%esp" later
// push %cs
///* Fall into .text of upx-compressed vmlinux. */
//-----