new file i386-linux.kernel.head-vmlinux.S

src/stub/src/i386-linux.kernel.head-vmlinux.S

@@ -0,0 +1,62 @@
+/*
+;  i386-linux.kernel.vmlinux-head.S -- set up stack for vmlinux/i386 format
+;
+;  This file is part of the UPX executable compressor.
+;
+;  Copyright (C) 2006 John Reiser
+;  All Rights Reserved.
+;
+;  UPX and the UCL library are free software; you can redistribute them
+;  and/or modify them under the terms of the GNU General Public License as
+;  published by the Free Software Foundation; either version 2 of
+;  the License, or (at your option) any later version.
+;
+;  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; see the file COPYING.
+;  If not, write to the Free Software Foundation, Inc.,
+;  59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+;
+;  John Reiser
+;  <jreiser@users.sourceforge.net>
+*/
+// In: %esi=0x90000 setup data "real_mode pointer"
+        #cli  # this must be true already
+////    .byte 0xf1  # qemu debug only
+
+        /* The only facts about segments here, that are true for all kernels:
+         * %cs is a valid "flat" code segment; no other segment reg is valid;
+         * the next segment after %cs is a valid "flat" data segment, but
+         * no segment register designates it yet.
+         */
+        movl %cs,%eax; addl $1<<3,%eax  # the next segment after %cs
+        movl %eax,%ds
+        movl %eax,%es
+        leal 0x9000(%esi),%ecx  # 0x99000 typical
+        movl %ecx,-8(%ecx)  # 32-bit offset for stack pointer
+        movl %eax,-4(%ecx)  # segment for stack pointer
+        lss -8(%ecx),%esp  # %ss:%esp= %ds:0x99000
+            /* Linux Documentation/i386/boot.txt "SAMPLE BOOT CONFIGURATION" says
+                 0x8000-0x8FFF  Stack and heap  [inside the "real mode segment",
+                 just below the command line at offset 0x9000].
+
+                 arch/i386/boot/compressed/head.S "Do the decompression ..." says
+                 %esi contains the "real mode pointer" [as a 32-bit addr].
+
+                 In any case, avoid EBDA (Extended BIOS Data Area) below 0xA0000.
+                 boot.txt says 0x9A000 is the limit.  LILO goes up to 0x9B000.
+            */
+
+        pushl $0; popf  # subsumes "cli; cld"; also clears NT for buggy BIOS
+
+        push %cs
+// PackVmlinuxI386::pack knows the format of the next two instructions.
+        movl $ ENTRY_POINT,%eax  # destination of uncompression (and entry point)
+        call COMPRESSED_LENGTH
+// Compressed data appears >here<, then decompressor.
+
+// vi:ts=8:et:nowrap