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btxldr: future-proof argument passing from boot1/2-ish to loader

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Place the arguments at a fixed offset of 0x800 withing the argument area
(of size 0x1000).  Allow variable size extended arguments first of which
should be a size of the extended arguments (including the size
parameter).

Consolidate all related definitions in a new i386/common/bootargs.h header.

Many thanks to jhb and bde for their guidance and reviews.

Reviewed by:	jhb, bde
Approved by:	jhb
MFC after:	1 month
This commit is contained in:
avg 2012-05-09 08:04:29 +00:00
parent c4c31a507d
commit a5d68259c2
9 changed files with 99 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
sys/boot/i386/btx/btx/Makefile
View File

@ -12,6 +12,7 @@ BOOT_BTX_FLAGS=0x0
.endif
CFLAGS+=-DBTX_FLAGS=${BOOT_BTX_FLAGS}
CFLAGS+=-I${.CURDIR}/../../common
.if defined(BTX_SERIAL)
BOOT_COMCONSOLE_PORT?= 0x3f8

4
sys/boot/i386/btx/btx/btx.S
View File

@ -15,6 +15,8 @@
* $FreeBSD$
*/
#include <bootargs.h>
/*
* Memory layout.
*/
@ -205,7 +207,7 @@ init.8: xorl %ecx,%ecx # Zero
movl $MEM_USR,%edx # User base address
movzwl %ss:BDA_MEM,%eax # Get free memory
shll $0xa,%eax # To bytes
subl $0x1000,%eax # Less arg space
subl $ARGSPACE,%eax # Less arg space
subl %edx,%eax # Less base
movb $SEL_UDATA,%cl # User data selector
pushl %ecx # Set SS

1
sys/boot/i386/btx/btxldr/Makefile
View File

@ -6,6 +6,7 @@ NO_MAN=
SRCS= btxldr.S
CFLAGS+=-DLOADER_ADDRESS=${LOADER_ADDRESS}
CFLAGS+=-I${.CURDIR}/../../common
.if defined(BTXLDR_VERBOSE)
CFLAGS+=-DBTXLDR_VERBOSE

22
sys/boot/i386/btx/btxldr/btxldr.S
View File

@ -15,6 +15,8 @@
* $FreeBSD$
*/
#include <bootargs.h>
#define RBX_MUTE 0x10 /* -m */
#define OPT_SET(opt) (1 << (opt))
@ -89,7 +91,7 @@ start: cld # String ops inc
call hexout # stack
call putstr # pointer
movl $m_args,%esi # Format string
leal 0x4(%esp,1),%ebx # First argument
leal 0x4(%esp),%ebx # First argument
movl $0x6,%ecx # Count
start.1: movl (%ebx),%eax # Get argument and
addl $0x4,%ebx # bump pointer
@ -97,24 +99,28 @@ start.1: movl (%ebx),%eax # Get argument and
loop start.1 # Till done
call putstr # End message
#endif
movl $0x48,%ecx # Allocate space
subl %ecx,%ebp # for bootinfo
movl 0x18(%esp,1),%esi # Source: bootinfo
movl BA_BOOTINFO+4(%esp),%esi # Source: bootinfo
cmpl $0x0, %esi # If the bootinfo pointer
je start_null_bi # is null, don't copy it
movl BI_SIZE(%esi),%ecx # Allocate space
subl %ecx,%ebp # for bootinfo
movl %ebp,%edi # Destination
rep # Copy
movsb # it
movl %ebp,0x18(%esp,1) # Update pointer
movl %ebp,BA_BOOTINFO+4(%esp) # Update pointer
movl %edi,%ebp # Restore base pointer
#ifdef BTXLDR_VERBOSE
movl $m_rel_bi,%esi # Display
movl %ebp,%eax # bootinfo
call hexout # relocation
call putstr # message
#endif
start_null_bi: movl $0x18,%ecx # Allocate space
subl %ecx,%ebp # for arguments
leal 0x4(%esp,1),%esi # Source
start_null_bi: movl $BOOTARGS_SIZE,%ecx # Fixed size of arguments
testl $KARGS_FLAGS_EXTARG, BA_BOOTFLAGS+4(%esp) # Check for extra data
jz start_fixed # Skip if the flag is not set
addl BOOTARGS_SIZE+4(%esp),%ecx # Add size of variable args
start_fixed: subl $ARGOFF,%ebp # Place args at fixed offset
leal 0x4(%esp),%esi # Source
movl %ebp,%edi # Destination
rep # Copy
movsb # them

3
sys/boot/i386/btx/lib/Makefile
View File

@ -3,7 +3,8 @@
PROG= crt0.o
INTERNALPROG=
NO_MAN=
SRCS= btxcsu.s btxsys.s btxv86.s
SRCS= btxcsu.S btxsys.s btxv86.s
CFLAGS+=-I${.CURDIR}/../../common
LDFLAGS=-Wl,-r
.include <bsd.prog.mk>

6
sys/boot/i386/btx/lib/btxcsu.s → sys/boot/i386/btx/lib/btxcsu.S
View File

@ -15,6 +15,8 @@
# $FreeBSD$
#include <bootargs.h>
#
# BTX C startup code (ELF).
#
@ -24,10 +26,6 @@
#
.global _start
#
# Constants.
#
.set ARGADJ,0xfa0 # Argument adjustment
#
# Client entry point.
#
_start: cld

69
sys/boot/i386/common/bootargs.h Normal file
View File

@ -0,0 +1,69 @@
/*-
* Copyright (c) 2012 Andriy Gapon <avg@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms are freely
* permitted provided that the above copyright notice and this
* paragraph and the following disclaimer are duplicated in all
* such forms.
*
* This software is provided "AS IS" and without any express or
* implied warranties, including, without limitation, the implied
* warranties of merchantability and fitness for a particular
* purpose.
*
* $FreeBSD$
*/
#ifndef _BOOT_I386_ARGS_H_
#define _BOOT_I386_ARGS_H_
#define KARGS_FLAGS_CD 0x1
#define KARGS_FLAGS_PXE 0x2
#define KARGS_FLAGS_ZFS 0x4
#define KARGS_FLAGS_EXTARG 0x8 /* variably sized extended argument */
#define BOOTARGS_SIZE 24 /* sizeof(struct bootargs) */
#define BA_BOOTFLAGS 8 /* offsetof(struct bootargs, bootflags) */
#define BA_BOOTINFO 20 /* offsetof(struct bootargs, bootinfo) */
#define BI_SIZE 48 /* offsetof(struct bootinfo, bi_size) */
/*
* We reserve some space above BTX allocated stack for the arguments
* and certain data that could hang off them. Currently only struct bootinfo
* is supported in that category. The bootinfo is placed at the top
* of the arguments area and the actual arguments are placed at ARGOFF offset
* from the top and grow towards the top. Hopefully we have enough space
* for bootinfo and the arguments to not run into each other.
* Arguments area below ARGOFF is reserved for future use.
*/
#define ARGSPACE 0x1000 /* total size of the BTX args area */
#define ARGOFF 0x800 /* actual args offset within the args area */
#define ARGADJ (ARGSPACE - ARGOFF)
#ifndef __ASSEMBLER__
struct bootargs
{
uint32_t howto;
uint32_t bootdev;
uint32_t bootflags;
union {
struct {
uint32_t pxeinfo;
uint32_t reserved;
};
uint64_t zfspool;
};
uint32_t bootinfo;
/*
* If KARGS_FLAGS_EXTARG is set in bootflags, then the above fields
* are followed by a uint32_t field that specifies a size of the
* extended arguments (including the size field).
*/
};
#endif /*__ASSEMBLER__*/
#endif /* !_BOOT_I386_ARGS_H_ */

23
sys/boot/i386/loader/main.c
View File

@ -39,28 +39,17 @@ __FBSDID("$FreeBSD$");
#include <sys/reboot.h>
#include "bootstrap.h"
#include "common/bootargs.h"
#include "libi386/libi386.h"
#include "btxv86.h"
#define KARGS_FLAGS_CD 0x1
#define KARGS_FLAGS_PXE 0x2
#define KARGS_FLAGS_ZFS 0x4
CTASSERT(sizeof(struct bootargs) == BOOTARGS_SIZE);
CTASSERT(offsetof(struct bootargs, bootinfo) == BA_BOOTINFO);
CTASSERT(offsetof(struct bootargs, bootflags) == BA_BOOTFLAGS);
CTASSERT(offsetof(struct bootinfo, bi_size) == BI_SIZE);
/* Arguments passed in from the boot1/boot2 loader */
static struct
{
u_int32_t howto;
u_int32_t bootdev;
u_int32_t bootflags;
union {
struct {
u_int32_t pxeinfo;
u_int32_t res2;
};
uint64_t zfspool;
};
u_int32_t bootinfo;
} *kargs;
static struct bootargs *kargs;
static u_int32_t initial_howto;
static u_int32_t initial_bootdev;

4
sys/boot/i386/zfsboot/zfsboot.c
View File

@ -41,9 +41,7 @@ __FBSDID("$FreeBSD$");
#include "drv.h"
#include "util.h"
#include "cons.h"
/* Hint to loader that we came from ZFS */
#define KARGS_FLAGS_ZFS 0x4
#include "bootargs.h"
#define PATH_DOTCONFIG "/boot.config"
#define PATH_CONFIG "/boot/config"