linux/arch/um/include/as-layout.h
Jeff Dike 536788fe2d uml: runtime host VMSPLIT detection
Calculate TASK_SIZE at run-time by figuring out the host's VMSPLIT - this is
needed on i386 if UML is to run on hosts with varying VMSPLITs without
recompilation.

TASK_SIZE is now defined in terms of a variable, task_size.  This gets rid of
an include of pgtable.h from processor.h, which can cause include loops.

On i386, task_size is calculated early in boot by probing the address space in
a binary search to figure out where the boundary between usable and non-usable
memory is.  This tries to make sure that a page that is considered to be in
userspace is, or can be made, read-write.  I'm concerned about a system-global
VDSO page in kernel memory being hit and considered to be a userspace page.

On x86_64, task_size is just the old value of CONFIG_TOP_ADDR.

A bunch of config variable are gone now.  CONFIG_TOP_ADDR is directly replaced
by TASK_SIZE.  NEST_LEVEL is gone since the relocation of the stubs makes it
irrelevant.  All the HOST_VMSPLIT stuff is gone.  All references to these in
arch/um/Makefile are also gone.

I noticed and fixed a missing extern in os.h when adding os_get_task_size.

Note: This has been revised to fix the 32-bit UML on 64-bit host bug that
Miklos ran into.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:42 -08:00

69 lines
1.6 KiB
C

/*
* Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#ifndef __START_H__
#define __START_H__
#include "uml-config.h"
#include "kern_constants.h"
/*
* Stolen from linux/const.h, which can't be directly included since
* this is used in userspace code, which has no access to the kernel
* headers. Changed to be suitable for adding casts to the start,
* rather than "UL" to the end.
*/
/* Some constant macros are used in both assembler and
* C code. Therefore we cannot annotate them always with
* 'UL' and other type specifiers unilaterally. We
* use the following macros to deal with this.
*/
#ifdef __ASSEMBLY__
#define _AC(X, Y) (Y)
#else
#define __AC(X, Y) (X (Y))
#define _AC(X, Y) __AC(X, Y)
#endif
#define STUB_START _AC(, 0x100000)
#define STUB_CODE _AC((unsigned long), STUB_START)
#define STUB_DATA _AC((unsigned long), STUB_CODE + UM_KERN_PAGE_SIZE)
#define STUB_END _AC((unsigned long), STUB_DATA + UM_KERN_PAGE_SIZE)
#ifndef __ASSEMBLY__
#include "sysdep/ptrace.h"
struct cpu_task {
int pid;
void *task;
};
extern struct cpu_task cpu_tasks[];
extern unsigned long low_physmem;
extern unsigned long high_physmem;
extern unsigned long uml_physmem;
extern unsigned long uml_reserved;
extern unsigned long end_vm;
extern unsigned long start_vm;
extern unsigned long long highmem;
extern unsigned long _stext, _etext, _sdata, _edata, __bss_start, _end;
extern unsigned long _unprotected_end;
extern unsigned long brk_start;
extern unsigned long host_task_size;
extern int linux_main(int argc, char **argv);
extern void (*sig_info[])(int, struct uml_pt_regs *);
#endif
#endif