linux/arch/um/kernel/um_arch.c
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

399 lines
8.8 KiB
C

/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/utsname.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/setup.h>
#include "as-layout.h"
#include "arch.h"
#include "init.h"
#include "kern.h"
#include "kern_util.h"
#include "mem_user.h"
#include "os.h"
#define DEFAULT_COMMAND_LINE "root=98:0"
/* Changed in add_arg and setup_arch, which run before SMP is started */
static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };
static void __init add_arg(char *arg)
{
if (strlen(command_line) + strlen(arg) + 1 > COMMAND_LINE_SIZE) {
printf("add_arg: Too many command line arguments!\n");
exit(1);
}
if (strlen(command_line) > 0)
strcat(command_line, " ");
strcat(command_line, arg);
}
/*
* These fields are initialized at boot time and not changed.
* XXX This structure is used only in the non-SMP case. Maybe this
* should be moved to smp.c.
*/
struct cpuinfo_um boot_cpu_data = {
.loops_per_jiffy = 0,
.ipi_pipe = { -1, -1 }
};
unsigned long thread_saved_pc(struct task_struct *task)
{
/* FIXME: Need to look up userspace_pid by cpu */
return os_process_pc(userspace_pid[0]);
}
/* Changed in setup_arch, which is called in early boot */
static char host_info[(__NEW_UTS_LEN + 1) * 5];
static int show_cpuinfo(struct seq_file *m, void *v)
{
int index = 0;
#ifdef CONFIG_SMP
index = (struct cpuinfo_um *) v - cpu_data;
if (!cpu_online(index))
return 0;
#endif
seq_printf(m, "processor\t: %d\n", index);
seq_printf(m, "vendor_id\t: User Mode Linux\n");
seq_printf(m, "model name\t: UML\n");
seq_printf(m, "mode\t\t: skas\n");
seq_printf(m, "host\t\t: %s\n", host_info);
seq_printf(m, "bogomips\t: %lu.%02lu\n\n",
loops_per_jiffy/(500000/HZ),
(loops_per_jiffy/(5000/HZ)) % 100);
return 0;
}
static void *c_start(struct seq_file *m, loff_t *pos)
{
return *pos < NR_CPUS ? cpu_data + *pos : NULL;
}
static void *c_next(struct seq_file *m, void *v, loff_t *pos)
{
++*pos;
return c_start(m, pos);
}
static void c_stop(struct seq_file *m, void *v)
{
}
const struct seq_operations cpuinfo_op = {
.start = c_start,
.next = c_next,
.stop = c_stop,
.show = show_cpuinfo,
};
/* Set in linux_main */
unsigned long uml_physmem;
unsigned long uml_reserved; /* Also modified in mem_init */
unsigned long start_vm;
unsigned long end_vm;
/* Set in uml_ncpus_setup */
int ncpus = 1;
/* Set in early boot */
static int have_root __initdata = 0;
/* Set in uml_mem_setup and modified in linux_main */
long long physmem_size = 32 * 1024 * 1024;
static char *usage_string =
"User Mode Linux v%s\n"
" available at http://user-mode-linux.sourceforge.net/\n\n";
static int __init uml_version_setup(char *line, int *add)
{
printf("%s\n", init_utsname()->release);
exit(0);
return 0;
}
__uml_setup("--version", uml_version_setup,
"--version\n"
" Prints the version number of the kernel.\n\n"
);
static int __init uml_root_setup(char *line, int *add)
{
have_root = 1;
return 0;
}
__uml_setup("root=", uml_root_setup,
"root=<file containing the root fs>\n"
" This is actually used by the generic kernel in exactly the same\n"
" way as in any other kernel. If you configure a number of block\n"
" devices and want to boot off something other than ubd0, you \n"
" would use something like:\n"
" root=/dev/ubd5\n\n"
);
static int __init no_skas_debug_setup(char *line, int *add)
{
printf("'debug' is not necessary to gdb UML in skas mode - run \n");
printf("'gdb linux'");
return 0;
}
__uml_setup("debug", no_skas_debug_setup,
"debug\n"
" this flag is not needed to run gdb on UML in skas mode\n\n"
);
#ifdef CONFIG_SMP
static int __init uml_ncpus_setup(char *line, int *add)
{
if (!sscanf(line, "%d", &ncpus)) {
printf("Couldn't parse [%s]\n", line);
return -1;
}
return 0;
}
__uml_setup("ncpus=", uml_ncpus_setup,
"ncpus=<# of desired CPUs>\n"
" This tells an SMP kernel how many virtual processors to start.\n\n"
);
#endif
static int __init Usage(char *line, int *add)
{
const char **p;
printf(usage_string, init_utsname()->release);
p = &__uml_help_start;
while (p < &__uml_help_end) {
printf("%s", *p);
p++;
}
exit(0);
return 0;
}
__uml_setup("--help", Usage,
"--help\n"
" Prints this message.\n\n"
);
static void __init uml_checksetup(char *line, int *add)
{
struct uml_param *p;
p = &__uml_setup_start;
while (p < &__uml_setup_end) {
int n;
n = strlen(p->str);
if (!strncmp(line, p->str, n) && p->setup_func(line + n, add))
return;
p++;
}
}
static void __init uml_postsetup(void)
{
initcall_t *p;
p = &__uml_postsetup_start;
while (p < &__uml_postsetup_end) {
(*p)();
p++;
}
return;
}
static int panic_exit(struct notifier_block *self, unsigned long unused1,
void *unused2)
{
bust_spinlocks(1);
show_regs(&(current->thread.regs));
bust_spinlocks(0);
uml_exitcode = 1;
os_dump_core();
return 0;
}
static struct notifier_block panic_exit_notifier = {
.notifier_call = panic_exit,
.next = NULL,
.priority = 0
};
/* Set during early boot */
unsigned long task_size;
EXPORT_SYMBOL(task_size);
unsigned long host_task_size;
unsigned long brk_start;
unsigned long end_iomem;
EXPORT_SYMBOL(end_iomem);
#define MIN_VMALLOC (32 * 1024 * 1024)
extern char __binary_start;
int __init linux_main(int argc, char **argv)
{
unsigned long avail, diff;
unsigned long virtmem_size, max_physmem;
unsigned int i, add;
char * mode;
for (i = 1; i < argc; i++) {
if ((i == 1) && (argv[i][0] == ' '))
continue;
add = 1;
uml_checksetup(argv[i], &add);
if (add)
add_arg(argv[i]);
}
if (have_root == 0)
add_arg(DEFAULT_COMMAND_LINE);
host_task_size = os_get_task_size();
/*
* TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
* out
*/
task_size = host_task_size & PGDIR_MASK;
/* OS sanity checks that need to happen before the kernel runs */
os_early_checks();
can_do_skas();
if (proc_mm && ptrace_faultinfo)
mode = "SKAS3";
else
mode = "SKAS0";
printf("UML running in %s mode\n", mode);
brk_start = (unsigned long) sbrk(0);
/*
* Increase physical memory size for exec-shield users
* so they actually get what they asked for. This should
* add zero for non-exec shield users
*/
diff = UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
if (diff > 1024 * 1024) {
printf("Adding %ld bytes to physical memory to account for "
"exec-shield gap\n", diff);
physmem_size += UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
}
uml_physmem = (unsigned long) &__binary_start & PAGE_MASK;
/* Reserve up to 4M after the current brk */
uml_reserved = ROUND_4M(brk_start) + (1 << 22);
setup_machinename(init_utsname()->machine);
highmem = 0;
iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
/*
* Zones have to begin on a 1 << MAX_ORDER page boundary,
* so this makes sure that's true for highmem
*/
max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER)) - 1);
if (physmem_size + iomem_size > max_physmem) {
highmem = physmem_size + iomem_size - max_physmem;
physmem_size -= highmem;
#ifndef CONFIG_HIGHMEM
highmem = 0;
printf("CONFIG_HIGHMEM not enabled - physical memory shrunk "
"to %Lu bytes\n", physmem_size);
#endif
}
high_physmem = uml_physmem + physmem_size;
end_iomem = high_physmem + iomem_size;
high_memory = (void *) end_iomem;
start_vm = VMALLOC_START;
setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
if (init_maps(physmem_size, iomem_size, highmem)) {
printf("Failed to allocate mem_map for %Lu bytes of physical "
"memory and %Lu bytes of highmem\n", physmem_size,
highmem);
exit(1);
}
virtmem_size = physmem_size;
avail = TASK_SIZE - start_vm;
if (physmem_size > avail)
virtmem_size = avail;
end_vm = start_vm + virtmem_size;
if (virtmem_size < physmem_size)
printf("Kernel virtual memory size shrunk to %lu bytes\n",
virtmem_size);
atomic_notifier_chain_register(&panic_notifier_list,
&panic_exit_notifier);
uml_postsetup();
stack_protections((unsigned long) &init_thread_info);
os_flush_stdout();
return start_uml();
}
void __init setup_arch(char **cmdline_p)
{
paging_init();
strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
*cmdline_p = command_line;
setup_hostinfo(host_info, sizeof host_info);
}
void __init check_bugs(void)
{
arch_check_bugs();
os_check_bugs();
}
void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
{
}
#ifdef CONFIG_SMP
void alternatives_smp_module_add(struct module *mod, char *name,
void *locks, void *locks_end,
void *text, void *text_end)
{
}
void alternatives_smp_module_del(struct module *mod)
{
}
#endif