linux/arch/um/kernel/um_arch.c
Tom Spink 40fb16a360 uml: deal with inaccessible address space start
This patch makes os_get_task_size locate the bottom of the address space,
as well as the top.  This is for systems which put a lower limit on mmap
addresses.  It works by manually scanning pages from zero onwards until a
valid page is found.

Because the bottom of the address space may not be zero, it's not
sufficient to assume the top of the address space is the size of the
address space.  The size is the difference between the top address and
bottom address.

[jdike@addtoit.com: changed the name to reflect that this function is
supposed to return the top of the process address space, not its size and
changed the return value to reflect that.  Also some minor formatting
changes]
Signed-off-by: Tom Spink <tspink@gmail.com>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-06 11:29:10 -07:00

403 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 const 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'\n");
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) {
size_t 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 long stack;
unsigned int i;
int 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_top_address();
/*
* 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;
stack = (unsigned long) argv;
stack &= ~(1024 * 1024 - 1);
avail = stack - 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