linux/arch/um/kernel/exec.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

99 lines
2.1 KiB
C

/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include "linux/stddef.h"
#include "linux/fs.h"
#include "linux/smp_lock.h"
#include "linux/ptrace.h"
#include "linux/sched.h"
#include "asm/current.h"
#include "asm/processor.h"
#include "asm/uaccess.h"
#include "as-layout.h"
#include "mem_user.h"
#include "skas.h"
#include "os.h"
void flush_thread(void)
{
void *data = NULL;
int ret;
arch_flush_thread(&current->thread.arch);
ret = unmap(&current->mm->context.id, 0, STUB_START, 0, &data);
ret = ret || unmap(&current->mm->context.id, STUB_END,
host_task_size - STUB_END, 1, &data);
if (ret) {
printk(KERN_ERR "flush_thread - clearing address space failed, "
"err = %d\n", ret);
force_sig(SIGKILL, current);
}
__switch_mm(&current->mm->context.id);
}
void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp)
{
set_fs(USER_DS);
PT_REGS_IP(regs) = eip;
PT_REGS_SP(regs) = esp;
}
#ifdef CONFIG_TTY_LOG
extern void log_exec(char **argv, void *tty);
#endif
static long execve1(char *file, char __user * __user *argv,
char __user *__user *env)
{
long error;
#ifdef CONFIG_TTY_LOG
struct tty_struct *tty;
mutex_lock(&tty_mutex);
tty = get_current_tty();
if (tty)
log_exec(argv, tty);
mutex_unlock(&tty_mutex);
#endif
error = do_execve(file, argv, env, &current->thread.regs);
if (error == 0) {
task_lock(current);
current->ptrace &= ~PT_DTRACE;
#ifdef SUBARCH_EXECVE1
SUBARCH_EXECVE1(&current->thread.regs.regs);
#endif
task_unlock(current);
}
return error;
}
long um_execve(char *file, char __user *__user *argv, char __user *__user *env)
{
long err;
err = execve1(file, argv, env);
if (!err)
UML_LONGJMP(current->thread.exec_buf, 1);
return err;
}
long sys_execve(char __user *file, char __user *__user *argv,
char __user *__user *env)
{
long error;
char *filename;
lock_kernel();
filename = getname(file);
error = PTR_ERR(filename);
if (IS_ERR(filename)) goto out;
error = execve1(filename, argv, env);
putname(filename);
out:
unlock_kernel();
return error;
}