lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

uml: runtime host VMSPLIT detection

Browse Source 
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>
This commit is contained in:
Jeff Dike
2008-02-08 04:22:07 -08:00
committed by Linus Torvalds
parent 2f569afd9c
commit 536788fe2d
15 changed files with 153 additions and 75 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
arch/um/kernel/um_arch.c
View File

@@ -241,6 +241,11 @@ static struct notifier_block panic_exit_notifier = {
};
/* 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);
@@ -267,6 +272,13 @@ int __init linux_main(int argc, char **argv)
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();
@@ -303,7 +315,7 @@ int __init linux_main(int argc, char **argv)
highmem = 0;
iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
max_physmem = CONFIG_TOP_ADDR - uml_physmem - iomem_size - MIN_VMALLOC;
max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
/*
* Zones have to begin on a 1 << MAX_ORDER page boundary,
@@ -335,7 +347,7 @@ int __init linux_main(int argc, char **argv)
}
virtmem_size = physmem_size;
avail = CONFIG_TOP_ADDR - start_vm;
avail = TASK_SIZE - start_vm;
if (physmem_size > avail)
virtmem_size = avail;
end_vm = start_vm + virtmem_size;