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authorJeff Dike <jdike@addtoit.com>2008-02-08 04:22:07 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 09:22:42 -0800
commit536788fe2d28e11db6aeda74207d95d750fb761f (patch)
tree73df2d3a46c542c71d3a84c20c8fd1ce617386a3 /arch/um/kernel/um_arch.c
parent2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b4 (diff)
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>
Diffstat (limited to 'arch/um/kernel/um_arch.c')
-rw-r--r--arch/um/kernel/um_arch.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 468aba990db..a6c1dd1cf5a 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -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;