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author | Jeff Dike <jdike@addtoit.com> | 2008-02-08 13:22:07 +0100 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-08 18:22:42 +0100 |
commit | 536788fe2d28e11db6aeda74207d95d750fb761f (patch) | |
tree | 73df2d3a46c542c71d3a84c20c8fd1ce617386a3 /arch/um/kernel | |
parent | CONFIG_HIGHPTE vs. sub-page page tables. (diff) | |
download | linux-536788fe2d28e11db6aeda74207d95d750fb761f.tar.xz linux-536788fe2d28e11db6aeda74207d95d750fb761f.zip |
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')
-rw-r--r-- | arch/um/kernel/exec.c | 2 | ||||
-rw-r--r-- | arch/um/kernel/um_arch.c | 16 |
2 files changed, 15 insertions, 3 deletions
diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c index 76a62c0cb2bc..f5d7f4569ba7 100644 --- a/arch/um/kernel/exec.c +++ b/arch/um/kernel/exec.c @@ -25,7 +25,7 @@ void flush_thread(void) ret = unmap(¤t->mm->context.id, 0, STUB_START, 0, &data); ret = ret || unmap(¤t->mm->context.id, STUB_END, - TASK_SIZE - STUB_END, 1, &data); + host_task_size - STUB_END, 1, &data); if (ret) { printk(KERN_ERR "flush_thread - clearing address space failed, " "err = %d\n", ret); diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index 468aba990dbd..a6c1dd1cf5a1 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; |