From 536788fe2d28e11db6aeda74207d95d750fb761f Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Fri, 8 Feb 2008 04:22:07 -0800 Subject: 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 Cc: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/exec.c | 2 +- arch/um/kernel/um_arch.c | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 3 deletions(-) (limited to 'arch/um/kernel') diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c index 76a62c0cb2b..f5d7f4569ba 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 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; -- cgit v1.2.3