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 --- include/asm-um/fixmap.h | 3 ++- include/asm-um/processor-generic.h | 5 +++-- 2 files changed, 5 insertions(+), 3 deletions(-) (limited to 'include/asm-um') diff --git a/include/asm-um/fixmap.h b/include/asm-um/fixmap.h index 89a87c18b927..9d2be52b8655 100644 --- a/include/asm-um/fixmap.h +++ b/include/asm-um/fixmap.h @@ -1,6 +1,7 @@ #ifndef __UM_FIXMAP_H #define __UM_FIXMAP_H +#include #include #include #include @@ -57,7 +58,7 @@ extern void __set_fixmap (enum fixed_addresses idx, * at the top of mem.. */ -#define FIXADDR_TOP (CONFIG_TOP_ADDR - 2 * PAGE_SIZE) +#define FIXADDR_TOP (TASK_SIZE - 2 * PAGE_SIZE) #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) diff --git a/include/asm-um/processor-generic.h b/include/asm-um/processor-generic.h index 7a1624cdaf7e..bed668824b5f 100644 --- a/include/asm-um/processor-generic.h +++ b/include/asm-um/processor-generic.h @@ -11,7 +11,6 @@ struct pt_regs; struct task_struct; #include "asm/ptrace.h" -#include "asm/pgtable.h" #include "registers.h" #include "sysdep/archsetjmp.h" @@ -92,7 +91,9 @@ static inline void mm_copy_segments(struct mm_struct *from_mm, /* * User space process size: 3GB (default). */ -#define TASK_SIZE (CONFIG_TOP_ADDR & PGDIR_MASK) +extern unsigned long task_size; + +#define TASK_SIZE (task_size) #undef STACK_TOP #undef STACK_TOP_MAX -- cgit v1.2.3