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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/os-Linux/sys-x86_64 | |
| 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/os-Linux/sys-x86_64')
| -rw-r--r-- | arch/um/os-Linux/sys-x86_64/Makefile | 2 | ||||
| -rw-r--r-- | arch/um/os-Linux/sys-x86_64/task_size.c | 5 |
2 files changed, 6 insertions, 1 deletions
diff --git a/arch/um/os-Linux/sys-x86_64/Makefile b/arch/um/os-Linux/sys-x86_64/Makefile index a42a4ef02e1e..a44a47f8f57b 100644 --- a/arch/um/os-Linux/sys-x86_64/Makefile +++ b/arch/um/os-Linux/sys-x86_64/Makefile @@ -3,7 +3,7 @@ # Licensed under the GPL # -obj-y = registers.o prctl.o signal.o +obj-y = registers.o prctl.o signal.o task_size.o USER_OBJS := $(obj-y) diff --git a/arch/um/os-Linux/sys-x86_64/task_size.c b/arch/um/os-Linux/sys-x86_64/task_size.c new file mode 100644 index 000000000000..fad6f57f8ee3 --- /dev/null +++ b/arch/um/os-Linux/sys-x86_64/task_size.c @@ -0,0 +1,5 @@ +unsigned long os_get_task_size(unsigned long shift) +{ + /* The old value of CONFIG_TOP_ADDR */ + return 0x7fc0000000; +} |