From 9786a8f3cbc61f990266e23ffdb338ee3118b03d Mon Sep 17 00:00:00 2001 From: Bodo Stroesser Date: Thu, 7 Jul 2005 17:56:50 -0700 Subject: [PATCH] uml: Proper clone support for skas0 This patch implements the clone-stub mechanism, which allows skas0 to run with proc_mm==0, even if the clib in UML uses modify_ldt. Note: There is a bug in skas3.v7 host patch, that avoids UML-skas from running properly on a SMP-box. In full skas3, I never really saw problems, but in skas0 they showed up. More commentary by jdike - What this patch does is makes sure that the host parent of each new host process matches the UML parent of the corresponding UML process. This ensures that any changed LDTs are inherited. This is done by having clone actually called by the UML process from its stub, rather than by the kernel. We have special syscall stubs that are loaded onto the stub code page because that code must be completely self-contained. These stubs are given C interfaces, and used like normal C functions, but there are subtleties. Principally, we have to be careful about stack variables in stub_clone_handler after the clone. The code is written so that there aren't any - everything boils down to a fixed address. If there were any locals, references to them after the clone would be wrong because the stack just changed. Signed-off-by: Bodo Stroesser Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/time.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/um/kernel/time.c') diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c index f829b309b63c..c40b611e3d93 100644 --- a/arch/um/kernel/time.c +++ b/arch/um/kernel/time.c @@ -48,6 +48,13 @@ void enable_timer(void) set_interval(ITIMER_VIRTUAL); } +void prepare_timer(void * ptr) +{ + int usec = 1000000/hz(); + *(struct itimerval *)ptr = ((struct itimerval) { { 0, usec }, + { 0, usec }}); +} + void disable_timer(void) { struct itimerval disable = ((struct itimerval) { { 0, 0 }, { 0, 0 }}); -- cgit v1.2.3