diff options
| author | Bodo Stroesser <bstroesser@fujitsu-siemens.com> | 2005-07-07 17:56:50 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-07-07 18:23:44 -0700 |
| commit | 9786a8f3cbc61f990266e23ffdb338ee3118b03d (patch) | |
| tree | c987811d30508728f954cc8aaa14de1f7fa5b44a /arch/um/kernel/skas/include | |
| parent | d67b569f5f620c0fb95d5212642746b7ba9d29e4 (diff) | |
[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 <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/um/kernel/skas/include')
| -rw-r--r-- | arch/um/kernel/skas/include/skas.h | 1 | ||||
| -rw-r--r-- | arch/um/kernel/skas/include/stub-data.h | 18 |
2 files changed, 19 insertions, 0 deletions
diff --git a/arch/um/kernel/skas/include/skas.h b/arch/um/kernel/skas/include/skas.h index d91a60f3830..d983ea84254 100644 --- a/arch/um/kernel/skas/include/skas.h +++ b/arch/um/kernel/skas/include/skas.h @@ -32,6 +32,7 @@ extern int protect(struct mm_id * mm_idp, unsigned long addr, extern void user_signal(int sig, union uml_pt_regs *regs, int pid); extern int new_mm(int from); extern int start_userspace(unsigned long stub_stack); +extern int copy_context_skas0(unsigned long stack, int pid); extern void get_skas_faultinfo(int pid, struct faultinfo * fi); extern long execute_syscall_skas(void *r); extern unsigned long current_stub_stack(void); diff --git a/arch/um/kernel/skas/include/stub-data.h b/arch/um/kernel/skas/include/stub-data.h new file mode 100644 index 00000000000..f6ed92c3727 --- /dev/null +++ b/arch/um/kernel/skas/include/stub-data.h @@ -0,0 +1,18 @@ +/* + * Copyright (C) 2005 Jeff Dike (jdike@karaya.com) + * Licensed under the GPL + */ + +#ifndef __STUB_DATA_H +#define __STUB_DATA_H + +#include <sys/time.h> + +struct stub_data { + long offset; + int fd; + struct itimerval timer; + long err; +}; + +#endif |