From 4ff83ce1114827f707b7f1f4f2e5f69de9df94ac Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Sun, 6 May 2007 14:51:08 -0700 Subject: uml: create as-layout.h This patch moves all the the symbols defined in um_arch.c, which are mostly boundaries between different parts of the UML kernel address space, to a new header, as-layout.h. There are also a few things here which aren't really related to address space layout, but which don't really have a better place to go. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/skas/process.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/um/kernel/skas/process.c') diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c index ae4fa71d3b8b..9c2a7d8c56fb 100644 --- a/arch/um/kernel/skas/process.c +++ b/arch/um/kernel/skas/process.c @@ -13,6 +13,7 @@ #include "asm/uaccess.h" #include "asm/atomic.h" #include "kern_util.h" +#include "as-layout.h" #include "skas.h" #include "os.h" #include "user_util.h" -- cgit v1.2.2 From 9218b1714949095bff9d9739d80f431d58e561d6 Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Sun, 6 May 2007 14:51:10 -0700 Subject: uml: remove user_util.h user_util.h isn't needed any more, so delete it and remove all includes of it. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/skas/process.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/um/kernel/skas/process.c') diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c index 9c2a7d8c56fb..ef36facd8fe9 100644 --- a/arch/um/kernel/skas/process.c +++ b/arch/um/kernel/skas/process.c @@ -16,7 +16,6 @@ #include "as-layout.h" #include "skas.h" #include "os.h" -#include "user_util.h" #include "tlb.h" #include "kern.h" #include "mode.h" -- cgit v1.2.2 From 0e7d18b57c39bedcbd181e3c06d13572b33e5380 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 9 May 2007 02:33:22 -0700 Subject: uml: turn build warnings into comments These haven't been fixed for ages. Just make comments out of them. arch/um/kernel/skas/process.c:181:2: warning: #warning Need to look up +userspace_pid by cpu arch/um/kernel/skas/process.c:187:2: warning: #warning Need to look up +userspace_pid by cpu arch/um/kernel/skas/process.c:194:2: warning: #warning need to loop over +userspace_pids in kill_off_processes_skas Signed-off-by: Miklos Szeredi Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/skas/process.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'arch/um/kernel/skas/process.c') diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c index ef36facd8fe9..a96ae1a0610e 100644 --- a/arch/um/kernel/skas/process.c +++ b/arch/um/kernel/skas/process.c @@ -178,20 +178,23 @@ int start_uml_skas(void) int external_pid_skas(struct task_struct *task) { -#warning Need to look up userspace_pid by cpu + /* FIXME: Need to look up userspace_pid by cpu */ return(userspace_pid[0]); } int thread_pid_skas(struct task_struct *task) { -#warning Need to look up userspace_pid by cpu + /* FIXME: Need to look up userspace_pid by cpu */ return(userspace_pid[0]); } void kill_off_processes_skas(void) { if(proc_mm) -#warning need to loop over userspace_pids in kill_off_processes_skas + /* + * FIXME: need to loop over userspace_pids in + * kill_off_processes_skas + */ os_kill_ptraced_process(userspace_pid[0], 1); else { struct task_struct *p; -- cgit v1.2.2 From c14b84949e127560084c7c56b365931c71c60768 Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Thu, 10 May 2007 22:22:34 -0700 Subject: uml: iRQ stacks Add a separate IRQ stack. This differs from i386 in having the entire interrupt run on a separate stack rather than starting on the normal kernel stack and switching over once some preparation has been done. The underlying mechanism, is of course, sigaltstack. Another difference is that interrupts that happen in userspace are handled on the normal kernel stack. These cause a wait wakeup instead of a signal delivery so there is no point in trying to switch stacks for these. There's no other stuff on the stack, so there is no extra stack consumption. This quirk makes it possible to have the entire interrupt run on a separate stack - process preemption (and calls to schedule()) happens on a normal kernel stack. If we enable CONFIG_PREEMPT, this will need to be rethought. The IRQ stack for CPU 0 is declared in the same way as the initial kernel stack. IRQ stacks for other CPUs will be allocated dynamically. An extra field was added to the thread_info structure. When the active thread_info is copied to the IRQ stack, the real_thread field points back to the original stack. This makes it easy to tell where to copy the thread_info struct back to when the interrupt is finished. It also serves as a marker of a nested interrupt. It is NULL for the first interrupt on the stack, and non-NULL for any nested interrupts. Care is taken to behave correctly if a second interrupt comes in when the thread_info structure is being set up or taken down. I could just disable interrupts here, but I don't feel like giving up any of the performance gained by not flipping signals on and off. If an interrupt comes in during these critical periods, the handler can't run because it has no idea what shape the stack is in. So, it sets a bit for its signal in a global mask and returns. The outer handler will deal with this signal itself. Atomicity is had with xchg. A nested interrupt that needs to bail out will xchg its signal mask into pending_mask and repeat in case yet another interrupt hit at the same time, until the mask stabilizes. The outermost interrupt will set up the thread_info and xchg a zero into pending_mask when it is done. At this point, nested interrupts will look at ->real_thread and see that no setup needs to be done. They can just continue normally. Similar care needs to be taken when exiting the outer handler. If another interrupt comes in while it is copying the thread_info, it will drop a bit into pending_mask. The outer handler will check this and if it is non-zero, will loop, set up the stack again, and handle the interrupt. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/skas/process.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/um/kernel/skas/process.c') diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c index a96ae1a0610e..2a69a7ce5792 100644 --- a/arch/um/kernel/skas/process.c +++ b/arch/um/kernel/skas/process.c @@ -163,8 +163,12 @@ static int start_kernel_proc(void *unused) extern int userspace_pid[]; +extern char cpu0_irqstack[]; + int start_uml_skas(void) { + stack_protections((unsigned long) &cpu0_irqstack); + set_sigstack(cpu0_irqstack, THREAD_SIZE); if(proc_mm) userspace_pid[0] = start_userspace(0); -- cgit v1.2.2