linux.git/arch/um, branch v2.6.22

uml: remove PAGE_SIZE from libc code

2007-06-16T20:16:16+00:00

Distros seem to be removing PAGE_SIZE from asm/page.h.  So, the libc side of
UML should stop using it.

I replace it with UM_KERN_PAGE_SIZE, which is defined to be the same as
PAGE_SIZE on the kernel side of the house.  I could also use getpagesize(),
but it's more important that UML have the same value of PAGE_SIZE everywhere.
It's conceivable that it could be built with a larger PAGE_SIZE, and use of
getpagesize() would break that badly.

PAGE_MASK got the same treatment, as it is closely tied to PAGE_SIZE.

Signed-off-by: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uml: get declaration of simple_strtoul

2007-06-09T00:23:33+00:00

Include linux/kernel.h wherever simple_strtoul is used.  This kills a
compile warning in stderr_console.c and potential ones in the other files.

This also fixes a bunch of style violations in exitcode.c.

Signed-off-by: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uml: fix kernel stack size on x86_64

2007-06-09T00:23:33+00:00

Force KERNEL_STACK_ORDER to be at least 1 on UML/x86_64, to avoid overflows.

Signed-off-by: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uml: improve PTRACE_SYSEMU checking

2007-05-24T03:14:12+00:00

Make the PTRACE_SYSEMU checking more robust.  It will make sure that system
call numbers are reported correctly.  If there is a problem, it will disable
PTRACE_SYSEMU use and use PTRACE_SYSCALL instead.

Thanks to Balaji G for helping reproduce this problem.

Signed-off-by: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

all-archs: consolidate .data section definition in asm-generic

2007-05-19T07:11:57+00:00

With this consolidation we can now modify the .data
section definition in one spot for all archs.

Signed-off-by: Sam Ravnborg

all-archs: consolidate .text section definition in asm-generic

2007-05-19T07:11:57+00:00

Move definition of .text section to asm-generic.

Signed-off-by: Sam Ravnborg

fix uml-x86_64

2007-05-16T01:56:37+00:00

__NR_syscall_max is done in x86_64 asm-offsets; do an equivalent in
uml kern_constants.h

Signed-off-by: Al Viro 
Acked-by: Jeff Dike 
Signed-off-by: Linus Torvalds

uml: shrink kernel stacks

2007-05-11T15:29:34+00:00

Make kernel stacks be 1 page on i386 and 2 pages on x86_64.  These match the
host values.

Signed-off-by: Jeff Dike 
Cc: Paolo 'Blaisorblade' Giarrusso 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uml: iRQ stacks

2007-05-11T15:29:34+00:00

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

uml: tidy IRQ code

2007-05-11T15:29:33+00:00

Some tidying of the irq code before introducing irq stacks.  Mostly
style fixes, but the timer handler calls the timer code directly
rather than going through the generic sig_handler_common_skas.

Signed-off-by: Jeff Dike 
Cc: Paolo 'Blaisorblade' Giarrusso 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds