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  1. 20 7月, 2007 16 次提交
  3. 19 7月, 2007 20 次提交
  5. 18 7月, 2007 4 次提交
    • J
      xen: disable all non-virtual drivers · dfdcdd42
      由 Jeremy Fitzhardinge 提交于 
      A domU Xen environment has no non-virtual drivers, so make sure
they're all disabled at once.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
      dfdcdd42
    • J
      xen: use iret directly when possible · 9ec2b804
      由 Jeremy Fitzhardinge 提交于 
      Most of the time we can simply use the iret instruction to exit the
kernel, rather than having to use the iret hypercall - the only
exception is if we're returning into vm86 mode, or from delivering an
NMI (which we don't support yet).

When running native, iret has the behaviour of testing for a pending
interrupt atomically with re-enabling interrupts.  Unfortunately
there's no way to do this with Xen, so there's a window in which we
could get a recursive exception after enabling events but before
actually returning to userspace.

This causes a problem: if the nested interrupt causes one of the
task's TIF_WORK_MASK flags to be set, they will not be checked again
before returning to userspace.  This means that pending work may be
left pending indefinitely, until the process enters and leaves the
kernel again.  The net effect is that a pending signal or reschedule
event could be delayed for an unbounded amount of time.

To deal with this, the xen event upcall handler checks to see if the
EIP is within the critical section of the iret code, after events
are (potentially) enabled up to the iret itself.  If its within this
range, it calls the iret critical section fixup, which adjusts the
stack to deal with any unrestored registers, and then shifts the
stack frame up to replace the previous invocation.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
      9ec2b804
    • J
      xen: suppress abs symbol warnings for unused reloc pointers · 600b2fc2
      由 Jeremy Fitzhardinge 提交于 
      arch/i386/xen/xen-asm.S defines some small pieces of code which are
used to implement a few paravirt_ops.  They're designed so they can be
used either in-place, or be inline patched into their callsites if
there's enough space.

Some of those operations need to make calls out (specifically, if you
re-enable events [interrupts], and there's a pending event at that
time).  These calls need the call instruction to be relocated if the
code is patched inline.  In this case xen_foo_reloc is a
section-relative symbol which points to xen_foo's required relocation.

Other operations have no need of a relocation, and so their
corresponding xen_bar_reloc is absolute 0.  These are the cases which
are triggering the warning.

This patch adds those symbols to the list of safe abs symbols.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Cc: Adrian Bunk <bunk@stusta.de>
      600b2fc2
    • J
      xen: Attempt to patch inline versions of common operations · 6487673b
      由 Jeremy Fitzhardinge 提交于 
      This patchs adds the mechanism to allow us to patch inline versions of
common operations.

The implementations of the direct-access versions save_fl, restore_fl,
irq_enable and irq_disable are now in assembler, and the same code is
used for both out of line and inline uses.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Keir Fraser <keir@xensource.com>
      6487673b