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  1. 03 9月, 2015 1 次提交
  3. 28 3月, 2015 1 次提交
    • J
      MIPS: Clear [MSA]FPE CSR.Cause after notify_die() · 64bedffe
      由 James Hogan 提交于 
      When handling floating point exceptions (FPEs) and MSA FPEs the Cause
bits of the appropriate control and status register (FCSR for FPEs and
MSACSR for MSA FPEs) are read and cleared before enabling interrupts,
presumably so that it doesn't have to go through the pain of restoring
those bits if the process is pre-empted, since writing those bits would
cause another immediate exception while still in the kernel.

The bits aren't normally ever restored again, since userland never
expects to see them set.

However for virtualisation it is necessary for the kernel to be able to
restore these Cause bits, as the guest may have been interrupted in an
FP exception handler but before it could read the Cause bits. This can
be done by registering a die notifier, to get notified of the exception
when such a value is restored, and if the PC was at the instruction
which is used to restore the guest state, the handler can step over it
and continue execution. The Cause bits can then remain set without
causing further exceptions.

For this to work safely a few changes are made:
- __build_clear_fpe and __build_clear_msa_fpe no longer clear the Cause
  bits, and now return from exception level with interrupts disabled
  instead of enabled.
- do_fpe() now clears the Cause bits and enables interrupts after
  notify_die() is called, so that the notifier can chose to return from
  exception without this happening.
- do_msa_fpe() acts similarly, but now actually makes use of the second
  argument (msacsr) and calls notify_die() with the new DIE_MSAFP,
  allowing die notifiers to be informed of MSA FPEs too.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
      64bedffe
  5. 05 8月, 2010 1 次提交
  7. 11 10月, 2008 1 次提交
  9. 31 7月, 2008 1 次提交
    • J
      [MIPS] kgdb: add arch support for the kernel's kgdb core · 88547001
      由 Jason Wessel 提交于 
      The new kgdb architecture specific handler registers and unregisters
dynamically for exceptions depending on when you configure a kgdb I/O
driver.

Aside from initializing the exceptions earlier in the boot process,
kgdb should have no impact on a device when it is compiled in so long
as an I/O module is not configured for use.

There have been quite a number of contributors during the existence of
this patch (see arch/mips/kernel/kgdb.c).  Most recently Jason
re-wrote the mips kgdb logic to use the die notification handlers.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
      88547001
  11. 09 5月, 2007 1 次提交
    • C
      move die notifier handling to common code · 1eeb66a1
      由 Christoph Hellwig 提交于 
      This patch moves the die notifier handling to common code.  Previous
various architectures had exactly the same code for it.  Note that the new
code is compiled unconditionally, this should be understood as an appel to
the other architecture maintainer to implement support for it aswell (aka
sprinkling a notify_die or two in the proper place)

arm had a notifiy_die that did something totally different, I renamed it to
arm_notify_die as part of the patch and made it static to the file it's
declared and used at.  avr32 used to pass slightly less information through
this interface and I brought it into line with the other architectures.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix vmalloc_sync_all bustage]
[bryan.wu@analog.com: fix vmalloc_sync_all in nommu]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: <linux-arch@vger.kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1eeb66a1
  13. 08 5月, 2007 1 次提交