If we have a series of events from userpsace, with %fprs=FPRS_FEF,
like follows:
ETRAP
ETRAP
VIS_ENTRY(fprs=0x4)
VIS_EXIT
RTRAP (kernel FPU restore with fpu_saved=0x4)
RTRAP
We will not restore the user registers that were clobbered by the FPU
using kernel code in the inner-most trap.
Traps allocate FPU save slots in the thread struct, and FPU using
sequences save the "dirty" FPU registers only.
This works at the initial trap level because all of the registers
get recorded into the top-level FPU save area, and we'll return
to userspace with the FPU disabled so that any FPU use by the user
will take an FPU disabled trap wherein we'll load the registers
back up properly.
But this is not how trap returns from kernel to kernel operate.
The simplest fix for this bug is to always save all FPU register state
for anything other than the top-most FPU save area.
Getting rid of the optimized inner-slot FPU saving code ends up
making VISEntryHalf degenerate into plain VISEntry.
Longer term we need to do something smarter to reinstate the partial
save optimizations. Perhaps the fundament error is having trap entry
and exit allocate FPU save slots and restore register state. Instead,
the VISEntry et al. calls should be doing that work.
This bug is about two decades old.
Reported-by: James Y Knight <jyknight@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Many of the atomic op implementations are the same except for one
instruction; fold the lot into a few CPP macros and reduce LoC.
This also prepares for easy addition of new ops.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/20140508135852.825281379@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The functions
__down_read
__down_read_trylock
__down_write
__down_write_trylock
__up_read
__up_write
__downgrade_write
are implemented inline, so remove corresponding EXPORT_SYMBOLs
(They lead to compile errors on RT kernel).
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sparc32 already supported it, as a consequence of using the
generic atomic64 implementation. And the sparc64 implementation
is rather trivial.
This allows us to set ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE for all
of sparc, and avoid the annoying warning from lib/atomic64_test.c
Signed-off-by: David S. Miller <davem@davemloft.net>
Linus removed the end-of-address-space hackery from
fs/namei.c:do_getname() so we really have to validate these edge
conditions and cannot cheat any more (as x86 used to as well).
Move to a common C implementation like x86 did. And if both
src and dst are sufficiently aligned we'll do word at a time
copies and checks as well.
Signed-off-by: David S. Miller <davem@davemloft.net>
For the explicit calls to .udiv/.umul in assembler, I made a
mechanical (read as: safe) transformation. I didn't attempt
to make any simplifications.
In particular, __ndelay and __udelay can be simplified significantly.
Some of the %y reads are unnecessary and these routines have no need
any longer for allocating a register window, they can be leaf
functions.
Signed-off-by: David S. Miller <davem@davemloft.net>
atomic24 support was used to semaphores in the past - but is no longer used.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove the duplicate entries from kernel/sparc_ksyms_*.c
The rationale behind this is that the EXPORT_SYMBOL() should be close to
their definition and we cannot add designate a symbol to be exported in
assembler so at least put it in a file in the same directory.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Additions by Julian Calaby:
* Rebased over sparc-2.6.git HEAD
Signed-off-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
David S. Miller