This adds code to handle alignment traps generated by the following
new floating-point load/store instructions, by emulating the
instruction in the kernel (as is done for other instructions that
generate alignment traps):
lfiwax load floating-point as integer word algebraic indexed
stfiwx store floating-point as integer word indexed
lfdp load floating-point double pair
lfdpx load floating-point double pair indexed
stfdp store floating-point double pair
stfdpx store floating-point double pair indexed
All these except stfiwx are new in POWER6.
lfdp/lfdpx/stfdp/stfdpx load and store 16 bytes of memory into an
even/odd FP register pair. In little-endian mode each 8-byte value is
byte-reversed separately (i.e. not as a 16-byte unit). lfiwax/stfiwx
load or store the lower 4 bytes of a floating-point register from/to
memory; lfiwax sets the upper 4 bytes of the FP register to the sign
extension of the value loaded.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Make the alignment exception handler use the new _inatomic variants
of __get/put_user. This fixes erroneous warnings in the very rare
cases where we manage to have copy_tofrom_user_inatomic() trigger
an alignment exception.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
arch/powerpc/kernel/align.c | 56 ++++++++++++++++++++++++--------------------
1 file changed, 31 insertions(+), 25 deletions(-)
Signed-off-by: Paul Mackerras <paulus@samba.org>
This adds the PowerPC part of the code to allow processes to change
their endian mode via prctl.
This also extends the alignment exception handler to be able to fix up
alignment exceptions that occur in little-endian mode, both for
"PowerPC" little-endian and true little-endian.
We always enter signal handlers in big-endian mode -- the support for
little-endian mode does not amount to the creation of a little-endian
user/kernel ABI. If the signal handler returns, the endian mode is
restored to what it was when the signal was delivered.
We have two new kernel CPU feature bits, one for PPC little-endian and
one for true little-endian. Most of the classic 32-bit processors
support PPC little-endian, and this is reflected in the CPU feature
table. There are two corresponding feature bits reported to userland
in the AT_HWCAP aux vector entry.
This is based on an earlier patch by Anton Blanchard.
Signed-off-by: Paul Mackerras <paulus@samba.org>
This patch merges align.c, the result isn't quite what was in ppc64 nor
what was in ppc32 :) It should implement all the functionalities of both
though. Kumar, since you played with that in the past, I suppose you
have some test cases for verifying that it works properly before I dig
out the 601 machine ? :)
Since it's likely that I won't be able to test all scenario, code
inspection is much welcome.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
