linux.git/arch/powerpc/kernel/align.c, branch v3.14

powerpc: Enable Little Endian Alignment Handler for Float Pair Instructions

2013-10-30T05:01:23+00:00

This patch enables alignment handling for the load/store floating point
pair instructions (lfdp, lfdpx, stfdp, stfdpx).  The handler routine
is properly coded and only needs to be enabled.

Signed-off-by: Tom Musta 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix Handler of Unaligned Load/Store Strings

2013-10-30T05:01:17+00:00

The alignment handler is incorrect for unaligned string instructions
in little endian mode.  These instructions access data as arrays of
bytes and thus are endian neutral.  However, the routine also handles
the load/store multiple instructions, which are NOT endian neutral.

This patch toggles the byte swapping flag for the string instructions
in little endian builds.  This effectively disables the byte swapping
logic.

Signed-off-by: Tom Musta 
Signed-off-by: Benjamin Herrenschmidt

Merge branch 'for-kvm' into next

2013-10-11T07:23:53+00:00

Topic branch for commits that the KVM tree might want to pull
in separately.

Hand merged a few files due to conflicts with the LE stuff

Signed-off-by: Benjamin Herrenschmidt

powerpc: Put FP/VSX and VR state into structures

2013-10-11T06:26:49+00:00

This creates new 'thread_fp_state' and 'thread_vr_state' structures
to store FP/VSX state (including FPSCR) and Altivec/VSX state
(including VSCR), and uses them in the thread_struct.  In the
thread_fp_state, the FPRs and VSRs are represented as u64 rather
than double, since we rarely perform floating-point computations
on the values, and this will enable the structures to be used
in KVM code as well.  Similarly FPSCR is now a u64 rather than
a structure of two 32-bit values.

This takes the offsets out of the macros such as SAVE_32FPRS,
REST_32FPRS, etc.  This enables the same macros to be used for normal
and transactional state, enabling us to delete the transactional
versions of the macros.   This also removes the unused do_load_up_fpu
and do_load_up_altivec, which were in fact buggy since they didn't
create large enough stack frames to account for the fact that
load_up_fpu and load_up_altivec are not designed to be called from C
and assume that their caller's stack frame is an interrupt frame.

Signed-off-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Handle VSX alignment faults in little endian mode

2013-10-11T05:48:38+00:00

Things are complicated by the fact that VSX elements are big
endian ordered even in little endian mode. 8 byte loads and
stores also write to the top 8 bytes of the register.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Add little endian support to alignment handler

2013-10-11T05:48:37+00:00

Handle most unaligned load and store faults in little
endian mode. Strings, multiples and VSX are not supported.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Alignment handler shouldn't access VSX registers with TS_FPR

2013-10-11T05:48:36+00:00

The TS_FPR macro selects the FPR component of a VSX register (the
high doubleword). emulate_vsx is using this macro to get the
address of the associated VSX register. This happens to work on big
endian, but fails on little endian.

Replace it with an explicit array access.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Remove hard coded FP offsets in alignment handler

2013-10-11T05:48:35+00:00

The alignment handler assumes big endian ordering when selecting
the low word of a 64bit floating point value. Use the existing
union which works in both little and big endian.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Remove open coded byte swap macro in alignment handler

2013-10-11T05:48:35+00:00

Use swab64/32/16 instead of open coding it.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Never handle VSX alignment exceptions from kernel

2013-08-27T04:44:26+00:00

The VSX alignment handler needs to write out the existing VSX
state to memory before operating on it (flush_vsx_to_thread()).
If we take a VSX alignment exception in the kernel bad things
will happen. It looks like we could write the kernel state out
to the user process, or we could handle the kernel exception
using data from the user process (depending if MSR_VSX is set
or not).

Worse still, if the code to read or write the VSX state causes an
alignment exception, we will recurse forever. I ended up with
hundreds of megabytes of kernel stack to look through as a result.

Floating point and SPE code have similar issues but already include
a user check. Add the same check to emulate_vsx().

With this patch any unaligned VSX loads and stores in the kernel
will show up as a clear oops rather than silent corruption of
kernel or userspace VSX state, or worse, corruption of a potentially
unlimited amount of kernel memory.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt