linux-stable.git/arch/powerpc/kernel/fpu.S, branch linux-3.13.y

powerpc: Don't corrupt user registers on 32-bit

2013-10-23T11:34:19+00:00

Commit de79f7b9f6 ("powerpc: Put FP/VSX and VR state into structures")
modified load_up_fpu() and load_up_altivec() in such a way that they
now use r7 and r8.  Unfortunately, the callers of these functions on
32-bit machines then return to userspace via fast_exception_return,
which doesn't restore all of the volatile GPRs, but only r1, r3 -- r6
and r9 -- r12.  This was causing userspace segfaults and other
userspace misbehaviour on 32-bit machines.

This fixes the problem by changing the register usage of load_up_fpu()
and load_up_altivec() to avoid using r7 and r8 and instead use r6 and
r10.  This also adds comments to those functions saying which registers
may be used.

Signed-off-by: Paul Mackerras 
Tested-by: Scott Wood  (on e500mc, so no altivec)
Signed-off-by: Benjamin Herrenschmidt

powerpc: Provide for giveup_fpu/altivec to save state in alternate location

2013-10-11T06:26:50+00:00

This provides a facility which is intended for use by KVM, where the
contents of the FP/VSX and VMX (Altivec) registers can be saved away
to somewhere other than the thread_struct when kernel code wants to
use floating point or VMX instructions.  This is done by providing a
pointer in the thread_struct to indicate where the state should be
saved to.  The giveup_fpu() and giveup_altivec() functions test these
pointers and save state to the indicated location if they are non-NULL.
Note that the MSR_FP/VEC bits in task->thread.regs->msr are still used
to indicate whether the CPU register state is live, even when an
alternate save location is being used.

This also provides load_fp_state() and load_vr_state() functions, which
load up FP/VSX and VMX state from memory into the CPU registers, and
corresponding store_fp_state() and store_vr_state() functions, which
store FP/VSX and VMX state into memory from the CPU registers.

Signed-off-by: Paul Mackerras 
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: Add FP/VSX and VMX register load functions for transactional memory

2013-02-15T05:58:52+00:00

This adds functions to restore the state of the FP/VSX registers from
what's stored in the thread_struct.  Two version for FP/VSX are required
since one restores them from transactional/checkpoint side of the
thread_struct and the other from the speculated side.

Similar functions are added for VMX registers.

Signed-off-by: Matt Evans 
Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt

powerpc: New macros for transactional memory support

2013-02-15T05:58:50+00:00

This adds new macros for saving and restoring checkpointed architected state
from and to the thread_struct.

It also adds some debugging macros for when your brain explodes trying to debug
your transactional memory enabled kernel.

Signed-off-by: Matt Evans 
Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Enforce usage of R0-R31 where possible

2012-07-10T09:18:30+00:00

Enforce the use of R0-R31 in macros where possible now we have all the
fixes in.

R0-R31 macros are removed here so that can't be used anymore.  They
should not be defined anywhere.

Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix usage of register macros getting ready for %r0 change

2012-07-10T09:17:55+00:00

Anything that uses a constructed instruction (ie. from ppc-opcode.h),
need to use the new R0 macro, as %r0 is not going to work.

Also convert usages of macros where we are just determining an offset
(usually for a load/store), like:
	std	r14,STK_REG(r14)(r1)
Can't use STK_REG(r14) as %r14 doesn't work in the STK_REG macro since
it's just calculating an offset.

Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Remove second definition of STACK_FRAME_OVERHEAD

2010-11-29T04:48:23+00:00

Since STACK_FRAME_OVERHEAD is defined in asm/ptrace.h and that
is ASSEMBER safe, we can just include that instead of going via
asm-offsets.h.

Signed-off-by: Stephen Rothwell 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Remove fpscr use from [kvm_]cvt_{fd,df}

2010-09-02T04:07:32+00:00

Neither lfs nor stfs touch the fpscr, so remove the restore/save of it
around them.

Signed-off-by: Andreas Schwab 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Use names rather than numbers for SPRGs (v2)

2009-08-20T00:12:27+00:00

The kernel uses SPRG registers for various purposes, typically in
low level assembly code as scratch registers or to hold per-cpu
global infos such as the PACA or the current thread_info pointer.

We want to be able to easily shuffle the usage of those registers
as some implementations have specific constraints realted to some
of them, for example, some have userspace readable aliases, etc..
and the current choice isn't always the best.

This patch should not change any code generation, and replaces the
usage of SPRN_SPRGn everywhere in the kernel with a named replacement
and adds documentation next to the definition of the names as to
what those are used for on each processor family.

The only parts that still use the original numbers are bits of KVM
or suspend/resume code that just blindly needs to save/restore all
the SPRGs.

Signed-off-by: Benjamin Herrenschmidt