The previous implementation did not cover all possible FPU combinations
and it silently allowed ABI incompatible objects to be loaded with the
wrong ABI. For example, the previous logic would set the FP_64 ABI as
the matching ABI for an FP_XX object combined with an FP_64A object.
This was wrong, and the matching ABI should have been FP_64A.
The previous logic is now replaced with a new one which determines
the appropriate FPU mode to be used rather than the FP ABI. This has
the advantage that the entire logic is much simpler since it is the FPU
mode we are interested in rather than the FP ABI resulting to code
simplifications. This also removes the now obsolete FP32XX_HYBRID_FPRS
option.

Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS32 R6 has a 64-bit FPU so add the necessary MIPS R6
definition.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

A prctl() call to set FR=0 for MIPS R6 should not be allowed
since FR=1 is the only option for R6 cores.

Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R2 FPU instructions are also present in MIPS R6 so amend the
preprocessor definitions to take MIPS R6 into consideration.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The ERETNC instruction, introduced in MIPS R5, is similar to the ERET
one, except it does not clear the LLB bit in the LLADDR register.
This feature is necessary to safely emulate R2 LL/SC instructions.
However, on context switches, we need to clear the LLAddr/LLB bit
in order to make sure that an SC instruction from the new thread
will never succeed if it happens to interrupt an LL operation on the
same address from the previous thread.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 removed quite a few R2 instructions. However, there
is plenty of <R6 userland code so we add an in-kernel emulator
so we can still be able to execute all R2 userland out there.

The emulator comes with a handy debugfs under /mips/ directory
(r2-emul-stats) to provide some basic statistics of the
instructions that are being emulated.

Below are some statistics from booting a minimal buildroot image:

Instruction     Total   BDslot
------------------------------
movs            236969  0
hilo            56686   0
muls            55279   0
divs            10941   0
dsps            0       0
bops            1       0
traps           0       0
fpus            0       0
loads           214981  17
stores          103364  0
llsc            56898   0
dsemul          150418  0
jr              370158
bltzl           43
bgezl           1594
bltzll          0
bgezll          0
bltzal          39
bgezal          39
beql            14503
bnel            138741
blezl           0
bgtzl           3988
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

If Config5/LLB is set in the core, then software can write the LLB
bit in the LLADDR register.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The LLBIT (bit 4) in the Config5 CP0 register indicates the software
availability of the Load-Linked bit. This bit is only set by hardware
and it has the following meaning:

0: LLB functionality is not supported
1: LLB functionality is supported. The following feature are also
supported:

- ERETNC instruction. Similar to ERET but it does not clear the LLB
bit in the LLAddr register.
- CP0 LLAddr/LLB bit must be set
- LLbit is software accessible through the LLAddr[0]

This will be used later on to emulate R2 LL/SC instructions.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 uses the <R6 sdc2 opcode for the new BNEZC and JIALC instructions
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 uses the <R6 ldc2 opcode for the new BEQZC and JIC instructions
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 uses the <R6 swc2 opcode for the new BALC instructions.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 uses the <R6 DADDI opcode for the new BNVC, BNEC and
BNEZLAC instructions.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 uses the <R6 ADDI opcode for the new BOVC, BEQC and
BEQZALC instructions.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 uses the <R6 LWC2 opcode for the new BC instruction.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 added the following four instructions which share the
BGTZ and BGTZL opcode:

BLTZALC: Compact branch-and-link if GPR rt is < to zero
BGTZALC: Compact branch-and-link if GPR rt is > to zero
BLTZL  : Compact branch if GPR rt is < to zero
BGTZL  : Compact branch if GPR rt is > to zero
BLTC   : Compact branch if GPR rs is less than GPR rt
BLTUC  : Similar to BLTC but unsigned
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 added the following four instructions which share the
BLEZ and BLEZL opcodes:

BLEZALC: Compact branch-and-link if GPR rt is <= to zero
BGEZALC: Compact branch-and-link if GPR rt is >= to zero
BLEZC  : Compact branch if GPR rt is <= to zero
BGEZC  : Compact branch if GPR rt is >= to zero
BGEC   : Compact branch if GPR rs is less than or equal to GPR rt
BGEUC  : Similar to BGEC but unsigned.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 introduced the following two branch instructions for COP1:

BC1EQZ: Branch if Cop1 (FPR) Register Bit 0 is Equal to Zero
BC1NEZ: Branch if Cop1 (FPR) Register Bit 0 is Not Equal to Zero
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 removed the BLTZL, BGEZL, BLTZAL, BGEZAL, BEQL, BNEL, BLEZL,
BGTZL branch likely instructions so we must not try to emulate them on
MIPS R6 if the R2-to-R6 emulator is not present.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The MIPS R6 JR instruction is an alias to the JALR one, so it may
need emulation for non-R6 userlands.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The secondary cache initialization and configuration code is processor
specific so we need to handle MIPS R6 cores as well.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The local_r4k_flush_cache_sigtramp function uses the 'cache'
instruction inside an asm block. However, MIPS R6 changed the
opcode for the cache instruction and as a result of which we
need to set the correct ISA level.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS uses the cpu_has_mips_r2_exec_hazard macro to determine whether the
EHB instruction is available or not. This is necessary for MIPS R6
which also supports the EHB instruction.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The MIPS R6 pref instruction only has 9 bits for the immediate
field so skip the micro-assembler PREF instruction if the offset
does not fit in 9 bits. Moreover, bit 30 (Pref_PrepareForStore) is
no longer valid in MIPS R6, so we change the default for all MIPS R6
processors to bit 5 (Pref_StoreStreamed).
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 dropped the unaligned load and store instructions so
we need to re-write this part of the code for R6 to store
one byte at a time.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 does not support the unaligned load and store instructions
so we add a special MIPS R6 case to copy one byte at a time if we
need to read/write to unaligned memory addresses.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 changed the opcodes for LL/SC instructions so we need to set
the appropriate ISA level.

Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The load/store unaligned instructions have been removed in MIPS R6
so we need to re-implement the related macros using the regular
load/store instructions. Moreover, the load/store from coprocessor 2
instructions have been reallocated in Release 6 so we will handle them
in the emulator instead.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The "addi" instruction will trap on overflows which is not something
we need in this code, so we replace that with "addiu".

Link: http://www.linux-mips.org/archives/linux-mips/2015-01/msg00430.html
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: <stable@vger.kernel.org> # v3.15+
Cc: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The jr instruction opcode has changed in R6 so make sure
the correct ISA level is set prior using that instruction.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Add the MIPS R6 related preprocessor definitions for FPU signal
related functions. MIPS R6 only has FR=1 so avoid checking that
bit on the C0/Status register.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Add the MIPS R6 related preprocessor definitions for save/restore
FPU related functions. We also set the appropriate ISA level
so the final return instruction "jr ra" will produce the correct
opcode on R6.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Add MIPS R6 support to cache and ftlb exceptions, as well as
to the hwrena and ebase register configuration.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Print 'mips64r6' and/or 'mips32r6' if the kernel is running on
a MIPS R6 core.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The instruction hazard barrier in the form of:

jr.hb	ra
nop

is valid on MIPS R6 as well.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Add MIPS R6 support when decoding the config0 c0 register.
Also add MIPS R6 support when examining the ebase c0 register
to get the core number and when getting the shadow set number
from the srsctl c0 register.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Just like MIPS R2, in MIPS R6 it is possible to determine if a
timer interrupt has happened or not.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

The current HW bugs checked in cpu-bugs64, do not apply to R6 cores
and they cause compilation problems due to removed <R6 instructions,
so do not check for them for the time being.
Reviewed-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 changed the opcodes for LL/SC instructions so we need to set
the appropriate ISA level.

Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

"sub $reg, imm" is not a real MIPS instruction. The assembler can
replace that with "addi $reg, -imm". However, addi has been removed
from R6, so we replace the "sub" instruction with the "addiu" one.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

MIPS R6 changed the opcodes for LL/SC instructions so we need to set
the appropriate ISA level.

Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>