Provide correct siginfo_t.si_stime on MIPS64

Bug description:
MIPS version of copy_siginfo() is not aware of alignment on platforms with
64-bit long integers, which leads to an incorrect si_stime passed to signal
handlers, because the last element (si_stime) of _sifields._sigchld is not
copied. If _MIPS_SZLONG is 64, then the _sifields starts at the offset of
4 * sizeof(int).

Patch description:
Use the generic copy_siginfo, which doesn't have this problem.
Signed-off-by: NPetr Malat <oss@malat.biz>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8671/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

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: NMarkos Chandras <markos.chandras@imgtec.com>

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

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

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

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

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

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

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

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

GCC versions supporting MIPS R6 use the ZC constraint to enforce a
9-bit offset for MIPS R6. We will use that for all MIPS R6 LL/SC
instructions.

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

The GCC_OFF12_ASM macro is used for 12-bit immediate constrains
but we will also use it for 9-bit constrains on MIPS R6 so we
rename it to something more appropriate.

Cc: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

MIPS R6, just like MIPS R2, have scratch pad storage, so add a new
symbol which is selected by MIPS R2 and R6.

Link: http://www.linux-mips.org/archives/linux-mips/2015-01/msg00389.html
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

MIPS R6 changed the 'cache' instruction opcode and reduced the
offset field to 8 bits. This means we now have to adjust the
base register every 256 bytes and as a result of which we can
no longer use the previous cache functions.
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

Add the MIPS R6 related definitions to the IRQ related macros
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

Add the MIPSR6 related definitions to MIPS hazards
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

Add MIPS R6 to the ISA definitions
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

The following instructions have been removed from MIPS R6

ulw, ulh, swl, lwr, lwl, swr.

However, all of them are used in the MIPS specific checksum implementation.
As a result of which, we will use the generic checksum on MIPS R6
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

The "add" instruction is actually a macro in binutils and depending on
the size of the immediate it can expand to an "addi" instruction.
However, the "addi" instruction traps on overflows which is not
something we want on address calculation.

Link: http://www.linux-mips.org/archives/linux-mips/2015-01/msg00121.html
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

EI/DI instructions are available in MIPS R6 so add the needed
definitions.
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

The HI/LO registers have been removed from MIPS R6. Instructions
such as MULT and DIV have been replaced with a new pair of
instructions for the HI/LO operations for example:

MULT -> MUL, MUH
DIV -> DIV, MOD

So we avoid preserving the pre-R6 HI/LO registers in MIPS R6
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

Define the MODULE_PROC_FAMILY for the MIPS R6 ISA.
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

There are certain places where the code uses .set mips32 or .set mips64
or .set arch=r4000. In preparation of MIPS R6 support, and in order to
use as less #ifdefs as possible, we define new macros to set similar
annotations for MIPS R6.
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

Add a CPU_QEMU_GENERIC case to various switch statements.
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

Latest versions of QEMU added support for mips32r6-generic and
mips64r6-generic cpu types so add related definitions in preparation
of MIPS R6 support. This is also used for QEMU R2 generic cpus.
Signed-off-by: NLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>

activate_mm() and switch_mm() call get_new_mmu_context() which in turn
can enable the HTW before the entryhi is changed with the new ASID.
Since the latter will enable the HTW in local_flush_tlb_all(),
then there is a small timing window where the HTW is running with the
new ASID but with an old pgd since the TLBMISS_HANDLER_SETUP_PGD
hasn't assigned a new one yet. In order to prevent that, we introduce a
simple htw counter to avoid starting HTW accidentally due to nested
htw_{start,stop}() sequences. Moreover, since various IPI calls can
enforce TLB flushing operations on a different core, such an operation
may interrupt another htw_{stop,start} in progress leading inconsistent
updates of the htw_seq variable. In order to avoid that, we disable the
interrupts whenever we update that variable.
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9118/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Whenever we modify a page table entry, we need to ensure that the HTW
will not fetch a stable entry. And for that to happen we need to ensure
that HTW is stopped before we modify the said entry otherwise the HTW
may already be in the process of reading that entry and fetching the
old information. As a result of which, we replace the htw_reset() calls
with htw_{stop,start} in more appropriate places. This also removes the
remaining users of htw_reset() and as a result we drop that macro
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9116/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

When we use htw_{start,stop}() outside of htw_reset(), we need
to ensure that c0 changes have been propagated properly before
we attempt to continue with subsequence memory operations.
Signed-off-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 3.17+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9114/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Userland code may be built using an ABI which permits linking to objects
that have more restrictive floating point requirements. For example,
userland code may be built to target the O32 FPXX ABI. Such code may be
linked with other FPXX code, or code built for either one of the more
restrictive FP32 or FP64. When linking with more restrictive code, the
overall requirement of the process becomes that of the more restrictive
code. The kernel has no way to know in advance which mode the process
will need to be executed in, and indeed it may need to change during
execution. The dynamic loader is the only code which will know the
overall required mode, and so it needs to have a means to instruct the
kernel to switch the FP mode of the process.

This patch introduces 2 new options to the prctl syscall which provide
such a capability. The FP mode of the process is represented as a
simple bitmask combining a number of mode bits mirroring those present
in the hardware. Userland can either retrieve the current FP mode of
the process:

  mode = prctl(PR_GET_FP_MODE);

or modify the current FP mode of the process:

  err = prctl(PR_SET_FP_MODE, new_mode);
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8899/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8928/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Its implementation is identical to MIPS.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>