MIPS: Allow vectored interrupt handler to reside everywhere for 64bit

Setting up vector interrupts worked only with handlers, which resided
in CKSEG0 space. This limits the kernel placement for 64bit platforms.
By patching in the offset into vi_handlers[] instead of the full
handler address, the vectored exception handler can load the
address by itself and jump to it.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

MIPS: Always use -Wa,-msoft-float and eliminate GAS_HAS_SET_HARDFLOAT

-Wa,-msoft-float is tested with as-option, which will be a problem for
clang with an upcoming change to move as-option to use KBUILD_AFLAGS
instead of KBUILD_CFLAGS due to a lack of '-mno-abicalls' in
KBUILD_AFLAGS at the point that this check occurs; $(cflags-y) is added
to KBUILD_AFLAGS towards the end of this file.

clang: error: ignoring '-fno-PIE' option as it cannot be used with implicit usage of -mabicalls and the N64 ABI [-Werror,-Woption-ignored]

This could be resolved by switching to a cc-option check but
'$(cflags-y)' would need to be added so that '-mno-abicalls' is present
for the test. However, this check is no longer necessary, as
-msoft-float is supported by all supported assembler versions (GNU as
2.25+ and LLVM 11+). Eliminate GAS_HAS_SET_HARDFLOAT and all of its
uses, inlining SET_HARDFLOAT where necessary.

Link: https://lore.kernel.org/202209101939.bvk64Fok-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

MIPS: Remove TX39XX support

No (active) developer owns this hardware, so let's remove Linux support.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

MIPS: remove asm/war.h

The major part for workaround handling has already moved to config
options. This change replaces the remaining defines by already
available config options and gets rid of war.h

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MIPS: Make check condition for SDBBP consistent with EJTAG spec

According to MIPS EJTAG Specification [1], a Debug Breakpoint
exception occurs when an SDBBP instruction is executed, the
CP0_DEBUG bit DBp indicates that a Debug Breakpoint exception
occurred.

When I read the original code, it looks a little confusing
at first glance, just check bit DBp for SDBBP to make the
code more readable, it will be much easier to understand.

[1] http://www.t-es-t.hu/download/mips/md00047f.pdf

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MIPS: handle Loongson-specific GSExc exception

Newer Loongson cores (Loongson-3A R2 and newer) use the
implementation-dependent ExcCode 16 to signal Loongson-specific
exceptions. The extended cause is put in the non-standard CP0.Diag1
register which is CP0 Register 22 Select 1, called GSCause in Loongson
manuals. Inside is an exception code bitfield called GSExcCode, only
codes 0 to 6 inclusive are documented (so far, in the Loongson 3A3000
User Manual, Volume 2).

During experiments, it was found that some undocumented unprivileged
instructions can trigger the also-undocumented GSExcCode 8 on Loongson
3A4000. Processor state is not corrupted, but we cannot continue without
further knowledge, and Loongson is not providing that information as of
this writing. So we send SIGILL on seeing this exception code to thwart
easy local DoS attacks.

Other exception codes are made fatal, partly because of insufficient
knowledge, also partly because they are not as easily reproduced. None
of them are encountered in the wild with upstream kernels and userspace
so far.

Some older cores (Loongson-3A1000 and Loongson-3B1500) have ExcCode 16
too, but the semantic is equivalent to GSExcCode 0. Because the
respective manuals did not mention the CP0.Diag1 register or its read
behavior, these cores are not covered in this patch, as MFC0 from
non-existent CP0 registers is UNDEFINED according to the MIPS
architecture spec.

Reviewed-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: WANG Xuerui <git@xen0n.name>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MIPS: Fix IRQ tracing when call handle_fpe() and handle_msa_fpe()

Register "a1" is unsaved in this function,
when CONFIG_TRACE_IRQFLAGS is enabled,
the TRACE_IRQS_OFF macro will call trace_hardirqs_off(),
and this may change register "a1".
The changed register "a1" as argument will be send
to do_fpe() and do_msa_fpe().

Signed-off-by: YuanJunQing <yuanjunqing66@163.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MIPS: asm: Rename some macros to avoid build errors

Use ASM_ prefix to rename some macros (PANIC and PRINT), in order to
avoid build errors (all users are updated as well):

1, PANIC conflicts with drivers/scsi/smartpqi/smartpqi_init.c
2, PRINT conflicts with net/netfilter/nf_conntrack_h323_asn1.c and net/
mac80211/debugfs_sta.c

Fixes: d339cd02b888eb8 ("MIPS: Move unaligned load/store helpers to inst.h")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MIPS: genex: Don't reload address unnecessarily

In ejtag_debug_handler() we must reload the address of
ejtag_debug_buffer_spinlock if an sc fails, since the address in k0 will
have been clobbered by the result of the sc instruction. In the case
where we simply load a non-zero value (ie. there's contention for the
lock) the address will not be clobbered & we can simply branch back to
repeat the load from memory without reloading the address into k0.

The primary motivation for this change is that it moves the target of
the bnez instruction to an instruction within the LL/SC loop (the LL
itself), which we know contains no other memory accesses & therefore
isn't affected by Loongson3 LL/SC errata.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

MIPS: genex: Add Loongson3 LL/SC workaround to ejtag_debug_handler

In ejtag_debug_handler we use LL & SC instructions to acquire & release
an open-coded spinlock. For Loongson3 systems affected by LL/SC errata
this requires that we insert a sync instruction prior to the LL in order
to ensure correct behavior of the LL/SC loop.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

MIPS: r4k-bugs64: Limit R4k bug checks to affected systems

Only build the checks for R4k errata workarounds if we expect that the
kernel might actually run on a system with an R4k CPU - ie.
CONFIG_SYS_HAS_CPU_R4X00=y & we're targeting a pre-MIPSr1 ISA revision.

Rename cpu-bugs64.c to r4k-bugs64.c to indicate the fact that the code
is specific to R4k CPUs.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org

MIPS: Remove unused R5432_CP0_INTERRUPT_WAR

R5432_CP0_INTERRUPT_WAR is defined as 0 for every system we support, and
so the workaround is never used. Remove the dead code.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org

MIPS: Avoid using .set mips0 to restore ISA

We currently have 2 commonly used methods for switching ISA within
assembly code, then restoring the original ISA.

1) Using a pair of .set push & .set pop directives. For example:

.set push
.set mips32r2
<some_insn>
.set pop

2) Using .set mips0 to restore the ISA originally specified on the
command line. For example:

.set mips32r2
<some_insn>
.set mips0

Unfortunately method 2 does not work with nanoMIPS toolchains, where the
assembler rejects the .set mips0 directive like so:

Error: cannot change ISA from nanoMIPS to mips0

In preparation for supporting nanoMIPS builds, switch all instances of
method 2 in generic non-platform-specific code to use push & pop as in
method 1 instead. The .set push & .set pop is arguably cleaner anyway,
and if nothing else it's good to consistently use one method.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21037/
Cc: linux-mips@linux-mips.org

MIPS: traps: Never enable FPU when CONFIG_MIPS_FP_SUPPORT=n

When CONFIG_MIPS_FP_SUPPORT=n we don't support floating point, so we'll
never need to enable the FPU. Avoid doing so on a Co-Processor Unusable
exception (do_cpu), and remove the Floating Point Exception handler
(do_fpe) which should never be executed when the FPU is disabled.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21007/
Cc: linux-mips@linux-mips.org

MIPS: Fix ejtag handler on SMP

On SMP systems, the shared ejtag debug buffer may be overwritten by
other cores, because every cores can generate ejtag exception at
same time.

Unfortunately, in that context, it's difficult to relax more registers
to access per cpu buffers. so use ll/sc to serialize the access.

[paul.burton@mips.com:
This could in theory be backported at least as far back as the
beginning of the git era, however in general it's exceedingly rare
that anyone would hit this without further changes, so it doesn't seem
worthwhile marking for backport.]

Signed-off-by: Heiher <r@hev.cc>
Patchwork: https://patchwork.linux-mips.org/patch/19507/
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: jhogan@kernel.org
Cc: ralf@linux-mips.org

MIPS: Add DWARF unwinding to assembly

This will allow kdump dumps to work correclty with MIPS and
future DWARF unwinding of the stack to give accurate tracebacks.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16990/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: IRQ Stack: Unwind IRQ stack onto task stack

When the separate IRQ stack was introduced, stack unwinding only
proceeded as far as the top of the IRQ stack, leading to kernel
backtraces being less useful, lacking the trace of what was interrupted.

Fix this by providing a means for the kernel to unwind the IRQ stack
onto the interrupted task stack. The processor state is saved to the
kernel task stack on interrupt. The IRQ_STACK_START macro reserves an
unsigned long at the top of the IRQ stack where the interrupted task
stack pointer can be saved. After the active stack is switched to the
IRQ stack, save the interrupted tasks stack pointer to the reserved
location.

Fix the stack unwinding code to look for the frame being the top of the
IRQ stack and if so get the next frame from the saved location. The
existing test does not work with the separate stack since the ra is no
longer pointed at ret_from_{irq,exception}.

The test to stop unwinding the stack 32 bytes from the top of a stack
must be modified to allow unwinding to continue up to the location of
the saved task stack pointer when on the IRQ stack. The low / high marks
of the stack are set depending on whether the sp is on an irq stack or
not.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Masanari Iida <standby24x7@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15788/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Check TLB before handle_ri_rdhwr() for Loongson-3

Loongson-3's micro TLB (ITLB) is not strictly a subset of JTLB. That
means: when a JTLB entry is replaced by hardware, there may be an old
valid entry exists in ITLB. So, a TLB miss exception may occur while
handle_ri_rdhwr() is running because it try to access EPC's content.
However, handle_ri_rdhwr() doesn't clear EXL, which makes a TLB Refill
exception be treated as a TLB Invalid exception and tlbp may fail. In
this case, if FTLB (which is usually set-associative instead of set-
associative) is enabled, a tlbp failure will cause an invalid tlbwi,
which will hang the whole system.

This patch rename handle_ri_rdhwr_vivt to handle_ri_rdhwr_tlbp and use
it for Loongson-3. It try to solve the same problem described as below,
but more straightforwards.

https://patchwork.linux-mips.org/patch/12591/

I think Loongson-2 has the same problem, but it has no FTLB, so we just
keep it as is.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: Rui Wang <wangr@lemote.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J . Hill <Steven.Hill@caviumnetworks.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15753/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: IRQ Stack: Fix erroneous jal to plat_irq_dispatch

Commit dda45f701c9d ("MIPS: Switch to the irq_stack in interrupts")
changed both the normal and vectored interrupt handlers. Unfortunately
the vectored version, "except_vec_vi_handler", was incorrectly modified
to unconditionally jal to plat_irq_dispatch, rather than doing a jalr to
the vectored handler that has been set up. This is ok for many platforms
which set the vectored handler to plat_irq_dispatch anyway, but will
cause problems with platforms that use other handlers.

Fixes: dda45f701c9d ("MIPS: Switch to the irq_stack in interrupts")
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15110/
Signed-off-by: James Hogan <james.hogan@imgtec.com>

MIPS: Switch to the irq_stack in interrupts

When enterring interrupt context via handle_int or except_vec_vi, switch
to the irq_stack of the current CPU if it is not already in use.

The current stack pointer is masked with the thread size and compared to
the base or the irq stack. If it does not match then the stack pointer
is set to the top of that stack, otherwise this is a nested irq being
handled on the irq stack so the stack pointer should be left as it was.

The in-use stack pointer is placed in the callee saved register s1. It
will be saved to the stack when plat_irq_dispatch is invoked and can be
restored once control returns here.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Acked-by: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14743/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Fix BUILD_ROLLBACK_PROLOGUE for microMIPS

When the kernel is built for microMIPS, branches targets need to be
known to be microMIPS code in order to result in bit 0 of the PC being
set. The branch target in the BUILD_ROLLBACK_PROLOGUE macro was simply
the end of the macro, which may be pointing at padding rather than at
code. This results in recent enough GNU linkers complaining like so:

mips-img-linux-gnu-ld: arch/mips/built-in.o: .text+0x3e3c: Unsupported branch between ISA modes.
mips-img-linux-gnu-ld: final link failed: Bad value
Makefile:936: recipe for target 'vmlinux' failed
make: *** [vmlinux] Error 1

Fix this by changing the branch target to be the start of the
appropriate handler, skipping over any padding.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14019/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: genex: Indent delay slots & clean whitespace

Various branches and jumps in noreorder parts of genex.S don't have
their delay slot instructions indented conventionally with the extra
space.

Fix these, as well as various other inconsistent whitespace problems in
this file, such as spaces used after some opcodes instead of a tab.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13196/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Support extended ASIDs

Add support for extended ASIDs as determined by the Config4.AE bit.
Since the only supported CPUs known to implement this are Netlogic XLP
and MIPS I6400, select this variable ASID support based upon
CONFIG_CPU_XLP and CONFIG_CPU_MIPSR6.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Jayachandran C. <jchandra@broadcom.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13211/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Add & use CP0_EntryHi ASID definitions

Add definitions for the ASID field in CP0_EntryHi (along with the soon
to be used ASIDX field), and use them in a few previously hardcoded
cases.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13205/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Fix LLVM build issue.

Matthew Fortune <Matthew.Fortune@imgtec.com> reports:

The genex.S file appears to mix the case of a macro between its definition and
use. A cut down example of this is below. The macro __build_clear_none has
lower case 'build' but ends up being instantiated with upper case BUILD. Can
this be fixed on master. It has been picked up by the LLVM integrated assembler
which is currently case sensitive. We are likely to fix the assembler as well
but the code is currently inconsistent in the kernel.

.macro __build_clear_none
.endm

.macro __BUILD_HANDLER exception handler clear verbose ext
.align 5
.globl handle_\exception; .align 2; .type handle_\exception, @function; .ent
handle_\exception, 0; handle_\exception: .frame $29, 184, $29
.set noat
.globl handle_\exception\ext; .type handle_\exception\ext, @function;
handle_\exception\ext:
__BUILD_clear_\clear
.endm

.macro BUILD_HANDLER exception handler clear verbose
__BUILD_HANDLER \exception \handler \clear \verbose _int
.endm

BUILD_HANDLER ftlb ftlb none silent

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: Matthew Fortune <Matthew.Fortune@imgtec.com>

MIPS: Use `FPU_CSR_ALL_X' in `__build_clear_fpe'

Replace a hardcoded numeric bitmask for FCSR cause bits with
`FPU_CSR_ALL_X' in `__build_clear_fpe'.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9684/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Clear [MSA]FPE CSR.Cause after notify_die()

When handling floating point exceptions (FPEs) and MSA FPEs the Cause
bits of the appropriate control and status register (FCSR for FPEs and
MSACSR for MSA FPEs) are read and cleared before enabling interrupts,
presumably so that it doesn't have to go through the pain of restoring
those bits if the process is pre-empted, since writing those bits would
cause another immediate exception while still in the kernel.

The bits aren't normally ever restored again, since userland never
expects to see them set.

However for virtualisation it is necessary for the kernel to be able to
restore these Cause bits, as the guest may have been interrupted in an
FP exception handler but before it could read the Cause bits. This can
be done by registering a die notifier, to get notified of the exception
when such a value is restored, and if the PC was at the instruction
which is used to restore the guest state, the handler can step over it
and continue execution. The Cause bits can then remain set without
causing further exceptions.

For this to work safely a few changes are made:
- __build_clear_fpe and __build_clear_msa_fpe no longer clear the Cause
bits, and now return from exception level with interrupts disabled
instead of enabled.
- do_fpe() now clears the Cause bits and enables interrupts after
notify_die() is called, so that the notifier can chose to return from
exception without this happening.
- do_msa_fpe() acts similarly, but now actually makes use of the second
argument (msacsr) and calls notify_die() with the new DIE_MSAFP,
allowing die notifiers to be informed of MSA FPEs too.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

MIPS: clear MSACSR cause bits when handling MSA FP exception

Much like for traditional scalar FP exceptions, the cause bits in the
MSACSR register need to be cleared following an MSA FP exception.
Without doing so the exception will simply be raised again whenever
the kernel restores MSACSR from a tasks saved context, leading to
undesirable spurious exceptions. Clear the cause bits from the
handle_msa_fpe function, mirroring the way handle_fpe clears the
cause bits in FCSR.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9164/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: kernel: genex: Set correct ISA level

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>

MIPS: Fix build with binutils 2.24.51+

Starting with version 2.24.51.20140728 MIPS binutils complain loudly
about mixing soft-float and hard-float object files, leading to this
build failure since GCC is invoked with "-msoft-float" on MIPS:

{standard input}: Warning: .gnu_attribute 4,3 requires `softfloat'
LD arch/mips/alchemy/common/built-in.o
mipsel-softfloat-linux-gnu-ld: Warning: arch/mips/alchemy/common/built-in.o
uses -msoft-float (set by arch/mips/alchemy/common/prom.o),
arch/mips/alchemy/common/sleeper.o uses -mhard-float

To fix this, we detect if GAS is new enough to support "-msoft-float" command
option, and if it does, we can let GCC pass it to GAS; but then we also need
to sprinkle the files which make use of floating point registers with the
necessary ".set hardfloat" directives.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: Markos Chandras <Markos.Chandras@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/8355/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: MT: Remove SMTC support

Nobody is maintaining SMTC anymore and there also seems to be no userbase.
Which is a pity - the SMTC technology primarily developed by Kevin D.
Kissell <kevink@paralogos.com> is an ingenious demonstration for the MT
ASE's power and elegance.

Based on Markos Chandras <Markos.Chandras@imgtec.com> patch
https://patchwork.linux-mips.org/patch/6719/ which while very similar did
no longer apply cleanly when I tried to merge it plus some additional
post-SMTC cleanup - SMTC was a feature as tricky to remove as it was to
merge once upon a time.

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

MIPS: Fix gigaton of warning building with microMIPS.

With binutils 2.24 the attempt to switch with microMIPS mode to MIPS III
mode through .set mips3 results in *lots* of warnings like

{standard input}: Assembler messages:
{standard input}:397: Warning: the 64-bit MIPS architecture does not support the `smartmips' extension

during a kernel build. Fixed by using .set arch=r4000 instead.

This breaks support for building the kernel with binutils 2.13 which
was supported for 32 bit kernels only anyway and 2.14 which was a bad
vintage for MIPS anyway.

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

MIPS: Dumb MSA FP exception handler

This patch adds a simple handler for MSA FP exceptions which delivers a
SIGFPE to the running task. In the future it should probably be extended
to re-execute the instruction with the MSACSR.NX bit set in order to
generate results for any elements which did not cause an exception
before delivering the SIGFPE signal.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6432/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Basic MSA context switching support

This patch adds support for context switching the MSA vector registers.
These 128 bit vector registers are aliased with the FP registers - an
FP register accesses the least significant bits of the vector register
with which it is aliased (ie. the register with the same index). Due to
both this & the requirement that the scalar FPU must be 64-bit (FR=1) if
enabled at the same time as MSA the kernel will enable MSA & scalar FP
at the same time for tasks which use MSA. If we restore the MSA vector
context then we might as well enable the scalar FPU since the reason it
was left disabled was to allow for lazy FP context restoring - but we
just restored the FP context as it's a subset of the vector context. If
we restore the FP context and have previously used MSA then we have to
restore the whole vector context anyway (see comment in
enable_restore_fp_context for details) so similarly we might as well
enable MSA.

Thus if a task does not use MSA then it will continue to behave as
without this patch - the scalar FP context will be saved & restored as
usual. But if a task executes an MSA instruction then it will save &
restore the vector context forever more.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6431/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Add support for FTLBs

The Fixed Page Size TLB (FTLB) is a set-associative dual entry TLB. Its
purpose is to reduce the number of TLB misses by increasing the effective
TLB size and keep the implementation complexity to minimum levels.
A supported core can have both VTLB and FTLB.

Reviewed-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6139/

MIPS: Print correct PC in trace dump after NMI exception

An NMI exception delivered from YAMON delivers the PC in ErrorPC
instead of EPC. It's also necessary to clear the Status.BEV
bit for the page fault exception handler to work properly.

[ralf@linux-mips: Let the assembler do the loading of the mask value rather
than the convoluted explicit %hi/%lo manual relocation sequence from the
original patch.]

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6035/
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/6084/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Idle: Break r4k_wait into two functions and fix it.

local_irq_enable() may expand into very different code, so it rather should
stay in C. Also this keeps the assembler code size constant which keeps
the rollback code simple. So it's best to split r4k_wait into two parts,
one C and one assembler.

Finally add the local_irq_enable() to r4k_wait to ensure the WAIT
instruction in __r4k_wait() will work properly.

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

Revert "MIPS: Allow ASID size to be determined at boot time."

This reverts commit d532f3d26716a39dfd4b88d687bd344fbe77e390.

The original commit has several problems:

1) Doesn't work with 64-bit kernels.

2) Calls TLBMISS_HANDLER_SETUP() before the code is generated.

3) Calls TLBMISS_HANDLER_SETUP() twice in per_cpu_trap_init() when
only one call is needed.

[ralf@linux-mips.org: Also revert the bits of the ASID patch which were
hidden in the KVM merge.]

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: "Steven J. Hill" <Steven.Hill@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/5242/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: microMIPS: Add support for exception handling.

All exceptions must be taken in microMIPS mode, never in classic
MIPS mode or the kernel falls apart. A few NOP instructions are
used to maintain the correct alignment of microMIPS versions of
the exception vectors.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>

MIPS: Allow ASID size to be determined at boot time.

Original patch by Ralf Baechle and removed by Harold Koerfgen
with commit f67e4ffc79905482c3b9b8c8dd65197bac7eb508. This
allows for more generic kernels since the size of the ASID
and corresponding masks can be determined at run-time. This
patch is also required for the new Aptiv cores and has been
tested on Malta and Malta Aptiv platforms.

[ralf@linux-mips.org: Added relevant part of fix
https://patchwork.linux-mips.org/patch/5213/]

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Whitespace cleanup.

Having received another series of whitespace patches I decided to do this
once and for all rather than dealing with this kind of patches trickling
in forever.

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

MIPS: Switch remaining assembler PAGE_SIZE users to <asm/asm-offsets.h>.

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

MIPS: Read watch registers with interrupts disabled.

If a context switch occurred between the watch exception and reading the
watch registers, it would be possible for the new process to corrupt their
state. Enabling interrupts only after the watch registers are read avoids
this race.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Override assembler target architecture for octeon.

Gas from binutils 2.19 fails to compile some cop1 instructions with
-march=octeon. Since the cop1 instructions are present in mips1, use
that arch instead. This will be fixed in binutils 2.20.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Watch exception handling for HARDWARE_WATCHPOINTS.

Here we hook up the watch exception handler so that it sends SIGTRAP when
the hardware watch registers are triggered.

Signed-off-by: David Daney <ddaney@avtrex.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] SMTC: Fix SMTC dyntick support.

Rework of SMTC support to make it work with the new clock event system,
allowing "tickless" operation, and to make it compatible with the use of
the "wait_irqoff" idle loop. The new clocking scheme means that the
previously optional IPI instant replay mechanism is now required, and has
been made more robust.

Signed-off-by: Kevin D. Kissell <kevink@paralogos.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] Fix potential latency problem due to non-atomic cpu_wait.

If an interrupt happened between checking of NEED_RESCHED and WAIT
instruction, adjust EPC to restart from checking of NEED_RESCHED.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] R4000/R4400 daddiu erratum workaround

This complements the generic R4000/R4400 errata workaround code and adds
bits for the daddiu problem. In most places it just modifies handwritten
assembly code so that the assembler is allowed to use a temporary register
as daddiu may now be treated as a macro that expands to a sequence of li
and daddu. It is the AT register or, where AT is unavailable or used
explicitly for another purpose, an explicitly-named register is selected,
using the .set at=<reg> feature added recently to gas. This feature is
only used if CONFIG_CPU_DADDI_WORKAROUNDS has been set, so if the
workaround remains disabled, the required version of binutils stays
unchanged.

Similarly, daddiu instructions put in branch delay slots in noreorder
fragments are now taken out of them and the assembler is allowed to
reorder them itself as possible (which it does making the whole idea of
scheduling them into delay slots manually questionable).

Also in the very few places where such a simple conversion was not
possible, a handcoded longer sequence is implemented.

Other than that there are changes to code responsible for building the
TLB fault and page clear/copy handlers to avoid daddiu as appropriate.
These are only effective if the erratum is verified to be present at the
run time.

Finally there is a trivial update to __delay(), because it uses daddiu in
a branch delay slot.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] Fix typo in R3000 TRACE_IRQFLAGS code

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] SMTC: Interrupt mask backstop hack

To support multiple TC microthreads acting as "CPUs" within a VPE,
VPE-wide interrupt mask bits must be specially manipulated during
interrupt handling. To support legacy drivers and interrupt controller
management code, SMTC has a "backstop" to track and if necessary restore
the interrupt mask. This has some performance impact on interrupt service
overhead. Disable it only if you know what you are doing.

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

[MIPS] lockdep: Deal with interrupt disable hazard in TRACE_IRQFLAGS

Between the mtc0 or di instruction that disables interrupts and the
following hazard barrier a processor may still take interrupts. If an
interrupt is taken after interrupts are disabled but before the state
is updated it will appear to restore_all that it is incorrectly returning
with interrupts disabled.

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] Export except_vec_vi_{mori,lui,ori} as text symbols.

Otherwise objdump will screw up disassembly.

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

[MIPS] VI: TRACE_IRQS_OFF clobbers $v0, so save & restore around call.

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

[MIPS] Fast path for rdhwr emulation for TLS

Add special short path for emulationg RDHWR which is used to support TLS.
Add an extra prologue for cpu_has_vtag_icache case.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] ret_from_irq adjustment

Make sure that RA on top of interrupt stack is an address of ret_from_irq,
so that dump_stack etc. can trace info interrupted context.

Also this patch fixes except_vec_vi_handler and __smtc_ipi_vector which
seems broken.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] Complete fixes after removal of pt_regs argument to int handlers.

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

[MIPS] Stacktrace build-fix and improvement

Fix build error due to stacktrace API change. Now save_stack_trace()
tries to save all kernel context, including interrupts and exception.
Also some asm code are changed a bit so that we can detect the end of
current context easily.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[MIPS] TRACE_IRQFLAGS_SUPPORT support.

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

[MIPS] Less noise on multithreading exceptions.

Make the MT handler silent and output the MT exception type at debug
priority.

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Remove obsolete #include <linux/config.h>

Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

[MIPS] Fix use of ehb instruction for non-R2 configurations.

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

[MIPS] MT: Improved multithreading support.

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

[MIPS] Rewrite all the assembler interrupt handlers to C.

Saves like 1,600 lines of code, is way easier to debug, compilers
frequently do a better job than the cut and paste type of handlers many
boards had. And finally having all the stuff done in a single place
also means alot of bug potencial for the MT ASE is gone.

The only surviving handler in assembler is the DECstation one; I hope
Maciej will rewrite it.

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

[MIPS] Remove stray .set mips3 resulting in 64-bit instruction in 32-bit kernels.

Only the NMI handler was affected so this is a low impact bug.

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

Virtual SMP support for the 34K.

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

More AP / SP bits for the 34K, the Malta bits and things. Still wants
a little polishing.

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

Support the MIPS32 / MIPS64 DSP ASE.

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

Fix typos and formatting.

Signed-off-by: Thiemo Seufer <ths@networkno.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

[PATCH] mips: fix build warnings

This patch has fixed the following warnings.

arch/mips/kernel/genex.S:250:5: warning: "CONFIG_64BIT" is not defined
arch/mips/math-emu/cp1emu.c:1128:5: warning: "__mips64" is not defined
arch/mips/math-emu/cp1emu.c:1206:5: warning: "__mips64" is not defined
arch/mips/math-emu/cp1emu.c:1270:5: warning: "__mips64" is not defined
arch/mips/math-emu/cp1emu.c:323:5: warning: "__mips64" is not defined
arch/mips/math-emu/cp1emu.c:808:5: warning: "__mips64" is not defined
arch/mips/math-emu/cp1emu.c:953:5: warning: "__mips64" is not defined
arch/mips/mm/tlbex.c:519:5: warning: "CONFIG_64BIT" is not defined
include/asm/reg.h:73:5: warning: "CONFIG_64BIT" is not defined

Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] mips: nuke trailing whitespace

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] mips: clean up 32/64-bit configuration

Start cleaning 32-bit vs. 64-bit configuration.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!