mips: Call lose_fpu(0) before initializing fcr31 in mips_set_personality_nan

If we still own the FPU after initializing fcr31, when we are preempted
the dirty value in the FPU will be read out and stored into fcr31,
clobbering our setting. This can cause an improper floating-point
environment after execve(). For example:

zsh% cat measure.c
#include <fenv.h>
int main() { return fetestexcept(FE_INEXACT); }
zsh% cc measure.c -o measure -lm
zsh% echo $((1.0/3)) # raising FE_INEXACT
0.33333333333333331
zsh% while ./measure; do ; done
(stopped in seconds)

Call lose_fpu(0) before setting fcr31 to prevent this.

Closes: https://lore.kernel.org/linux-mips/7a6aa1bbdbbe2e63ae96ff163fab0349f58f1b9e.camel@xry111.site/
Fixes: 9b26616c8d9d ("MIPS: Respect the ISA level in FCSR handling")
Cc: stable@vger.kernel.org
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MIPS: Modernize READ_IMPLIES_EXEC

I'm doing some thread necromancy of
https://lore.kernel.org/lkml/202007081624.82FA0CC1EA@keescook/

x86, arm64, and arm32 adjusted their READ_IMPLIES_EXEC logic to better
align with the safer defaults and the interactions with other mappings,
which I illustrated with this comment on x86:

/*
* An executable for which elf_read_implies_exec() returns TRUE will
* have the READ_IMPLIES_EXEC personality flag set automatically.
*
* The decision process for determining the results are:
*
* CPU: | lacks NX* | has NX, ia32 | has NX, x86_64 |
* ELF: | | | |
* ---------------------|------------|------------------|----------------|
* missing PT_GNU_STACK | exec-all | exec-all | exec-none |
* PT_GNU_STACK == RWX | exec-stack | exec-stack | exec-stack |
* PT_GNU_STACK == RW | exec-none | exec-none | exec-none |
*
* exec-all : all PROT_READ user mappings are executable, except when
* backed by files on a noexec-filesystem.
* exec-none : only PROT_EXEC user mappings are executable.
* exec-stack: only the stack and PROT_EXEC user mappings are
* executable.
*
* *this column has no architectural effect: NX markings are ignored by
* hardware, but may have behavioral effects when "wants X" collides with
* "cannot be X" constraints in memory permission flags, as in
* https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com
*
*/

For MIPS, the "lacks NX" above is the "!cpu_has_rixi" check. On x86,
we decided that the READ_IMPLIES_EXEC flag needed to reflect the
expectations, not the architectural behavior due to bad interactions
as noted above, as always returning "1" on non-NX hardware breaks
some mappings.

The other part of the issue is "what does the MIPS toolchain do for
PT_GNU_STACK?" The answer seems to be "by default, include PT_GNU_STACK,
but mark it executable" (likely due to concerns over non-NX hardware):

$ mipsel-linux-gnu-gcc -o hello_world hello_world.c
$ llvm-readelf -lW hellow_world | grep GNU_STACK
GNU_STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x10

Given that older hardware doesn't support non-executable memory, it
seems safe to make the "PT_GNU_STACK is absent" logic mean "assume
non-executable", but this might break very old software running on
modern MIPS. This situation matches the ia32-on-x86_64 logic x86
uses (which assumes needing READ_IMPLIES_EXEC in that situation). But
modern toolchains on modern MIPS hardware should follow a safer default
(assume NX stack).

A follow-up to this change would be to switch the MIPS toolchain to emit
a non-executable PT_GNU_STACK, as this seems to be unneeded.

Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Cc: Juxin Gao <gaojuxin@loongson.cn>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MIPS: Avoid FP ELF checks when CONFIG_MIPS_FP_SUPPORT=n

When CONFIG_MIPS_FP_SUPPORT=n we don't support floating point, so we can
avoid needless checks of ELF headers specifying the FP ABI or NaN
encoding to use. Deselect CONFIG_ARCH_BINFMT_ELF_STATE in this case to
avoid the need for our arch_elf_pt_proc() & arch_check_elf() functions,
and stub out the mips_set_personality_nan() & mips_set_personality_fp()
functions such that SET_PERSONALITY() doesn't need to worry about any of
this.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21011/
Cc: linux-mips@linux-mips.org

Update MIPS email addresses

MIPS will soon not be a part of Imagination Technologies, and as such
many @imgtec.com email addresses will no longer be valid. This patch
updates the addresses for those who:

- Have 10 or more patches in mainline authored using an @imgtec.com
email address, or any patches dated within the past year.

- Are still with Imagination but leaving as part of the MIPS business
unit, as determined from an internal email address list.

- Haven't already updated their email address (ie. JamesH) or expressed
a desire to be excluded (ie. Maciej).

- Acked v2 or earlier of this patch, which leaves Deng-Cheng, Matt &
myself.

New addresses are of the form firstname.lastname@mips.com, and all
verified against an internal email address list. An entry is added to
.mailmap for each person such that get_maintainer.pl will report the new
addresses rather than @imgtec.com addresses which will soon be dead.

Instances of the affected addresses throughout the tree are then
mechanically replaced with the new @mips.com address.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@mips.com>
Acked-by: Dengcheng Zhu <dengcheng.zhu@mips.com>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Matt Redfearn <matt.redfearn@mips.com>
Acked-by: Matt Redfearn <matt.redfearn@mips.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: trivial@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Update MIPS email addresses

MIPS will soon not be a part of Imagination Technologies, and as such
many @imgtec.com email addresses will no longer be valid. This patch
updates the addresses for those who:

- Have 10 or more patches in mainline authored using an @imgtec.com
email address, or any patches dated within the past year.

- Are still with Imagination but leaving as part of the MIPS business
unit, as determined from an internal email address list.

- Haven't already updated their email address (ie. JamesH) or expressed
a desire to be excluded (ie. Maciej).

- Acked v2 or earlier of this patch, which leaves Deng-Cheng, Matt &
myself.

New addresses are of the form firstname.lastname@mips.com, and all
verified against an internal email address list. An entry is added to
.mailmap for each person such that get_maintainer.pl will report the new
addresses rather than @imgtec.com addresses which will soon be dead.

Instances of the affected addresses throughout the tree are then
mechanically replaced with the new @mips.com address.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@mips.com>
Acked-by: Dengcheng Zhu <dengcheng.zhu@mips.com>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Matt Redfearn <matt.redfearn@mips.com>
Acked-by: Matt Redfearn <matt.redfearn@mips.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: trivial@kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17540/
Signed-off-by: James Hogan <jhogan@kernel.org>

fs: fix kernel_read prototype

Use proper ssize_t and size_t types for the return value and count
argument, move the offset last and make it an in/out argument like
all other read/write helpers, and make the buf argument a void pointer
to get rid of lots of casts in the callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

MIPS: Avoid BUG warning in arch_check_elf

arch_check_elf contains a usage of current_cpu_data that will call
smp_processor_id() with preemption enabled and therefore triggers a
"BUG: using smp_processor_id() in preemptible" warning when an fpxx
executable is loaded.

As a follow-up to commit b244614a60ab ("MIPS: Avoid a BUG warning during
prctl(PR_SET_FP_MODE, ...)"), apply the same fix to arch_check_elf by
using raw_current_cpu_data instead. The rationale quoted from the previous
commit:

"It is assumed throughout the kernel that if any CPU has an FPU, then
all CPUs would have an FPU as well, so it is safe to perform the check
with preemption enabled - change the code to use raw_ variant of the
check to avoid the warning."

Fixes: 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU mode checks")
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
CC: <stable@vger.kernel.org> # 4.0+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15951/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

tree-wide: replace config_enabled() with IS_ENABLED()

The use of config_enabled() against config options is ambiguous. In
practical terms, config_enabled() is equivalent to IS_BUILTIN(), but the
author might have used it for the meaning of IS_ENABLED(). Using
IS_ENABLED(), IS_BUILTIN(), IS_MODULE() etc. makes the intention
clearer.

This commit replaces config_enabled() with IS_ENABLED() where possible.
This commit is only touching bool config options.

I noticed two cases where config_enabled() is used against a tristate
option:

- config_enabled(CONFIG_HWMON)
[ drivers/net/wireless/ath/ath10k/thermal.c ]

- config_enabled(CONFIG_BACKLIGHT_CLASS_DEVICE)
[ drivers/gpu/drm/gma500/opregion.c ]

I did not touch them because they should be converted to IS_BUILTIN()
in order to keep the logic, but I was not sure it was the authors'
intention.

Link: http://lkml.kernel.org/r/1465215656-20569-1-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Stas Sergeev <stsp@list.ru>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Joshua Kinard <kumba@gentoo.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: yu-cheng yu <yu-cheng.yu@intel.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Will Drewry <wad@chromium.org>
Cc: Nikolay Martynov <mar.kolya@gmail.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Rafal Milecki <zajec5@gmail.com>
Cc: James Cowgill <James.Cowgill@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Tony Wu <tung7970@gmail.com>
Cc: Huaitong Han <huaitong.han@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Gelmini <andrea.gelmini@gelma.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Rabin Vincent <rabin@rab.in>
Cc: "Maciej W. Rozycki" <macro@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MIPS: non-exec stack & heap when non-exec PT_GNU_STACK is present

The stack and heap have both been executable by default on MIPS until
now. This patch changes the default to be non-executable, but only for
ELF binaries with a non-executable PT_GNU_STACK header present. This
does apply to both the heap & the stack, despite the name PT_GNU_STACK,
and this matches the behaviour of other architectures like ARM & x86.

Current MIPS toolchains do not produce the PT_GNU_STACK header, which
means that we can rely upon this patch not changing the behaviour of
existing binaries. The new default will only take effect for newly
compiled binaries once toolchains are updated to support PT_GNU_STACK,
and since those binaries are newly compiled they can be compiled
expecting the change in default behaviour. Again this matches the way in
which the ARM & x86 architectures handled their implementations of
non-executable memory.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: Maciej Rozycki <maciej.rozycki@imgtec.com>
Cc: Faraz Shahbazker <faraz.shahbazker@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13765/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Spelling fix lets -> let's

As noticed by Sergei in the discussion of Andrea Gelmini's patch series.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

MIPS: Add IEEE Std 754 conformance mode selection

Add an `ieee754=' kernel parameter to control IEEE Std 754 conformance
mode.

Use separate flags copied from the respective CPU feature flags, and
adjusted according to the conformance mode selected, to make binaries
requesting individual NaN encoding modes accepted or rejected as needed.
Update the initial setting for FCSR and, in the full FPU emulation mode,
its read-only mask accordingly. Accept the mode selection requested for
legacy processors as well.

As with the EF_MIPS_NAN2008 ELF file header flag adjust both ABS2008 and
NAN2008 bits at the same time, to match the choice made for hardware
currently implemented.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11481/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: ELF: Interpret the NAN2008 file header flag

Handle the EF_MIPS_NAN2008 ELF file header flag and refuse execution
where there is no support in the FPU for the NaN encoding mode requested
by a binary invoked. Ensure that the setting of the bit in the binary
matches one in any intepreter used. Set the thread's initial FCSR
contents according to the value of the EF_MIPS_NAN2008.

Set the values of the FCSR ABS2008 and NAN2008 bits both to the same
value if possible, to take the approach taken with existing FPU hardware
into account. As of now all implementations have both bits hardwired to
the same value, that is both are fixed at 0 or both are fixed at 1, even
though the architecture allows for implementations where the amount of
control implemented with each of these two individual bits is
independent of each other.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11479/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

ELF: Also pass any interpreter's file header to `arch_check_elf'

Also pass any interpreter's file header to `arch_check_elf' so that any
architecture handler can have a look at it if needed.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11478/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Use a union to access the ELF file header

Rewrite `arch_elf_pt_proc' and `arch_check_elf' using a union to access
the ELF file header.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11474/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: fix FP mode selection in lieu of .MIPS.abiflags data

Commit 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU
mode checks") reworked the ELF FP ABI mode selection logic, but when
CONFIG_MIPS_O32_FP64_SUPPORT is enabled it breaks the use of binaries
which have no PT_MIPS_ABIFLAGS program header & associated
.MIPS.abiflags section.

A default mode is selected based upon whether the ELF contains MIPS32 or
MIPS64 code, but that selection is made in arch_elf_pt_proc.
arch_elf_pt_proc only executes when a PT_MIPS_ABIFLAGS program header is
found. If one is not found then arch_elf_pt_proc is never called, and no
default overall_fp_mode value is selected. When arch_check_elf is
called, both abi0 & abi1 are MIPS_ABI_FP_UNKNOWN which leads to both
prog_req & interp_req being set to none_req. none_req matches none of
the conditions for mode selection at the end of arch_check_elf, so
overall_fp_mode is left untouched. Finally once mips_set_personality_fp
is called the BUG() in the default case is then hit & the kernel likely
panics.

Fix this by moving the selection of a default overall mode to the start
of arch_check_elf, which runs once per ELF executed regardless of
whether it has a PT_MIPS_ABIFLAGS program header.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.0+
Patchwork: http://patchwork.linux-mips.org/patch/9978/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: ELF: Drop `get_fp_abi'

Commit 46490b57 [MIPS: kernel: elf: Improve the overall ABI and FPU mode
checks] reduced `get_fp_abi' to an elaborate pass-through. Drop it
then.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9677/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: kernel: elf: Improve the overall ABI and FPU mode checks

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>

MIPS: ELF: fix loading o32 binaries on 64-bit kernels

Commit 90cee759f08a ("MIPS: ELF: Set FP mode according to .MIPS.abiflags")
introduced checking of the .MIPS.abiflags ELF section but did so through
the native sized "elfhdr" and "elf_phdr" structures regardless whether the
ELF was actually 32-bit or 64-bit. This produces wrong results when trying
to use a 64-bit kernel to load o32 ELF files.

Change the uses of the generic elf structures to their 32-bit versions.
Since the code bails out on any 64-bit cases, this is OK until they are
implemented.

Fixes: 90cee759f08a ("MIPS: ELF: Set FP mode according to .MIPS.abiflags")
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Maciej W. Rozycki <macro@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/8932/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Kconfig option to better exercise/debug hybrid FPRs

The hybrid FPR scheme exists to allow for compatibility between existing
FP32 code and newly compiled FP64A code. Such code should hopefully be
rare in the real world, and for the moment is difficult to come across.
All code except that built for the FP64 ABI can correctly execute using
the hybrid FPR scheme, so debugging the hybrid FPR implementation can
be eased by forcing all such code to use it. This is undesirable in
general due to the trap & emulate overhead of the hybrid FPR
implementation, but is a very useful option to have for debugging.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7680/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: ELF: Set FP mode according to .MIPS.abiflags

This patch reads the .MIPS.abiflags section when it is present, and sets
the FP mode of the task accordingly. Any loaded ELF files which do not
contain a .MIPS.abiflags section will continue to observe the previous
behaviour, that is FR=1 if EF_MIPS_FP64 is set else FR=0.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7681/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>