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path: root/arch/mips/math-emu/cp1emu.c
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2014-11-24MIPS: Support for hybrid FPRsPaul Burton
Hybrid FPRs is a scheme where scalar FP registers are 64b wide, but accesses to odd indexed single registers use bits 63:32 of the preceeding even indexed 64b register. In this mode all FP code except that built for the plain FP64 ABI can execute correctly. Most notably a combination of FP64A & FP32 code can execute correctly, allowing for existing FP32 binaries to be linked with new FP64A binaries that can make use of 64 bit FP & MSA. Hybrid FPRs are implemented by setting both the FR & FRE bits, trapping & emulating single precision FP instructions (via Reserved Instruction exceptions) whilst allowing others to execute natively. It therefore has a penalty in terms of execution speed, and should only be used when no fully native mode can be. As more binaries are recompiled to use either the FPXX or FP64(A) ABIs, the need for hybrid FPRs should diminish. However in the short to mid term it allows for a gradual transition towards that world, rather than a complete ABI break which is not feasible for some users & not desirable for many. A task will be executed using the hybrid FPR scheme when its TIF_HYBRID_FPREGS flag is set & TIF_32BIT_FPREGS is clear. A further patch will set the flags as necessary, this patch simply adds the infrastructure necessary for the hybrid FPR mode to work. 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/7683/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-11-07MIPS: Fix build with binutils 2.24.51+Manuel Lauss
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>
2014-10-21MIPS: cp1emu: Fix ISA restrictions for cop1x_op instructionsMarkos Chandras
Commit 08a07904e1828 ("MIPS: math-emu: Remove most ifdefery") removed the #ifdef ISA conditions and switched to runtime detection. However, according to the instruction set manual, the cop1x_op instructions are available in >=MIPS32r2 as well. This fixes a problem on MIPS32r2 with the ntpd package which failed to execute with a SIGILL exit code due to the fact that a madd.d instruction was not being emulated. Signed-off-by: Markos Chandras <markos.chandras@imgtec.com> Fixes: 08a07904e1828 ("MIPS: math-emu: Remove most ifdefery") Cc: <stable@vger.kernel.org> # v3.16+ Cc: linux-mips@linux-mips.org Reviewed-by: Paul Burton <paul.burton@imgtec.com> Reviewed-by: James Hogan <james.hogan@imgtec.com> Cc: Markos Chandras <markos.chandras@imgtec.com> Patchwork: https://patchwork.linux-mips.org/patch/8173/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-09-26MIPS: Fix MFC1 & MFHC1 emulation for 64-bit MIPS systemsPaul Burton
Commit bbd426f542cb "MIPS: Simplify FP context access" modified the SIFROMREG & SIFROMHREG macros such that they return unsigned rather than signed 32b integers. I had believed that to be fine, but inadvertently missed the MFC1 & MFHC1 cases which write to a struct pt_regs regs element. On MIPS32 this is fine, but on 64 bit those saved regs' fields are 64 bit wide. Using unsigned values caused the 32 bit value from the FP register to be zero rather than sign extended as the architecture specifies, causing incorrect emulation of the MFC1 & MFHc1 instructions. Fix by reintroducing the casts to signed integers, and therefore the sign extension. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: stable@vger.kernel.org # v3.15+ Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/7848/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-07-30MIPS: math-emu: Fix instruction decoding.Rob Kendrick
Tested-by: Aurelien Jarno <aurelien@aurel32.net> Reviewed-by: Aurelien Jarno <aurelien@aurel32.net> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-30MIPS: OCTEON: Enable use of FPUDavid Daney
Some versions of the assembler will not assemble CFC1 for OCTEON, so override the ISA for these. Add r4k_fpu.o to handle low level FPU initialization. Modify octeon_switch.S to save the FPU registers. And include r4k_switch.S to pick up more FPU support. Get rid of "#define cpu_has_fpu 0" Signed-off-by: David Daney <david.daney@cavium.com> Signed-off-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com> Cc: linux-mips@linux-mips.org Cc: James Hogan <james.hogan@imgtec.com> Cc: kvm@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/7006/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-30MIPS: math-emu: Add IEEE754 exception statistics to debugfsDeng-Cheng Zhu
Sometimes it's useful to let the user, while doing performance research, know what in the IEEE754 exceptions has caused many times of FP emulation when running a specific application. This patch adds 5 more files to /sys/kernel/debug/mips/fpuemustats/, whose filenames begin with "ieee754". These stats are in addition to the existing cp1ops, cp1xops, errors, loads and stores, which may not be useful in understanding the reasons of ieee754 exceptions. [ralf@linux-mips.org: Fixed reject due to other changes to the kernel FP assist software.] Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Steven.Hill@imgtec.com Cc: james.hogan@imgtec.com Patchwork: http://patchwork.linux-mips.org/patch/7044/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-23MIPS: math-emu: Reduce microMIPS bloat.Ralf Baechle
Move microMIPS32_to_MIPS32() to a separate file which only gets built for mipsMIPS configurations; for other configurations the optimizer eleminates calls to microMIPS32_to_MIPS32(). Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-23MIPS: math-emu: Switch to using the MIPS rounding modes.Ralf Baechle
Previously math-emu was using the IEEE-754 constants internally. These were differing by having the constants for rounding to +/- infinity switched, so a conversion was necessary. This would be entirely avoidable if the MIPS constants were used throughout, so get rid of the bloat. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-23MIPS: Sort out mm_isBranchInstr.Ralf Baechle
mm_isBranchInstr() did reside in the math emu code even though it logically is separate and also is used outside the math emu code. In addition GCC 4.9.0 leaves the following unnnecessarily bloated function body for a non-microMIPS configuration: <mm_isBranchInstr>: 105c: afa50004 sw a1,4(sp) 1060: afa60008 sw a2,8(sp) 1064: afa7000c sw a3,12(sp) 1068: 03e00008 jr ra 106c: 00001021 move v0,zero which stores arguments that are never going to be used on the stack frame. Move mm_isBranchInstr() from cp1emu.c to branch.c, then split mm_isBranchInstr() into a __mm_isBranchInstr() core and a mm_isBranchInstr() wrapper inline function which only invokes __mm_isBranchInstr() on microMIPS configurations. This shaves off 112 bytes off the kernel and improves code flow a bit. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-23MIPS: math-emu: Cleanup coding style.Ralf Baechle
o Only define variables in the outermost block o One empty line at most o Format comments as per CodingStyle o Update FSF address in licensing term comment o Spell FPU and MIPS in all capitals. o Remove ####-type of lines in comments. o Try to make things a bit most consistent between sp_*.c / dp_*.c files. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-23MIPS: math-emu: Convert debug printks to pr_debug getting.Ralf Baechle
And another bunch of #ifdefs bite the dust. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-21MIPS: math-emu: Remove most ifdefery.Ralf Baechle
Most of these tests should be runtime tests. This also finally means that on a MIPS III systems MIPS IV opcodes are going to result in an exception as they're supposed to. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-21MIPS: math-emu: Reformat code according to coding style.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-21MIPS: math-emu: Move all debug fs code to a separate file.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-21MIPS: math-emu: Header file weeding.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-21MIPS: math-emu: Use helpers to manipulate CAUSEF_BD flag.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-21MIPS: math-emu: Get rid of typedefs.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-03-31Merge branch '3.14-fixes' into mips-for-linux-nextRalf Baechle
2014-03-26MIPS: Clear upper bits of FP registers on emulator writesPaul Burton
The upper bits of an FP register are architecturally defined as unpredictable following an instructions which only writes the lower bits. The prior behaviour of the kernel is to leave them unmodified. This patch modifies that to clear the upper bits to zero. This is what the MSA architecture reference manual specifies should happen for its wider registers and is still permissible for scalar FP instructions given the bits unpredictability there. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: sergei.shtylyov@cogentembedded.com Patchwork: https://patchwork.linux-mips.org/patch/6435/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-03-26MIPS: Simplify FP context accessPaul Burton
This patch replaces the fpureg_t typedef with a "union fpureg" enabling easier access to 32 & 64 bit values. This allows the access macros used in cp1emu.c to be simplified somewhat. It will also make it easier to expand the width of the FP registers as will be done in a future patch in order to support the 128 bit registers introduced with MSA. No behavioural change is intended by this patch. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Reviewed-by: Qais Yousef <qais.yousef@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6532/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-03-11MIPS: math-emu: Fix prefx detection and COP1X function field definitionDeng-Cheng Zhu
When running applications which contain the instruction "prefx" on FPU-less CPUs, a message "Illegal instruction" will be seen. This instruction is supposed to be ignored by the FPU emulator. However, its current detection and function field encoding are incorrect. This patch fix the issue. Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com> Reviewed-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Reviewed-by: Paul Burton <paul.burton@imgtec.com> Acked-by: David Daney <david.daney@cavium.com> Cc: linux-mips@linux-mips.org Cc: Steven.Hill@imgtec.com Patchwork: https://patchwork.linux-mips.org/patch/6608/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-01-13MIPS: Support for 64-bit FP with O32 binariesPaul Burton
CPUs implementing MIPS32 R2 may include a 64-bit FPU, just as MIPS64 CPUs do. In order to preserve backwards compatibility a 64-bit FPU will act like a 32-bit FPU (by accessing doubles from the least significant 32 bits of an even-odd pair of FP registers) when the Status.FR bit is zero, again just like a mips64 CPU. The standard O32 ABI is defined expecting a 32-bit FPU, however recent toolchains support use of a 64-bit FPU from an O32 MIPS32 executable. When an ELF executable is built to use a 64-bit FPU a new flag (EF_MIPS_FP64) is set in the ELF header. With this patch the kernel will check the EF_MIPS_FP64 flag when executing an O32 binary, and set Status.FR accordingly. The addition of O32 64-bit FP support lessens the opportunity for optimisation in the FPU emulator, so a CONFIG_MIPS_O32_FP64_SUPPORT Kconfig option is introduced to allow this support to be disabled for those that don't require it. Inspired by an earlier patch by Leonid Yegoshin, but implemented more cleanly & correctly. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Paul Burton <paul.burton@imgtec.com> Patchwork: https://patchwork.linux-mips.org/patch/6154/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-01-13MIPS: microMIPS: mfhc1 & mthc1 support for the FPU emulatorSteven J. Hill
This patch adds support for microMIPS encodings of the mfhc1 & mthc1 instructions introduced in release 2 of the mips32 & mips64 architectures, converting them to their mips32 equivalents for the FPU emulator. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com> Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6110/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-01-13MIPS: math-emu: Add mfhc1 & mthc1 support.Leonid Yegoshin
This patch adds support for the mfhc1 & mthc1 instructions to the FPU emulator. These instructions were introduced in release 2 of the MIPS32 & MIPS64 architectures and allow access to the most significant 32 bits of a 64-bit FP register. [ralf@linux-mips.org: Fix ifdef hell added by original patch.] Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com> Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6112/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2013-08-26MIPS: Remove unreachable break statements from cp1emu.cDavid Daney
There were many cases of: return something; break; All those break statements are unreachable and thus redundant. Signed-off-by: David Daney <david.daney@cavium.com> Reviewed-by: Aaro Koskinen <aaro.koskinen@iki.fi> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/5727/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2013-08-20MIPS: Handle OCTEON BBIT instructions in FPU emulator.David Daney
The branch emulation needs to handle the OCTEON BBIT instructions, otherwise we get SIGILL instead of emulation. Signed-off-by: David Daney <david.daney@cavium.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/5726/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2013-07-01MIPS: Don't try to decode microMIPS branch instructions where they cannot exist.David Daney
In mm_isBranchInstr() we can short circuit the entire function if !cpu_has_mmips. Signed-off-by: David Daney <david.daney@cavium.com> Acked-by: Steven J. Hill <Steven.Hill@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/5326/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2013-05-09MIPS: microMIPS: Floating point support.Leonid Yegoshin
Add logic needed to do floating point emulation in microMIPS mode. Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Signed-off-by: Steven J. Hill <Steven. Hill@imgtec.com>
2013-02-01MIPS: Whitespace cleanup.Ralf Baechle
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>
2012-12-13MIPS: Fix for warning from FPU emulation codeRalf Baechle
The default implementation of 'cpu_has_fpu' macro calls smp_processor_id() which causes this warning to be printed when preemption is enabled: [ 4.664000] Algorithmics/MIPS FPU Emulator v1.5 [ 4.676000] BUG: using smp_processor_id() in preemptible [00000000] code: ini [ 4.700000] caller is fpu_emulator_cop1Handler+0x434/0x27b8 This problem got introduced in November 2009 by af1d2af877ef6c36990671bc86a5b9c5bb50b1da (lmo) [MIPS: Fix emulation of 64-bit FPU on 64-bit CPUs.] rsp. da0bac33413b2888d3623dad3ad19ce76b688f07 (kernel.org) [MIPS: Fix emulation of 64-bit FPU on FPU-less 64-bit CPUs.] in 2.6.32. Fixed by rewriting cop1_64bit() to return a constant whenever possible but most importantly avoid the use pf cpu_has_fpu entirely. Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Reported-by: Jayachandran C <jchandra@broadcom.com> Initial-patch-by: Jayachandran C <jchandra@broadcom.com> Patchwork: https://patchwork.linux-mips.org/patch/4225/
2011-12-07MIPS Kprobes: Refactor branch emulationManeesh Soni
This patch refactors MIPS branch emulation code so as to allow skipping delay slot instruction in case of branch likely instructions when branch is not taken. This is useful for keeping the code common for use cases like kprobes where one would like to handle the branch instructions keeping the delay slot instuction also in picture for branch likely instructions. Also allow emulation when instruction to be decoded is not at pt_regs->cp0_epc as in case of kprobes where pt_regs->cp0_epc points to the breakpoint instruction. The patch also exports the function for modules. Signed-off-by: Maneesh Soni <manesoni@cisco.com> Signed-off-by: Victor Kamensky <kamensky@cisco.com> Cc: David Daney <david.daney@cavium.com> Cc: ananth@in.ibm.com Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/2913/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2011-07-01perf: Remove the nmi parameter from the swevent and overflow interfacePeter Zijlstra
The nmi parameter indicated if we could do wakeups from the current context, if not, we would set some state and self-IPI and let the resulting interrupt do the wakeup. For the various event classes: - hardware: nmi=0; PMI is in fact an NMI or we run irq_work_run from the PMI-tail (ARM etc.) - tracepoint: nmi=0; since tracepoint could be from NMI context. - software: nmi=[0,1]; some, like the schedule thing cannot perform wakeups, and hence need 0. As one can see, there is very little nmi=1 usage, and the down-side of not using it is that on some platforms some software events can have a jiffy delay in wakeup (when arch_irq_work_raise isn't implemented). The up-side however is that we can remove the nmi parameter and save a bunch of conditionals in fast paths. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Michael Cree <mcree@orcon.net.nz> Cc: Will Deacon <will.deacon@arm.com> Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com> Cc: Anton Blanchard <anton@samba.org> Cc: Eric B Munson <emunson@mgebm.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: David S. Miller <davem@davemloft.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Don Zickus <dzickus@redhat.com> Link: http://lkml.kernel.org/n/tip-agjev8eu666tvknpb3iaj0fg@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-12-16MIPS: Send proper signal and siginfo on FP emulator faults.David Daney
We were unconditionally sending SIGBUS with an empty siginfo on FP emulator faults. This differs from what happens when real floating point hardware would get a fault. For most faults we need to send SIGSEGV with the faulting address filled in in the struct siginfo. Reported-by: Camm Maguire <camm@maguirefamily.org> Signed-off-by: David Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Cc: Camm Maguire <camm@maguirefamily.org> Patchwork: https://patchwork.linux-mips.org/patch/1727/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2010-10-29MIPS: add support for software performance eventsDeng-Cheng Zhu
Software events are required as part of the measurable stuff by the Linux performance counter subsystem. Here is the list of events added by this patch: PERF_COUNT_SW_PAGE_FAULTS PERF_COUNT_SW_PAGE_FAULTS_MIN PERF_COUNT_SW_PAGE_FAULTS_MAJ PERF_COUNT_SW_ALIGNMENT_FAULTS PERF_COUNT_SW_EMULATION_FAULTS Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com> To: linux-mips@linux-mips.org Cc: a.p.zijlstra@chello.nl Cc: paulus@samba.org Cc: mingo@elte.hu Cc: acme@redhat.com Cc: jamie.iles@picochip.com Acked-by: David Daney <ddaney@caviumnetworks.com> Reviewed-by: Matt Fleming <matt@console-pimps.org> Patchwork: https://patchwork.linux-mips.org/patch/1686/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2010-10-18Update broken web addresses in arch directory.Justin P. Mattock
The patch below updates broken web addresses in the arch directory. Signed-off-by: Justin P. Mattock <justinmattock@gmail.com> Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: Finn Thain <fthain@telegraphics.com.au> Cc: Randy Dunlap <rdunlap@xenotime.net> Reviewed-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-05-21MIPS: Coding style cleanups of access of FCSR rounding mode bitsShane McDonald
Replaces references to the magic number 0x3 with constants and macros indicating the real purpose of those bits. They are the rounding mode bits of the FCSR register. Signed-off-by: Shane McDonald <mcdonald.shane@gmail.com> To: anemo@mba.ocn.ne.jp To: kevink@paralogos.com To: linux-mips@linux-mips.org To: sshtylyov@mvista.com Patchwork: http://patchwork.linux-mips.org/patch/1206/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2010-05-15 MIPS FPU emulator: allow Cause bits of FCSR to be writeable by ctc1Shane McDonald
In the FPU emulator code of the MIPS, the Cause bits of the FCSR register are not currently writeable by the ctc1 instruction. In odd corner cases, this can cause problems. For example, a case existed where a divide-by-zero exception was generated by the FPU, and the signal handler attempted to restore the FPU registers to their state before the exception occurred. In this particular setup, writing the old value to the FCSR register would cause another divide-by-zero exception to occur immediately. The solution is to change the ctc1 instruction emulator code to allow the Cause bits of the FCSR register to be writeable. This is the behaviour of the hardware that the code is emulating. This problem was found by Shane McDonald, but the credit for the fix goes to Kevin Kissell. In Kevin's words: I submit that the bug is indeed in that ctc_op: case of the emulator. The Cause bits (17:12) are supposed to be writable by that instruction, but the CTC1 emulation won't let them be updated by the instruction. I think that actually if you just completely removed lines 387-388 [...] things would work a good deal better. At least, it would be a more accurate emulation of the architecturally defined FPU. If I wanted to be really, really pedantic (which I sometimes do), I'd also protect the reserved bits that aren't necessarily writable. Signed-off-by: Shane McDonald <mcdonald.shane@gmail.com> To: anemo@mba.ocn.ne.jp To: kevink@paralogos.com To: sshtylyov@mvista.com Patchwork: http://patchwork.linux-mips.org/patch/1205/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> ---
2009-12-17MIPS: Collect FPU emulator statistics per-CPU.David Daney
On SMP systems, the collection of statistics can cause cache line bouncing in the lines associated with the counters. Also there are races incrementing the counters on multiple CPUs. To fix both problems, we collect the statistics in per-CPU variables, and add them up in the debugfs read operation. As a test I ran the LTP float_bessel test on a 12 CPU Octeon system. Without CONFIG_DEBUG_FS : 2602 seconds. With CONFIG_DEBUG_FS: 2640 seconds. With non-cpu-local atomic statistics: 14569 seconds. Signed-off-by: David Daney <ddaney@caviumnetworks.com> Cc: linux-mips@linux-mips.org Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-11-13MIPS: Fix emulation of 64-bit FPU on FPU-less 64-bit CPUs.David Daney
Running a 64-bit kernel on a 64-bit CPU without an FPU would cause the emulator to run in 32-bit mode. The c0_Status.FR bit is wired to zero on systems without an FPU, so using that bit to decide how the emulator behaves doesn't allow for proper emulation on 64-bit FPU-less processors. Instead, we need to select the emulator mode based on the user-space ABI. Since the thread flag TIF_32BIT_REGS is used to set c0_Status.FR, we can just use it to decide if the emulator should be in 32-bit or 64-bit mode. Signed-off-by: David Daney <ddaney@caviumnetworks.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-10-30MIPS: Switch FPU emulator trap to BREAK instruction.Ralf Baechle
Arguably using the address error handler has always been ugly. But with processors that handle unaligned loads and stores in hardware the current mechanism ceases to work so switch it to a BREAK instruction and allocate break code 514 to the FPU emulator. Yoichi Yuasa provided a build fix for CONFIG_BUG=n. Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
2008-10-27MIPS: Fix debugfs_create_*'s error checking method for arch/mips/math-emu/Zhaolei
debugfs_create_*() returns NULL on error. Make its caller debugfs_fpuemu return -ENODEV on error. Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-10-11[MIPS] checkfiles: Fix "need space after that ','" errors.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-10-11[MIPS] Fix "no space between function name and open parenthesis" warnings.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-07-13[MIPS] math-emu minor cleanupAtsushi Nemoto
Declaring emulpc and contpc as "unsigned long" can get rid of some casts. This also get rid of some sparse warnings. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-07-10[MIPS] Add debugfs files to show fpuemu statisticsAtsushi Nemoto
Export contents of struct mips_fpu_emulator_stats via debugfs. There is no way to read these statistics for now but they (at least the "emulated" count) might be sometimes useful for performance tuning on FPU-less CPUs. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-10-09[MIPS] Make sure cpu_has_fpu is used only in atomic contextAtsushi Nemoto
Make sure cpu_has_fpu (which uses smp_processor_id()) is used only in atomic context. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-06-19[MIPS] Unify mips_fpu_soft_struct and mips_fpu_hard_structs.Atsushi Nemoto
The struct mips_fpu_soft_struct and mips_fpu_hard_struct are completely same now and the kernel fpu emulator assumes that. This patch unifies them to mips_fpu_struct and get rid of mips_fpu_union. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Get rid of SINGLE_ONLY_FPU. Linux does not support half FPU other thanRalf Baechle
by emulation of a full FPU. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Fix all the get_user / put_user related sparse warnings.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>