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2021-07-13MIPS: Fix unreachable code issueGustavo A. R. Silva1-1/+1
Fix the following warning (mips-randconfig): arch/mips/include/asm/fpu.h:79:3: warning: fallthrough annotation in unreachable code [-Wimplicit-fallthrough] Originally, the /* fallthrough */ comment was introduced by commit: 597ce1723e0f ("MIPS: Support for 64-bit FP with O32 binaries") and it was wrongly replaced with fallthrough; by commit: c9b029903466 ("MIPS: Use fallthrough for arch/mips") As the original comment is actually useful, fix this issue by removing unreachable fallthrough; statement and place the original /* fallthrough */ comment back. Fixes: c9b029903466 ("MIPS: Use fallthrough for arch/mips") Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/lkml/60edca25.k00ut905IFBjPyt5%25lkp@intel.com/ Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-05-22mips: Add MIPS Release 5 supportSerge Semin1-2/+2
There are five MIPS32/64 architecture releases currently available: from 1 to 6 except fourth one, which was intentionally skipped. Three of them can be called as major: 1st, 2nd and 6th, that not only have some system level alterations, but also introduced significant core/ISA level updates. The rest of the MIPS architecture releases are minor. Even though they don't have as much ISA/system/core level changes as the major ones with respect to the previous releases, they still provide a set of updates (I'd say they were intended to be the intermediate releases before a major one) that might be useful for the kernel and user-level code, when activated by the kernel or compiler. In particular the following features were introduced or ended up being available at/after MIPS32/64 Release 5 architecture: + the last release of the misaligned memory access instructions, + virtualisation - VZ ASE - is optional component of the arch, + SIMD - MSA ASE - is optional component of the arch, + DSP ASE is optional component of the arch, + CP0.Status.FR=1 for CP1.FIR.F64=1 (pure 64-bit FPU general registers) must be available if FPU is implemented, + CP1.FIR.Has2008 support is required so CP1.FCSR.{ABS2008,NAN2008} bits are available. + UFR/UNFR aliases to access CP0.Status.FR from user-space by means of ctc1/cfc1 instructions (enabled by CP0.Config5.UFR), + CP0.COnfig5.LLB=1 and eretnc instruction are implemented to without accidentally clearing LL-bit when returning from an interrupt, exception, or error trap, + XPA feature together with extended versions of CPx registers is introduced, which needs to have mfhc0/mthc0 instructions available. So due to these changes GNU GCC provides an extended instructions set support for MIPS32/64 Release 5 by default like eretnc/mfhc0/mthc0. Even though the architecture alteration isn't that big, it still worth to be taken into account by the kernel software. Finally we can't deny that some optimization/limitations might be found in future and implemented on some level in kernel or compiler. In this case having even intermediate MIPS architecture releases support would be more than useful. So the most of the changes provided by this commit can be split into either compile- or runtime configs related. The compile-time related changes are caused by adding the new CONFIG_CPU_MIPS32_R5/CONFIG_CPU_MIPSR5 configs and concern the code activating MIPSR2 or MIPSR6 already implemented features (like eretnc/LLbit, mthc0/mfhc0). In addition CPU_HAS_MSA can be now freely enabled for MIPS32/64 release 5 based platforms as this is done for CPU_MIPS32_R6 CPUs. The runtime changes concerns the features which are handled with respect to the MIPS ISA revision detected at run-time by means of CP0.Config.{AT,AR} bits. Alas these fields can be used to detect either r1 or r2 or r6 releases. But since we know which CPUs in fact support the R5 arch, we can manually set MIPS_CPU_ISA_M32R5/MIPS_CPU_ISA_M64R5 bit of c->isa_level and then use cpu_has_mips32r5/cpu_has_mips64r5 where it's appropriate. Since XPA/EVA provide too complex alterationss and to have them used with MIPS32 Release 2 charged kernels (for compatibility with current platform configs) they are left to be setup as a separate kernel configs. Co-developed-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru> Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Paul Burton <paulburton@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Rob Herring <robh+dt@kernel.org> Cc: devicetree@vger.kernel.org Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2020-05-07MIPS: Use fallthrough for arch/mipsLiangliang Huang1-1/+1
Convert the various /* fallthrough */ comments to the pseudo-keyword fallthrough; Done via script: https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/ Signed-off-by: Liangliang Huang <huangll@lemote.com> Reviewed-by: Huacai Chen <chenhc@lemote.com> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2019-05-30treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152Thomas Gleixner1-5/+1
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>
2018-11-09MIPS: Stub asm/fpu.h functionsPaul Burton1-3/+82
Provide stub versions of functions in asm/fpu.h when CONFIG_MIPS_FP_SUPPORT=n. Two approaches are taken to the functions provided: - Functions which can safely be called when FP is not enabled provide stubs which return an error where appropriate or are simple no-ops. - Functions which should only ever be called in cases where cpu_has_fpu is true or the FPU was successfully enabled are declared extern & annotated with __compiletime_error() to detect cases in which they are called incorrectly. Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/21006/ Cc: linux-mips@linux-mips.org
2018-11-09MIPS: Drop forward declarations of sigcontext in asm/fpu.hPaul Burton1-3/+0
asm/fpu.h contains forward declarations of struct sigcontext & struct sigcontext32 which appear to have been unused since commit 137f6f3e284e ("MIPS: Cleanup signal code initialization"). Remove the dead code. Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/21015/ Cc: linux-mips@linux-mips.org
2018-11-09MIPS: Simplify FP context initializationPaul Burton1-32/+25
MIPS has up until now had 3 different ways for a task's floating point context to be initialized: - If the task's first use of FP involves it gaining ownership of an FPU then _init_fpu() is used to initialize the FPU's registers such that they all contain ~0, and the FPU registers will be stored to struct thread_info later (eg. when context switching). - If the task first uses FP on a CPU without an associated FPU then fpu_emulator_init_fpu() initializes the task's floating point register state in struct thread_info such that all floating point register contain the bit pattern 0x7ff800007ff80000, different to the _init_fpu() behaviour. - If a task's floating point context is first accessed via ptrace then init_fp_ctx() initializes the floating point register state in struct thread_info to ~0, giving equivalent state to _init_fpu(). The _init_fpu() path has 2 separate implementations - one for r2k/r3k style systems & one for r4k style systems. The _init_fpu() path also requires that we be careful to clear & restore the value of the Config5.FRE bit on modern systems in order to avoid inadvertently triggering floating point exceptions. None of this code is in a performance critical hot path - it runs only the first time a task uses floating point. As such it doesn't seem to warrant the complications of maintaining the _init_fpu() path. Remove _init_fpu() & fpu_emulator_init_fpu(), instead using init_fp_ctx() consistently to initialize floating point register state in struct thread_info. Upon a task's first use of floating point this will typically mean that we initialize state in memory & then load it into FPU registers using _restore_fp() just as we would on a context switch. For other paths such as __compute_return_epc_for_insn() or mipsr2_decoder() this results in a significant simplification of the work to be done. Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/21002/ Cc: linux-mips@linux-mips.org
2017-04-06Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linusLinus Torvalds1-0/+1
Pull MIPS fixes from Ralf Baechle: "Lantiq: - Fix adding xbar resoures causing a panic Loongson3: - Some Loongson 3A don't identify themselves as having an FTLB so hardwire that knowledge into CPU probing. - Handle Loongson 3 TLB peculiarities in the fast path of the RDHWR emulation. - Fix invalid FTLB entries with huge page on VTLB+FTLB platforms - Add missing calculation of S-cache and V-cache cache-way size Ralink: - Fix typos in rt3883 pinctrl data Generic: - Force o32 fp64 support on 32bit MIPS64r6 kernels - Yet another build fix after the linux/sched.h changes - Wire up statx system call - Fix stack unwinding after introduction of IRQ stack - Fix spinlock code to build even for microMIPS with recent binutils SMP-CPS: - Fix retrieval of VPE mask on big endian CPUs" * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: MIPS: IRQ Stack: Unwind IRQ stack onto task stack MIPS: c-r4k: Fix Loongson-3's vcache/scache waysize calculation MIPS: Flush wrong invalid FTLB entry for huge page MIPS: Check TLB before handle_ri_rdhwr() for Loongson-3 MIPS: Add MIPS_CPU_FTLB for Loongson-3A R2 MIPS: Lantiq: fix missing xbar kernel panic MIPS: smp-cps: Fix retrieval of VPE mask on big endian CPUs MIPS: Wire up statx system call MIPS: Include asm/ptrace.h now linux/sched.h doesn't MIPS: ralink: Fix typos in rt3883 pinctrl MIPS: End spinlocks with .insn MIPS: Force o32 fp64 support on 32bit MIPS64r6 kernels
2017-03-08MIPS: Include asm/ptrace.h now linux/sched.h doesn'tJames Hogan1-0/+1
Use of the task_pt_regs() based macros in MIPS' asm/processor.h for accessing the user context on the kernel stack need the definition of struct pt_regs from asm/ptrace.h. __own_fpu() in asm/fpu.h uses these macros but implicitly depended on linux/sched.h to include asm/ptrace.h. Since commit f780d89a0e82 ("sched/headers: Remove <asm/ptrace.h> from <linux/sched.h>") however linux/sched.h no longer includes asm/ptrace.h, so include it explicitly from asm/fpu.h where it is needed instead. This fixes build errors such as: ./arch/mips/include/asm/fpu.h: In function '__own_fpu': ./arch/mips/include/asm/processor.h:385:31: error: invalid application of 'sizeof' to incomplete type 'struct pt_regs' THREAD_SIZE - 32 - sizeof(struct pt_regs)) ^ Fixes: f780d89a0e82 ("sched/headers: Remove <asm/ptrace.h> from <linux/sched.h>") Signed-off-by: James Hogan <james.hogan@imgtec.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/15386/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2017-03-08MIPS: Add missing include filesArnd Bergmann1-0/+1
After the split of linux/sched.h, several platforms in arch/mips stopped building. Add the respective additional #include statements to fix the problem I first tried adding these into asm/processor.h, but ran into circular header dependencies with that which I could not figure out. The commit I listed as causing the problem is the branch merge, as there is likely a combination of multiple patches in that branch. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mips@linux-mips.org Cc: ralf@linux-mips.org Fixes: 1827adb11ad2 ("Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip") Link: http://lkml.kernel.org/r/20170308072931.3836696-1-arnd@arndb.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar1-0/+1
<linux/sched/task_stack.h> We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/task_stack.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-02MIPS: Fix FPU disable with preemptionJames Hogan1-0/+4
The FPU should not be left enabled after a task context switch. This isn't usually a problem as the FPU enable bit is updated before returning to userland, however it can potentially mask kernel bugs, and in fact KVM assumes it won't happen and won't clear the FPU enable bit before returning to the guest, which allows the guest to use stale FPU context. Interrupts and exceptions save and restore most bits of the CP0 Status register which contains the FPU enable bit (CU1). When the kernel needs to enable or disable the FPU (for example due to attempted FPU use by userland, or the scheduler being invoked) both the actual Status register and the saved value in the userland context are updated. However this doesn't work correctly with full kernel preemption enabled, since the FPU enable bit can be cleared from within an interrupt when the scheduler is invoked, and only the userland context is updated, not the interrupt context. For example: 1) Enter kernel with FPU already enabled, TIF_USEDFPU=1, Status.CU1=1 saved. 2) Take a timer interrupt while in kernel mode, Status.CU1=1 saved. 3) Timer interrupt invokes scheduler to preempt the task, which clears TIF_USEDFPU, disables the FPU in Status register (Status.CU1=0), and the value stored in user context from step (1), but not the interrupt context from step (2). 4) When the process is scheduled back in again Status.CU1=0. 5) The interrupt context from step (2) is restored, which sets Status.CU1=1. So from user context point of view, preemption has re-enabled FPU! 6) If the scheduler is invoked again (via preemption or voluntarily) before returning to userland, TIF_USEDFPU=0 so the FPU is not disabled before the task context switch. 7) The next task resumes from the context switch with FPU enabled! The restoring of the Status register on return from interrupt/exception is already selective about which bits to restore, leaving the interrupt mask bits alone so enabling/disabling of CPU interrupt lines can persist. Extend this to also leave both the CU1 bit (FPU enable) and the FR bit (which specifies the FPU mode and gets changed with CU1). This prevents a stale Status value being restored in step (5) above and persisting through subsequent context switches. Also switch to the use of definitions from asm/mipsregs.h while we're at it. Since this change also affects the restoration of Status register on the path back to userland, it increases the sensitivity of the kernel to the problem of the FPU being left enabled, allowing it to propagate to userland, therefore a warning is also added to lose_fpu_inatomic() to point out any future reoccurances before they do any damage. Signed-off-by: James Hogan <james.hogan@imgtec.com> Reviewed-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/12303/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-09-03MIPS: Tidy up FPU context switchingPaul Burton1-8/+13
Rather than saving the scalar FP or vector context in the assembly resume function, reuse the existing C code we have in fpu.h to do exactly that. This reduces duplication, results in a much easier to read resume function & should allow the compiler to optimise out more MSA code due to is_msa_enabled()/cpu_has_msa being known-zero at compile time for kernels without MSA support. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-kernel@vger.kernel.org Cc: James Hogan <james.hogan@imgtec.com> Cc: Markos Chandras <markos.chandras@imgtec.com> Cc: Manuel Lauss <manuel.lauss@gmail.com> Patchwork: https://patchwork.linux-mips.org/patch/10830/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-07-19MIPS: fpu.h: Allow 64-bit FPU on a 64-bit MIPS R6 CPUMarkos Chandras1-1/+1
Commit 6134d94923d0 ("MIPS: asm: fpu: Allow 64-bit FPU on MIPS32 R6") added support for 64-bit FPU on a 32-bit MIPS R6 processor but it missed the 64-bit CPU case leading to FPU failures when requesting FR=1 mode (which is always the case for MIPS R6 userland) when running a 32-bit kernel on a 64-bit CPU. We also fix the MIPS R2 case. Signed-off-by: Markos Chandras <markos.chandras@imgtec.com> Fixes: 6134d94923d0 ("MIPS: asm: fpu: Allow 64-bit FPU on MIPS32 R6") Reviewed-by: Paul Burton <paul.burton@imgtec.com> Cc: <stable@vger.kernel.org> # 4.0+ Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/10734/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-04-13Merge branch '4.1-fp' into mips-for-linux-nextRalf Baechle1-7/+13
2015-04-08MIPS: Respect the ISA level in FCSR handlingMaciej W. Rozycki1-3/+4
Define the central place the default FCSR value is set from, initialised in `cpu_probe'. Determine the FCSR mask applied to values written to the register with CTC1 in the full emulation mode and via ptrace(2), according to the ISA level of processor hardware or the writability of bits 31:18 if actual FPU hardware is used. Software may rely on FCSR bits whose functions our emulator does not implement, so it should not allow them to be set or software may get confused. For ptrace(2) it's just sanity. [ralf@linux-mips.org: Fixed double inclusion of <asm/current.h>.] Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9711/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-03-27MIPS: disable FPU if the mode is unsupportedPaul Burton1-7/+12
The expected semantics of __enable_fpu are for the FPU to be enabled in the given mode if possible, otherwise for the FPU to be left disabled and SIGFPE returned. The FPU was incorrectly being left enabled in cases where the desired value for FR was unavailable. Without ensuring the FPU is disabled in this case, it would be possible for userland to go on to execute further FP instructions natively in the incorrect mode, rather than those instructions being trapped & emulated as they need to be. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9167/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-03-27MIPS: lose_fpu(): Disable FPU when MSA enabledJames Hogan1-0/+1
The lose_fpu() function only disables the FPU in CP0_Status.CU1 if the FPU is in use and MSA isn't enabled. This isn't necessarily a problem because KSTK_STATUS(current), the version of CP0_Status stored on the kernel stack on entry from user mode, does always get updated and gets restored when returning to user mode, but I don't think it was intended, and it is inconsistent with the case of only the FPU being in use. Sometimes leaving the FPU enabled may also mask kernel bugs where FPU operations are executed when the FPU might not be enabled. So lets disable the FPU in the MSA case too. Fixes: 33c771ba5c5d ("MIPS: save/disable MSA in lose_fpu") Signed-off-by: James Hogan <james.hogan@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/9323/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-02-22Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linusLinus Torvalds1-1/+2
Pull MIPS updates from Ralf Baechle: "This is the main pull request for MIPS: - a number of fixes that didn't make the 3.19 release. - a number of cleanups. - preliminary support for Cavium's Octeon 3 SOCs which feature up to 48 MIPS64 R3 cores with FPU and hardware virtualization. - support for MIPS R6 processors. Revision 6 of the MIPS architecture is a major revision of the MIPS architecture which does away with many of original sins of the architecture such as branch delay slots. This and other changes in R6 require major changes throughout the entire MIPS core architecture code and make up for the lion share of this pull request. - finally some preparatory work for eXtendend Physical Address support, which allows support of up to 40 bit of physical address space on 32 bit processors" [ Ahh, MIPS can't leave the PAE brain damage alone. It's like every CPU architect has to make that mistake, but pee in the snow by changing the TLA. But whether it's called PAE, LPAE or XPA, it's horrid crud - Linus ] * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (114 commits) MIPS: sead3: Corrected get_c0_perfcount_int MIPS: mm: Remove dead macro definitions MIPS: OCTEON: irq: add CIB and other fixes MIPS: OCTEON: Don't do acknowledge operations for level triggered irqs. MIPS: OCTEON: More OCTEONIII support MIPS: OCTEON: Remove setting of processor specific CVMCTL icache bits. MIPS: OCTEON: Core-15169 Workaround and general CVMSEG cleanup. MIPS: OCTEON: Update octeon-model.h code for new SoCs. MIPS: OCTEON: Implement DCache errata workaround for all CN6XXX MIPS: OCTEON: Add little-endian support to asm/octeon/octeon.h MIPS: OCTEON: Implement the core-16057 workaround MIPS: OCTEON: Delete unused COP2 saving code MIPS: OCTEON: Use correct instruction to read 64-bit COP0 register MIPS: OCTEON: Save and restore CP2 SHA3 state MIPS: OCTEON: Fix FP context save. MIPS: OCTEON: Save/Restore wider multiply registers in OCTEON III CPUs MIPS: boot: Provide more uImage options MIPS: Remove unneeded #ifdef __KERNEL__ from asm/processor.h MIPS: ip22-gio: Remove legacy suspend/resume support mips: pci: Add ifdef around pci_proc_domain ...
2015-02-17MIPS: asm: fpu: Allow 64-bit FPU on MIPS32 R6Markos Chandras1-1/+2
MIPS32 R6 has a 64-bit FPU so add the necessary MIPS R6 definition. Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
2015-01-13MIPS: FRE: Use set/clear_c0_config5 instead of open coded sequences.Ralf Baechle1-5/+3
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-01-13MIPS: Do not fiddle with FRE unless FRE is actually available.Ralf Baechle1-16/+27
Commit 4227a2d4efc9c84f35826dc4d1e6dc183f6c1c05 (MIPS: Support for hybrid FPRs) changes the kernel to execute read_c0_config5() even on processors that don't have a Config5 register. According to the arch spec the behaviour of trying to read or write this register is UNDEFINED where this register doesn't exist, that is merely looking at this register is already cruel because that might kill a kitten. In case of Qemu older than v2.2 Qemu has elected to implement this UNDEFINED behaviour by taking a RI exception - which then fries the kernel: [...] Freeing YAMON memory: 956k freed Freeing unused kernel memory: 240K (80674000 - 806b0000) Reserved instruction in kernel code[#1]: CPU: 0 PID: 1 Comm: init Not tainted 3.18.0-rc6-00058-g4227a2d #26 task: 86047588 ti: 86048000 task.ti: 86048000 $ 0 : 00000000 77a638cc 00000000 00000000 [...] For qemu v2.2.0 commit f31b035a9f10dc9b57f01c426110af845d453ce2 (target-mips: correctly handle access to unimplemented CP0 register) changed the behaviour to returning zero on read and ignoring writes which more matches how typical hardware implementations actually behave. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-11-24MIPS: Support for hybrid FPRsPaul Burton1-8/+41
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 Lauss1-2/+2
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>
2014-08-02MIPS: disable preemption whilst initialising MSAPaul Burton1-4/+0
Preemption must be disabled throughout the process of enabling the FPU, enabling MSA & initialising the vector registers. Without doing so it is possible to lose the FPU or MSA whilst initialising them causing that initialisation to fail. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/7307/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-08-02MIPS: save/disable MSA in lose_fpuPaul Burton1-3/+12
The kernel depends upon MSA never being enabled when the FPU is not, a condition which is currently violated in a few places (whilst saving sigcontext, following mips_cpu_save). Catch all the problem cases by disabling MSA in lose_fpu, after saving context if necessary. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/7302/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-23MIPS: math-emu: Inline fpu_emulator_init_fpu()Ralf Baechle1-3/+4
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-03-31Merge branch '3.14-fixes' into mips-for-linux-nextRalf Baechle1-1/+1
2014-03-27MIPS: Simplify FP context accessPaul Burton1-1/+1
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>
2014-03-14MIPS: Replace CONFIG_MIPS64 and CONFIG_MIPS32_R2Paul Bolle1-1/+1
Commit 597ce1723e0f ("MIPS: Support for 64-bit FP with O32 binaries") introduced references to two undefined Kconfig macros. CONFIG_MIPS32_R2 should clearly be replaced with CONFIG_CPU_MIPS32_R2. And CONFIG_MIPS64 should be replaced with CONFIG_64BIT. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/6522/ Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-02-06MIPS: fpu.h: Fix build when CONFIG_BUG is not setAaro Koskinen1-0/+2
__enable_fpu produces a build failure when CONFIG_BUG is not set: In file included from arch/mips/kernel/cpu-probe.c:24:0: arch/mips/include/asm/fpu.h: In function '__enable_fpu': arch/mips/include/asm/fpu.h:77:1: error: control reaches end of non-void function [-Werror=return-type] This is regression introduced in 3.14-rc1. Fix that. Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi> Acked-by: Paul Burton <paul.burton@imgtec.com> Cc: John Crispin <blogic@openwrt.org> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6504/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-01-14MIPS: Support for 64-bit FP with O32 binariesPaul Burton1-15/+76
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>
2014-01-14MIPS: Remove unused {en,dis}able_fpu macrosPaul Burton1-13/+0
These macros are not used anywhere in the kernel. Remove them. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6111/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2013-02-01MIPS: Whitespace cleanup.Ralf Baechle1-3/+3
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>
2009-12-17MIPS: Cleanup signal code initializationRalf Baechle1-8/+0
Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/709/
2008-10-11MIPS: Move headfiles to new location below arch/mips/includeRalf Baechle1-0/+153
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>