kernel/arch/mips/include/asm/cpu-info.h, branch linux-rolling-stable

MIPS: disable MMID when not supported by the hardware

2025-07-16T16:34:36Z

It is possible that MMID is supported at the CPU level, but its integration in a SoC prevents its usage. For instance, if the System-level Interconnect (also known as Network on Chip) does not support global invalidation, then the MMID feature is not usable. The current implementation of MMID relies on the GINV* instructions. This patch allows the disabling of MMID based on a device tree property, as this issue cannot be detected at runtime. MMID is set up very early during the boot process, even before device tree data can be accessed. Therefore, when we determine whether MMID needs to be disabled, some MMID setup has already been performed for the boot CPU. Consequently, we must revert the MMID setup on the first CPU before disabling the feature for the subsequent CPUs that will be initialized later. Signed-off-by: Gregory CLEMENT Signed-off-by: Thomas Bogendoerfer

MIPS: emulate CPUCFG instruction on older Loongson64 cores

2020-05-24T07:26:55Z

CPUCFG is the instruction for querying processor characteristics on newer Loongson processors, much like CPUID of x86. Since the instruction is supposedly designed to provide a unified way to do feature detection (without having to, for example, parse /proc/cpuinfo which is too heavyweight), it is important to provide compatibility for older cores without native support. Fortunately, most of the fields can be synthesized without changes to semantics. Performance is not really big a concern, because feature detection logic is not expected to be invoked very often in typical userland applications. The instruction can't be emulated on LOONGSON_2EF cores, according to FlyGoat's experiments. Because the LWC2 opcode is assigned to other valid instructions on 2E and 2F, no RI exception is raised for us to intercept. So compatibility is only extended back furthest to Loongson-3A1000. Loongson-2K is covered too, as it is basically a remix of various blocks from the 3A/3B models from a kernel perspective. This is lightly based on Loongson's work on their Linux 3.10 fork, for being the authority on the right feature flags to fill in, where things aren't otherwise discoverable. Signed-off-by: WANG Xuerui Reviewed-by: Jiaxun Yang Cc: Huacai Chen Cc: Jiaxun Yang Cc: Tiezhu Yang Signed-off-by: Thomas Bogendoerfer

mips: Add MIPS Release 5 support

2020-05-22T07:09:01Z

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 Signed-off-by: Alexey Malahov Signed-off-by: Serge Semin Cc: Thomas Bogendoerfer Cc: Paul Burton Cc: Ralf Baechle Cc: Arnd Bergmann Cc: Rob Herring Cc: devicetree@vger.kernel.org Signed-off-by: Thomas Bogendoerfer

MIPS: Expand MIPS32 ASIDs to 64 bits

2018-12-05T22:46:44Z

ASIDs have always been stored as unsigned longs, ie. 32 bits on MIPS32 kernels. This is problematic because it is feasible for the ASID version to overflow & wrap around to zero. We currently attempt to handle this overflow by simply setting the ASID version to 1, using asid_first_version(), but we make no attempt to account for the fact that there may be mm_structs with stale ASIDs that have versions which we now reuse due to the overflow & wrap around. Encountering this requires that: 1) A struct mm_struct X is active on CPU A using ASID (V,n). 2) That mm is not used on CPU A for the length of time that it takes for CPU A's asid_cache to overflow & wrap around to the same version V that the mm had in step 1. During this time tasks using the mm could either be sleeping or only scheduled on other CPUs. 3) Some other mm Y becomes active on CPU A and is allocated the same ASID (V,n). 4) mm X now becomes active on CPU A again, and now incorrectly has the same ASID as mm Y. Where struct mm_struct ASIDs are represented above in the format (version, EntryHi.ASID), and on a typical MIPS32 system version will be 24 bits wide & EntryHi.ASID will be 8 bits wide. The length of time required in step 2 is highly dependent upon the CPU & workload, but for a hypothetical 2GHz CPU running a workload which generates a new ASID every 10000 cycles this period is around 248 days. Due to this long period of time & the fact that tasks need to be scheduled in just the right (or wrong, depending upon your inclination) way, this is obviously a difficult bug to encounter but it's entirely possible as evidenced by reports. In order to fix this, simply extend ASIDs to 64 bits even on MIPS32 builds. This will extend the period of time required for the hypothetical system above to encounter the problem from 28 days to around 3 trillion years, which feels safely outside of the realms of possibility. The cost of this is slightly more generated code in some commonly executed paths, but this is pretty minimal: | Code Size Gain | Percentage -----------------------|----------------|------------- decstation_defconfig | +270 | +0.00% 32r2el_defconfig | +652 | +0.01% 32r6el_defconfig | +1000 | +0.01% I have been unable to measure any change in performance of the LMbench lat_ctx or lat_proc tests resulting from the 64b ASIDs on either 32r2el_defconfig+interAptiv or 32r6el_defconfig+I6500 systems. Signed-off-by: Paul Burton Suggested-by: James Hogan References: https://lore.kernel.org/linux-mips/80B78A8B8FEE6145A87579E8435D78C30205D5F3@fzex.ruijie.com.cn/ References: https://lore.kernel.org/linux-mips/1488684260-18867-1-git-send-email-jiwei.sun@windriver.com/ Cc: Jiwei Sun Cc: Yu Huabing Cc: stable@vger.kernel.org # 2.6.12+ Cc: linux-mips@vger.kernel.org

MIPS: Add CPU cluster number accessors

2017-08-29T22:57:27Z

Introduce cpu_cluster() & cpu_set_cluster() accessor functions in the same vein as cpu_core(), cpu_vpe_id() & their set variants. These will be used in further patches to allow users to get or set a CPUs cluster number. Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17012/ Signed-off-by: Ralf Baechle

MIPS: Unify checks for sibling CPUs

2017-08-29T22:57:27Z

Up until now we have open-coded checks for whether CPUs are siblings, with slight variations on whether we consider the package ID or not. This will only get more complex when we introduce cluster support, so in preparation for that this patch introduces a cpus_are_siblings() function which can be used to check whether or not 2 CPUs are siblings in a consistent manner. By checking globalnumber with the VP ID masked out this also has the neat side effect of being ready for multi-cluster systems already. Signed-off-by: Paul Burton Acked-by: Rafael J. Wysocki Acked-by: Thomas Gleixner Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17011/ Signed-off-by: Ralf Baechle

MIPS: Store core & VP IDs in GlobalNumber-style variable

2017-08-29T22:57:27Z

This patch modifies the way we store core & VP IDs such that we store them in a single 32 bit integer whose format matches that of the MIPSr6 GlobalNumber register. Whereas we have previously stored core & VP IDs in separate fields, storing them in a single GlobalNumber-like field: 1) Reduces the size of struct cpuinfo_mips by 4 bytes, and will allow it to not grow when cluster support is added. 2) Gives us a natural place to store cluster number, which matches up with what the architecture provides. 3) Will be useful in the future as a parameter to the MIPSr6 GINVI instruction to specify a target CPU whose icache that instruction should operate on. The cpu_set*() accessor functions are moved out of the asm/cpu-info.h header in order to allow them to use the WARN_ON macro, which is unusable in asm/cpu-info.h due to include ordering. Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17010/ Signed-off-by: Ralf Baechle

MIPS: Abstract CPU core & VP(E) ID access through accessor functions

2017-08-29T22:57:26Z

We currently have fields in struct cpuinfo_mips for the core & VP(E) ID of a particular CPU, and various pieces of code directly access those fields. This patch abstracts such access by introducing accessor functions cpu_core(), cpu_set_core(), cpu_vpe_id() & cpu_set_vpe_id() and having code that needs to access these values call those functions rather than directly accessing the struct cpuinfo_mips fields. This prepares us for changes to the way in which those values are stored in later patches. The cpu_vpe_id() function is introduced even though we already had a cpu_vpe_id() macro for a couple of reasons: 1) It's more consistent with the core, and future cluster, accessors. 2) It ensures a sensible return type without explicit casts. 3) It's generally preferable to use functions rather than macros. Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17009/ Signed-off-by: Ralf Baechle

Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus

2017-05-12T16:56:30Z

Pull MIPS updates from James Hogan: "math-emu: - Add missing clearing of BLTZALL and BGEZALL emulation counters - Fix BC1EQZ and BC1NEZ condition handling - Fix BLEZL and BGTZL identification BPF: - Add JIT support for SKF_AD_HATYPE - Use unsigned access for unsigned SKB fields - Quit clobbering callee saved registers in JIT code - Fix multiple problems in JIT skb access helpers Loongson 3: - Select MIPS_L1_CACHE_SHIFT_6 Octeon: - Remove vestiges of CONFIG_CAVIUM_OCTEON_2ND_KERNEL - Remove unused L2C types and macros. - Remove unused SLI types and macros. - Fix compile error when USB is not enabled. - Octeon: Remove unused PCIERCX types and macros. - Octeon: Clean up platform code. SNI: - Remove recursive include of cpu-feature-overrides.h Sibyte: - Export symbol periph_rev to sb1250-mac network driver. - Fix Kconfig warning. Generic platform: - Enable Root FS on NFS in generic_defconfig SMP-MT: - Use CPU interrupt controller IPI IRQ domain support UASM: - Add support for LHU for uasm. - Remove needless ISA abstraction mm: - Add 48-bit VA space and 4-level page tables for 4K pages. PCI: - Add controllers before the specified head irqchip driver for MIPS CPU: - Replace magic 0x100 with IE_SW0 - Prepare for non-legacy IRQ domains - Introduce IPI IRQ domain support MAINTAINERS: - Update email-id of Rahul Bedarkar NET: - sb1250-mac: Add missing MODULE_LICENSE() CPUFREQ: - Loongson2: drop set_cpus_allowed_ptr() Misc: - Disable Werror when W= is set - Opt into HAVE_COPY_THREAD_TLS - Enable GENERIC_CPU_AUTOPROBE - Use common outgoing-CPU-notification code - Remove dead define of ST_OFF - Remove CONFIG_ARCH_HAS_ILOG2_U{32,64} - Stengthen IPI IRQ domain sanity check - Remove confusing else statement in __do_page_fault() - Don't unnecessarily include kmalloc.h into . - Delete unused definition of SMP_CACHE_SHIFT. - Delete redundant definition of SMP_CACHE_BYTES" * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (39 commits) MIPS: Sibyte: Fix Kconfig warning. MIPS: Sibyte: Export symbol periph_rev to sb1250-mac network driver. NET: sb1250-mac: Add missing MODULE_LICENSE() MAINTAINERS: Update email-id of Rahul Bedarkar MIPS: Remove confusing else statement in __do_page_fault() MIPS: Stengthen IPI IRQ domain sanity check MIPS: smp-mt: Use CPU interrupt controller IPI IRQ domain support irqchip: mips-cpu: Introduce IPI IRQ domain support irqchip: mips-cpu: Prepare for non-legacy IRQ domains irqchip: mips-cpu: Replace magic 0x100 with IE_SW0 MIPS: Remove CONFIG_ARCH_HAS_ILOG2_U{32,64} MIPS: generic: Enable Root FS on NFS in generic_defconfig MIPS: mach-rm: Remove recursive include of cpu-feature-overrides.h MIPS: Opt into HAVE_COPY_THREAD_TLS CPUFREQ: Loongson2: drop set_cpus_allowed_ptr() MIPS: uasm: Remove needless ISA abstraction MIPS: Remove dead define of ST_OFF MIPS: Use common outgoing-CPU-notification code MIPS: math-emu: Fix BC1EQZ and BC1NEZ condition handling MIPS: r2-on-r6-emu: Clear BLTZALL and BGEZALL debugfs counters ...

MIPS: Delete redundant definition of SMP_CACHE_BYTES.

2017-04-10T09:56:08Z

already defines SMP_CACHE_BYTES as L1_CACHE_BYTES. This change results in a build error in which directly includes . Fix this by including instead. Signed-off-by: Ralf Baechle