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65b71cc3 |
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07-Apr-2024 |
Christoph Müllner <christoph.muellner@vrull.eu> |
riscv: T-Head: Test availability bit before enabling MAE errata T-Head's memory attribute extension (XTheadMae) (non-compatible equivalent of RVI's Svpbmt) is currently assumed for all T-Head harts. However, QEMU recently decided to drop acceptance of guests that write reserved bits in PTEs. As XTheadMae uses reserved bits in PTEs and Linux applies the MAE errata for all T-Head harts, this broke the Linux startup on QEMU emulations of the C906 emulation. This patch attempts to address this issue by testing the MAE-enable bit in the th.sxstatus CSR. This CSR is available in HW and can be emulated in QEMU. This patch also makes the XTheadMae probing mechanism reliable, because a test for the right combination of mvendorid, marchid, and mimpid is not sufficient to enable MAE. Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu> Link: https://lore.kernel.org/r/20240407213236.2121592-3-christoph.muellner@vrull.eu Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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6179d4a2 |
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07-Apr-2024 |
Christoph Müllner <christoph.muellner@vrull.eu> |
riscv: thead: Rename T-Head PBMT to MAE T-Head's vendor extension to set page attributes has the name MAE (memory attribute extension). Let's rename it, so it is clear what this referes to. Link: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadmae.adoc Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu> Link: https://lore.kernel.org/r/20240407213236.2121592-2-christoph.muellner@vrull.eu Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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36904926 |
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14-Nov-2023 |
Jisheng Zhang <jszhang@kernel.org> |
riscv: errata: thead: use pa based instructions for CMO T-HEAD CPUs such as C906/C910/C920 support phy address based CMO, use them so that we don't need to convert to virt address. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reviewed-by: Guo Ren <guoren@kernel.org> Link: https://lore.kernel.org/r/20231114143338.2406-3-jszhang@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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a4ff64ed |
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14-Nov-2023 |
Jisheng Zhang <jszhang@kernel.org> |
riscv: errata: thead: use riscv_nonstd_cache_ops for CMO Previously, we use alternative mechanism to dynamically patch the CMO operations for THEAD C906/C910 during boot for performance reason. But as pointed out by Arnd, "there is already a significant cost in accessing the invalidated cache lines afterwards, which is likely going to be much higher than the cost of an indirect branch". And indeed, there's no performance difference with GMAC and EMMC per my test on Sipeed Lichee Pi 4A board. Use riscv_nonstd_cache_ops for THEAD C906/C910 CMO to simplify the alternative code, and to acchieve Arnd's goal -- "I think moving the THEAD ops at the same level as all nonstandard operations makes sense, but I'd still leave CMO as an explicit fast path that avoids the indirect branch. This seems like the right thing to do both for readability and for platforms on which the indirect branch has a noticeable overhead." Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20231114143338.2406-2-jszhang@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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f2d14bc4 |
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18-Aug-2023 |
Evan Green <evan@rivosinc.com> |
RISC-V: alternative: Remove feature_probe_func Now that we're testing unaligned memory copy and making that determination generically, there are no more users of the vendor feature_probe_func(). While I think it's probably going to need to come back, there are no users right now, so let's remove it until it's needed. Signed-off-by: Evan Green <evan@rivosinc.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230818194136.4084400-3-evan@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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31ca5d49 |
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14-Jun-2023 |
Jisheng Zhang <jszhang@kernel.org> |
riscv: errata: thead: only set cbom size & noncoherent during boot The CBOM size and whether the HW is noncoherent is known and determined during booting and won't change after that. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230614165504.532-2-jszhang@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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a2a58b5c |
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29-Apr-2023 |
Randy Dunlap <rdunlap@infradead.org> |
RISC-V: fix sifive and thead section mismatches in errata When CONFIG_MODULES is set, __init_or_module becomes <empty>, but when CONFIG_MODULES is not set, __init_or_module becomes __init. In the latter case, it causes section mismatch warnings: WARNING: modpost: vmlinux.o: section mismatch in reference: riscv_fill_cpu_mfr_info (section: .text) -> sifive_errata_patch_func (section: .init.text) WARNING: modpost: vmlinux.o: section mismatch in reference: riscv_fill_cpu_mfr_info (section: .text) -> thead_errata_patch_func (section: .init.text) Fixes: bb3f89487fd9 ("RISC-V: hwprobe: Remove __init on probe_vendor_features()") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Evan Green <evan@rivosinc.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230429155247.12131-1-rdunlap@infradead.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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bb3f8948 |
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20-Apr-2023 |
Evan Green <evan@rivosinc.com> |
RISC-V: hwprobe: Remove __init on probe_vendor_features() probe_vendor_features() is now called from smp_callin(), which is not __init code and runs during cpu hotplug events. Remove the __init_or_module decoration from it and the functions it calls to avoid walking into outer space. Fixes: 62a31d6e38bd ("RISC-V: hwprobe: Support probing of misaligned access performance") Signed-off-by: Evan Green <evan@rivosinc.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230420194934.1871356-1-evan@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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62a31d6e |
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07-Apr-2023 |
Evan Green <evan@rivosinc.com> |
RISC-V: hwprobe: Support probing of misaligned access performance This allows userspace to select various routines to use based on the performance of misaligned access on the target hardware. Rather than adding DT bindings, this change taps into the alternatives mechanism used to probe CPU errata. Add a new function pointer alongside the vendor-specific errata_patch_func() that probes for desirable errata (otherwise known as "features"). Unlike the errata_patch_func(), this function is called on each CPU as it comes up, so it can save feature information per-CPU. The T-head C906 has fast unaligned access, both as defined by GCC [1], and in performing a basic benchmark, which determined that byte copies are >50% slower than a misaligned word copy of the same data size (source for this test at [2]): bytecopy size f000 count 50000 offset 0 took 31664899 us wordcopy size f000 count 50000 offset 0 took 5180919 us wordcopy size f000 count 50000 offset 1 took 13416949 us [1] https://github.com/gcc-mirror/gcc/blob/master/gcc/config/riscv/riscv.cc#L353 [2] https://pastebin.com/EPXvDHSW Co-developed-by: Palmer Dabbelt <palmer@rivosinc.com> Signed-off-by: Evan Green <evan@rivosinc.com> Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu> Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Paul Walmsley <paul.walmsley@sifive.com> Link: https://lore.kernel.org/r/20230407231103.2622178-5-evan@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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ff19a8de |
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24-Feb-2023 |
Andrew Jones <ajones@ventanamicro.com> |
riscv: alternatives: Rename errata_id to patch_id Alternatives are used for both errata and cpufeatures. Use a more generic name, 'patch_id', as in "ID of code patching site", to avoid confusion when alternatives are used for cpufeatures. Signed-off-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu> Link: https://lore.kernel.org/r/20230224154601.88163-5-ajones@ventanamicro.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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9493e6f3 |
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12-Feb-2023 |
Conor Dooley <conor.dooley@microchip.com> |
RISC-V: take text_mutex during alternative patching Guenter reported a splat during boot, that Samuel pointed out was the lockdep assertion failing in patch_insn_write(): WARNING: CPU: 0 PID: 0 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x222/0x2f6 epc : patch_insn_write+0x222/0x2f6 ra : patch_insn_write+0x21e/0x2f6 epc : ffffffff800068c6 ra : ffffffff800068c2 sp : ffffffff81803df0 gp : ffffffff81a1ab78 tp : ffffffff81814f80 t0 : ffffffffffffe000 t1 : 0000000000000001 t2 : 4c45203a76637369 s0 : ffffffff81803e40 s1 : 0000000000000004 a0 : 0000000000000000 a1 : ffffffffffffffff a2 : 0000000000000004 a3 : 0000000000000000 a4 : 0000000000000001 a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000052464e43 s2 : ffffffff80b4889c s3 : 000000000000082c s4 : ffffffff80b48828 s5 : 0000000000000828 s6 : ffffffff8131a0a0 s7 : 0000000000000fff s8 : 0000000008000200 s9 : ffffffff8131a520 s10: 0000000000000018 s11: 000000000000000b t3 : 0000000000000001 t4 : 000000000000000d t5 : ffffffffd8180000 t6 : ffffffff81803bc8 status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003 [<ffffffff800068c6>] patch_insn_write+0x222/0x2f6 [<ffffffff80006a36>] patch_text_nosync+0xc/0x2a [<ffffffff80003b86>] riscv_cpufeature_patch_func+0x52/0x98 [<ffffffff80003348>] _apply_alternatives+0x46/0x86 [<ffffffff80c02d36>] apply_boot_alternatives+0x3c/0xfa [<ffffffff80c03ad8>] setup_arch+0x584/0x5b8 [<ffffffff80c0075a>] start_kernel+0xa2/0x8f8 This issue was exposed by 702e64550b12 ("riscv: fpu: switch has_fpu() to riscv_has_extension_likely()"), as it is the patching in has_fpu() that triggers the splats in Guenter's report. Take the text_mutex before doing any code patching to satisfy lockdep. Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support") Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head") Fixes: 1a0e5dbd3723 ("riscv: sifive: Add SiFive alternative ports") Reported-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/all/20230212154333.GA3760469@roeck-us.net/ Signed-off-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Samuel Holland <samuel@sholland.org> Tested-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20230212194735.491785-1-conor@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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bfd6fc5d |
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11-Feb-2023 |
Samuel Holland <samuel@sholland.org> |
riscv: Fix early alternative patching Now that the text to patch is located using a relative offset from the alternative entry, the text address should be computed without applying the kernel mapping offset, both before and after VM setup. Fixes: 8d23e94a4433 ("riscv: switch to relative alternative entries") Signed-off-by: Samuel Holland <samuel@sholland.org> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Guo Ren <guoren@kernel.org> Reviewed-by: Jisheng Zhang <jszhang@kernel.org> Tested-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230212021534.59121-2-samuel@sholland.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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8d23e94a |
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28-Jan-2023 |
Jisheng Zhang <jszhang@kernel.org> |
riscv: switch to relative alternative entries Instead of using absolute addresses for both the old instrucions and the alternative instructions, use offsets relative to the alt_entry values. So this not only cuts the size of the alternative entry, but also meets the prerequisite for patching alternatives in the vDSO, since absolute alternative entries are subject to dynamic relocation, which is incompatible with the vDSO building. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230128172856.3814-10-jszhang@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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65e9fb08 |
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11-Oct-2022 |
Heiko Stuebner <heiko@sntech.de> |
drivers/perf: riscv_pmu_sbi: add support for PMU variant on T-Head C9xx cores With the T-HEAD C9XX cores being designed before or during the ratification to the SSCOFPMF extension, it implements functionality very similar but not equal to it. It implements overflow handling and also some privilege-mode filtering. While SSCOFPMF supports this for all modes, the C9XX only implements the filtering for M-mode and S-mode but not user-mode. So add some adaptions to allow the C9XX to still handle its PMU through the regular SBI PMU interface instead of defining new interfaces or drivers. To work properly, this requires a matching change in SBI, though the actual interface between kernel and SBI does not change. The main differences are a the overflow CSR and irq number. As the reading of the overflow-csr is in the hot-path during irq handling, use an errata and alternatives to not introduce new conditionals there. Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Link: https://lore.kernel.org/all/20221011231841.2951264-2-heiko@sntech.de/ Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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14057733 |
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05-Sep-2022 |
Heiko Stuebner <heiko@sntech.de> |
riscv: check for kernel config option in t-head memory types errata The t-head variant of page-based memory types should also check first for the enabled kernel config option. Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head") Signed-off-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Guo Ren <guoren@kernel.org> Link: https://lore.kernel.org/r/20220905111027.2463297-6-heiko@sntech.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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499590c0 |
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05-Sep-2022 |
Heiko Stuebner <heiko@sntech.de> |
riscv: use BIT() macros in t-head errata init Using the appropriate BIT macro makes the code better readable. Suggested-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Guo Ren <guoren@kernel.org> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Link: https://lore.kernel.org/r/20220905111027.2463297-4-heiko@sntech.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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f055268e |
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05-Sep-2022 |
Heiko Stuebner <heiko@sntech.de> |
riscv: drop some idefs from CMO initialization Wrapping things in #ifdefs makes the code harder to read while we also have IS_ENABLED() macros to do this in regular code and the extension detection is not _that_ runtime critical. So define a stub for riscv_noncoherent_supported() in the non-CONFIG_RISCV_DMA_NONCOHERENT case and move the code to us IS_ENABLED. Suggested-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Guo Ren <guoren@kernel.org> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Link: https://lore.kernel.org/r/20220905111027.2463297-3-heiko@sntech.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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8f7e001e |
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12-Sep-2022 |
Palmer Dabbelt <palmer@rivosinc.com> |
RISC-V: Clean up the Zicbom block size probing This fixes two issues: I truncated the warning's hart ID when porting to the 64-bit hart ID code, and the original code's warning handling could fire on an uninitialized hart ID. The biggest change here is that riscv_cbom_block_size is no longer initialized, as IMO the default isn't sane: there's nothing in the ISA that mandates any specific cache block size, so falling back to one will just silently produce the wrong answer on some systems. This also changes the probing order so the cache block size is known before enabling Zicbom support. CC: stable@vger.kernel.org CC: Andrew Jones <ajones@ventanamicro.com> CC: Heiko Stuebner <heiko@sntech.de> CC: Atish Patra <atishp@rivosinc.com> Fixes: 3aefb2ee5bdd ("riscv: implement Zicbom-based CMO instructions + the t-head variant") Fixes: 1631ba1259d6 ("riscv: Add support for non-coherent devices using zicbom extension") Reported-by: kernel test robot <lkp@intel.com> Reported-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> [Conor: fixed the redefinition errors] Tested-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Conor Dooley <conor.dooley@microchip.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20220912224800.998121-1-mail@conchuod.ie Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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d20ec752 |
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06-Jul-2022 |
Heiko Stuebner <heiko@sntech.de> |
riscv: implement cache-management errata for T-Head SoCs The T-Head C906 and C910 implement a scheme for handling cache operations different from the generic Zicbom extension. Add an errata for it next to the generic dma coherency ops. Reviewed-by: Samuel Holland <samuel@sholland.org> Tested-by: Samuel Holland <samuel@sholland.org> Reviewed-by: Guo Ren <guoren@kernel.org> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Link: https://lore.kernel.org/r/20220706231536.2041855-5-heiko@sntech.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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1771c8c9 |
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26-May-2022 |
Heiko Stuebner <heiko@sntech.de> |
riscv: remove usage of function-pointers from cpufeatures and t-head errata Having a list of alternatives to check with a per-entry function pointer to a check function is nice style-wise. But in case of early-alternatives it can clash with the non-relocated kernel and the function pointer in the list pointing to a completely wrong location. This isn't an issue with one or two list entries, as in that case the compiler seems to unroll the loop and even usage of the list structure and then only does relative jumps into the check functions based on this. When adding a third entry to either list though, the issue that was hiding there from the beginning is triggered resulting a jump to a memory address that isn't part of the kernel at all. The list of features/erratas only contained an unused name and the pointer to the check function, so an easy solution for the problem is to just unroll the loop in code, dismantle the whole list structure and just call the relevant check functions one by one ourself. For the T-Head errata this includes moving the stage-check inside the check functions. The issue is only relevant for things that might be called for early- alternatives (T-Head and possible future main extensions), so the SiFive erratas were not affected from the beginning, as they got an early return for early-alternatives in the original patchset. Signed-off-by: Heiko Stuebner <heiko@sntech.de> Tested-by: Samuel Holland <samuel@sholland.org> Link: https://lore.kernel.org/r/20220526205646.258337-6-heiko@sntech.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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a35707c3 |
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11-May-2022 |
Heiko Stuebner <heiko@sntech.de> |
riscv: add memory-type errata for T-Head Some current cpus based on T-Head cores implement memory-types way different than described in the svpbmt spec even going so far as using PTE bits marked as reserved. Add the T-Head vendor-id and necessary errata code to replace the affected instructions. Signed-off-by: Heiko Stuebner <heiko@sntech.de> Tested-by: Samuel Holland <samuel@sholland.org> Link: https://lore.kernel.org/r/20220511192921.2223629-13-heiko@sntech.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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