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Conor Dooley <conor.dooley@microchip.com> says: Here's my attempt at fixing both the use of an FPU on XIP kernels and the issue that Jason ran into where CONFIG_FPU, which needs the alternatives frame work for has_fpu() checks, could be enabled without the alternatives actually being present. For the former, a "slow" fallback that does not use alternatives is added to riscv_has_extension_[un]likely() that can be used with XIP. Obviously, we want to make use of Jisheng's alternatives based approach where possible, so any users of riscv_has_extension_[un]likely() will want to make sure that they select RISCV_ALTERNATIVE. If they don't however, they'll hit the fallback path which (should, sparing a silly mistake from me!) behave in the same way, thus succeeding silently. Sounds like a To prevent "depends on !XIP_KERNEL; select RISCV_ALTERNATIVE" spreading like the plague through the various places that want to check for the presence of extensions, and sidestep the potential silent "success" mentioned above, all users RISCV_ALTERNATIVE are converted from selects to dependencies, with the option being selected for all !XIP_KERNEL builds. I know that the VDSO was a key place that Jisheng wanted to use the new helper rather than static branches, and I think the fallback path should not cause issues there. See the thread at [1] for the prior discussion. 1 - https://lore.kernel.org/linux-riscv/20230128172856.3814-1-jszhang@kernel.org/T/#m21390d570997145d31dd8bb95002fd61f99c6573 [Palmer: these were also merged into fixes, but there's a cleanup that depends on the merge so I'm taking it into for-next as well.] * b4-shazam-merge: RISC-V: always select RISCV_ALTERNATIVE for non-xip kernels RISC-V: add non-alternative fallback for riscv_has_extension_[un]likely() Link: https://lore.kernel.org/r/20230324100538.3514663-1-conor.dooley@microchip.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> * commit '1ee7fc3f4d0a93831a20d5566f203d5ad6d44de8': RISC-V: always select RISCV_ALTERNATIVE for non-xip kernels RISC-V: add non-alternative fallback for riscv_has_extension_[un]likely()
80 lines
2.4 KiB
Text
80 lines
2.4 KiB
Text
menu "CPU errata selection"
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config ERRATA_SIFIVE
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bool "SiFive errata"
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depends on RISCV_ALTERNATIVE
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help
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All SiFive errata Kconfig depend on this Kconfig. Disabling
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this Kconfig will disable all SiFive errata. Please say "Y"
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here if your platform uses SiFive CPU cores.
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Otherwise, please say "N" here to avoid unnecessary overhead.
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config ERRATA_SIFIVE_CIP_453
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bool "Apply SiFive errata CIP-453"
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depends on ERRATA_SIFIVE && 64BIT
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default y
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help
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This will apply the SiFive CIP-453 errata to add sign extension
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to the $badaddr when exception type is instruction page fault
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and instruction access fault.
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If you don't know what to do here, say "Y".
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config ERRATA_SIFIVE_CIP_1200
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bool "Apply SiFive errata CIP-1200"
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depends on ERRATA_SIFIVE && 64BIT
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default y
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help
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This will apply the SiFive CIP-1200 errata to repalce all
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"sfence.vma addr" with "sfence.vma" to ensure that the addr
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has been flushed from TLB.
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If you don't know what to do here, say "Y".
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config ERRATA_THEAD
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bool "T-HEAD errata"
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depends on RISCV_ALTERNATIVE
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help
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All T-HEAD errata Kconfig depend on this Kconfig. Disabling
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this Kconfig will disable all T-HEAD errata. Please say "Y"
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here if your platform uses T-HEAD CPU cores.
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Otherwise, please say "N" here to avoid unnecessary overhead.
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config ERRATA_THEAD_PBMT
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bool "Apply T-Head memory type errata"
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depends on ERRATA_THEAD && 64BIT && MMU
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select RISCV_ALTERNATIVE_EARLY
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default y
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help
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This will apply the memory type errata to handle the non-standard
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memory type bits in page-table-entries on T-Head SoCs.
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If you don't know what to do here, say "Y".
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config ERRATA_THEAD_CMO
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bool "Apply T-Head cache management errata"
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depends on ERRATA_THEAD && MMU
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select RISCV_DMA_NONCOHERENT
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default y
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help
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This will apply the cache management errata to handle the
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non-standard handling on non-coherent operations on T-Head SoCs.
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If you don't know what to do here, say "Y".
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config ERRATA_THEAD_PMU
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bool "Apply T-Head PMU errata"
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depends on ERRATA_THEAD && RISCV_PMU_SBI
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default y
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help
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The T-Head C9xx cores implement a PMU overflow extension very
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similar to the core SSCOFPMF extension.
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This will apply the overflow errata to handle the non-standard
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behaviour via the regular SBI PMU driver and interface.
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If you don't know what to do here, say "Y".
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endmenu # "CPU errata selection"
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