linux/arch/riscv/Kconfig.erratas
Conor Dooley 1ee7fc3f4d
RISC-V: always select RISCV_ALTERNATIVE for non-xip kernels
When moving switch_to's has_fpu() over to using
riscv_has_extension_likely() rather than static branches, the FPU code
gained a dependency on the alternatives framework.
That dependency has now been removed, as riscv_has_extension_ikely() now
contains a fallback path, using __riscv_isa_extension_available(), but
if CONFIG_RISCV_ALTERNATIVE isn't selected when CONFIG_FPU is, has_fpu()
checks will not benefit from the "fast path" that the alternatives
framework provides.

We want to ensure that alternatives are available whenever
riscv_has_extension_[un]likely() is used, rather than silently falling
back to the slow path, but rather than rely on selecting
RISCV_ALTERNATIVE in the myriad of locations that may use
riscv_has_extension_[un]likely(), select it (almost) always instead by
adding it to the main RISCV config entry.
xip kernels cannot make use of the alternatives framework, so it is not
enabled for those configurations, although this is the status quo.

All current sites that select RISCV_ALTERNATIVE are converted to
dependencies on the option instead. The explicit dependencies on
!XIP_KERNEL can be dropped, as RISCV_ALTERNATIVE is not user selectable.

Fixes: 702e64550b ("riscv: fpu: switch has_fpu() to riscv_has_extension_likely()")
Link: https://lore.kernel.org/all/ZBruFRwt3rUVngPu@zx2c4.com/
Reported-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20230324100538.3514663-3-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-03-29 11:48:39 -07:00

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menu "CPU errata selection"
config ERRATA_SIFIVE
bool "SiFive errata"
depends on RISCV_ALTERNATIVE
help
All SiFive errata Kconfig depend on this Kconfig. Disabling
this Kconfig will disable all SiFive errata. Please say "Y"
here if your platform uses SiFive CPU cores.
Otherwise, please say "N" here to avoid unnecessary overhead.
config ERRATA_SIFIVE_CIP_453
bool "Apply SiFive errata CIP-453"
depends on ERRATA_SIFIVE && 64BIT
default y
help
This will apply the SiFive CIP-453 errata to add sign extension
to the $badaddr when exception type is instruction page fault
and instruction access fault.
If you don't know what to do here, say "Y".
config ERRATA_SIFIVE_CIP_1200
bool "Apply SiFive errata CIP-1200"
depends on ERRATA_SIFIVE && 64BIT
default y
help
This will apply the SiFive CIP-1200 errata to repalce all
"sfence.vma addr" with "sfence.vma" to ensure that the addr
has been flushed from TLB.
If you don't know what to do here, say "Y".
config ERRATA_THEAD
bool "T-HEAD errata"
depends on RISCV_ALTERNATIVE
help
All T-HEAD errata Kconfig depend on this Kconfig. Disabling
this Kconfig will disable all T-HEAD errata. Please say "Y"
here if your platform uses T-HEAD CPU cores.
Otherwise, please say "N" here to avoid unnecessary overhead.
config ERRATA_THEAD_PBMT
bool "Apply T-Head memory type errata"
depends on ERRATA_THEAD && 64BIT && MMU
select RISCV_ALTERNATIVE_EARLY
default y
help
This will apply the memory type errata to handle the non-standard
memory type bits in page-table-entries on T-Head SoCs.
If you don't know what to do here, say "Y".
config ERRATA_THEAD_CMO
bool "Apply T-Head cache management errata"
depends on ERRATA_THEAD && MMU
select RISCV_DMA_NONCOHERENT
default y
help
This will apply the cache management errata to handle the
non-standard handling on non-coherent operations on T-Head SoCs.
If you don't know what to do here, say "Y".
config ERRATA_THEAD_PMU
bool "Apply T-Head PMU errata"
depends on ERRATA_THEAD && RISCV_PMU_SBI
default y
help
The T-Head C9xx cores implement a PMU overflow extension very
similar to the core SSCOFPMF extension.
This will apply the overflow errata to handle the non-standard
behaviour via the regular SBI PMU driver and interface.
If you don't know what to do here, say "Y".
endmenu # "CPU errata selection"