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| author | Conor Dooley <conor.dooley@microchip.com> | 2023-03-24 10:05:39 +0000 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-03-29 11:48:39 -0700 |
| commit | 1ee7fc3f4d0a93831a20d5566f203d5ad6d44de8 (patch) | |
| tree | ba3bdeadf7deffb6bc14b77051cde2d8de8bbcef /arch/riscv/Kconfig.erratas | |
| parent | 1aa866931b8026a0dd636e9ef7b5c5dfb4cc5ce8 (diff) | |
| download | lwn-1ee7fc3f4d0a93831a20d5566f203d5ad6d44de8.tar.gz lwn-1ee7fc3f4d0a93831a20d5566f203d5ad6d44de8.zip | |
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: 702e64550b12 ("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>
Diffstat (limited to 'arch/riscv/Kconfig.erratas')
| -rw-r--r-- | arch/riscv/Kconfig.erratas | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/arch/riscv/Kconfig.erratas b/arch/riscv/Kconfig.erratas index 69621ae6d647..0c8f4652cd82 100644 --- a/arch/riscv/Kconfig.erratas +++ b/arch/riscv/Kconfig.erratas @@ -2,8 +2,7 @@ menu "CPU errata selection" config ERRATA_SIFIVE bool "SiFive errata" - depends on !XIP_KERNEL - select RISCV_ALTERNATIVE + depends on RISCV_ALTERNATIVE help All SiFive errata Kconfig depend on this Kconfig. Disabling this Kconfig will disable all SiFive errata. Please say "Y" @@ -35,8 +34,7 @@ config ERRATA_SIFIVE_CIP_1200 config ERRATA_THEAD bool "T-HEAD errata" - depends on !XIP_KERNEL - select RISCV_ALTERNATIVE + 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" |