diff options
| author | Andrew Jones <ajones@ventanamicro.com> | 2023-02-24 17:26:28 +0100 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-03-14 21:26:05 -0700 |
| commit | d25f256332cc795b0fe16ba541fe0c05f0eb2c59 (patch) | |
| tree | da6ab591ea70d5ab40ea8e2743fa1137c7b7a7e0 /arch/riscv/include/asm/alternative.h | |
| parent | 7ea5a73617e931230a46150dc7c1bbfd98f24c8e (diff) | |
RISC-V: cpufeatures: Put the upper 16 bits of patch ID to work
cpufeature IDs are consecutive integers starting at 26, so a 32-bit
patch ID allows an aircraft carrier load of feature IDs. Repurposing
the upper 16 bits still leaves a boat load of feature IDs and gains
16 bits which may be used to control patching on a per patch-site
basis.
This will be initially used in Zicboz's application to clear_page(),
as Zicboz's block size must also be considered. In that case, the
upper 16-bit value's role will be to convey the maximum block size
which the Zicboz clear_page() implementation supports.
cpufeature patch sites which need to check for the existence or
absence of other cpufeatures may also be able to make use of this.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230224162631.405473-6-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/include/asm/alternative.h')
| -rw-r--r-- | arch/riscv/include/asm/alternative.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h index c8dea9e94310..58ccd2f8cab7 100644 --- a/arch/riscv/include/asm/alternative.h +++ b/arch/riscv/include/asm/alternative.h @@ -13,10 +13,14 @@ #ifdef CONFIG_RISCV_ALTERNATIVE #include <linux/init.h> +#include <linux/kernel.h> #include <linux/types.h> #include <linux/stddef.h> #include <asm/hwcap.h> +#define PATCH_ID_CPUFEATURE_ID(p) lower_16_bits(p) +#define PATCH_ID_CPUFEATURE_VALUE(p) upper_16_bits(p) + #define RISCV_ALTERNATIVES_BOOT 0 /* alternatives applied during regular boot */ #define RISCV_ALTERNATIVES_MODULE 1 /* alternatives applied during module-init */ #define RISCV_ALTERNATIVES_EARLY_BOOT 2 /* alternatives applied before mmu start */ |