On Thu, Apr 11, 2024 at 09:11:14PM -0700, Charlie Jenkins wrote:
Create vendor variants of the existing extension helpers. If the existing functions were instead modified to support vendor extensions, a branch based on the ext value being greater than RISCV_ISA_VENDOR_EXT_BASE would have to be introduced. This additional branch would have an unnecessary performance impact.
Signed-off-by: Charlie Jenkins charlie@rivosinc.com
I've not looked at the "main" patch in the series that adds all of the probing and structures for representing this info yet beyond a cursory glance, but it feels like we're duplicating a bunch of infrastructure here before it is necessary. The IDs are all internal to Linux, so I'd rather we kept everything in the same structure until we have more than a handful of vendor extensions. With this patch (and the theadpmu stuff) we will have three vendor extensions which feels like a drop in the bucket compared to the standard ones.
arch/riscv/include/asm/cpufeature.h | 54 +++++++++++++++++++++++++++++++++++++ arch/riscv/kernel/cpufeature.c | 34 ++++++++++++++++++++--- 2 files changed, 84 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h index db2ab037843a..8f19e3681b4f 100644 --- a/arch/riscv/include/asm/cpufeature.h +++ b/arch/riscv/include/asm/cpufeature.h @@ -89,6 +89,10 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, unsigned i #define riscv_isa_extension_available(isa_bitmap, ext) \ __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext) +bool __riscv_isa_vendor_extension_available(const unsigned long *vendor_isa_bitmap, unsigned int bit); +#define riscv_isa_vendor_extension_available(isa_bitmap, ext) \
- __riscv_isa_vendor_extension_available(isa_bitmap, RISCV_ISA_VENDOR_EXT_##ext)
static __always_inline bool __riscv_has_extension_likely_alternatives(const unsigned long ext) { @@ -117,6 +121,8 @@ __riscv_has_extension_unlikely_alternatives(const unsigned long ext) return true; } +/* Standard extension helpers */
static __always_inline bool riscv_has_extension_likely(const unsigned long ext) { @@ -163,4 +169,52 @@ static __always_inline bool riscv_cpu_has_extension_unlikely(int cpu, const unsi return __riscv_isa_extension_available(hart_isa[cpu].isa, ext); } +/* Vendor extension helpers */
+static __always_inline bool +riscv_has_vendor_extension_likely(const unsigned long ext) +{
- compiletime_assert(ext < RISCV_ISA_VENDOR_EXT_MAX,
"ext must be < RISCV_ISA_VENDOR_EXT_MAX");- if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
return __riscv_has_extension_likely_alternatives(ext);- else
return __riscv_isa_vendor_extension_available(NULL, ext);+}
+static __always_inline bool +riscv_has_vendor_extension_unlikely(const unsigned long ext) +{
- compiletime_assert(ext < RISCV_ISA_VENDOR_EXT_MAX,
"ext must be < RISCV_ISA_VENDOR_EXT_MAX");- if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
return __riscv_has_extension_unlikely_alternatives(ext);- else
return __riscv_isa_vendor_extension_available(NULL, ext);+}
+static __always_inline bool riscv_cpu_has_vendor_extension_likely(int cpu, const unsigned long ext) +{
- compiletime_assert(ext < RISCV_ISA_VENDOR_EXT_MAX,
"ext must be < RISCV_ISA_VENDOR_EXT_MAX");- if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
return __riscv_has_extension_likely_alternatives(ext);- else
return __riscv_isa_vendor_extension_available(hart_isa_vendor[cpu].isa, ext);+}
+static __always_inline bool riscv_cpu_has_vendor_extension_unlikely(int cpu, const unsigned long ext) +{
- compiletime_assert(ext < RISCV_ISA_VENDOR_EXT_MAX,
"ext must be < RISCV_ISA_VENDOR_EXT_MAX");- if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
return __riscv_has_extension_unlikely_alternatives(ext);- else
return __riscv_isa_vendor_extension_available(hart_isa_vendor[cpu].isa, ext);+}
Same stuff about constant folding applies to these, I think these should just mirror the existing functions (if needed at all).
Cheers, Conor.