diff mbox series

[v3,2/3] RISC-V: Introduce riscv_isa_extension_check

Message ID 20221129143447.49714-3-ajones@ventanamicro.com (mailing list archive)
State Accepted
Commit 132cfeb2b7fd98af63acc50511ee420cc2152b9b
Delegated to: Palmer Dabbelt
Headers show
Series RISC-V: Ensure Zicbom has a valid block size | expand


Context Check Description
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conchuod/fixes_present success Fixes tag not required for -next series
conchuod/verify_signedoff success Signed-off-by tag matches author and committer
conchuod/kdoc success Errors and warnings before: 0 this patch: 0
conchuod/module_param success Was 0 now: 0
conchuod/build_rv32_defconfig success Build OK
conchuod/build_warn_rv64 success Errors and warnings before: 0 this patch: 0
conchuod/dtb_warn_rv64 success Errors and warnings before: 0 this patch: 0
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conchuod/build_rv64_nommu_k210_defconfig success Build OK
conchuod/verify_fixes success No Fixes tag
conchuod/build_rv64_nommu_virt_defconfig success Build OK

Commit Message

Andrew Jones Nov. 29, 2022, 2:34 p.m. UTC
Currently any isa extension found in the isa string is set in the
isa bitmap. An isa extension set in the bitmap indicates that the
extension is present and may be used (a.k.a is enabled). However,
when an extension cannot be used due to missing dependencies or
errata it should not be added to the bitmap. Introduce a function
where additional checks may be placed in order to determine if an
extension should be enabled or not.

Note, the checks may simply indicate an issue with the DT, but,
since extensions may be used in early boot, it's not always possible
to simply produce an error at the point the issue is determined.
It's best to keep the extension disabled and produce an error.

No functional change intended, as the function is only introduced
and always returns true. A later patch will provide checks for an
isa extension.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
 arch/riscv/kernel/cpufeature.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)
diff mbox series


diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 4677320d7e31..220be7222129 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -68,6 +68,11 @@  bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
+static bool riscv_isa_extension_check(int id)
+	return true;
 void __init riscv_fill_hwcap(void)
 	struct device_node *node;
@@ -189,7 +194,8 @@  void __init riscv_fill_hwcap(void)
 #define SET_ISA_EXT_MAP(name, bit)						\
 			do {							\
 				if ((ext_end - ext == sizeof(name) - 1) &&	\
-				     !memcmp(ext, name, sizeof(name) - 1))	\
+				     !memcmp(ext, name, sizeof(name) - 1) &&	\
+				     riscv_isa_extension_check(bit))		\
 					set_bit(bit, this_isa);			\
 			} while (false)						\
@@ -198,8 +204,10 @@  void __init riscv_fill_hwcap(void)
 			if (!ext_long) {
 				int nr = *ext - 'a';
-				this_hwcap |= isa2hwcap[nr];
-				set_bit(nr, this_isa);
+				if (riscv_isa_extension_check(nr)) {
+					this_hwcap |= isa2hwcap[nr];
+					set_bit(nr, this_isa);
+				}
 			} else {