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RISC-V: Improve use of isa2hwcap[]

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Improve isa2hwcap[] by removing it from static storage, as
riscv_fill_hwcap() is only called once, and by reducing its size
from 256 bytes to 26. The latter improvement is possible because
isa2hwcap[] will never be indexed with capital letters and we can
precompute the offsets from 'a'.

No functional change intended.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20221129143447.49714-2-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Andrew Jones 2022-11-29 15:34:45 +01:00 committed by Palmer Dabbelt
parent 5c20a3a9df
commit 726855549c
No known key found for this signature in database
GPG key ID: 2E1319F35FBB1889
1 changed files with 11 additions and 9 deletions
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20
arch/riscv/kernel/cpufeature.c
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@ -74,15 +74,15 @@ void __init riscv_fill_hwcap(void)
const char *isa;
char print_str[NUM_ALPHA_EXTS + 1];
int i, j, rc;
static unsigned long isa2hwcap[256] = {0};
unsigned long isa2hwcap[26] = {0};
unsigned long hartid;
isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
isa2hwcap['a' - 'a'] = COMPAT_HWCAP_ISA_A;
isa2hwcap['f' - 'a'] = COMPAT_HWCAP_ISA_F;
isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
elf_hwcap = 0;
@ -196,8 +196,10 @@ void __init riscv_fill_hwcap(void)
if (unlikely(ext_err))
continue;
if (!ext_long) {
this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
set_bit(*ext - 'a', this_isa);
int nr = *ext - 'a';
this_hwcap |= isa2hwcap[nr];
set_bit(nr, this_isa);
} else {
SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);