Re: [PATCH v2 1/2] riscv: allow case-insensitive ISA string parsing

[Andrew Jones]

On Fri, Apr 28, 2023 at 10:16:00PM +0800, Yangyu Chen wrote:
> According to RISC-V Hart Capabilities Table (RHCT) description in UEFI
> Forum ECR, the format of the ISA string is defined in the RISC-V
> unprivileged specification which is case-insensitive. However, the
> current ISA string parser in the kernel does not support ISA strings
> with uppercase letters.
> 
> This patch modifies the ISA string parser in the kernel to support
> case-insensitive ISA string parsing.
> 
> Signed-off-by: Yangyu Chen <cyy@xxxxxxxxxxxx>
> ---
>  arch/riscv/kernel/cpu.c        |  3 ++-
>  arch/riscv/kernel/cpufeature.c | 25 ++++++++++++-------------
>  2 files changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index 8400f0cc9704..52b92a267121 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -4,6 +4,7 @@
>   */
>  
>  #include <linux/cpu.h>
> +#include <linux/ctype.h>
>  #include <linux/init.h>
>  #include <linux/seq_file.h>
>  #include <linux/of.h>
> @@ -41,7 +42,7 @@ int riscv_of_processor_hartid(struct device_node *node, unsigned long *hart)
>  		pr_warn("CPU with hartid=%lu has no \"riscv,isa\" property\n", *hart);
>  		return -ENODEV;
>  	}
> -	if (isa[0] != 'r' || isa[1] != 'v') {
> +	if (tolower(isa[0]) != 'r' || tolower(isa[1]) != 'v') {
>  		pr_warn("CPU with hartid=%lu has an invalid ISA of \"%s\"\n", *hart, isa);
>  		return -ENODEV;
>  	}
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 59d58ee0f68d..d1991c12e546 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -119,13 +119,10 @@ void __init riscv_fill_hwcap(void)
>  		}
>  
>  		temp = isa;
> -#if IS_ENABLED(CONFIG_32BIT)
> -		if (!strncmp(isa, "rv32", 4))
> +		if (IS_ENABLED(CONFIG_32BIT) && !strncasecmp(isa, "rv32", 4))
>  			isa += 4;
> -#elif IS_ENABLED(CONFIG_64BIT)
> -		if (!strncmp(isa, "rv64", 4))
> +		else if (IS_ENABLED(CONFIG_64BIT) && !strncasecmp(isa, "rv64", 4))
>  			isa += 4;
> -#endif
>  		/* The riscv,isa DT property must start with rv64 or rv32 */
>  		if (temp == isa)
>  			continue;
> @@ -136,6 +133,7 @@ void __init riscv_fill_hwcap(void)
>  			bool ext_long = false, ext_err = false;
>  
>  			switch (*ext) {
> +			case 'S':
>  			case 's':
>  				/**
>  				 * Workaround for invalid single-letter 's' & 'u'(QEMU).
> @@ -143,19 +141,20 @@ void __init riscv_fill_hwcap(void)
>  				 * not valid ISA extensions. It works until multi-letter
>  				 * extension starting with "Su" appears.
>  				 */
> -				if (ext[-1] != '_' && ext[1] == 'u') {
> +				if (ext[-1] != '_' && tolower(ext[1]) == 'u') {
>  					++isa;
>  					ext_err = true;
>  					break;
>  				}
>  				fallthrough;
> +			case 'X':
>  			case 'x':
> +			case 'Z':
>  			case 'z':
>  				ext_long = true;
>  				/* Multi-letter extension must be delimited */
>  				for (; *isa && *isa != '_'; ++isa)
> -					if (unlikely(!islower(*isa)
> -						     && !isdigit(*isa)))
> +					if (unlikely(!isalnum(*isa)))
>  						ext_err = true;
>  				/* Parse backwards */
>  				ext_end = isa;
> @@ -166,7 +165,7 @@ void __init riscv_fill_hwcap(void)
>  				/* Skip the minor version */
>  				while (isdigit(*--ext_end))
>  					;
> -				if (ext_end[0] != 'p'
> +				if (tolower(ext_end[0]) != 'p'
>  				    || !isdigit(ext_end[-1])) {
>  					/* Advance it to offset the pre-decrement */
>  					++ext_end;
> @@ -178,7 +177,7 @@ void __init riscv_fill_hwcap(void)
>  				++ext_end;
>  				break;
>  			default:
> -				if (unlikely(!islower(*ext))) {
> +				if (unlikely(!isalpha(*ext))) {
>  					ext_err = true;
>  					break;
>  				}
> @@ -188,7 +187,7 @@ void __init riscv_fill_hwcap(void)
>  				/* Skip the minor version */
>  				while (isdigit(*++isa))
>  					;
> -				if (*isa != 'p')
> +				if (tolower(*isa) != 'p')
>  					break;
>  				if (!isdigit(*++isa)) {
>  					--isa;
> @@ -205,7 +204,7 @@ 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) &&	\
> +				     !strncasecmp(ext, name, sizeof(name) - 1) &&	\
>  				     riscv_isa_extension_check(bit))		\
>  					set_bit(bit, this_isa);			\
>  			} while (false)						\
> @@ -213,7 +212,7 @@ void __init riscv_fill_hwcap(void)
>  			if (unlikely(ext_err))
>  				continue;
>  			if (!ext_long) {
> -				int nr = *ext - 'a';
> +				int nr = tolower(*ext) - 'a';
>  
>  				if (riscv_isa_extension_check(nr)) {
>  					this_hwcap |= isa2hwcap[nr];
> -- 
> 2.40.0
>

Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>

Thanks,
drew