Re: [PATCH v2 03/10] RISC-V: shunt isa_ext_arr to cpufeature.c

From: Andrew Jones
Date: Fri Jun 30 2023 - 03:29:15 EST

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On Thu, Jun 29, 2023 at 09:28:49AM +0100, Conor Dooley wrote:
> To facilitate using one struct to define extensions, rather than having
> several, shunt isa_ext_arr to cpufeature.c, where it will be used for
> probing extension presence also.
> As that scope of the array as widened, prefix it with riscv & drop the
> type from the variable name.
>
> Since the new array is const, print_isa() needs a wee bit of cleanup to
> avoid complaints about losing the const qualifier.
>
> Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
> Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> ---
> Changes in v2:
> - Drop the empty element from the end of the array, it was adding a bug
> anyway as I was not decrementing the result of ARRAY_SIZE() by one.
> Likely I meant to drop it originally and forgot, as dropping the
> decrement was intentional.

I don't think v1 introduced a bug, because you changed the condition to
'<' from '<=' to account for not subtracting one. Both the original code
and v1 were doing a useless __riscv_isa_extension_available() check of
RISCV_ISA_EXT_MAX, though, which this version removes.

Thanks,
drew

> ---
> arch/riscv/include/asm/hwcap.h | 3 ++
> arch/riscv/kernel/cpu.c | 75 +---------------------------------
> arch/riscv/kernel/cpufeature.c | 67 ++++++++++++++++++++++++++++++
> 3 files changed, 72 insertions(+), 73 deletions(-)
>
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index f041bfa7f6a0..7a57e6109aef 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -76,6 +76,9 @@ struct riscv_isa_ext_data {
> unsigned int isa_ext_id;
> };
>
> +extern const struct riscv_isa_ext_data riscv_isa_ext[];
> +extern const size_t riscv_isa_ext_count;
> +
> unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
>
> #define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index ddd7634e4c1d..269a32ceb595 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -160,81 +160,10 @@ arch_initcall(riscv_cpuinfo_init);
>
> #ifdef CONFIG_PROC_FS
>
> -#define __RISCV_ISA_EXT_DATA(UPROP, EXTID) \
> - { \
> - .uprop = #UPROP, \
> - .isa_ext_id = EXTID, \
> - }
> -
> -/*
> - * The canonical order of ISA extension names in the ISA string is defined in
> - * chapter 27 of the unprivileged specification.
> - *
> - * Ordinarily, for in-kernel data structures, this order is unimportant but
> - * isa_ext_arr defines the order of the ISA string in /proc/cpuinfo.
> - *
> - * The specification uses vague wording, such as should, when it comes to
> - * ordering, so for our purposes the following rules apply:
> - *
> - * 1. All multi-letter extensions must be separated from other extensions by an
> - * underscore.
> - *
> - * 2. Additional standard extensions (starting with 'Z') must be sorted after
> - * single-letter extensions and before any higher-privileged extensions.
> -
> - * 3. The first letter following the 'Z' conventionally indicates the most
> - * closely related alphabetical extension category, IMAFDQLCBKJTPVH.
> - * If multiple 'Z' extensions are named, they must be ordered first by
> - * category, then alphabetically within a category.
> - *
> - * 3. Standard supervisor-level extensions (starting with 'S') must be listed
> - * after standard unprivileged extensions. If multiple supervisor-level
> - * extensions are listed, they must be ordered alphabetically.
> - *
> - * 4. Standard machine-level extensions (starting with 'Zxm') must be listed
> - * after any lower-privileged, standard extensions. If multiple
> - * machine-level extensions are listed, they must be ordered
> - * alphabetically.
> - *
> - * 5. Non-standard extensions (starting with 'X') must be listed after all
> - * standard extensions. If multiple non-standard extensions are listed, they
> - * must be ordered alphabetically.
> - *
> - * An example string following the order is:
> - * rv64imadc_zifoo_zigoo_zafoo_sbar_scar_zxmbaz_xqux_xrux
> - *
> - * New entries to this struct should follow the ordering rules described above.
> - */
> -static struct riscv_isa_ext_data isa_ext_arr[] = {
> - __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
> - __RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ),
> - __RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
> - __RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
> - __RISCV_ISA_EXT_DATA(zifencei, RISCV_ISA_EXT_ZIFENCEI),
> - __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
> - __RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
> - __RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
> - __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
> - __RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
> - __RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
> - __RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
> - __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
> - __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
> - __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
> - __RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
> - __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
> - __RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
> -};
> -
> static void print_isa_ext(struct seq_file *f)
> {
> - struct riscv_isa_ext_data *edata;
> - int i = 0, arr_sz;
> -
> - arr_sz = ARRAY_SIZE(isa_ext_arr) - 1;
> -
> - for (i = 0; i <= arr_sz; i++) {
> - edata = &isa_ext_arr[i];
> + for (int i = 0; i < riscv_isa_ext_count; i++) {
> + const struct riscv_isa_ext_data *edata = &riscv_isa_ext[i];
> if (!__riscv_isa_extension_available(NULL, edata->isa_ext_id))
> continue;
> seq_printf(f, "_%s", edata->uprop);
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index bdcf460ea53d..fb476153fffc 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -99,6 +99,73 @@ static bool riscv_isa_extension_check(int id)
> return true;
> }
>
> +#define __RISCV_ISA_EXT_DATA(UPROP, EXTID) \
> + { \
> + .uprop = #UPROP, \
> + .isa_ext_id = EXTID, \
> + }
> +
> +/*
> + * The canonical order of ISA extension names in the ISA string is defined in
> + * chapter 27 of the unprivileged specification.
> + *
> + * Ordinarily, for in-kernel data structures, this order is unimportant but
> + * isa_ext_arr defines the order of the ISA string in /proc/cpuinfo.
> + *
> + * The specification uses vague wording, such as should, when it comes to
> + * ordering, so for our purposes the following rules apply:
> + *
> + * 1. All multi-letter extensions must be separated from other extensions by an
> + * underscore.
> + *
> + * 2. Additional standard extensions (starting with 'Z') must be sorted after
> + * single-letter extensions and before any higher-privileged extensions.
> + *
> + * 3. The first letter following the 'Z' conventionally indicates the most
> + * closely related alphabetical extension category, IMAFDQLCBKJTPVH.
> + * If multiple 'Z' extensions are named, they must be ordered first by
> + * category, then alphabetically within a category.
> + *
> + * 3. Standard supervisor-level extensions (starting with 'S') must be listed
> + * after standard unprivileged extensions. If multiple supervisor-level
> + * extensions are listed, they must be ordered alphabetically.
> + *
> + * 4. Standard machine-level extensions (starting with 'Zxm') must be listed
> + * after any lower-privileged, standard extensions. If multiple
> + * machine-level extensions are listed, they must be ordered
> + * alphabetically.
> + *
> + * 5. Non-standard extensions (starting with 'X') must be listed after all
> + * standard extensions. If multiple non-standard extensions are listed, they
> + * must be ordered alphabetically.
> + *
> + * An example string following the order is:
> + * rv64imadc_zifoo_zigoo_zafoo_sbar_scar_zxmbaz_xqux_xrux
> + *
> + * New entries to this struct should follow the ordering rules described above.
> + */
> +const struct riscv_isa_ext_data riscv_isa_ext[] = {
> + __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
> + __RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ),
> + __RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
> + __RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
> + __RISCV_ISA_EXT_DATA(zifencei, RISCV_ISA_EXT_ZIFENCEI),
> + __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
> + __RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
> + __RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
> + __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
> + __RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
> + __RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
> + __RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
> + __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
> + __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
> + __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
> + __RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
> + __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
> +};
> +
> +const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);
> +
> void __init riscv_fill_hwcap(void)
> {
> struct device_node *node;
> --
> 2.40.1
>

Next message: Greg Kroah-Hartman: "Re: [PATCH 2/2] include/uapi pps.h: drop not needed PPS_MAX_SOURCES define"
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In reply to: Evan Green: "Re: [PATCH v2 03/10] RISC-V: shunt isa_ext_arr to cpufeature.c"
Next in thread: Conor Dooley: "[PATCH v2 07/10] RISC-V: split riscv_fill_hwcap() in 3"
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