[PATCH v4] lib: utils: fdt_helper: simplify fdt_parse_isa_extensions() helper
Peter Lin
peter.lin at sifive.com
Fri Sep 12 01:56:56 PDT 2025
Hi Xiang,
Still have an issue, when a secondary hart calls hart_detect_features()
the FDT ISA bits set by the boot hart are cleared here [1]. I think it is still
necessary to cache the ISA bitmap somewhere before it gets OR'ed
into hfeatures->extensions.
[1] https://github.com/riscv-software-src/opensbi/blob/153cdeea5350837c1206a2d2b6189fd0ba06d1f2/lib/sbi/sbi_hart.c#L836-L837
On Fri, Sep 12, 2025 at 3:06 PM Xiang W <wxjstz at 126.com> wrote:
>
> The fdt_isa_bitmap was previously used as a temporary array
> to store ISA extensions when parsing device-tree.
> To reduce scratch space consumption, set the ISA bitmap
> directly in hfeature->extensions, allows us to remove the
> fdt_parse_isa_all_harts() as fdt_parse_isa_extensions() can
> now handle the task directly.
>
> Signed-off-by: Xiang W <wxjstz at 126.com>
> Co-authored-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
> ---
> include/sbi_utils/fdt/fdt_helper.h | 3 +-
> lib/utils/fdt/fdt_helper.c | 63 ++++++++----------------------
> platform/generic/platform.c | 3 +-
> 3 files changed, 18 insertions(+), 51 deletions(-)
>
> diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h
> index 04c850cc..2ece7f5e 100644
> --- a/include/sbi_utils/fdt/fdt_helper.h
> +++ b/include/sbi_utils/fdt/fdt_helper.h
> @@ -54,8 +54,7 @@ int fdt_parse_cbom_block_size(const void *fdt, int cpu_offset, unsigned long *c
>
> int fdt_parse_timebase_frequency(const void *fdt, unsigned long *freq);
>
> -int fdt_parse_isa_extensions(const void *fdt, unsigned int hartid,
> - unsigned long *extensions);
> +int fdt_parse_isa_extensions(const void *fdt);
>
> int fdt_parse_gaisler_uart_node(const void *fdt, int nodeoffset,
> struct platform_uart_data *uart);
> diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
> index 0f4859c1..64f928f7 100644
> --- a/lib/utils/fdt/fdt_helper.c
> +++ b/lib/utils/fdt/fdt_helper.c
> @@ -324,9 +324,7 @@ int fdt_parse_timebase_frequency(const void *fdt, unsigned long *freq)
>
> #define RISCV_ISA_EXT_NAME_LEN_MAX 32
>
> -static unsigned long fdt_isa_bitmap_offset;
> -
> -static int fdt_parse_isa_one_hart(const char *isa, unsigned long *extensions)
> +static int fdt_parse_isa_one_hart(struct sbi_scratch *scratch, const char *isa)
> {
> size_t i, j, isa_len;
> char mstr[RISCV_ISA_EXT_NAME_LEN_MAX];
> @@ -379,7 +377,8 @@ static int fdt_parse_isa_one_hart(const char *isa, unsigned long *extensions)
>
> #define set_multi_letter_ext(name, bit) \
> if (!strcmp(mstr, name)) { \
> - __set_bit(bit, extensions); \
> + sbi_hart_update_extension( \
> + scratch, bit, true); \
> continue; \
> }
>
> @@ -393,29 +392,32 @@ static int fdt_parse_isa_one_hart(const char *isa, unsigned long *extensions)
> return 0;
> }
>
> -static void fdt_parse_isa_extensions_one_hart(const char *isa,
> - unsigned long *extensions,
> - int len)
> +static void fdt_parse_isa_extensions_one_hart(struct sbi_scratch *scratch,
> + const char *isa, int len)
> {
> size_t i;
>
> for (i = 0; i < SBI_HART_EXT_MAX; i++) {
> if (fdt_stringlist_contains(isa, len, sbi_hart_ext[i].name))
> - __set_bit(sbi_hart_ext[i].id, extensions);
> + sbi_hart_update_extension(scratch, sbi_hart_ext[i].id, true);
> }
> }
>
> -static int fdt_parse_isa_all_harts(const void *fdt)
> +int fdt_parse_isa_extensions(const void *fdt)
> {
> + static bool done;
> u32 hartid;
> const fdt32_t *val;
> - unsigned long *hart_exts;
> struct sbi_scratch *scratch;
> int err, cpu_offset, cpus_offset, len;
>
> - if (!fdt || !fdt_isa_bitmap_offset)
> + if (!fdt)
> return SBI_EINVAL;
>
> + if (done)
> + return 0;
> + done = true;
> +
> cpus_offset = fdt_path_offset(fdt, "/cpus");
> if (cpus_offset < 0)
> return cpus_offset;
> @@ -432,13 +434,10 @@ static int fdt_parse_isa_all_harts(const void *fdt)
> if (!scratch)
> return SBI_ENOENT;
>
> - hart_exts = sbi_scratch_offset_ptr(scratch,
> - fdt_isa_bitmap_offset);
> -
> val = fdt_getprop(fdt, cpu_offset, "riscv,isa-extensions", &len);
> if (val && len > 0) {
> - fdt_parse_isa_extensions_one_hart((const char *)val,
> - hart_exts, len);
> + fdt_parse_isa_extensions_one_hart(scratch,
> + (const char *)val, len);
> continue;
> }
>
> @@ -446,7 +445,7 @@ static int fdt_parse_isa_all_harts(const void *fdt)
> if (!val || len <= 0)
> return SBI_ENOENT;
>
> - err = fdt_parse_isa_one_hart((const char *)val, hart_exts);
> + err = fdt_parse_isa_one_hart(scratch, (const char *)val);
> if (err)
> return err;
> }
> @@ -454,36 +453,6 @@ static int fdt_parse_isa_all_harts(const void *fdt)
> return 0;
> }
>
> -int fdt_parse_isa_extensions(const void *fdt, unsigned int hartid,
> - unsigned long *extensions)
> -{
> - int rc, i;
> - unsigned long *hart_exts;
> - struct sbi_scratch *scratch;
> -
> - if (!fdt_isa_bitmap_offset) {
> - fdt_isa_bitmap_offset = sbi_scratch_alloc_offset(
> - sizeof(*hart_exts) *
> - BITS_TO_LONGS(SBI_HART_EXT_MAX));
> - if (!fdt_isa_bitmap_offset)
> - return SBI_ENOMEM;
> -
> - rc = fdt_parse_isa_all_harts(fdt);
> - if (rc)
> - return rc;
> - }
> -
> - scratch = sbi_hartid_to_scratch(hartid);
> - if (!scratch)
> - return SBI_ENOENT;
> -
> - hart_exts = sbi_scratch_offset_ptr(scratch, fdt_isa_bitmap_offset);
> -
> - for (i = 0; i < BITS_TO_LONGS(SBI_HART_EXT_MAX); i++)
> - extensions[i] |= hart_exts[i];
> - return 0;
> -}
> -
> static int fdt_parse_uart_node_common(const void *fdt, int nodeoffset,
> struct platform_uart_data *uart,
> unsigned long default_freq,
> diff --git a/platform/generic/platform.c b/platform/generic/platform.c
> index 47e771ad..7e3417b0 100644
> --- a/platform/generic/platform.c
> +++ b/platform/generic/platform.c
> @@ -251,8 +251,7 @@ int generic_final_init(bool cold_boot)
> int generic_extensions_init(struct sbi_hart_features *hfeatures)
> {
> /* Parse the ISA string from FDT and enable the listed extensions */
> - return fdt_parse_isa_extensions(fdt_get_address(), current_hartid(),
> - hfeatures->extensions);
> + return fdt_parse_isa_extensions(fdt_get_address());
> }
>
> int generic_domains_init(void)
> --
> 2.47.3
>
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