[PATCH 1/4] RISC-V: create ISA string separately - not as part of cpuinfo

Heiko Stuebner
2023-04-24T19:49:48Z

From: Heiko Stuebner <heiko.stuebner@vrull.eu>

The isa string is a very central part of the RISC-V architecture, so will
be needed in other places as well.

So in a first step decouple the generation of the runtime isa-string from
/proc/cpuinfo - its current only user.

The resulting string should not differ from the previously generated one.

Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
---
arch/riscv/kernel/cpu.c | 70 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 62 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 3df38052dcbd..ebc478f0a16c 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -193,10 +193,33 @@ static struct riscv_isa_ext_data isa_ext_arr[] = {
__RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
};

-static void print_isa_ext(struct seq_file *f)
+static int strlen_isa_ext(void)
{
struct riscv_isa_ext_data *edata;
- int i = 0, arr_sz;
+ int ext_len = 0, i, arr_sz;
+
+ arr_sz = ARRAY_SIZE(isa_ext_arr) - 1;
+
+ /* No extension support available */
+ if (arr_sz <= 0)
+ return 0;
+
+ for (i = 0; i <= arr_sz; i++) {
+ edata = &isa_ext_arr[i];
+ if (!__riscv_isa_extension_available(NULL, edata->isa_ext_id))
+ continue;
+
+ /* string length + underscore */
+ ext_len += strlen(edata->uprop) + 1;
+ }
+
+ return ext_len;
+}
+
+static void strcat_isa_ext(char *isa_str)
+{
+ struct riscv_isa_ext_data *edata;
+ int i, arr_sz;

arr_sz = ARRAY_SIZE(isa_ext_arr) - 1;

@@ -208,7 +231,8 @@ static void print_isa_ext(struct seq_file *f)
edata = &isa_ext_arr[i];
if (!__riscv_isa_extension_available(NULL, edata->isa_ext_id))
continue;
- seq_printf(f, "_%s", edata->uprop);
+ strcat(isa_str, "_");
+ strcat(isa_str, edata->uprop);
}
}

@@ -220,19 +244,49 @@ static void print_isa_ext(struct seq_file *f)
*/
static const char base_riscv_exts[13] = "imafdqcbkjpvh";

-static void print_isa(struct seq_file *f, const char *isa)
+static char *riscv_create_isa_string(const char *isa)
{
+ int maxlen = 4;
+ char *isa_str;
int i;

- seq_puts(f, "isa\t\t: ");
+ /* calculate the needed string length */
+ for (i = 0; i < sizeof(base_riscv_exts); i++)
+ if (__riscv_isa_extension_available(NULL, base_riscv_exts[i] - 'a'))
+ maxlen++;
+ maxlen += strlen_isa_ext();
+
+ isa_str = kzalloc(maxlen, GFP_KERNEL);
+ if (!isa_str)
+ return ERR_PTR(-ENOMEM);
+
/* Print the rv[64/32] part */
- seq_write(f, isa, 4);
+ strncat(isa_str, isa, 4);
+
for (i = 0; i < sizeof(base_riscv_exts); i++) {
if (__riscv_isa_extension_available(NULL, base_riscv_exts[i] - 'a'))
/* Print only enabled the base ISA extensions */
- seq_write(f, &base_riscv_exts[i], 1);
+ strncat(isa_str, &base_riscv_exts[i], 1);
+ }
+
+ strcat_isa_ext(isa_str);
+
+ return isa_str;
+}
+
+static void print_isa(struct seq_file *f, const char *isa)
+{
+ char *isa_str;
+
+ seq_puts(f, "isa\t\t: ");
+
+ isa_str = riscv_create_isa_string(isa);
+ if (!IS_ERR(isa_str)) {
+ seq_write(f, isa_str, strlen(isa_str));
+ kfree(isa_str);
+ } else {
+ seq_puts(f, "unknown");
}
- print_isa_ext(f);
seq_puts(f, "\n");
}

--
2.39.0