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target/riscv: misa to ISA string conversion fix 

Some bits in RISC-V `misa' CSR should not be reflected in the ISA
string.  For instance, `S' and `U' (represents existence of supervisor
and user mode, respectively) in `misa' CSR must not be copied since
neither `S' nor `U' are valid single-letter extensions.

This commit also removes all reserved/dropped single-letter "extensions"
from the list.

-   "B": Not going to be a single-letter extension (misa.B is reserved).
-   "J": Not going to be a single-letter extension (misa.J is reserved).
-   "K": Not going to be a single-letter extension (misa.K is reserved).
-   "L": Dropped.
-   "N": Dropped.
-   "T": Dropped.

It also clarifies that the variable `riscv_single_letter_exts' is a
single-letter extension order list.

Signed-off-by: Tsukasa OI <research_trasio@irq.a4lg.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <4a4c11213a161a7eedabe46abe58b351bb0e2ef2.1648473008.git.research_trasio@irq.a4lg.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Tsukasa OI 2022-03-28 22:11:23 +09:00 committed by Alistair Francis
parent f32d82f6c3
commit 0e2c377023
1 changed files with 5 additions and 5 deletions
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10
target/riscv/cpu.c
View File

@ -34,7 +34,7 @@
/* RISC-V CPU definitions */
static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG";
static const char riscv_single_letter_exts[] = "IEMAFDQCPVH";
const char * const riscv_int_regnames[] = {
"x0/zero", "x1/ra", "x2/sp", "x3/gp", "x4/tp", "x5/t0", "x6/t1",
@ -911,12 +911,12 @@ static void riscv_cpu_class_init(ObjectClass *c, void *data)
char *riscv_isa_string(RISCVCPU *cpu)
{
int i;
const size_t maxlen = sizeof("rv128") + sizeof(riscv_exts) + 1;
const size_t maxlen = sizeof("rv128") + sizeof(riscv_single_letter_exts);
char *isa_str = g_new(char, maxlen);
char *p = isa_str + snprintf(isa_str, maxlen, "rv%d", TARGET_LONG_BITS);
for (i = 0; i < sizeof(riscv_exts); i++) {
if (cpu->env.misa_ext & RV(riscv_exts[i])) {
*p++ = qemu_tolower(riscv_exts[i]);
for (i = 0; i < sizeof(riscv_single_letter_exts) - 1; i++) {
if (cpu->env.misa_ext & RV(riscv_single_letter_exts[i])) {
*p++ = qemu_tolower(riscv_single_letter_exts[i]);
}
}
*p = '\0';