From: Richard Henderson <richard.hender...@linaro.org>
Do not examine a random host return address, but
properly compute the next pc for the guest cpu.
Fixes: f18637cd611 ("RISC-V: Add misa runtime write support")
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarb...@ventanamicro.com>
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
Message-ID: <20250425152311.804338-8-richard.hender...@linaro.org>
[ Changes by AF:
- Change `& ~3` to `& 3`
]
Signed-off-by: Alistair Francis <alistair.fran...@wdc.com>
---
target/riscv/csr.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 53458491da..288edeedea 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -30,6 +30,8 @@
#include "accel/tcg/getpc.h"
#include "qemu/guest-random.h"
#include "qapi/error.h"
+#include "tcg/insn-start-words.h"
+#include "internals.h"
#include <stdbool.h>
/* CSR function table public API */
@@ -2099,6 +2101,19 @@ static RISCVException read_misa(CPURISCVState *env, int
csrno,
return RISCV_EXCP_NONE;
}
+static target_ulong get_next_pc(CPURISCVState *env, uintptr_t ra)
+{
+ uint64_t data[INSN_START_WORDS];
+
+ /* Outside of a running cpu, env contains the next pc. */
+ if (ra == 0 || !cpu_unwind_state_data(env_cpu(env), ra, data)) {
+ return env->pc;
+ }
+
+ /* Within unwind data, [0] is pc and [1] is the opcode. */
+ return data[0] + insn_len(data[1]);
+}
+
static RISCVException write_misa(CPURISCVState *env, int csrno,
target_ulong val, uintptr_t ra)
{
@@ -2114,11 +2129,8 @@ static RISCVException write_misa(CPURISCVState *env, int
csrno,
/* Mask extensions that are not supported by this hart */
val &= env->misa_ext_mask;
- /*
- * Suppress 'C' if next instruction is not aligned
- * TODO: this should check next_pc
- */
- if ((val & RVC) && (GETPC() & ~3) != 0) {
+ /* Suppress 'C' if next instruction is not aligned. */
+ if ((val & RVC) && (get_next_pc(env, ra) & 3) != 0) {
val &= ~RVC;
}
--
2.49.0
