Re: [PATCH 02/17] target/avr: Fix buffer read in avr_print_insn

[Pierrick Bouvier]

On 3/23/25 10:37, Richard Henderson wrote:

Do not unconditionally attempt to read 4 bytes, as there
may only be 2 bytes remaining in the translator cache.

Cc: qemu-sta...@nongnu.org
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
  target/avr/disas.c | 21 ++++++++++++++-------
  1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/target/avr/disas.c b/target/avr/disas.c
index b7689e8d7c..d341030174 100644
--- a/target/avr/disas.c
+++ b/target/avr/disas.c
@@ -68,28 +68,35 @@ static bool decode_insn(DisasContext *ctx, uint16_t insn);

int avr_print_insn(bfd_vma addr, disassemble_info *info)

  {
-    DisasContext ctx;
+    DisasContext ctx = { info };
      DisasContext *pctx = &ctx;
      bfd_byte buffer[4];
      uint16_t insn;
      int status;

- ctx.info = info;

-
-    status = info->read_memory_func(addr, buffer, 4, info);
+    status = info->read_memory_func(addr, buffer, 2, info);
      if (status != 0) {
          info->memory_error_func(status, addr, info);
          return -1;
      }
      insn = bfd_getl16(buffer);
-    ctx.next_word = bfd_getl16(buffer + 2);
-    ctx.next_word_used = false;
+
+    status = info->read_memory_func(addr + 2, buffer + 2, 2, info);
+    if (status == 0) {
+        ctx.next_word = bfd_getl16(buffer + 2);
+    }

if (!decode_insn(&ctx, insn)) {

          output(".db", "0x%02x, 0x%02x", buffer[0], buffer[1]);
      }

- return ctx.next_word_used ? 4 : 2;

+    if (!ctx.next_word_used) {
+        return 2;
+    } else if (status == 0) {
+        return 4;
+    }
+    info->memory_error_func(status, addr + 2, info);
+    return -1;
  }

Reviewed-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>