On 9/7/24 15:45, Peter Maydell wrote:
When we converted the LDAPR/STLR instructions to decodetree we
accidentally introduced a regression where the offset is negative.
The 9-bit immediate field is signed, and the old hand decoder
correctly used sextract32() to get it out of the insn word,
but the ldapr_stlr_i pattern in the decode file used "imm:9"
instead of "imm:s9", so it treated the field as unsigned.
Fix the pattern to treat the field as a signed immediate.
Cc: qemu-sta...@nongnu.org
Fixes: 2521b6073b7 ("target/arm: Convert LDAPR/STLR (imm) to decodetree")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2419
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
target/arm/tcg/a64.decode | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
index 223eac3cac2..f873e8bc8b9 100644
--- a/target/arm/tcg/a64.decode
+++ b/target/arm/tcg/a64.decode
@@ -520,7 +520,7 @@ LDAPR sz:2 111 0 00 1 0 1 11111 1100 00 rn:5 rt:5
LDRA 11 111 0 00 m:1 . 1 ......... w:1 1 rn:5 rt:5 imm=%ldra_imm
&ldapr_stlr_i rn rt imm sz sign ext
-@ldapr_stlr_i .. ...... .. . imm:9 .. rn:5 rt:5 &ldapr_stlr_i
+@ldapr_stlr_i .. ...... .. . imm:s9 .. rn:5 rt:5 &ldapr_stlr_i
BTW I noted some instr formats use 'uimm*' for unsigned immediate.
Maybe we could recommend/enforce that, having 'imm*' always signed.
