From 243705aa6ea3465b20e9f5a8bfcf36d3153f3c10 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 19 Jun 2023 11:20:18 +0100 Subject: target/arm: Fix return value from LDSMIN/LDSMAX 8/16 bit atomics The atomic memory operations are supposed to return the old memory data value in the destination register. This value is not sign-extended, even if the operation is the signed minimum or maximum. (In the pseudocode for the instructions the returned data value is passed to ZeroExtend() to create the value in the register.) We got this wrong because we were doing a 32-to-64 zero extend on the result for 8 and 16 bit data values, rather than the correct amount of zero extension. Fix the bug by using ext8u and ext16u for the MO_8 and MO_16 data sizes rather than ext32u. Cc: qemu-stable@nongnu.org Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20230602155223.2040685-2-peter.maydell@linaro.org --- target/arm/tcg/translate-a64.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c index aa93f37e21..246e3c1514 100644 --- a/target/arm/tcg/translate-a64.c +++ b/target/arm/tcg/translate-a64.c @@ -3545,8 +3545,22 @@ static void disas_ldst_atomic(DisasContext *s, uint32_t insn, */ fn(tcg_rt, clean_addr, tcg_rs, get_mem_index(s), mop); - if ((mop & MO_SIGN) && size != MO_64) { - tcg_gen_ext32u_i64(tcg_rt, tcg_rt); + if (mop & MO_SIGN) { + switch (size) { + case MO_8: + tcg_gen_ext8u_i64(tcg_rt, tcg_rt); + break; + case MO_16: + tcg_gen_ext16u_i64(tcg_rt, tcg_rt); + break; + case MO_32: + tcg_gen_ext32u_i64(tcg_rt, tcg_rt); + break; + case MO_64: + break; + default: + g_assert_not_reached(); + } } } -- cgit v1.2.3