target-arm: Handle UNDEF and UNPREDICTABLE cases for VLDM, VSTM

Handle the UNDEF and UNPREDICTABLE cases for VLDM and VSTM. In
particular, we now generate an undef exception for overlarge imm8
values rather than generating 1000+ TCG ops and hitting an assertion.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target-arm/translate.c b/target-arm/translate.c
index c7961b809711100588bb23cbeea1cae48a138bae..7acb498277c2d2da639de3f5b7f9c34a1ad16031 100644 (file)
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -3397,17 +3397,18 @@ static int disas_vfp_insn(CPUState * env, DisasContext *s, uint32_t insn)
                 VFP_DREG_D(rd, insn);
             else
                 rd = VFP_SREG_D(insn);
-            if (s->thumb && rn == 15) {
-                addr = tcg_temp_new_i32();
-                tcg_gen_movi_i32(addr, s->pc & ~2);
-            } else {
-                addr = load_reg(s, rn);
-            }
             if ((insn & 0x01200000) == 0x01000000) {
                 /* Single load/store */
                 offset = (insn & 0xff) << 2;
                 if ((insn & (1 << 23)) == 0)
                     offset = -offset;
+                if (s->thumb && rn == 15) {
+                    /* This is actually UNPREDICTABLE */
+                    addr = tcg_temp_new_i32();
+                    tcg_gen_movi_i32(addr, s->pc & ~2);
+                } else {
+                    addr = load_reg(s, rn);
+                }
                 tcg_gen_addi_i32(addr, addr, offset);
                 if (insn & (1 << 20)) {
                     gen_vfp_ld(s, dp, addr);
@@ -3419,11 +3420,34 @@ static int disas_vfp_insn(CPUState * env, DisasContext *s, uint32_t insn)
                 tcg_temp_free_i32(addr);
             } else {
                 /* load/store multiple */
+                int w = insn & (1 << 21);
                 if (dp)
                     n = (insn >> 1) & 0x7f;
                 else
                     n = insn & 0xff;
 
+                if (w && !(((insn >> 23) ^ (insn >> 24)) & 1)) {
+                    /* P == U , W == 1  => UNDEF */
+                    return 1;
+                }
+                if (n == 0 || (rd + n) > 32 || (dp && n > 16)) {
+                    /* UNPREDICTABLE cases for bad immediates: we choose to
+                     * UNDEF to avoid generating huge numbers of TCG ops
+                     */
+                    return 1;
+                }
+                if (rn == 15 && w) {
+                    /* writeback to PC is UNPREDICTABLE, we choose to UNDEF */
+                    return 1;
+                }
+
+                if (s->thumb && rn == 15) {
+                    /* This is actually UNPREDICTABLE */
+                    addr = tcg_temp_new_i32();
+                    tcg_gen_movi_i32(addr, s->pc & ~2);
+                } else {
+                    addr = load_reg(s, rn);
+                }
                 if (insn & (1 << 24)) /* pre-decrement */
                     tcg_gen_addi_i32(addr, addr, -((insn & 0xff) << 2));
 
@@ -3443,7 +3467,7 @@ static int disas_vfp_insn(CPUState * env, DisasContext *s, uint32_t insn)
                     }
                     tcg_gen_addi_i32(addr, addr, offset);
                 }
-                if (insn & (1 << 21)) {
+                if (w) {
                     /* writeback */
                     if (insn & (1 << 24))
                         offset = -offset * n;