From c2d9644e6d517170bf6520f633628259a8460d48 Mon Sep 17 00:00:00 2001 From: Roman Kapl Date: Mon, 20 Aug 2018 11:24:31 +0100 Subject: [PATCH] target/arm: Fix crash on conditional instruction in an IT block If an instruction is conditional (like CBZ) and it is executed conditionally (using the ITx instruction), a jump to an undefined label is generated, and QEMU crashes. CBZ in IT block is an UNPREDICTABLE behavior, but we should not crash. Honouring the condition code is allowed by the spec in this case (constrained unpredictable, ARMv8, section K1.1.7), and matches what we do for other "UNPREDICTABLE inside an IT block" instructions. Fix the 'skip on condition' code to create a new label only if it does not already exist. Previously multiple labels were created, but only the last one of them was set. Signed-off-by: Roman Kapl Reviewed-by: Richard Henderson Message-id: 20180816120533.6587-1-rka@sysgo.com [PMM: fixed ^ 1 being applied to wrong argument, fixed typo] Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- target/arm/translate.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-) diff --git a/target/arm/translate.c b/target/arm/translate.c index f845da7c6383..14aa2cd3cd56 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -8480,6 +8480,22 @@ static void gen_srs(DisasContext *s, s->base.is_jmp = DISAS_UPDATE; } +/* Generate a label used for skipping this instruction */ +static void arm_gen_condlabel(DisasContext *s) +{ + if (!s->condjmp) { + s->condlabel = gen_new_label(); + s->condjmp = 1; + } +} + +/* Skip this instruction if the ARM condition is false */ +static void arm_skip_unless(DisasContext *s, uint32_t cond) +{ + arm_gen_condlabel(s); + arm_gen_test_cc(cond ^ 1, s->condlabel); +} + static void disas_arm_insn(DisasContext *s, unsigned int insn) { unsigned int cond, val, op1, i, shift, rm, rs, rn, rd, sh; @@ -8709,9 +8725,7 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn) if (cond != 0xe) { /* if not always execute, we generate a conditional jump to next instruction */ - s->condlabel = gen_new_label(); - arm_gen_test_cc(cond ^ 1, s->condlabel); - s->condjmp = 1; + arm_skip_unless(s, cond); } if ((insn & 0x0f900000) == 0x03000000) { if ((insn & (1 << 21)) == 0) { @@ -11205,9 +11219,7 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn) /* Conditional branch. */ op = (insn >> 22) & 0xf; /* Generate a conditional jump to next instruction. */ - s->condlabel = gen_new_label(); - arm_gen_test_cc(op ^ 1, s->condlabel); - s->condjmp = 1; + arm_skip_unless(s, op); /* offset[11:1] = insn[10:0] */ offset = (insn & 0x7ff) << 1; @@ -12131,8 +12143,7 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn) case 1: case 3: case 9: case 11: /* czb */ rm = insn & 7; tmp = load_reg(s, rm); - s->condlabel = gen_new_label(); - s->condjmp = 1; + arm_gen_condlabel(s); if (insn & (1 << 11)) tcg_gen_brcondi_i32(TCG_COND_EQ, tmp, 0, s->condlabel); else @@ -12295,9 +12306,7 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn) break; } /* generate a conditional jump to next instruction */ - s->condlabel = gen_new_label(); - arm_gen_test_cc(cond ^ 1, s->condlabel); - s->condjmp = 1; + arm_skip_unless(s, cond); /* jump to the offset */ val = (uint32_t)s->pc + 2; @@ -12676,9 +12685,7 @@ static void thumb_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu) uint32_t cond = dc->condexec_cond; if (cond != 0x0e) { /* Skip conditional when condition is AL. */ - dc->condlabel = gen_new_label(); - arm_gen_test_cc(cond ^ 1, dc->condlabel); - dc->condjmp = 1; + arm_skip_unless(dc, cond); } }