From 049edada5e93df096c66a059e1171942238fc472 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 30 Jan 2023 18:24:42 +0000 Subject: [PATCH] target/arm: Make HSTR_EL2 traps take priority over UNDEF-at-EL1 The semantics of HSTR_EL2 require that it traps cpreg accesses to EL2 for: * EL1 accesses * EL0 accesses, if the access is not UNDEFINED when the trap bit is 0 (You can see this in the I_ZFGJP priority ordering, where HSTR_EL2 traps from EL1 to EL2 are priority 12, UNDEFs are priority 13, and HSTR_EL2 traps from EL0 are priority 15.) However, we don't get this right for EL1 accesses which UNDEF because the register doesn't exist at all or because its ri->access bits non-configurably forbid the access. At EL1, check for the HSTR_EL2 trap early, before either of these UNDEF reasons. We have to retain the HSTR_EL2 check in access_check_cp_reg(), because at EL0 any kind of UNDEF-to-EL1 (including "no such register", "bad ri->access" and "ri->accessfn returns 'trap to EL1'") takes precedence over the trap to EL2. But we only need to do that check for EL0 now. Signed-off-by: Peter Maydell Tested-by: Fuad Tabba Reviewed-by: Richard Henderson Message-id: 20230130182459.3309057-7-peter.maydell@linaro.org Message-id: 20230127175507.2895013-7-peter.maydell@linaro.org --- target/arm/op_helper.c | 6 +++++- target/arm/translate.c | 28 +++++++++++++++++++++++++++- 2 files changed, 32 insertions(+), 2 deletions(-) diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c index 660dae696d..7797a137af 100644 --- a/target/arm/op_helper.c +++ b/target/arm/op_helper.c @@ -658,7 +658,11 @@ const void *HELPER(access_check_cp_reg)(CPUARMState *env, uint32_t key, goto fail; } - if (!is_a64(env) && arm_current_el(env) < 2 && ri->cp == 15 && + /* + * HSTR_EL2 traps from EL1 are checked earlier, in generated code; + * we only need to check here for traps from EL0. + */ + if (!is_a64(env) && arm_current_el(env) == 0 && ri->cp == 15 && (arm_hcr_el2_eff(env) & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE)) { uint32_t mask = 1 << ri->crn; diff --git a/target/arm/translate.c b/target/arm/translate.c index 9252a464a1..f4bfe55158 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -4760,6 +4760,32 @@ static void do_coproc_insn(DisasContext *s, int cpnum, int is64, break; } + if (s->hstr_active && cpnum == 15 && s->current_el == 1) { + /* + * At EL1, check for a HSTR_EL2 trap, which must take precedence + * over the UNDEF for "no such register" or the UNDEF for "access + * permissions forbid this EL1 access". HSTR_EL2 traps from EL0 + * only happen if the cpreg doesn't UNDEF at EL0, so we do those in + * access_check_cp_reg(), after the checks for whether the access + * configurably trapped to EL1. + */ + uint32_t maskbit = is64 ? crm : crn; + + if (maskbit != 4 && maskbit != 14) { + /* T4 and T14 are RES0 so never cause traps */ + TCGv_i32 t; + DisasLabel over = gen_disas_label(s); + + t = load_cpu_offset(offsetoflow32(CPUARMState, cp15.hstr_el2)); + tcg_gen_andi_i32(t, t, 1u << maskbit); + tcg_gen_brcondi_i32(TCG_COND_EQ, t, 0, over.label); + tcg_temp_free_i32(t); + + gen_exception_insn(s, 0, EXCP_UDEF, syndrome); + set_disas_label(s, over); + } + } + if (!ri) { /* * Unknown register; this might be a guest error or a QEMU @@ -4788,7 +4814,7 @@ static void do_coproc_insn(DisasContext *s, int cpnum, int is64, return; } - if (s->hstr_active || ri->accessfn || + if ((s->hstr_active && s->current_el == 0) || ri->accessfn || (arm_dc_feature(s, ARM_FEATURE_XSCALE) && cpnum < 14)) { /* * Emit code to perform further access permissions checks at -- 2.30.2