From f030e96d27c50a13a5295927d90853680dbc1052 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 8 Feb 2024 15:33:46 +0000 Subject: [PATCH] target/arm: Don't get MDCR_EL2 in pmu_counter_enabled() before checking ARM_FEATURE_PMU MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It doesn't make sense to read the value of MDCR_EL2 on a non-A-profile CPU, and in fact if you try to do it we will assert: #6 0x00007ffff4b95e96 in __GI___assert_fail (assertion=0x5555565a8c70 "!arm_feature(env, ARM_FEATURE_M)", file=0x5555565a6e5c "../../target/arm/helper.c", line=12600, function=0x5555565a9560 <__PRETTY_FUNCTION__.0> "arm_security_space_below_el3") at ./assert/assert.c:101 #7 0x0000555555ebf412 in arm_security_space_below_el3 (env=0x555557bc8190) at ../../target/arm/helper.c:12600 #8 0x0000555555ea6f89 in arm_is_el2_enabled (env=0x555557bc8190) at ../../target/arm/cpu.h:2595 #9 0x0000555555ea942f in arm_mdcr_el2_eff (env=0x555557bc8190) at ../../target/arm/internals.h:1512 We might call pmu_counter_enabled() on an M-profile CPU (for example from the migration pre/post hooks in machine.c); this should always return false because these CPUs don't set ARM_FEATURE_PMU. Avoid the assertion by not calling arm_mdcr_el2_eff() before we have done the early return for "PMU not present". This fixes an assertion failure if you try to do a loadvm or savevm for an M-profile board. Cc: qemu-stable@nongnu.org Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2155 Signed-off-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Richard Henderson Message-id: 20240208153346.970021-1-peter.maydell@linaro.org (cherry picked from commit ac1d88e9e7ca0bed83e91e07ce6d0597f10cc77d) Signed-off-by: Michael Tokarev --- target/arm/helper.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/target/arm/helper.c b/target/arm/helper.c index 6515c5e89c..df1646de3a 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -1169,13 +1169,21 @@ static bool pmu_counter_enabled(CPUARMState *env, uint8_t counter) bool enabled, prohibited = false, filtered; bool secure = arm_is_secure(env); int el = arm_current_el(env); - uint64_t mdcr_el2 = arm_mdcr_el2_eff(env); - uint8_t hpmn = mdcr_el2 & MDCR_HPMN; + uint64_t mdcr_el2; + uint8_t hpmn; + /* + * We might be called for M-profile cores where MDCR_EL2 doesn't + * exist and arm_mdcr_el2_eff() will assert, so this early-exit check + * must be before we read that value. + */ if (!arm_feature(env, ARM_FEATURE_PMU)) { return false; } + mdcr_el2 = arm_mdcr_el2_eff(env); + hpmn = mdcr_el2 & MDCR_HPMN; + if (!arm_feature(env, ARM_FEATURE_EL2) || (counter < hpmn || counter == 31)) { e = env->cp15.c9_pmcr & PMCRE;