From 34c45d53026d9c135415d034a8bc30c1a30acf1c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Thu, 17 Dec 2015 13:37:15 +0000 Subject: target-arm: kvm - re-inject guest debug exceptions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If we can't find details for the debug exception in our debug state then we can assume the exception is due to debugging inside the guest. To inject the exception into the guest state we re-use the TCG exception code (do_interrupt). However while guest debugging is in effect we currently can't handle the guest using single step as we will keep trapping to back to userspace. GDB makes heavy use of single-step behind the scenes which effectively means the guest's ability to debug itself is disabled while it is being debugged. Signed-off-by: Alex Bennée Message-id: 1449599553-24713-6-git-send-email-alex.bennee@linaro.org [PMM: Fixed a few typos in comments and commit message] Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- target-arm/kvm64.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) (limited to 'target-arm/kvm64.c') diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c index 771ecdbafe..bb9531f33c 100644 --- a/target-arm/kvm64.c +++ b/target-arm/kvm64.c @@ -871,6 +871,7 @@ bool kvm_arm_handle_debug(CPUState *cs, struct kvm_debug_exit_arch *debug_exit) { int hsr_ec = debug_exit->hsr >> ARM_EL_EC_SHIFT; ARMCPU *cpu = ARM_CPU(cs); + CPUClass *cc = CPU_GET_CLASS(cs); CPUARMState *env = &cpu->env; /* Ensure PC is synchronised */ @@ -881,7 +882,14 @@ bool kvm_arm_handle_debug(CPUState *cs, struct kvm_debug_exit_arch *debug_exit) if (cs->singlestep_enabled) { return true; } else { - error_report("Came out of SINGLE STEP when not enabled"); + /* + * The kernel should have suppressed the guest's ability to + * single step at this point so something has gone wrong. + */ + error_report("%s: guest single-step while debugging unsupported" + " (%"PRIx64", %"PRIx32")\n", + __func__, env->pc, debug_exit->hsr); + return false; } break; case EC_AA64_BKPT: @@ -908,12 +916,14 @@ bool kvm_arm_handle_debug(CPUState *cs, struct kvm_debug_exit_arch *debug_exit) __func__, debug_exit->hsr, env->pc); } - /* If we don't handle this it could be it really is for the - guest to handle */ - qemu_log_mask(LOG_UNIMP, - "%s: re-injecting exception not yet implemented" - " (0x%"PRIx32", %"PRIx64")\n", - __func__, hsr_ec, env->pc); + /* If we are not handling the debug exception it must belong to + * the guest. Let's re-use the existing TCG interrupt code to set + * everything up properly. + */ + cs->exception_index = EXCP_BKPT; + env->exception.syndrome = debug_exit->hsr; + env->exception.vaddress = debug_exit->far; + cc->do_interrupt(cs); return false; } -- cgit v1.2.3