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target-arm: kvm - re-inject guest debug exceptions 

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 <alex.bennee@linaro.org>
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 <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Alex Bennée 2015-12-17 13:37:15 +00:00 committed by Peter Maydell
parent e4482ab7e3
commit 34c45d5302
2 changed files with 27 additions and 9 deletions
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12
target-arm/helper-a64.c
View File

@ -25,6 +25,7 @@
#include "qemu/bitops.h"
#include "internals.h"
#include "qemu/crc32c.h"
#include "sysemu/kvm.h"
#include <zlib.h> /* For crc32 */
/* C2.4.7 Multiply and divide */
@ -469,7 +470,8 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
new_el);
if (qemu_loglevel_mask(CPU_LOG_INT)
&& !excp_is_internal(cs->exception_index)) {
qemu_log_mask(CPU_LOG_INT, "...with ESR 0x%" PRIx32 "\n",
qemu_log_mask(CPU_LOG_INT, "...with ESR %x/0x%" PRIx32 "\n",
env->exception.syndrome >> ARM_EL_EC_SHIFT,
env->exception.syndrome);
}
@ -535,6 +537,12 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
aarch64_restore_sp(env, new_el);
env->pc = addr;
cs->interrupt_request |= CPU_INTERRUPT_EXITTB;
qemu_log_mask(CPU_LOG_INT, "...to EL%d PC 0x%" PRIx64 " PSTATE 0x%x\n",
new_el, env->pc, pstate_read(env));
if (!kvm_enabled()) {
cs->interrupt_request |= CPU_INTERRUPT_EXITTB;
}
}
#endif

24
target-arm/kvm64.c
View File

@ -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;
}