Peter Maydell <peter.maydell@xxxxxxxxxx> writes:
> On 12 November 2015 at 16:20, Alex Bennée <alex.bennee@xxxxxxxxxx> wrote:
>> This adds support for single-step. There isn't much to do on the QEMU
>> side as after we set-up the request for single step via the debug ioctl
>> it is all handled within the kernel.
>>
>> Signed-off-by: Alex Bennée <alex.bennee@xxxxxxxxxx>
>>
>> ---
>> v2
>> - convert to using HSR_EC
>> v3
>> - use internals.h definitions
>> ---
>> target-arm/kvm.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/target-arm/kvm.c b/target-arm/kvm.c
>> index 50f70ef..d505a7e 100644
>> --- a/target-arm/kvm.c
>> +++ b/target-arm/kvm.c
>> @@ -535,6 +535,13 @@ static int kvm_handle_debug(CPUState *cs, struct kvm_run *run)
>> kvm_cpu_synchronize_state(cs);
>>
>> switch (hsr_ec) {
>> + case EC_SOFTWARESTEP:
>> + if (cs->singlestep_enabled) {
>> + return true;
>> + } else {
>> + error_report("Came out of SINGLE STEP when not enabled");
>> + }
>> + break;
>> case EC_AA64_BKPT:
>> if (kvm_find_sw_breakpoint(cs, env->pc)) {
>> return true;
>> @@ -595,6 +602,9 @@ int kvm_arch_on_sigbus(int code, void *addr)
>>
>> void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug *dbg)
>> {
>> + if (cs->singlestep_enabled) {
>> + dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
>> + }
>
> Doesn't kvm_update_guest_debug() already set these bits, or am
> I misreading it?
Yeah. This raises an interesting problem about what to do when we don't
have the capability. I could suppress those bits in the update function
but that seems a bit hacky.
Looking at the GDB capability code there doesn't seem to report
breakpoint capability short of just failing when you try to set one.
>
>> if (kvm_sw_breakpoints_active(cs)) {
>> dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
>> }
>> --
>> 2.6.3
>
> thanks
> -- PMM
--
Alex Bennée
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