Re: [Qemu-devel] [PATCH 4/5 v3][RESEND] ppc: Add software breakpoint support

[address@hidden]

> -----Original Message-----
> From: Madhavan Srinivasan [mailto:address@hidden
> Sent: Tuesday, June 24, 2014 8:59 PM
> To: Bhushan Bharat-R65777; address@hidden
> Cc: address@hidden; address@hidden
> Subject: Re: [PATCH 4/5 v3][RESEND] ppc: Add software breakpoint support
> 
> On Tuesday 24 June 2014 05:40 PM, Bharat Bhushan wrote:
> > This patch allow insert/remove software breakpoint
> >
> > Signed-off-by: Bharat Bhushan <address@hidden>
> > ---
> >  target-ppc/kvm.c | 71
> > +++++++++++++++++++++++++++++++++++++++++++++-----------
> >  1 file changed, 57 insertions(+), 14 deletions(-)
> >
> > diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index
> > 5238de7..8e2dbb3 100644
> > --- a/target-ppc/kvm.c
> > +++ b/target-ppc/kvm.c
> > @@ -1317,6 +1317,53 @@ static int kvmppc_handle_dcr_write(CPUPPCState *env,
> uint32_t dcrn, uint32_t dat
> >      return 0;
> >  }
> >
> > +int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct
> > +kvm_sw_breakpoint *bp) {
> > +    /* Mixed endian case is not handled */
> > +    uint32_t sc = debug_inst_opcode;
> > +
> > +    if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) 
> > ||
> > +        cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&sc, 4, 1)) {
> 
> Instead of hard coding, can we use sizeof ()?

Yes

> 
> > +        return -EINVAL;
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> > +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct
> > +kvm_sw_breakpoint *bp) {
> > +    uint32_t sc;
> > +
> > +    if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&sc, 4, 0) ||
> > +        sc != debug_inst_opcode ||
> > +        cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 1)) 
> > {
> > +        return -EINVAL;
> > +    }
> > +
> 
> Same. Can we use sizeof?

Yes

> 
> > +    return 0;
> > +}
> > +
> > +void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug
> > +*dbg) {
> > +    /* Software Breakpoint updates */
> > +    if (kvm_sw_breakpoints_active(cs)) {
> > +        dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
> > +    }
> > +}
> > +
> > +static int kvm_handle_debug(PowerPCCPU *cpu, struct kvm_run *run) {
> > +    CPUState *cs = CPU(cpu);
> > +    struct kvm_debug_exit_arch *arch_info = &run->debug.arch;
> > +    int handle = 0;
> > +
> > +    if (kvm_find_sw_breakpoint(cs, arch_info->address)) {
> > +        handle = 1;
> > +    }
> > +
> > +    return handle;
> > +}
> > +
> >  int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)  {
> >      PowerPCCPU *cpu = POWERPC_CPU(cs); @@ -1357,6 +1404,16 @@ int
> > kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
> >          ret = 0;
> >          break;
> >
> > +    case KVM_EXIT_DEBUG:
> > +        DPRINTF("handle debug exception\n");
> > +        if (kvm_handle_debug(cpu, run)) {
> > +            ret = EXCP_DEBUG;
> > +            break;
> > +        }
> > +        /* re-enter, this exception was guest-internal */
> 
> Kindly can you explain when this will happen?

If the debug interrupt condition (breakpoint/watchpoint etc) is not set by 
qemu, i.e that is set by guest. 

Thanks
-Bharat

> 
> > +        ret = 0;
> > +        break;
> > +
> >      default:
> >          fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason);
> >          ret = -1;
> > @@ -2044,16 +2101,6 @@ void kvm_arch_init_irq_routing(KVMState *s)  {
> > }
> >
> > -int kvm_arch_insert_sw_breakpoint(CPUState *cpu, struct
> > kvm_sw_breakpoint *bp) -{
> > -    return -EINVAL;
> > -}
> > -
> > -int kvm_arch_remove_sw_breakpoint(CPUState *cpu, struct
> > kvm_sw_breakpoint *bp) -{
> > -    return -EINVAL;
> > -}
> > -
> >  int kvm_arch_insert_hw_breakpoint(target_ulong addr, target_ulong
> > len, int type)  {
> >      return -EINVAL;
> > @@ -2068,10 +2115,6 @@ void kvm_arch_remove_all_hw_breakpoints(void)
> >  {
> >  }
> >
> > -void kvm_arch_update_guest_debug(CPUState *cpu, struct
> > kvm_guest_debug *dbg) -{ -}
> > -
> >  struct kvm_get_htab_buf {
> >      struct kvm_get_htab_header header;
> >      /*
> >