Valentin Ghita <valentingh...@google.com> writes:
> The DEBUGEN bit is set by the debugger when it is connected to the
> core. Software can use this bit to check if a debug session is active.
>
> Add a function in gdbstub to check if the debugger is attached to a CPU
> and use this information when the DHCSR register is read in armv7m_nvic.
>
> Signed-off-by: Valentin Ghita <valentingh...@google.com>
Nack - use of the gdbstub should be transparent to the guest. It is not
trying to model any real JTAG/External debug hardware here.
> ---
> gdbstub.c | 10 ++++++++++
> hw/intc/armv7m_nvic.c | 4 ++++
> include/exec/gdbstub.h | 6 ++++++
> 3 files changed, 20 insertions(+)
>
> diff --git a/gdbstub.c b/gdbstub.c
> index 3c14c6a038..d4e39db8e7 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -3585,6 +3585,16 @@ int gdbserver_start(const char *device)
> return 0;
> }
>
> +bool gdb_attached(CPUState *cpu)
> +{
> + GDBProcess *process = gdb_get_cpu_process(cpu);
> + if (process != NULL) {
> + return process->attached;
> + }
> +
> + return false;
> +}
> +
> static void register_types(void)
> {
> type_register_static(&char_gdb_type_info);
> diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
> index 13df002ce4..d6fff94bca 100644
> --- a/hw/intc/armv7m_nvic.c
> +++ b/hw/intc/armv7m_nvic.c
> @@ -21,6 +21,7 @@
> #include "sysemu/runstate.h"
> #include "target/arm/cpu.h"
> #include "exec/exec-all.h"
> +#include "exec/gdbstub.h"
> #include "exec/memop.h"
> #include "qemu/log.h"
> #include "qemu/module.h"
> @@ -1510,6 +1511,9 @@ static uint32_t nvic_readl(NVICState *s, uint32_t
> offset, MemTxAttrs attrs)
> }
> /* We provide minimal-RAS only: RFSR is RAZ/WI */
> return 0;
> + case 0xdf0: /* DHCSR */
> + /* Bit 0: DEBUGEN. */
> + return gdb_attached(CPU(cpu)) ? 1 : 0;
> case 0xf34: /* FPCCR */
> if (!cpu_isar_feature(aa32_vfp_simd, cpu)) {
> return 0;
> diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
> index a024a0350d..383f4e5224 100644
> --- a/include/exec/gdbstub.h
> +++ b/include/exec/gdbstub.h
> @@ -177,6 +177,12 @@ static inline uint8_t * gdb_get_reg_ptr(GByteArray *buf,
> int len)
> */
> int gdbserver_start(const char *port_or_device);
>
> +/**
> + * gdb_attached: check if GDB is attached to a given CPU.
> + * @cpu: the CPU to check if GDB is attached to.
> + */
> +bool gdb_attached(CPUState *cpu);
> +
> /**
> * gdb_has_xml:
> * This is an ugly hack to cope with both new and old gdb.
--
Alex Bennée
