target/arm: gdbstub: Guard M-profile code with CONFIG_TCG

This code is only relevant when TCG is present in the build. Building
with --disable-tcg --enable-xen on an x86 host we get:

$ ../configure --target-list=x86_64-softmmu,aarch64-softmmu --disable-tcg --enable-xen
$ make -j$(nproc)
...
libqemu-aarch64-softmmu.fa.p/target_arm_gdbstub.c.o: in function `m_sysreg_ptr':
 ../target/arm/gdbstub.c:358: undefined reference to `arm_v7m_get_sp_ptr'
 ../target/arm/gdbstub.c:361: undefined reference to `arm_v7m_get_sp_ptr'

libqemu-aarch64-softmmu.fa.p/target_arm_gdbstub.c.o: in function `arm_gdb_get_m_systemreg':
../target/arm/gdbstub.c:405: undefined reference to `arm_v7m_mrs_control'

Signed-off-by: Fabiano Rosas <farosas@suse.de>
Message-id: 20230628164821.16771-1-farosas@suse.de
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/gdbstub.c

@@ -324,6 +324,7 @@ static int arm_gen_dynamic_sysreg_xml(CPUState *cs, int base_reg)
     return cpu->dyn_sysreg_xml.num;
 }
 
+#ifdef CONFIG_TCG
 typedef enum {
     M_SYSREG_MSP,
     M_SYSREG_PSP,
@@ -481,6 +482,7 @@ static int arm_gen_dynamic_m_secextreg_xml(CPUState *cs, int orig_base_reg)
     return cpu->dyn_m_secextreg_xml.num;
 }
 #endif
+#endif /* CONFIG_TCG */
 
 const char *arm_gdb_get_dynamic_xml(CPUState *cs, const char *xmlname)
 {
@@ -561,6 +563,7 @@ void arm_cpu_register_gdb_regs_for_features(ARMCPU *cpu)
                              arm_gen_dynamic_sysreg_xml(cs, cs->gdb_num_regs),
                              "system-registers.xml", 0);
 
+#ifdef CONFIG_TCG
     if (arm_feature(env, ARM_FEATURE_M) && tcg_enabled()) {
         gdb_register_coprocessor(cs,
             arm_gdb_get_m_systemreg, arm_gdb_set_m_systemreg,
@@ -575,4 +578,5 @@ void arm_cpu_register_gdb_regs_for_features(ARMCPU *cpu)
         }
 #endif
     }
+#endif /* CONFIG_TCG */
 }