[PATCH v3 15/19] target/arm: Make m_helper.c optional via CONFIG_ARM_V7M

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

From: Thomas Huth <thuth@redhat.com>

We've already got the CONFIG_ARM_V7M switch, but it currently can
not be disabled yet. The m_helper.c code should not be compiled
into the binary if the switch is not enabled. We also have to
provide some stubs in a separate file to make sure that we still
can link the other code without CONFIG_ARM_V7M.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20190903154810.27365-4-thuth@redhat.com>
[PMD: add write_v7m_exception() stub when not using TCG,
      remove CONFIG_ARM_V7M=y in default-configs/arm-softmmu.mak]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 default-configs/arm-softmmu.mak |  6 ----
 target/arm/cpu.h                |  7 ++++
 target/arm/m_helper-stub.c      | 59 +++++++++++++++++++++++++++++++++
 target/arm/Makefile.objs        |  3 +-
 4 files changed, 68 insertions(+), 7 deletions(-)
 create mode 100644 target/arm/m_helper-stub.c

diff --git a/default-configs/arm-softmmu.mak b/default-configs/arm-softmmu.mak
index 511d74da58..7ae8006556 100644
--- a/default-configs/arm-softmmu.mak
+++ b/default-configs/arm-softmmu.mak
@@ -1,11 +1,5 @@
 # Default configuration for arm-softmmu
 
-# CONFIG_SEMIHOSTING is always required on this architecture
-CONFIG_SEMIHOSTING=y
-
-# TODO: ARM_V7M is currently always required - make this more flexible!
-CONFIG_ARM_V7M=y
-
 # CONFIG_PCI_DEVICES=n
 # CONFIG_TEST_DEVICES=n
 
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 4ffd991b6f..84e14ce5a9 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1278,7 +1278,14 @@ void pmu_init(ARMCPU *cpu);
 /* Write a new value to v7m.exception, thus transitioning into or out
  * of Handler mode; this may result in a change of active stack pointer.
  */
+#if !defined(CONFIG_TCG)
+static inline void write_v7m_exception(CPUARMState *env, uint32_t new_exc)
+{
+    g_assert_not_reached();
+}
+#else
 void write_v7m_exception(CPUARMState *env, uint32_t new_exc);
+#endif
 
 /* Map EL and handler into a PSTATE_MODE.  */
 static inline unsigned int aarch64_pstate_mode(unsigned int el, bool handler)
diff --git a/target/arm/m_helper-stub.c b/target/arm/m_helper-stub.c
new file mode 100644
index 0000000000..9316a9995b
--- /dev/null
+++ b/target/arm/m_helper-stub.c
@@ -0,0 +1,59 @@
+/*
+ * ARM V7M related stubs.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "exec/helper-proto.h"
+#include "internals.h"
+
+void HELPER(v7m_bxns)(CPUARMState *env, uint32_t dest)
+{
+    abort();
+}
+
+void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest)
+{
+    abort();
+}
+
+uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg)
+{
+    abort();
+}
+
+void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val)
+{
+    abort();
+}
+
+uint32_t HELPER(v7m_tt)(CPUARMState *env, uint32_t addr, uint32_t op)
+{
+    abort();
+}
+
+void HELPER(v7m_preserve_fp_state)(CPUARMState *env)
+{
+    abort();
+}
+
+void write_v7m_exception(CPUARMState *env, uint32_t new_exc)
+{
+    abort();
+}
+
+void HELPER(v7m_vlldm)(CPUARMState *env, uint32_t fptr)
+{
+    abort();
+}
+
+void HELPER(v7m_vlstm)(CPUARMState *env, uint32_t fptr)
+{
+    abort();
+}
+
+ARMMMUIdx arm_v7m_mmu_idx_for_secstate(CPUARMState *env, bool secstate)
+{
+    abort();
+}
diff --git a/target/arm/Makefile.objs b/target/arm/Makefile.objs
index a0df58526b..993899d731 100644
--- a/target/arm/Makefile.objs
+++ b/target/arm/Makefile.objs
@@ -66,7 +66,8 @@ obj-y += tlb_helper.o debug_helper.o
 obj-y += translate.o op_helper.o
 obj-y += crypto_helper.o
 obj-y += iwmmxt_helper.o vec_helper.o neon_helper.o
-obj-y += m_helper.o
+obj-$(CONFIG_ARM_V7M) += m_helper.o
+obj-$(call lnot,$(CONFIG_ARM_V7M)) += m_helper-stub.o
 
 obj-$(CONFIG_ARM_V4) += cpu_v4.o
 obj-$(CONFIG_ARM_V5) += cpu_v5.o
-- 
2.21.1