[PATCHv3 01/13] scripts/gdb: Provide linux constants

[Kieran Bingham]

Some macro's and defines are needed when parsing memory, and without
compiling the kernel as -g3 they are not available in the debug-symbols.

We use the pre-processor here to extract constants to a dedicated module
for the linux debugger extensions

Top level Kbuild is used to call in and generate the constants file,
while maintaining dependencies on autogenerated files in
include/generated

CC: mmarek@xxxxxxxx
CC: linux-kbuild@xxxxxxxxxxxxxxx

Signed-off-by: Kieran Bingham <kieran.bingham@xxxxxxxxxx>
---
Changes since v1:

Kbuild:
 - Call to generate constants_py with dependancy on generated files

scripts/gdb/linux/Makefile:
 - Use call if_changed, and correct quiet invocation
 - Annouce "GEN  $@" instead of GDB PP

scripts/gdb/linux/constants.py.in:
 - Updated to use better macro implementations for one line defines
---
 Kbuild                            | 10 ++++++++++
 scripts/gdb/linux/Makefile        | 12 +++++++++++-
 scripts/gdb/linux/constants.py.in | 32 ++++++++++++++++++++++++++++++++
 scripts/gdb/vmlinux-gdb.py        |  1 +
 4 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 scripts/gdb/linux/constants.py.in

diff --git a/Kbuild b/Kbuild
index f55cefd9bf29..3d0ae152af7c 100644
--- a/Kbuild
+++ b/Kbuild
@@ -5,6 +5,7 @@
 # 2) Generate timeconst.h
 # 3) Generate asm-offsets.h (may need bounds.h and timeconst.h)
 # 4) Check for missing system calls
+# 5) Generate constants.py (may need bounds.h)
 
 # Default sed regexp - multiline due to syntax constraints
 define sed-y
@@ -96,5 +97,14 @@ quiet_cmd_syscalls = CALL    $<
 missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
 	$(call cmd,syscalls)
 
+#####
+# 5) Generate constants for Python GDB integration
+#
+
+extra-$(CONFIG_GDB_SCRIPTS) += build_constants_py
+
+build_constants_py: $(obj)/$(timeconst-file) $(obj)/$(bounds-file)
+	@$(MAKE) $(build)=scripts/gdb/linux $@
+
 # Keep these three files during make clean
 no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)
diff --git a/scripts/gdb/linux/Makefile b/scripts/gdb/linux/Makefile
index 6cf1ecf61057..cd129e65d1ff 100644
--- a/scripts/gdb/linux/Makefile
+++ b/scripts/gdb/linux/Makefile
@@ -8,4 +8,14 @@ ifneq ($(KBUILD_SRC),)
 endif
 	@:
 
-clean-files := *.pyc *.pyo $(if $(KBUILD_SRC),*.py)
+quiet_cmd_gen_constants_py = GEN     $@
+      cmd_gen_constants_py = \
+	$(CPP) -E -x c -P $(c_flags) $< > $@ ;\
+	sed -i '1,/<!-- end-c-headers -->/d;' $@
+
+$(obj)/constants.py: $(SRCTREE)/$(obj)/constants.py.in
+	$(call if_changed,gen_constants_py)
+
+build_constants_py: $(obj)/constants.py
+
+clean-files := *.pyc *.pyo $(if $(KBUILD_SRC),*.py) $(obj)/constants.py
diff --git a/scripts/gdb/linux/constants.py.in b/scripts/gdb/linux/constants.py.in
new file mode 100644
index 000000000000..79d9d0092452
--- /dev/null
+++ b/scripts/gdb/linux/constants.py.in
@@ -0,0 +1,32 @@
+/*
+ * gdb helper commands and functions for Linux kernel debugging
+ *
+ *  Kernel constants derived from include files.
+ *
+ * Copyright (c) 2016 Linaro Ltd
+ *
+ * Authors:
+ *  Kieran Bingham <kieran.bingham@xxxxxxxxxx>
+ *
+ * This work is licensed under the terms of the GNU GPL version 2.
+ *
+ */
+
+/* We need to stringify expanded macros so that they can be parsed */
+#define STRING(x) #x
+#define XSTRING(x) STRING(x)
+
+#define LX_VALUE(x) LX_##x = x
+#define LX_GDBPARSED(x) LX_##x = gdb.parse_and_eval(XSTRING(x))
+
+/*
+ * IS_ENABLED generates (a || b) which is not compatible with python
+ * We can only switch on configuration items we know are available
+ * Therefore - IS_BUILTIN() is more appropriate
+ */
+#define LX_CONFIG(x) LX_##x = IS_BUILTIN(x)
+
+/* The build system will take care of deleting everything above this marker */
+<!-- end-c-headers -->
+
+import gdb
diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
index d5943eca19cd..6e0b0afd888a 100644
--- a/scripts/gdb/vmlinux-gdb.py
+++ b/scripts/gdb/vmlinux-gdb.py
@@ -30,3 +30,4 @@ else:
     import linux.cpus
     import linux.lists
     import linux.proc
+    import linux.constants
-- 
2.5.0