xen/build: Add cppcheck and cppcheck-html make rules

cppcheck can be used to check Xen code quality.

To create a report do "make cppcheck" on a built tree adding any options
you added during the process you used to build xen (like CROSS_COMPILE
or XEN_TARGET_ARCH). This will generate an xml report xen-cppcheck.xml.

To create a html report do "make cppcheck-html" in the same way and a
full report to be seen in a browser will be generated in
cppcheck-htmlreport/index.html.

For better results it is recommended to build your own cppcheck from the
latest sources that you can find at [1].
Development and result analysis has been done with cppcheck 2.7.

The Makefile rule is searching for all C files which have been compiled
(ie which have a generated .o file) and is running cppcheck on all of
them using the current configuration of xen so only the code actually
compiled is checked.

A new tool is introduced to merge all cppcheck reports into one global
report including all findings and removing duplicates.

Some extra variables can be used to customize the report:
- CPPCHECK can be used to give the full path to the cppcheck binary to
use (default is to use the one from the standard path).
- CPPCHECK_HTMLREPORT can be used to give the full path to
cppcheck-htmlreport (default is to use the one from the standard path).

This has been tested on several arm configurations (x86 should work but
has not been tested).

[1] https://cppcheck.sourceforge.io/

Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
Signed-off-by: Michal Orzel <michal.orzel@arm.com>
[stefano: add in-code comment on commit]
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Julien Grall <jgrall@amazon.com>

.gitignore

@@ -7,6 +7,7 @@
 *.o
 *.d
 *.d2
+*.c.cppcheck
 *.opic
 *.a
 *.so
@@ -296,6 +297,7 @@ xen/.banner
 xen/.config
 xen/.config.old
 xen/.xen.elf32
+xen/xen-cppcheck.xml
 xen/System.map
 xen/arch/x86/boot/mkelf32
 xen/arch/x86/boot/cmdline.S
@@ -316,6 +318,7 @@ xen/arch/*/efi/runtime.c
 xen/arch/*/include/asm/asm-offsets.h
 xen/common/config_data.S
 xen/common/config.gz
+xen/cppcheck-htmlreport
 xen/include/headers*.chk
 xen/include/compat/*
 xen/include/config/

xen/Makefile

@@ -453,7 +453,7 @@ endif # need-config
 
 __all: build
 
-main-targets := build install uninstall clean distclean MAP
+main-targets := build install uninstall clean distclean MAP cppcheck cppcheck-html
 .PHONY: $(main-targets)
 ifneq ($(XEN_TARGET_ARCH),x86_32)
 $(main-targets): %: _% ;
@@ -543,15 +543,17 @@ _clean:
 	$(Q)$(MAKE) $(clean)=tools/kconfig
 	find . \( -name "*.o" -o -name ".*.d" -o -name ".*.d2" \
 		-o -name ".*.o.tmp" -o -name "*~" -o -name "core" \
-		-o -name '*.lex.c' -o -name '*.tab.[ch]' \
+		-o -name '*.lex.c' -o -name '*.tab.[ch]' -o -name '*.c.cppcheck' \
 		-o -name "*.gcno" -o -name ".*.cmd" -o -name "lib.a" \) -exec rm -f {} \;
 	rm -f include/asm $(TARGET) $(TARGET).gz $(TARGET).efi $(TARGET).efi.map $(TARGET)-syms $(TARGET)-syms.map
 	rm -f asm-offsets.s arch/*/include/asm/asm-offsets.h
 	rm -f .banner .allconfig.tmp include/xen/compile.h
+	rm -f xen-cppcheck.xml
 
 .PHONY: _distclean
 _distclean: clean
 	rm -f tags TAGS cscope.files cscope.in.out cscope.out cscope.po.out GTAGS GPATH GRTAGS GSYMS .config source
+	rm -rf $(CPPCHECK_HTMLREPORT_OUTDIR)
 
 $(TARGET).gz: $(TARGET)
 	gzip -n -f -9 < $< > $@.new
@@ -625,6 +627,84 @@ cloc:
 	    done; \
 	done | cloc --list-file=-
 
+# What cppcheck command to use.
+# To get proper results, it is recommended to build cppcheck manually from the
+# latest source and use CPPCHECK to give the full path to the built version.
+CPPCHECK ?= cppcheck
+
+# What cppcheck-htmlreport to use.
+# If you give the full path to a self compiled cppcheck, this should be set
+# to the full path to cppcheck-html in the htmlreport directory of cppcheck.
+# On recent distribution, this is available in the standard path.
+CPPCHECK_HTMLREPORT ?= cppcheck-htmlreport
+
+# By default we generate the report in cppcheck-htmlreport directory in the
+# build directory. This can be changed by giving a directory in this variable.
+CPPCHECK_HTMLREPORT_OUTDIR ?= cppcheck-htmlreport
+
+# Compile flags to pass to cppcheck:
+# - include directories and defines Xen Makefile is passing (from CFLAGS)
+# - include config.h as this is passed directly to the compiler.
+# - define CPPCHECK as we use to disable or enable some specific part of the
+#   code to solve some cppcheck issues.
+# - explicitely enable some cppcheck checks as we do not want to use "all"
+#   which includes unusedFunction which gives wrong positives as we check file
+#   per file.
+#
+# Compiler defines are in compiler-def.h which is included in config.h
+#
+CPPCHECKFLAGS := -DCPPCHECK --max-ctu-depth=10 \
+                 --enable=style,information,missingInclude \
+                 --include=$(srctree)/include/xen/config.h \
+                 -I $(srctree)/xsm/flask/include \
+                 -I $(srctree)/include/xen/libfdt \
+                 $(filter -D% -I%,$(CFLAGS))
+
+# We need to find all C files (as we are not checking assembly files) so
+# we find all generated .o files which have a .c corresponding file.
+CPPCHECKFILES := $(wildcard $(patsubst $(objtree)/%.o,$(srctree)/%.c, \
+                 $(filter-out $(objtree)/tools/%, \
+                 $(shell find $(objtree) -name "*.o"))))
+
+quiet_cmd_cppcheck_xml = CPPCHECK $(patsubst $(srctree)/%,%,$<)
+cmd_cppcheck_xml = $(CPPCHECK) -v -q --xml $(CPPCHECKFLAGS) \
+                   --output-file=$@ $<
+
+quiet_cmd_merge_cppcheck_reports = CPPCHECK-MERGE $@
+cmd_merge_cppcheck_reports = $(srctree)/tools/merge_cppcheck_reports.py $^ $@
+
+quiet_cmd_cppcheck_html = CPPCHECK-HTML $<
+cmd_cppcheck_html = $(CPPCHECK_HTMLREPORT) --file=$< --source-dir=$(srctree) \
+                    --report-dir=$(CPPCHECK_HTMLREPORT_OUTDIR) --title=Xen
+
+PHONY += _cppcheck _cppcheck-html cppcheck-version
+
+_cppcheck-html: xen-cppcheck.xml
+	$(call if_changed,cppcheck_html)
+
+_cppcheck: xen-cppcheck.xml
+
+xen-cppcheck.xml: $(patsubst $(srctree)/%.c,$(objtree)/%.c.cppcheck,$(CPPCHECKFILES))
+ifeq ($(CPPCHECKFILES),)
+	$(error Please build Xen before running cppcheck)
+endif
+	$(call if_changed,merge_cppcheck_reports)
+
+$(objtree)/%.c.cppcheck: $(srctree)/%.c $(objtree)/include/generated/autoconf.h $(objtree)/include/generated/compiler-def.h | cppcheck-version
+	$(call if_changed,cppcheck_xml)
+
+cppcheck-version:
+ifeq ($(shell which $(CPPCHECK)),)
+	$(error Cannot find cppcheck executable: $(CPPCHECK))
+endif
+ifeq ($(shell $(CPPCHECK) --version | awk '{print ($$2 < 2.7)}'),1)
+	$(error Please upgrade your cppcheck to version 2.7 or greater)
+endif
+
+# Put this in generated headers this way it is cleaned by include/Makefile
+$(objtree)/include/generated/compiler-def.h:
+	$(Q)$(CC) -dM -E -o $@ - < /dev/null
+
 endif #config-build
 endif # need-sub-make
 

xen/arch/arm/include/asm/processor.h

@@ -219,9 +219,15 @@
                          SCTLR_Axx_ELx_A    | SCTLR_Axx_ELx_C   |\
                          SCTLR_Axx_ELx_WXN  | SCTLR_Axx_ELx_EE)
 
+/*
+ * Cppcheck preprocessor is wrongly throwing the error here so disable
+ * this check for cppcheck runs.
+ */
+#ifndef CPPCHECK
 #if (SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != 0xffffffffffffffffUL
 #error "Inconsistent SCTLR_EL2 set/clear bits"
 #endif
+#endif
 
 #endif
 

xen/include/xen/config.h

@@ -7,6 +7,10 @@
 #ifndef __XEN_CONFIG_H__
 #define __XEN_CONFIG_H__
 
+#ifdef CPPCHECK
+#include <generated/compiler-def.h>
+#endif
+
 #include <xen/kconfig.h>
 
 #ifndef __ASSEMBLY__

xen/include/xen/kconfig.h

@@ -8,6 +8,10 @@
  * these only work with boolean option.
  */
 
+/* cppcheck is failing to parse the macro so use a dummy one */
+#ifdef CPPCHECK
+#define IS_ENABLED(option) option
+#else
 /*
  * Getting something that works in C and CPP for an arg that may or may
  * not be defined is tricky.  Here, if we have "#define CONFIG_BOOGER 1"
@@ -27,5 +31,6 @@
  * otherwise.
  */
 #define IS_ENABLED(option) config_enabled(option)
+#endif
 
 #endif /* __XEN_KCONFIG_H */

xen/tools/merge_cppcheck_reports.py

@@ -0,0 +1,86 @@
+#!/usr/bin/env python
+
+"""
+This script acts as a tool to merge XML files created by cppcheck.
+Usage:
+    merge_cppcheck_reports.py [FILES] [OUTPUT]
+
+    FILES  - list of XML files with extension .cppcheck
+    OUTPUT - file to store results (with .xml extension).
+             If not specified, the script will print results to stdout.
+"""
+
+import sys
+from xml.etree import ElementTree
+
+def elements_equal(el1, el2):
+    if type(el1) != type(el2): return False
+
+    if el1.find('location') is None: return False
+    if el2.find('location') is None: return False
+
+    el1_location = str(el1.find('location').attrib)
+    el2_location = str(el2.find('location').attrib)
+
+    if el1_location != el2_location: return False
+
+    return True
+
+def contain_element(new, lst):
+    for elem in lst:
+        if elements_equal(new, elem):
+            return True
+    return False
+
+def merge(files):
+    try:
+        result_xml_root = ElementTree.parse(files[0]).getroot()
+    except:
+        print("Xml parsing error in %s\n" % (files[0]))
+        print("Please upgrade your cppcheck to version 2.7 or greater")
+        sys.exit(1)
+    insert_point = result_xml_root.findall("errors")[0]
+    curr = 1
+    total = len(files)
+    numelem = len(insert_point)
+    for xml_file in files[1:]:
+        try:
+            xml_root = ElementTree.parse(xml_file).getroot()
+        except:
+            print("Xml parsing error in %s\n" % (xml_file))
+            print("Please upgrade your cppcheck to version 2.7 or greater")
+            sys.exit(1)
+        curr_elem_list = list(insert_point)
+        new_elem_list = list(xml_root.findall("errors")[0])
+        for xml_error_elem in new_elem_list:
+            if not contain_element(xml_error_elem, curr_elem_list):
+                insert_point.insert(1,xml_error_elem)
+                numelem = numelem + 1
+        curr = curr + 1
+        sys.stdout.write('\r')
+        sys.stdout.write(" %d / %d" % (curr,total))
+        sys.stdout.flush()
+
+    sys.stdout.write('\r\n')
+    print("Done: %d elements" % (numelem))
+    return result_xml_root
+
+def run():
+    files = []
+    output = None
+    for i in sys.argv[1:]:
+        output = i if '.xml' in i else None
+        files.append(i) if '.cppcheck' in i else None
+
+    result = merge(files)
+
+    if result is None:
+        return
+
+    if output is not None:
+        ElementTree.ElementTree(result).write(output)
+    else:
+        print(ElementTree.tostring(result).decode('utf-8'))
+
+if __name__ == '__main__':
+    run()