xen: Add MISRA support to cppcheck make rule

cppcheck MISRA addon can be used to check for non compliance to some of
the MISRA standard rules.

Add a CPPCHECK_MISRA variable that can be set to "y" using make command
line to generate a cppcheck report including cppcheck misra checks.

When MISRA checking is enabled, a file with a text description suitable
for cppcheck misra addon is generated out of Xen documentation file
which lists the rules followed by Xen (docs/misra/rules.rst).

By default MISRA checking is turned off.

While adding cppcheck-misra files to gitignore, also fix the missing /
for htmlreport gitignore

Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@arm.com>
Tested-by: Michal Orzel <michal.orzel@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

.gitignore

@@ -297,7 +297,6 @@ 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
@@ -318,7 +317,8 @@ 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/cppcheck-htmlreport/
+xen/cppcheck-misra.*
 xen/include/headers*.chk
 xen/include/compat/*
 xen/include/config/
@@ -347,6 +347,7 @@ xen/xsm/flask/xenpolicy-*
 tools/flask/policy/policy.conf
 tools/flask/policy/xenpolicy-*
 xen/xen
+xen/xen-cppcheck.xml
 xen/xen-syms
 xen/xen-syms.map
 xen/xen.*

xen/Makefile

@@ -547,7 +547,7 @@ _clean:
 	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
+	rm -f cppcheck-misra.* xen-cppcheck.xml
 
 .PHONY: _distclean
 _distclean: clean
@@ -641,6 +641,10 @@ CPPCHECK_HTMLREPORT ?= cppcheck-htmlreport
 # build directory. This can be changed by giving a directory in this variable.
 CPPCHECK_HTMLREPORT_OUTDIR ?= cppcheck-htmlreport
 
+# By default we do not check misra rules, to enable pass "CPPCHECK_MISRA=y" to
+# make command line.
+CPPCHECK_MISRA ?= n
+
 # 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.
@@ -665,6 +669,15 @@ CPPCHECKFILES := $(wildcard $(patsubst $(objtree)/%.o,$(srctree)/%.c, \
                  $(filter-out $(objtree)/tools/%, \
                  $(shell find $(objtree) -name "*.o"))))
 
+# Headers and files required to run cppcheck on a file
+CPPCHECKDEPS := $(objtree)/include/generated/autoconf.h \
+                $(objtree)/include/generated/compiler-def.h
+
+ifeq ($(CPPCHECK_MISRA),y)
+    CPPCHECKFLAGS += --addon=cppcheck-misra.json
+    CPPCHECKDEPS += cppcheck-misra.json
+endif
+
 quiet_cmd_cppcheck_xml = CPPCHECK $(patsubst $(srctree)/%,%,$<)
 cmd_cppcheck_xml = $(CPPCHECK) -v -q --xml $(CPPCHECKFLAGS) \
                    --output-file=$@ $<
@@ -689,7 +702,7 @@ ifeq ($(CPPCHECKFILES),)
 endif
 	$(call if_changed,merge_cppcheck_reports)
 
-$(objtree)/%.c.cppcheck: $(srctree)/%.c $(objtree)/include/generated/autoconf.h $(objtree)/include/generated/compiler-def.h | cppcheck-version
+$(objtree)/%.c.cppcheck: $(srctree)/%.c $(CPPCHECKDEPS) | cppcheck-version
 	$(call if_changed,cppcheck_xml)
 
 cppcheck-version:
@@ -702,6 +715,18 @@ cppcheck-version:
 		exit 1; \
 	fi
 
+# List of Misra rules to respect is written inside a doc.
+# In order to have some helpful text in the cppcheck output, generate a text
+# file containing the rules identifier, classification and text from the Xen
+# documentation file. Also generate a json file with the right arguments for
+# cppcheck in json format including the list of rules to ignore.
+#
+cppcheck-misra.txt: $(XEN_ROOT)/docs/misra/rules.rst $(srctree)/tools/convert_misra_doc.py
+	$(Q)$(srctree)/tools/convert_misra_doc.py -i $< -o $@ -j $(@:.txt=.json)
+
+# convert_misra_doc is generating both files.
+cppcheck-misra.json: cppcheck-misra.txt
+
 # 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

xen/tools/convert_misra_doc.py

@@ -0,0 +1,173 @@
+#!/usr/bin/env python
+
+"""
+This script is converting the misra documentation RST file into a text file
+that can be used as text-rules for cppcheck.
+Usage:
+    convert_misr_doc.py -i INPUT [-o OUTPUT] [-j JSON]
+
+    INPUT  - RST file containing the list of misra rules.
+    OUTPUT - file to store the text output to be used by cppcheck.
+             If not specified, the result will be printed to stdout.
+    JSON   - cppcheck json file to be created (optional).
+"""
+
+import sys, getopt, re
+
+def main(argv):
+    infile = ''
+    outfile = ''
+    outstr = sys.stdout
+    jsonfile = ''
+
+    try:
+        opts, args = getopt.getopt(argv,"hi:o:j:",["input=","output=","json="])
+    except getopt.GetoptError:
+        print('convert-misra.py -i <input> [-o <output>] [-j <json>')
+        sys.exit(2)
+    for opt, arg in opts:
+        if opt == '-h':
+            print('convert-misra.py -i <input> [-o <output>] [-j <json>')
+            print('  If output is not specified, print to stdout')
+            sys.exit(1)
+        elif opt in ("-i", "--input"):
+            infile = arg
+        elif opt in ("-o", "--output"):
+            outfile = arg
+        elif opt in ("-j", "--json"):
+            jsonfile = arg
+
+    try:
+        file_stream = open(infile, 'rt')
+    except:
+        print('Error opening ' + infile)
+        sys.exit(1)
+
+    if outfile:
+        try:
+            outstr = open(outfile, "w")
+        except:
+            print('Error creating ' + outfile)
+            sys.exit(1)
+
+    # Each rule start with '   * - `[Dir|Rule]' and is followed by the
+    # severity, the summary and then notes
+    # Only the summary can be multi line
+    pattern_dir = re.compile(r'^   \* - `Dir ([0-9]+.[0-9]+).*$')
+    pattern_rule = re.compile(r'^   \* - `Rule ([0-9]+.[0-9]+).*$')
+    pattern_col = re.compile(r'^     - (.*)$')
+    # allow empty notes
+    pattern_notes = re.compile(r'^     -.*$')
+    pattern_cont = re.compile(r'^      (.*)$')
+
+    rule_number = ''
+    rule_severity = ''
+    rule_summary = ''
+    rule_state  = 0
+    rule_list = []
+
+    # Start search by cppcheck misra
+    outstr.write('Appendix A Summary of guidelines\n')
+
+    for line in file_stream:
+
+        line = line.replace('\r', '').replace('\n', '')
+
+        if len(line) == 0:
+            continue
+
+        # New Rule or Directive
+        if rule_state == 0:
+            # new Rule
+            res = pattern_rule.match(line)
+            if res:
+                rule_number = res.group(1)
+                rule_list.append(rule_number)
+                rule_state = 1
+                continue
+
+            # new Directive
+            res = pattern_dir.match(line)
+            if res:
+                rule_number = res.group(1)
+                rule_list.append(rule_number)
+                rule_state = 1
+                continue
+            continue
+
+        # Severity
+        elif rule_state == 1:
+            res =pattern_col.match(line)
+            if res:
+                rule_severity = res.group(1)
+                rule_state = 2
+                continue
+
+            print('No severity for rule ' + rule_number)
+            sys.exit(1)
+
+        # Summary
+        elif rule_state == 2:
+            res = pattern_col.match(line)
+            if res:
+                rule_summary = res.group(1)
+                rule_state = 3
+                continue
+
+            print('No summary for rule ' + rule_number)
+            sys.exit(1)
+
+        # Notes or summary continuation
+        elif rule_state == 3:
+            res = pattern_cont.match(line)
+            if res:
+                rule_summary += res.group(1)
+                continue
+            res = pattern_notes.match(line)
+            if res:
+                outstr.write('Rule ' + rule_number + ' ' + rule_severity
+                             + '\n')
+                outstr.write(rule_summary + ' (Misra rule ' + rule_number
+                             + ')\n')
+                rule_state = 0
+                rule_number = ''
+                continue
+            print('No notes for rule ' + rule_number)
+            sys.exit(1)
+
+        else:
+            print('Impossible case in state machine')
+            sys.exit(1)
+
+    skip_list = []
+
+    # Search for missing rules and add a dummy text with the rule number
+    for i in list(range(1,22)):
+        for j in list(range(1,22)):
+            if str(i) + '.' + str(j) not in rule_list:
+                outstr.write('Rule ' + str(i) + '.' + str(j) + '\n')
+                outstr.write('No description for rule ' + str(i) + '.' + str(j)
+                             + '\n')
+                skip_list.append(str(i) + '.' + str(j))
+
+    # Make cppcheck happy by starting the appendix
+    outstr.write('Appendix B\n')
+    outstr.write('\n')
+    if outfile:
+        outstr.close()
+
+    if jsonfile:
+        with open(jsonfile, "w") as f:
+            f.write('{\n')
+            f.write('    "script": "misra.py",\n')
+            f.write('    "args": [\n')
+            if outfile:
+                f.write('      "--rule-texts=' + outfile + '",\n')
+
+            f.write('      "--suppress-rules=' + ",".join(skip_list) + '"\n')
+            f.write('    ]\n')
+            f.write('}\n')
+        f.close()
+
+if __name__ == "__main__":
+   main(sys.argv[1:])