* Re: [PATCH v5] Makefile: Add clang-tidy and static analyzer support to makefile
2020-07-22 23:10 ` [PATCH v5] Makefile: Add clang-tidy and static analyzer support to makefile Nathan Huckleberry
@ 2020-07-23 18:45 ` Nick Desaulniers
0 siblings, 0 replies; 2+ messages in thread
From: Nick Desaulniers @ 2020-07-23 18:45 UTC (permalink / raw)
To: Nathan Huckleberry, Bill Wendling
Cc: Masahiro Yamada, Michal Marek, Linux Kbuild mailing list, LKML,
clang-built-linux, Pirama Arumuga Nainar
On Wed, Jul 22, 2020 at 4:11 PM 'Nathan Huckleberry' via Clang Built
Linux <clang-built-linux@googlegroups.com> wrote:
>
> This patch adds clang-tidy and the clang static-analyzer as make
> targets. The goal of this patch is to make static analysis tools
> usable and extendable by any developer or researcher who is familiar
> with basic c++.
>
> The current static analysis tools require intimate knowledge of the
> internal workings of the static analysis. Clang-tidy and the clang
> static analyzers expose an easy to use api and allow users unfamiliar
> with clang to write new checks with relative ease.
>
> ===Clang-tidy===
>
> Clang-tidy is an easily extendable 'linter' that runs on the AST.
> Clang-tidy checks are easy to write and understand. A check consists of
> two parts, a matcher and a checker. The matcher is created using a
> domain specific language that acts on the AST
> (https://clang.llvm.org/docs/LibASTMatchersReference.html). When AST
> nodes are found by the matcher a callback is made to the checker. The
> checker can then execute additional checks and issue warnings.
>
> Here is an example clang-tidy check to report functions that have calls
> to local_irq_disable without calls to local_irq_enable and vice-versa.
> Functions flagged with __attribute((annotation("ignore_irq_balancing")))
> are ignored for analysis. (https://reviews.llvm.org/D65828)
>
> ===Clang static analyzer===
>
> The clang static analyzer is a more powerful static analysis tool that
> uses symbolic execution to find bugs. Currently there is a check that
> looks for potential security bugs from invalid uses of kmalloc and
> kfree. There are several more general purpose checks that are useful for
> the kernel.
>
> The clang static analyzer is well documented and designed to be
> extensible.
> (https://clang-analyzer.llvm.org/checker_dev_manual.html)
> (https://github.com/haoNoQ/clang-analyzer-guide/releases/download/v0.1/clang-analyzer-guide-v0.1.pdf)
>
> The main draw of the clang tools is how accessible they are. The clang
> documentation is very nice and these tools are built specifically to be
> easily extendable by any developer. They provide an accessible method of
> bug-finding and research to people who are not overly familiar with the
> kernel codebase.
>
> Signed-off-by: Nathan Huckleberry <nhuck@google.com>
> ---
> Changes v4->v5
> * Use PEP8 style
> * Other misc style fixes
> MAINTAINERS | 1 +
> Makefile | 3 +
> scripts/clang-tools/Makefile.clang-tools | 23 ++++++
> .../{ => clang-tools}/gen_compile_commands.py | 0
> scripts/clang-tools/run-clang-tools.py | 76 +++++++++++++++++++
> 5 files changed, 103 insertions(+)
> create mode 100644 scripts/clang-tools/Makefile.clang-tools
> rename scripts/{ => clang-tools}/gen_compile_commands.py (100%)
> create mode 100755 scripts/clang-tools/run-clang-tools.py
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1d4aa7f942de..a444564e5572 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -4198,6 +4198,7 @@ W: https://clangbuiltlinux.github.io/
> B: https://github.com/ClangBuiltLinux/linux/issues
> C: irc://chat.freenode.net/clangbuiltlinux
> F: Documentation/kbuild/llvm.rst
> +F: scripts/clang-tools/
> K: \b(?i:clang|llvm)\b
>
> CLEANCACHE API
> diff --git a/Makefile b/Makefile
> index fe0164a654c7..3e2df010b342 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -747,6 +747,7 @@ KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races)
>
> include scripts/Makefile.kcov
> include scripts/Makefile.gcc-plugins
> +include scripts/clang-tools/Makefile.clang-tools
>
> ifdef CONFIG_READABLE_ASM
> # Disable optimizations that make assembler listings hard to read.
> @@ -1543,6 +1544,8 @@ help:
> @echo ' export_report - List the usages of all exported symbols'
> @echo ' headerdep - Detect inclusion cycles in headers'
> @echo ' coccicheck - Check with Coccinelle'
> + @echo ' clang-analyzer - Check with clang static analyzer'
> + @echo ' clang-tidy - Check with clang-tidy'
> @echo ''
> @echo 'Tools:'
> @echo ' nsdeps - Generate missing symbol namespace dependencies'
> diff --git a/scripts/clang-tools/Makefile.clang-tools b/scripts/clang-tools/Makefile.clang-tools
> new file mode 100644
> index 000000000000..5c9d76f77595
> --- /dev/null
> +++ b/scripts/clang-tools/Makefile.clang-tools
> @@ -0,0 +1,23 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Copyright (C) Google LLC, 2020
> +#
> +# Author: Nathan Huckleberry <nhuck@google.com>
> +#
> +PHONY += clang-tidy
> +clang-tidy:
> +ifdef CONFIG_CC_IS_CLANG
> + $(PYTHON3) scripts/clang-tools/gen_compile_commands.py
> + $(PYTHON3) scripts/clang-tools/run-clang-tools.py clang-tidy compile_commands.json
> +else
> + $(error clang-tidy requires CC=clang)
> +endif
> +
> +PHONY += clang-analyzer
> +clang-analyzer:
> +ifdef CONFIG_CC_IS_CLANG
> + $(PYTHON3) scripts/clang-tools/gen_compile_commands.py
> + $(PYTHON3) scripts/clang-tools/run-clang-tools.py clang-analyzer compile_commands.json
> +else
> + $(error clang-analyzer requires CC=clang)
> +endif
> diff --git a/scripts/gen_compile_commands.py b/scripts/clang-tools/gen_compile_commands.py
> similarity index 100%
> rename from scripts/gen_compile_commands.py
> rename to scripts/clang-tools/gen_compile_commands.py
> diff --git a/scripts/clang-tools/run-clang-tools.py b/scripts/clang-tools/run-clang-tools.py
> new file mode 100755
> index 000000000000..41ed15d99933
> --- /dev/null
> +++ b/scripts/clang-tools/run-clang-tools.py
> @@ -0,0 +1,76 @@
> +#!/usr/bin/env python
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Copyright (C) Google LLC, 2020
> +#
> +# Author: Nathan Huckleberry <nhuck@google.com>
> +#
> +"""A helper routine run clang-tidy and the clang static-analyzer on
> +compile_commands.json.
> +"""
> +
> +import argparse
> +import json
> +import logging
> +import multiprocessing
> +import os
> +import subprocess
> +import sys
> +
> +
> +def parse_arguments():
> + """Set up and parses command-line arguments.
> + Returns:
> + args: Dict of parsed args
> + Has keys: [file, type]
> + """
> + usage = """Run clang-tidy or the clang static-analyzer on a
> + compilation database."""
> + parser = argparse.ArgumentParser(description=usage)
> +
> + type_help = "Type of analysis to be performed"
> + parser.add_argument("type",
> + choices=["clang-tidy", "clang-analyzer"],
> + help=type_help)
> + file_path_help = "Path to the compilation database to parse"
> + parser.add_argument("file", type=str, help=file_path_help)
> +
> + args = parser.parse_args()
> +
> + return args
> +
> +
> +def init(l, t):
> + global lock
> + global analysis_type
> + lock = l
> + analysis_type = t
> +
> +
> +def run_analysis(entry):
> + filename = entry["file"]
> + # Disable all checks, then re-enable the ones we want
> + checks = "-checks=-*,{}".format("linuxkernel-*" if analysis_type ==
> + "clang-tidy" else "clang-analyzer-*")
ugh, sorry, I have one last nit. This line bothers me for two reasons:
1. The use of ternary statements is preferred when it is more concise
than than an if/else statement. If the ternary doesn't fit on one
line, is it still more concise? The wrapping of the condition here
is...upsetting.
2. `format` is nice when string interpolation is needed within the
middle of a string, but when you're simply appending to the end of a
string, it might be more concise to use the `+=` operator.
I think this statement would would be nicer as:
```python
checks = "-check=-*,"
checks += "linuxkernel-*" if analysis_type == "clang-tidy" else
"clang-analyzer-*"
```
If PEP8 requires line length <= 80; then maybe
```python
checks = "-check=-*,"
if analysis_type == "clang-tidy":
checks += "linuxkernel-*"
else:
checks += "clang-analyzer-*"
```
is more appropriate. Bill, thoughts?
> + p = subprocess.run(
> + ["clang-tidy", "-p", os.getcwd(), checks, filename],
> + stdout=subprocess.PIPE,
> + stderr=subprocess.STDOUT)
> + with lock:
> + sys.stderr.buffer.write(p.stdout)
> +
> +
> +def main():
> + args = parse_arguments()
> + filename = args.file
> +
> + lock = multiprocessing.Lock()
> + pool = multiprocessing.Pool(initializer=init, initargs=(lock, args.type))
> + # Read JSON data into the datastore variable
> + with open(filename, "r") as f:
> + datastore = json.load(f)
> + pool.map(run_analysis, datastore)
> +
> +
> +if __name__ == "__main__":
> + main()
> --
> 2.28.0.rc0.105.gf9edc3c819-goog
>
> --
--
Thanks,
~Nick Desaulniers
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