all: add clean_rules config to help CleanPath for specific targets

[jiangenj]

In some targets like android, we got addr2line info like: /proc/self/cwd/common/kernel/kcov.c:852
To cleanup the path, we need to remove /proc/self/cwd/ prefix, and add relative path to common directory,
so we can have clean_rules like:
"/proc/self/cwd/common:kernel_platform/common"

More examples:
"clean_rules" : [
"/proc/self/cwd/common/../vendor:vendor",
"/proc/self/cwd/common/../soc-repo:kernel_platform/soc-repo",
"/proc/self/cwd/vendor:vendor",
"/proc/self/cwd/common:kernel_platform/common"
]

---

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[jiangenj]

@a-nogikh there is no reviewer for the PR, can you check once?

[a-nogikh]

I'll take a closer look in a couple of days, somewhat short on time at the moment.

[a-nogikh]

We already have quite extensive path rewriting logic around here:

syzkaller/pkg/cover/backend/dwarf.go

Lines 553 to 611 in c6512ef

	// Source files for Android may be split between two subdirectories: the common AOSP kernel
	// and the device-specific drivers: https://source.android.com/docs/setup/build/building-pixel-kernels.
	// Android build system references these subdirectories in various ways, which often results in
	// paths to non-existent files being recorded in the debug info.
	//
	// cleanPathAndroid() assumes that the subdirectories reside in `srcDir`, with their names being listed in
	// `delimiters`.
	// If one of the `delimiters` occurs in the `path`, it is stripped together with the path prefix, and the
	// remaining file path is appended to `srcDir + delimiter`.
	// If none of the `delimiters` occur in the `path`, `path` is treated as a relative path that needs to be
	// looked up in `srcDir + delimiters[i]`.
	func cleanPathAndroid(path, srcDir string, delimiters []string, existFn func(string) bool) (string, string) {
	if len(delimiters) == 0 {
	return "", ""
	}
	reStr := "(" + strings.Join(delimiters, "|") + ")(.*)"
	re := regexp.MustCompile(reStr)
	match := re.FindStringSubmatch(path)
	if match != nil {
	delimiter := match[1]
	filename := match[2]
	path := filepath.Clean(srcDir + delimiter + filename)
	return filename, path
	}
	// None of the delimiters found in `path`: it is probably a relative path to the source file.
	// Try to look it up in every subdirectory of srcDir.
	for _, delimiter := range delimiters {
	absPath := filepath.Clean(srcDir + delimiter + path)
	if existFn(absPath) {
	return path, absPath
	}
	}
	return "", ""
	}
	func CleanPath(path, objDir, srcDir, buildDir string, splitBuildDelimiters []string) (string, string) {
	filename := ""
	path = filepath.Clean(path)
	aname, apath := cleanPathAndroid(path, srcDir, splitBuildDelimiters, osutil.IsExist)
	if aname != "" {
	return aname, apath
	}
	absPath := osutil.Abs(path)
	switch {
	case strings.HasPrefix(absPath, objDir):
	// Assume the file was built there.
	path = strings.TrimPrefix(absPath, objDir)
	filename = filepath.Join(objDir, path)
	case strings.HasPrefix(absPath, buildDir):
	// Assume the file was moved from buildDir to srcDir.
	path = strings.TrimPrefix(absPath, buildDir)
	filename = filepath.Join(srcDir, path)
	default:
	// Assume this is relative path.
	filename = filepath.Join(srcDir, path)
	}
	return strings.TrimLeft(filepath.Clean(path), "/\\"), filename
	}

So syzkaller already trims KernelBuildSrc and prepends KernelSrc (both are set in pkg/mgrconfig).

Why wouldn't it work in your case?

[jiangenj]

No, it won't work, here's my full cleanRules

        "clean_rules": [
                "/proc/self/cwd/out/android16-6.12/common/security/selinux/flask.h:external/selinux/libsepol/src/flask.h",
                "/proc/self/cwd/out/android16-6.12/common/../vendor:vendor",
                "/proc/self/cwd/out/android16-6.12/common/../soc-repo:kernel_platform/soc-repo",
                "/proc/self/cwd/out/android16-6.12/common:kernel_platform/common",
                "/proc/self/cwd/common/../vendor:vendor",
                "/proc/self/cwd/common/../soc-repo:kernel_platform/soc-repo",
                "/proc/self/cwd/vendor:vendor",
                "/proc/self/cwd/common:kernel_platform/common",
                "/proc/self/cwd/soc-repo/../vendor:vendor",
                "/proc/self/cwd/soc-repo:kernel_platform/soc-repo"
        ]

as you can see there are different kinds of prefixes as in below from vmlinux, android gki modules and vendor modules.

/proc/self/cwd/out/android16-6.12/common/../vendor,
/proc/self/cwd/out/android16-6.12/common/../soc-repo,
/proc/self/cwd/out/android16-6.12/common,
/proc/self/cwd/common/../vendor,
/proc/self/cwd/common/../soc-repo,
/proc/self/cwd/vendor,
/proc/self/cwd/common,
/proc/self/cwd/soc-repo/../vendor,
/proc/self/cwd/soc-repo:kernel_platform/soc-repo

Vendor/OEM android trees are different from AOSP one (there is no rule to say where to put kernel and oot module tree), like my KernelSrc is like /TOPDIR, android kernel is inside /TOPDIR/kernel_platform/common, soc-repo in /TOPDIR/kernel_platform/soc-repo and vendor (oot tree) in /TOPDIR/vendor.

So these delimiters in the syzkaller code are not enough.

	if splitBuild {
		// Path prefixes used by Android Pixel kernels. See
		// https://source.android.com/docs/setup/build/building-pixel-kernels for more
		// details.
		delimiters = []string{"/aosp/", "/private/"}
	}

I think we need to allow a flexible way to cleanPath in config file for different build versions.