Received-SPF: pass (google.com: domain of linux-kernel+bounces-165678-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Date: Wed,  1 May 2024 18:06:18 +0000
Precedence: bulk
Mime-Version: 1.0
Message-ID: <20240501180622.1676340-1-edliaw@google.com>
Subject: [PATCH v3] selftests/vDSO: Explicit unsigned char conversion for elf_hash
From: Edward Liaw <edliaw@google.com>
To: linux-kernel@vger.kernel.org, Shuah Khan <shuah@kernel.org>, 
	Nathan Chancellor <nathan@kernel.org>, Nick Desaulniers <ndesaulniers@google.com>, 
	Bill Wendling <morbo@google.com>, Justin Stitt <justinstitt@google.com>, 
	"H. Peter Anvin" <hpa@linux.intel.com>, Andy Lutomirski <luto@mit.edu>
Cc: linux-kselftest@vger.kernel.org, kernel-team@android.com, 
	Edward Liaw <edliaw@google.com>, llvm@lists.linux.dev
Content-Type: text/plain; charset="UTF-8"

Fixes clang compilation warnings by adding explicit unsigned conversion:

parse_vdso.c:206:22: warning: passing 'const char *' to parameter of
 type 'const unsigned char *' converts between pointers to integer types
 where one is of the unique plain 'char' type and the other is not
 [-Wpointer-sign]
        ver_hash = elf_hash(version);
                            ^~~~~~~
parse_vdso.c:59:52: note: passing argument to parameter 'name' here
static unsigned long elf_hash(const unsigned char *name)
                                                   ^
parse_vdso.c:207:46: warning: passing 'const char *' to parameter of
 type 'const unsigned char *' converts between pointers to integer types
 where one is of the unique plain 'char' type and the other is not
 [-Wpointer-sign]
        ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
                                                    ^~~~
parse_vdso.c:59:52: note: passing argument to parameter 'name' here
static unsigned long elf_hash(const unsigned char *name)

Fixes: 98eedc3a9dbf ("Document the vDSO and add a reference parser")
Signed-off-by: Edward Liaw <edliaw@google.com>
---
v2: update commit message with correct compiler warning
v3: fix checkpatch errors and indentation
---
 tools/testing/selftests/vDSO/parse_vdso.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 413f75620a35..9e29ff0657ea 100644
--- a/tools/testing/selftests/vDSO/parse_vdso.c
+++ b/tools/testing/selftests/vDSO/parse_vdso.c
@@ -203,8 +203,9 @@ void *vdso_sym(const char *version, const char *name)
 	if (!vdso_info.valid)
 		return 0;

-	ver_hash = elf_hash(version);
-	ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
+	ver_hash = elf_hash((const unsigned char *)version);
+	ELF(Word) chain = vdso_info.bucket[
+		elf_hash((const unsigned char *)name) % vdso_info.nbucket];

 	for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) {
 		ELF(Sym) *sym = &vdso_info.symtab[chain];
--
2.45.0.rc0.197.gbae5840b3b-goog