linux-kernel - [PATCH 02/15] selftests/seccomp: Provide generic syscall setting macro

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Message-Id: <20200912110820.597135-3-keescook@chromium.org>
Date:   Sat, 12 Sep 2020 04:08:07 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Thadeu Lima de Souza Cascardo <cascardo@...onical.com>,
        Max Filippov <jcmvbkbc@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christian Brauner <christian@...uner.io>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>,
        linux-kselftest@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-xtensa@...ux-xtensa.org,
        linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 02/15] selftests/seccomp: Provide generic syscall setting macro

In order to avoid "#ifdef"s in the main function bodies, create a new
macro, SYSCALL_NUM_SET(), where arch-specific logic can live.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index fef15080b575..1c83e743bfb1 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -1760,6 +1760,17 @@ TEST_F(TRACE_poke, getpid_runs_normally)
 # error "Do not know how to find your architecture's registers and syscalls"
 #endif
 
+/*
+ * Most architectures can change the syscall by just updating the
+ * associated register. This is the default if not defined above.
+ */
+#ifndef SYSCALL_NUM_SET
+# define SYSCALL_NUM_SET(_regs, _nr)		\
+	do {					\
+		SYSCALL_NUM(_regs) = (_nr);	\
+	} while (0)
+#endif
+
 /* When the syscall return can't be changed, stub out the tests for it. */
 #ifdef SYSCALL_NUM_RET_SHARE_REG
 # define EXPECT_SYSCALL_RETURN(val, action)	EXPECT_EQ(-1, action)
@@ -1830,14 +1841,14 @@ void change_syscall(struct __test_metadata *_metadata,
 	defined(__s390__) || defined(__hppa__) || defined(__riscv) || \
 	defined(__xtensa__) || defined(__csky__) || defined(__sh__)
 	{
-		SYSCALL_NUM(regs) = syscall;
+		SYSCALL_NUM_SET(regs, syscall);
 	}
 #elif defined(__mips__)
 	{
 		if (SYSCALL_NUM(regs) == __NR_O32_Linux)
 			regs.SYSCALL_SYSCALL_NUM = syscall;
 		else
-			SYSCALL_NUM(regs) = syscall;
+			SYSCALL_NUM_SET(regs, syscall);
 	}
 
 #elif defined(__arm__)
-- 
2.25.1