linux-kernel - [PATCH 3/5] selftests/x86: do not rely on int $0x80 in test_mremap

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Date:   Sun, 11 Feb 2018 12:10:11 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        x86@...nel.org, shuah@...nel.org
Cc:     Dmitry Safonov <dsafonov@...tuozzo.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 3/5] selftests/x86: do not rely on int $0x80 in test_mremap_vdso.c

On 64bit builds, we should not rely on int $0x80 working (it only does if
CONFIG_IA32_EMULATION is enabled). Without this patch, the move test may
succeed, but the int $0x80 cause a segfault, resulting in a false negative
output of this selftest.

CC: Dmitry Safonov <dsafonov@...tuozzo.com>
CC: Andy Lutomirski <luto@...nel.org>
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
---
 tools/testing/selftests/x86/test_mremap_vdso.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
index bf0d687c7db7..64f11c8d9b76 100644
--- a/tools/testing/selftests/x86/test_mremap_vdso.c
+++ b/tools/testing/selftests/x86/test_mremap_vdso.c
@@ -90,8 +90,12 @@ int main(int argc, char **argv, char **envp)
 			vdso_size += PAGE_SIZE;
 		}
 
+#ifdef __i386__
 		/* Glibc is likely to explode now - exit with raw syscall */
 		asm volatile ("int $0x80" : : "a" (__NR_exit), "b" (!!ret));
+#else /* __x86_64__ */
+		syscall(SYS_exit, ret);
+#endif
 	} else {
 		int status;
 
-- 
2.16.1