linux-kernel - [tip:x86/pti] selftests/x86: Do not rely on "int $0x80" in test_mremap

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Message-ID: <tip-2cbc0d66de0480449c75636f55697c7ff3af61fc@git.kernel.org>
Date:   Tue, 13 Feb 2018 01:06:20 -0800
From:   tip-bot for Dominik Brodowski <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux@...inikbrodowski.net, luto@...nel.org, hpa@...or.com,
        dsafonov@...tuozzo.com, linux-kernel@...r.kernel.org,
        mingo@...nel.org, tglx@...utronix.de,
        torvalds@...ux-foundation.org, peterz@...radead.org
Subject: [tip:x86/pti] selftests/x86: Do not rely on "int $0x80" in
 test_mremap_vdso.c

Commit-ID:  2cbc0d66de0480449c75636f55697c7ff3af61fc
Gitweb:     https://git.kernel.org/tip/2cbc0d66de0480449c75636f55697c7ff3af61fc
Author:     Dominik Brodowski <linux@...inikbrodowski.net>
AuthorDate: Sun, 11 Feb 2018 12:10:11 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 13 Feb 2018 09:05:37 +0100

selftests/x86: Do not rely on "int $0x80" in test_mremap_vdso.c

On 64-bit builds, we should not rely on "int $0x80" working (it only does if
CONFIG_IA32_EMULATION=y is enabled).

Without this patch, the move test may succeed, but the "int $0x80" causes
a segfault, resulting in a false negative output of this self-test.

Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Dmitry Safonov <dsafonov@...tuozzo.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kselftest@...r.kernel.org
Cc: shuah@...nel.org
Link: http://lkml.kernel.org/r/20180211111013.16888-4-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 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 bf0d687..64f11c8 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;