linux-kernel - [PATCH 4.9 59/77] selftests/x86: Do not rely on "int $0x80" in single_step

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Date:   Wed, 21 Feb 2018 13:49:08 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Andy Lutomirski <luto@...nel.org>,
        Dmitry Safonov <dsafonov@...tuozzo.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kselftest@...r.kernel.org, shuah@...nel.org,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.9 59/77] selftests/x86: Do not rely on "int $0x80" in single_step_syscall.c

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dominik Brodowski <linux@...inikbrodowski.net>

commit 4105c69703cdeba76f384b901712c9397b04e9c2 upstream.

On 64-bit builds, we should not rely on "int $0x80" working (it only does if
CONFIG_IA32_EMULATION=y is enabled). To keep the "Set TF and check int80"
test running on 64-bit installs with CONFIG_IA32_EMULATION=y enabled, build
this test only if we can also build 32-bit binaries (which should be a
good approximation for that).

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/20180211111013.16888-5-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 tools/testing/selftests/x86/Makefile              |    2 ++
 tools/testing/selftests/x86/single_step_syscall.c |    5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -26,11 +26,13 @@ CAN_BUILD_X86_64 := $(shell ./check_cc.s
 ifeq ($(CAN_BUILD_I386),1)
 all: all_32
 TEST_PROGS += $(BINARIES_32)
+EXTRA_CFLAGS += -DCAN_BUILD_32
 endif
 
 ifeq ($(CAN_BUILD_X86_64),1)
 all: all_64
 TEST_PROGS += $(BINARIES_64)
+EXTRA_CFLAGS += -DCAN_BUILD_64
 endif
 
 all_32: $(BINARIES_32)
--- a/tools/testing/selftests/x86/single_step_syscall.c
+++ b/tools/testing/selftests/x86/single_step_syscall.c
@@ -119,7 +119,9 @@ static void check_result(void)
 
 int main()
 {
+#ifdef CAN_BUILD_32
 	int tmp;
+#endif
 
 	sethandler(SIGTRAP, sigtrap, 0);
 
@@ -139,12 +141,13 @@ int main()
 		      : : "c" (post_nop) : "r11");
 	check_result();
 #endif
-
+#ifdef CAN_BUILD_32
 	printf("[RUN]\tSet TF and check int80\n");
 	set_eflags(get_eflags() | X86_EFLAGS_TF);
 	asm volatile ("int $0x80" : "=a" (tmp) : "a" (SYS_getpid)
 			: INT80_CLOBBERS);
 	check_result();
+#endif
 
 	/*
 	 * This test is particularly interesting if fast syscalls use