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

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

From: Dominik Brodowski <[email protected]>

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 <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dmitry Safonov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 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
@@ -30,11 +30,13 @@ 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


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