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

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

From: Dominik Brodowski linux@dominikbrodowski.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@dominikbrodowski.net Cc: Andy Lutomirski luto@kernel.org Cc: Dmitry Safonov dsafonov@virtuozzo.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: linux-kselftest@vger.kernel.org Cc: shuah@kernel.org Link: http://lkml.kernel.org/r/20180211111013.16888-5-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.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

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