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

Web:        https://git.kernel.org/torvalds/c/4105c69703cdeba76f384b901712c9397b04e9c2
Commit:     4105c69703cdeba76f384b901712c9397b04e9c2
Parent:     2cbc0d66de0480449c75636f55697c7ff3af61fc
Refname:    refs/heads/master
Author:     Dominik Brodowski <[email protected]>
AuthorDate: Tue Feb 13 09:13:21 2018 +0100
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu Feb 15 01:15:48 2018 +0100

    selftests/x86: Do not rely on "int $0x80" in single_step_syscall.c
    
    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]>
---
 tools/testing/selftests/x86/Makefile              | 2 ++
 tools/testing/selftests/x86/single_step_syscall.c | 5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 91fbfa8fdc15..73b8ef665c98 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -30,11 +30,13 @@ CAN_BUILD_X86_64 := $(shell ./check_cc.sh $(CC) trivial_64bit_program.c)
 ifeq ($(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)
diff --git a/tools/testing/selftests/x86/single_step_syscall.c b/tools/testing/selftests/x86/single_step_syscall.c
index a48da95c18fd..ddfdd635de16 100644
--- 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