selftests/x86: Disable the ldt_gdt_64 test for now

amluto · Ingo Molnar · commit 0f672809f91a · 2016-01-12T11:09:26.000+01:00
ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its tests. On 32-bit builds, this works fine, but on 64-bit builds, it only works if the kernel has proper SS sigcontext handling for 64-bit user programs. Since the SS fixes are currently reverted, restrict the test case to 32 bits for now. In principle, I could change the test to use a different segment register, but it would be messy: CS can't point to the LDT for 64-bit code, and the other registers don't result in immediate faults because they aren't reloaded on kernel -> user transitions. When we fix sigcontext (in 4.6?), we can revert this. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/231591d9122d282402d8f53175134f8db5b3bc73.1452561752.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
@@ -4,9 +4,10 @@ include ../lib.mk
 
 .PHONY: all all_32 all_64 warn_32bit_failure clean
 
-TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt syscall_nt ptrace_syscall
+TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall
 TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault sigreturn test_syscall_vdso unwind_vdso \
-			test_FCMOV test_FCOMI test_FISTTP
+			test_FCMOV test_FCOMI test_FISTTP \
+			ldt_gdt
 
 TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
 BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32)
