Commit 11586553 authored by John Hubbard's avatar John Hubbard Committed by Shuah Khan
Browse files

selftests/x86: build fsgsbase_restore.c with clang 



When building with clang, via:

    make LLVM=1 -C tools/testing/selftests

Fix this by moving the inline asm to "pure" assembly, in two new files:
clang_helpers_32.S, clang_helpers_64.S.

As a bonus, the pure asm avoids the need for ifdefs, and is now very
simple and easy on the eyes.

Acked-by: default avatarMuhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: default avatarShuah Khan <skhan@linuxfoundation.org>
parent bf967fb3

tools/testing/selftests/x86/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -113,6 +113,8 @@ endef 
$(eval $(call extra-files,sysret_ss_attrs_64,thunks.S))

$(eval $(call extra-files,ptrace_syscall_32,raw_syscall_helper_32.S))

$(eval $(call extra-files,test_syscall_vdso_32,thunks_32.S))

$(eval $(call extra-files,fsgsbase_restore_64,clang_helpers_64.S))

$(eval $(call extra-files,fsgsbase_restore_32,clang_helpers_32.S))



# check_initial_reg_state is special: it needs a custom entry, and it

# needs to be static so that its interpreter doesn't destroy its initial

tools/testing/selftests/x86/clang_helpers_32.S

0 → 100644
+11 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * 32-bit assembly helpers for asm operations that lack support in both gcc and

 * clang. For example, clang asm does not support segment prefixes.

 */

.global dereference_seg_base

dereference_seg_base:

	mov %fs:(0), %eax

	ret



.section .note.GNU-stack,"",%progbits

tools/testing/selftests/x86/clang_helpers_64.S

0 → 100644
+12 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * 64-bit assembly helpers for asm operations that lack support in both gcc and

 * clang. For example, clang asm does not support segment prefixes.

 */

.global dereference_seg_base



dereference_seg_base:

	mov %gs:(0), %rax

	ret



.section .note.GNU-stack,"",%progbits

tools/testing/selftests/x86/fsgsbase_restore.c

+5 −6
Original line number Diff line number Diff line
@@ -39,12 +39,11 @@ 
# define SEG "%fs"

#endif



static unsigned int dereference_seg_base(void)

{

	int ret;

	asm volatile ("mov %" SEG ":(0), %0" : "=rm" (ret));

	return ret;

}

/*

 * Defined in clang_helpers_[32|64].S, because unlike gcc, clang inline asm does

 * not support segmentation prefixes.

 */

unsigned int dereference_seg_base(void);



static void init_seg(void)

{