First of all, in order to build with clang at all, one must first apply Valentin Obst's build fix for LLVM [1]. Once that is done, then when building with clang, via:
make LLVM=1 -C tools/testing/selftests
...the build fails because clang's inline asm doesn't support all of the features that are used in the asm() snippet in sysret_rip.c.
Fix this by moving the asm code into the clang_helpers_64.S file, where it can be built with the assembler's full set of features.
[1] https://lore.kernel.org/all/20240329-selftests-libmk-llvm-rfc-v1-1-2f9ed7d1c...
Signed-off-by: John Hubbard jhubbard@nvidia.com --- tools/testing/selftests/x86/Makefile | 1 + .../testing/selftests/x86/clang_helpers_64.S | 16 +++++++++++++++ tools/testing/selftests/x86/sysret_rip.c | 20 ++++++------------- 3 files changed, 23 insertions(+), 14 deletions(-)
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile index 99bc2ef84f5a..d0bb32bd5538 100644 --- a/tools/testing/selftests/x86/Makefile +++ b/tools/testing/selftests/x86/Makefile @@ -115,6 +115,7 @@ $(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 $(call extra-files,fsgsbase_restore_32,clang_helpers_32.S)) +$(eval $(call extra-files,sysret_rip_64,clang_helpers_64.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 diff --git a/tools/testing/selftests/x86/clang_helpers_64.S b/tools/testing/selftests/x86/clang_helpers_64.S index 0d81c71cad97..185a69dbf39c 100644 --- a/tools/testing/selftests/x86/clang_helpers_64.S +++ b/tools/testing/selftests/x86/clang_helpers_64.S @@ -9,4 +9,20 @@ dereference_seg_base: mov %gs:(0), %rax ret
+.global test_page +.global test_syscall_insn + +.pushsection ".text", "ax" +.balign 4096 +test_page: .globl test_page + .fill 4094,1,0xcc + +test_syscall_insn: + syscall + +.ifne . - test_page - 4096 + .error "test page is not one page long" +.endif +.popsection + .section .note.GNU-stack,"",%progbits diff --git a/tools/testing/selftests/x86/sysret_rip.c b/tools/testing/selftests/x86/sysret_rip.c index 84d74be1d902..b30de9aaa6d4 100644 --- a/tools/testing/selftests/x86/sysret_rip.c +++ b/tools/testing/selftests/x86/sysret_rip.c @@ -22,21 +22,13 @@ #include <sys/mman.h> #include <assert.h>
- -asm ( - ".pushsection ".text", "ax"\n\t" - ".balign 4096\n\t" - "test_page: .globl test_page\n\t" - ".fill 4094,1,0xcc\n\t" - "test_syscall_insn:\n\t" - "syscall\n\t" - ".ifne . - test_page - 4096\n\t" - ".error "test page is not one page long"\n\t" - ".endif\n\t" - ".popsection" - ); - +/* + * These items are in clang_helpers_64.S, in order to avoid clang inline asm + * limitations: + */ +void test_syscall_ins(void); extern const char test_page[]; + static void const *current_test_page_addr = test_page;
static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),