On Wed, Nov 17, 2021 at 9:48 AM Ilie Halip <ilie.halip@xxxxxxxxx> wrote: > > Building with clang & LLVM_IAS=1 leads to an error: > arch/s390/lib/test_unwind.c:179:4: error: invalid register pair > " mvcl %%r1,%%r1\n" > ^ > > The test creates an invalid instruction that would trap at runtime, but the > LLVM inline assembler tries to validate it at compile time too. > > Use the raw instruction opcode instead. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1421 > Reported-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > Signed-off-by: Ilie Halip <ilie.halip@xxxxxxxxx> Ilie, thanks for the patch! So if I understand https://sourceware.org/binutils/docs/as/s390-Directives.html#s390-Directives https://sourceware.org/binutils/docs/as/s390-Formats.html that `e,` prefix is for 16B opcodes? LGTM, thanks again. Suggested-by: Ulrich Weigand <Ulrich.Weigand@xxxxxxxxxx> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> I triple checked that GAS, clang, and GNU objdump are in agreement in terms of encoding here. > --- > arch/s390/lib/test_unwind.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/s390/lib/test_unwind.c b/arch/s390/lib/test_unwind.c > index cfc5f5557c06..d342bc884b94 100644 > --- a/arch/s390/lib/test_unwind.c > +++ b/arch/s390/lib/test_unwind.c > @@ -176,7 +176,7 @@ static noinline int unwindme_func4(struct unwindme *u) > * trigger specification exception > */ > asm volatile( > - " mvcl %%r1,%%r1\n" > + " .insn e,0x0e11\n" /* mvcl %%r1,%%r1" */ > "0: nopr %%r7\n" > EX_TABLE(0b, 0b) > :); > -- > 2.25.1 > -- Thanks, ~Nick Desaulniers
