s390/entry: workaround llvm's IAS limitations

llvm's integrated assembler cannot handle immediate values which are
calculated with two local labels:

<instantiation>:3:13: error: invalid operand for instruction
 clgfi %r14,.Lsie_done - .Lsie_gmap

Workaround this by adding clang specific code which reads the specific
value from memory. Since this code is within the hot paths of the kernel
and adds an additional memory reference, keep the original code, and add
ifdef'ed code.

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20220511120532.2228616-5-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index a6b45eaa345063b266395e3b8f8c99bd3d135323..df41132ccd06898c03fc0d40d92535d190f7ce80 100644 (file)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -172,9 +172,19 @@ _LPP_OFFSET        = __LC_LPP
        lgr     %r14,\reg
        larl    %r13,\start
        slgr    %r14,%r13
-       lghi    %r13,\end - \start
-       clgr    %r14,%r13
+#ifdef CONFIG_AS_IS_LLVM
+       clgfrl  %r14,.Lrange_size\@
+#else
+       clgfi   %r14,\end - \start
+#endif
        jhe     \outside_label
+#ifdef CONFIG_AS_IS_LLVM
+       .section .rodata, "a"
+       .align 4
+.Lrange_size\@:
+       .long   \end - \start
+       .previous
+#endif
        .endm
 
        .macro SIEEXIT