Test robot reports the following error with clang-16.0.6:
In file included from kernel/rseq.c:75:
include/linux/rseq_entry.h:141:3: error: invalid operand for instruction
unsafe_get_user(offset, &ucs->post_commit_offset, efault);
^
include/linux/uaccess.h:608:2: note: expanded from macro 'unsafe_get_user'
arch_unsafe_get_user(x, ptr, local_label); \
^
arch/powerpc/include/asm/uaccess.h:518:2: note: expanded from macro
'arch_unsafe_get_user'
__get_user_size_goto(__gu_val, __gu_addr, sizeof(*(p)), e); \
^
arch/powerpc/include/asm/uaccess.h:284:2: note: expanded from macro
'__get_user_size_goto'
__get_user_size_allowed(x, ptr, size, __gus_retval); \
^
arch/powerpc/include/asm/uaccess.h:275:10: note: expanded from macro
'__get_user_size_allowed'
case 8: __get_user_asm2(x, (u64 __user *)ptr, retval); break; \
^
arch/powerpc/include/asm/uaccess.h:258:4: note: expanded from macro
'__get_user_asm2'
" li %1+1,0\n" \
^
<inline asm>:7:5: note: instantiated into assembly here
li 31+1,0
^
1 error generated.
On PPC32, for 64 bits vars a pair of registers is used. Usually the
lower register in the pair is the high part and the higher register is
the low part. GCC uses r3/r4 ... r11/r12 ... r14/r15 ... r30/r31
In older kernel code inline assembly was using %1 and %1+1 to represent
64 bits values. However here it looks like clang uses r31 as high part,
allthough r32 doesn't exist hence the error.
Allthoug %1+1 should work, most places now use %L1 instead of %1+1, so
let's do the same here.
With that change, the build doesn't fail anymore and a disassembly shows
clang uses r17/r18 and r31/r14 pair when GCC would have used r16/r17 and
r30/r31:
Disassembly of section .fixup:
00000000 <.fixup>:
0: 38 a0 ff f2 li r5,-14
4: 3a 20 00 00 li r17,0
8: 3a 40 00 00 li r18,0
c: 48 00 00 00 b c <.fixup+0xc>
c: R_PPC_REL24 .text+0xbc
10: 38 a0 ff f2 li r5,-14
14: 3b e0 00 00 li r31,0
18: 39 c0 00 00 li r14,0
1c: 48 00 00 00 b 1c <.fixup+0x1c>
1c: R_PPC_REL24 .text+0x144
Reported-by: kernel test robot <[email protected]>
Closes:
https://lore.kernel.org/oe-kbuild-all/[email protected]/
Fixes: c20beffeec3c ("powerpc/uaccess: Use flexible addressing with
__put_user()/__get_user()")
Signed-off-by: Christophe Leroy (CS GROUP) <[email protected]>
---
I set Fixes: tag to the commit that recently replaced %1+1 by %L1 in the main
part of the macro as the fix would be uncomplete otherwise but the problem has
been there since commit 2df5e8bcca53 ("powerpc: merge uaccess.h")
---
arch/powerpc/include/asm/uaccess.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/uaccess.h
b/arch/powerpc/include/asm/uaccess.h
index ba1d878c3f404..570b3d91e2e40 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -255,7 +255,7 @@ __gus_failed:
\
".section .fixup,\"ax\"\n" \
"4: li %0,%3\n" \
" li %1,0\n" \
- " li %1+1,0\n" \
+ " li %L1,0\n" \
" b 3b\n" \
".previous\n" \
EX_TABLE(1b, 4b) \
--
2.49.0
