Re: Build Warnings at arch/powerpc/

Christophe Leroy
2025-03-04T17:50:03Z

Le 04/03/2025 à 16:44, Venkat Rao Bagalkote a écrit :
> Hello Christophe,
>
>
> On 04/03/25 6:43 pm, Christophe Leroy wrote:
>>
>>
>> Le 04/03/2025 à 14:03, Venkat Rao Bagalkote a écrit :
>>> [Vous ne recevez pas souvent de courriers de venkat88@linux.ibm.com.
>>> Découvrez pourquoi ceci est important à https://
>>> eur01.safelinks.protection.outlook.com/?
>>> url=https%3A%2F%2Faka.ms%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C3657f07f71b149ba489e08dd5b336e9a%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638766998669498918%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=ZM65b%2F3BuUDy5Iet3kE1%2B%2BXKdjmM86UFsJwBmSHeiv4%3D&reserved=0 LearnAboutSenderIdentification ]
>>>
>>> On 04/03/25 6:08 pm, Madhavan Srinivasan wrote:
>>>>
>>>> On 3/4/25 4:58 PM, Madhavan Srinivasan wrote:
>>>>>
>>>>> On 3/4/25 2:26 PM, Christophe Leroy wrote:
>>>>>>
>>>>>> Le 04/03/2025 à 07:13, Madhavan Srinivasan a écrit :
>>>>>>>
>>>>>>> On 3/4/25 10:42 AM, Venkat Rao Bagalkote wrote:
>>>>>>>> Greetings!!
>>>>>>>>
>>>>>>>>
>>>>>>>> Observing build warnings with linux-next and powerpc repo's.
>>>>>>>> Issue is currently not seen on mainline yet.
>>>>>>>>
>>>>>>>> PPC Repo: https://eur01.safelinks.protection.outlook.com/?
>>>>>>>> url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fpowerpc%2Flinux.git&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C6e17cc771a204b2998b508dd5b1cf2cf%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638766902127463526%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=f0ubC0BiY%2Fw2XLfXcX955JKhJ%2BRkUmTUVO4fV%2F%2F4v2Y%3D&reserved=0 merge branch
>>>>>>>>
>>>>>>>> PPC Kernel Version: 6.14.0-rc4-g1304f486dbf1
>>>>>>>> next Repo: https://eur01.safelinks.protection.outlook.com/?
>>>>>>>> url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fnext%2Flinux-next.git&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C6e17cc771a204b2998b508dd5b1cf2cf%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638766902127477000%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=GSDtRBQ35owCeEpjMMCNiJw3iizdrUPQcHznop2BLeQ%3D&reserved=0 master branch
>>>>>>>>
>>>>>>>> next Kernel Version: 6.14.0-rc5-next-20250303
>>>>>>>>
>>>>>>>>
>>>>>>>> On linux-next kernel issue got introduced b/w next-20250227 and
>>>>>>>> next-20250303
>>>>>>>>
>>>>>>>>
>>>>>>>> Build Warnings:
>>>>>>>>
>>>>>>>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning:
>>>>>>>> objtool: .text+0xe84: intra_function_call not a direct call
>>>>>>>> arch/powerpc/crypto/ghashp8-ppc.o: warning:
>>>>>>>> objtool: .text+0x22c: unannotated intra-function call
>>>>>>>> arch/powerpc/kernel/switch.o: warning: objtool: .text+0x4:
>>>>>>>> intra_function_call not a direct call
>>>>>>>>
>>>>>>>>
>>>>>>> Can you please specific the compiler and compiler version you
>>>>>>> found this issue with
>>>>>>>
>>>>>> Can you also tell which defconfig you are using or provide
>>>>>> your .config
>>>>>>
>>>>>> It might also be helpfull if you can provide a disassembly of the
>>>>>> three file.o around the warned address.
>>>>> I could recreate the issue with gcc 11.4.1 20231218 with today's
>>>>> linux-next (but could not recreate with gcc 14 or gcc 11.3.0)
>>>>>
>>>>> (20d5c66e1810 (HEAD -> master, tag: next-20250304, origin/master,
>>>>> origin/HEAD) Add linux-next specific files for 20250304)
>>>>>
>>>>> warning for one of the switch.S file :
>>>>>
>>>>>    CC      arch/powerpc/kernel/syscalls.o
>>>>>    AS      arch/powerpc/kernel/switch.o
>>>>> arch/powerpc/kernel/switch.o: warning: objtool: .text+0x4:
>>>>> intra_function_call not a direct call
>>>> I guess this is becos, for bl .+4, we recently added in the
>>>> arch_decode_instruction (decode.c) to set the type as INSN_OTHER
>>>>
>>>>          case 18: /* b[l][a] */
>>>>                  if (ins == 0x48000005)  /* bl .+4 */
>>>>                          typ = INSN_OTHER;
>>>>
>>>> Which I think is the issue here, changing it to INSN_CALL from
>>>> INSN_OTHER fixes the warning
>>>>
>>>> diff --git a/tools/objtool/arch/powerpc/decode.c b/tools/objtool/
>>>> arch/ powerpc/decode.c
>>>> index 26d5050424a9..ffd63a61a585 100644
>>>> --- a/tools/objtool/arch/powerpc/decode.c
>>>> +++ b/tools/objtool/arch/powerpc/decode.c
>>>> @@ -56,7 +56,7 @@ int arch_decode_instruction(struct objtool_file
>>>> *file, const struct section *sec
>>>>          switch (opcode) {
>>>>          case 18: /* b[l][a] */
>>>>                  if (ins == 0x48000005)  /* bl .+4 */
>>>> -                       typ = INSN_OTHER;
>>>> +                       typ = INSN_CALL;
>>>>                  else if (ins & 1)       /* bl[a] */
>>>>                          typ = INSN_CALL;
>>>>                  else            /* b[a] */
>>>>
>>>>
>>>> Maddy
>>>>
>>> Maddy,
>>>
>>> I changed the code manually and gave it a try. The Proposed fix,
>>> partially fixes the issue. It gets rid of two of the warnings, but below
>>> warning still persists.
>>
>> It fixes the issue for you but will reintroduce the issue with clang.
>>
>> The real fix is to remove the ANNOTATE_INTRA_FUNCTION_CALL in:
>>
>> arch/powerpc/kernel/switch.S:42: ANNOTATE_INTRA_FUNCTION_CALL
>> arch/powerpc/kvm/book3s_hv_rmhandlers.S:1527:
>> ANNOTATE_INTRA_FUNCTION_CALL
>> arch/powerpc/kvm/book3s_hv_rmhandlers.S:1534:
>> ANNOTATE_INTRA_FUNCTION_CALL
>
>
> Removed ANNOTATE_INTRA_FUNCTION_CALL in above mentioned line, and it
> fixes couple of warnings. But below warning still persists.
>
> arch/powerpc/crypto/ghashp8-ppc.o: warning: objtool: .text+0x22c:
> unannotated intra-function call.
>
>>
>> Can you give it a try ?
>>
>> For the last one, can you provide an assembly dump ? You get it with
>> "objtool -dr arch/powerpc/crypto/ghashp8-ppc.o"
>
>
> Assembly dump:
>
> objdump -dr arch/powerpc/crypto/ghashp8-ppc.o
>
> arch/powerpc/crypto/ghashp8-ppc.o:     file format elf64-powerpcle
>
>
> Disassembly of section .text:
>
> 0000000000000140 <gcm_ghash_p8>:
>  140:    f8 ff 00 3c     lis     r0,-8
...
>  20c:    20 00 80 4e     blr
>  210:    00 00 00 00     .long 0x0
>  214:    00 0c 14 00     .long 0x140c00
>  218:    00 00 04 00     .long 0x40000
>  21c:    00 00 00 00     .long 0x0
>  220:    47 48 41 53     rlwimi. r1,r26,9,1,3
>  224:    48 20 66 6f     xoris   r6,r27,8264
>  228:    72 20 50 6f     xoris   r16,r26,8306
>  22c:    77 65 72 49     bla     1726574 <gcm_ghash_p8+0x1726434> <==
...

It corresponds to:

_GLOBAL(gcm_ghash_p8)
lis 0,0xfff8
...
blr
.long 0
.byte 0,12,0x14,0,0,0,4,0
.long 0
.size gcm_ghash_p8,.-gcm_ghash_p8

.byte
71,72,65,83,72,32,102,111,114,32,80,111,119,101,114,73,83,65,32,50,46,48,55,44,32,67,82,89,80,84,79,71,65,77,83,32,98,121,32,60,97,112,112,114,111,64,111,112,101,110,115,115,108,46,111,114,103,62,0
.align 2
.align 2

This is raw data that is after the function end and that shouldn't be
taken into account as text by objtool. But ghashp8-ppc.S is generated by
a perl script and should have been marked as OBJECT_FILES_NON_STANDARD.

For some reason, commit 109303336a0c ("crypto: vmx - Move to
arch/powerpc/crypto") missed it. So now that 'bla' is understood as a
call instruction, we hit the problem.

Can you try with following fix:

diff --git a/arch/powerpc/crypto/Makefile b/arch/powerpc/crypto/Makefile
index 9b38f4a7bc15..2f00b22b0823 100644
--- a/arch/powerpc/crypto/Makefile
+++ b/arch/powerpc/crypto/Makefile
@@ -51,3 +51,4 @@ $(obj)/aesp8-ppc.S $(obj)/ghashp8-ppc.S: $(obj)/%.S:
$(src)/%.pl FORCE
OBJECT_FILES_NON_STANDARD_aesp10-ppc.o := y
OBJECT_FILES_NON_STANDARD_ghashp10-ppc.o := y
OBJECT_FILES_NON_STANDARD_aesp8-ppc.o := y
+OBJECT_FILES_NON_STANDARD_ghashp8-ppc.o := y

Christophe