Re: Build Warnings at arch/powerpc/

Venkat Rao Bagalkote
2025-03-04T13:03:33Z

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.leroy2%40cs-soprasteria.com%7C8e0f8501f09c48dbb43608dd5ae3c9bf%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638766656585342184%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=e5BrJzcrtlITkLF31KltGExQ5Qe8fDVTMV6VfR4w9o8%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.leroy2%40cs-soprasteria.com%7C8e0f8501f09c48dbb43608dd5ae3c9bf%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638766656585355246%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=meQyZfB75HhJFCL6AX93slsyVwnogGPYFabDXl%2FLzDA%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.

arch/powerpc/crypto/ghashp8-ppc.o: warning: objtool: .text+0x22c:
unannotated intra-function call

>> CC arch/powerpc/kernel/irq.o
>> CC arch/powerpc/kernel/align.o
>> CC arch/powerpc/kernel/signal_64.o
>>
>> Objdump of switch.o:
>> arch/powerpc/kernel/switch.o: file format elf64-powerpcle
>>
>> Disassembly of section .text:
>>
>> 0000000000000000 <flush_branch_caches>:
>> 0: a6 02 28 7d mflr r9
>> 4: 05 00 00 48 bl 8 <flush_branch_caches+0x8>
>> 8: 05 00 00 48 bl c <flush_branch_caches+0xc>
>> c: 05 00 00 48 bl 10 <flush_branch_caches+0x10>
>> 10: 05 00 00 48 bl 14 <flush_branch_caches+0x14>
>> 14: 05 00 00 48 bl 18 <flush_branch_caches+0x18>
>> 18: 05 00 00 48 bl 1c <flush_branch_caches+0x1c>
>> 1c: 05 00 00 48 bl 20 <flush_branch_caches+0x20>
>> 20: 05 00 00 48 bl 24 <flush_branch_caches+0x24>
>> 24: 05 00 00 48 bl 28 <flush_branch_caches+0x28>
>> 28: 05 00 00 48 bl 2c <flush_branch_caches+0x2c>
>>
>>
>> arch/powerpc/kernel/switch.S failing src section:
>>
>> .balign 32
>> .global flush_branch_caches
>> flush_branch_caches:
>> /* Save LR into r9 */
>> mflr r9
>>
>> // Flush the link stack
>> .rept 64
>> ANNOTATE_INTRA_FUNCTION_CALL
>> bl .+4
>> .endr
>> b 1f
>> nops 6
>>
>> Maddy
>>
>>
>>> Christophe
>>
>
Regards,

Venkat.