linux-kernel - [Linux v5.8-rc4] objtool warnings with gcc-10

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Message-ID: <CA+icZUVgJFXJ3C_iYK8HrsuhAy3R9U1RDB6mPkOS52JcnU4mDQ@mail.gmail.com>
Date:   Mon, 6 Jul 2020 09:09:55 +0200
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [Linux v5.8-rc4] objtool warnings with gcc-10

[ Please CC me I am not subscribed to this mailing-list ]

Hi Josh and Peter,

today I switched over from Linux v5.7.y to Linux v5.8-rc4 and built
the first time with GCC version 10 on Debian/testing AMD64.

$ cat /proc/version
Linux version 5.8.0-rc4-1-amd64-gcc10 (sedat.dilek@...il.com@...za)
(gcc-10 (Debian 10.1.0-4) 10.1.0, GNU ld (GNU Binutils for Debian)
2.34) #1~bullseye+dileks1 SMP 2020-07-06

I see these objtool warnings (which are new to me):

$ grep warning: build-log_5.8.0-rc4-1-amd64-gcc10.txt | sort
arch/x86/kernel/cpu/mce/core.o: warning: objtool: mce_panic()+0x118:
unreachable instruction
drivers/atm/horizon.o: warning: objtool: interrupt_handler()+0x19f:
unreachable instruction
drivers/message/fusion/mptbase.o: warning: objtool:
mpt_Soft_Hard_ResetHandler()+0x33a: unreachable instruction
drivers/scsi/aic7xxx/aic79xx_core.o: warning: objtool:
ahd_intr.part.0()+0x10f: unreachable instruction
drivers/scsi/pcmcia/aha152x_core.o: warning: objtool: run()+0x4c0:
unreachable instruction
fs/btrfs/backref.o: warning: objtool:
btrfs_backref_finish_upper_links()+0x309: unreachable instruction
fs/btrfs/extent_io.o: warning: objtool: __set_extent_bit.cold()+0xc:
unreachable instruction
fs/btrfs/relocation.o: warning: objtool:
update_backref_cache.part.0()+0x1de: unreachable instruction
kernel/exit.o: warning: objtool: __x64_sys_exit_group()+0x14:
unreachable instruction
net/core/skbuff.o: warning: objtool: skb_push.cold()+0x15: unreachable
instruction

I have not checked the Wild Wild Web or any mailing-lists.

Please let me know if you need further informations.

My kernel-config and dmesg-output are attached.

Thanks.

Regards,
- Sedat -

View attachment "dmesg-T_5.8.0-rc4-1-amd64-gcc10.txt" of type "text/plain" (70586 bytes)

Download attachment "config-5.8.0-rc4-1-amd64-gcc10" of type "application/octet-stream" (232894 bytes)