2019-11-09 23:07:27

by Jeffrin Thalakkottoor

[permalink] [raw]
Subject: objtool: skb_push.cold()+0x15: unreachable instruction

hello,

i got a warning during kernel compilation.

net/core/skbuff.o: warning: objtool: skb_push.cold()+0x15: unreachable instruction

related clips...

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(gdb) l skb_push.cold
1880 void *skb_push(struct sk_buff *skb, unsigned int len)
1881 {
1882 skb->data -= len;
1883 skb->len += len;
1884 if (unlikely(skb->data < skb->head))
1885 skb_under_panic(skb, len, __builtin_return_address(0));
1886 return skb->data;
1887 }
1888 EXPORT_SYMBOL(skb_push);
1889
(gdb) l *0xffffffff815ffc8e
0xffffffff815ffc8e is in skb_push (net/core/skbuff.c:1885).
1880 void *skb_push(struct sk_buff *skb, unsigned int len)
1881 {
1882 skb->data -= len;
1883 skb->len += len;
1884 if (unlikely(skb->data < skb->head))
1885 skb_under_panic(skb, len, __builtin_return_address(0));
1886 return skb->data;
1887 }
1888 EXPORT_SYMBOL(skb_push);
1889
(gdb)

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$uname -a
Linux debian 5.4.0-rc1+ #1 SMP Sat Nov 9 21:29:48 IST 2019 x86_64 GNU/Linux
$

this kernel is from linux-kselftest tree

---------------------------x-------------x------------------------------

$gcc --version
gcc (Debian 9.2.1-14) 9.2.1 20191025
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

-------------------------x-------------------x-----------------------------

Linux debian 5.4.0-rc1+ #1 SMP Sat Nov 9 21:29:48 IST 2019 x86_64 GNU/Linux

GNU Make 4.2.1
Binutils 2.33.1
Util-linux 2.33.1
Mount 2.33.1
Linux C Library 2.29
Dynamic linker (ldd) 2.29
Procps 3.3.15
Kbd 2.0.4
Console-tools 2.0.4
Sh-utils 8.30
Udev 241

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--
software engineer
rajagiri school of engineering and technology