Re: memcmp in modules

From: Tetsuo Handa
Date: Mon Apr 22 2013 - 10:26:26 EST


Andy Shevchenko wrote:
> What did I miss?

Well, as of linux-next-20130422, memcmp() is not correctly exported to modules.
Since linux-3.9-rc8 correctly exports memcmp(), this problem seems to be introduced
in linux-next tree. Also, this problem seems to involve CONFIG_MODVERSIONS=y.

[root@localhost linux-next]# modprobe ipv6
FATAL: Error inserting ipv6 (/lib/modules/3.9.0-rc8-next-20130422/kernel/net/ipv6/ipv6.ko): Invalid argument
[root@localhost linux-next]# dmesg
ipv6: no symbol version for memcmp
ipv6: Unknown symbol memcmp (err -22)

Since arch/x86/include/asm/string_64.h uses

int memcmp(const void *cs, const void *ct, size_t count);

while arch/x86/include/asm/string_32.h uses

#define memcmp __builtin_memcmp

changing to what you have tried

#define memcmp(a, b, n) __builtin_memcmp(a, b, n)

or changing to what x86_64 does

int memcmp(const void *cs, const void *ct, size_t count);

might solve this problem. But I don't know which one is correct solution...
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