From: Borislav Petkov <bp@alien8.de>
Date: Thu, 23 Dec 2021 17:19:06 +0100

On Thu, Dec 23, 2021 at 01:21:55AM +0100, Alexander Lobakin wrote:

quoted

For now, that condition from remove_dot():

if (m && (s[n + m] == '.' || s[n + m] == 0))

which was designed to test if it's a dot or a \0 after the suffix
is never satisfied.
This is due to that s[n + m] always points to the last digit of a
numeric suffix, not on the symbol next to it:

param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0'

So it's off by one and was like that since 2014.

What's the relevance of this? Looking at

  7d02b490e93c ("Kbuild, lto: Drop .number postfixes in modpost")

what you're fixing here is something LTO-related. How do you trigger
this?

It's just a couple lines below. I trigger this using `-z uniq-symbol`
which uses numeric suffixes for globals as well.

For a Cc:stable patch, I'm missing a lot of context.

It fixes a commit dated 2014, thus Cc:stable. Although the
remove_dot() might've been introduced for neverlanded GCC LTO, but
in fact numeric suffixes are used a lot by the toolchains in regular
builds as well. Just not for globals, that's why it's "well hidden".

quoted

`-z uniq-symbol` linker flag which we are planning to use to

				     ^^

Who's "we"?

I thought it's a common saying in commit messages, isn't it?

quoted

simplify livepatching brings numeric suffixes back, fix this.
Otherwise:

ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL

Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning")
Cc: stable@vger.kernel.org # 3.17+
Signed-off-by: Alexander Lobakin <redacted>

...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Thanks,
Al