linux-kernel - Re: [PATCH] kgdbts: Switch to do_sys

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Date:   Sun, 28 Mar 2021 14:40:02 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Douglas Anderson <dianders@...omium.org>,
        Jason Wessel <jason.wessel@...driver.com>,
        kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kgdbts: Switch to do_sys_openat2() for breakpoint testing

On Thu, Mar 25, 2021 at 09:48:07AM +0000, Daniel Thompson wrote:
> Currently kgdbts can get stuck waiting for do_sys_open() to be called
> in some of the current tests. This is because C compilers often
> automatically inline this function, which is a very thin wrapper around
> do_sys_openat2(), into some of its callers. gcc-10 does this on (at least)
> both x86 and arm64.
> 
> We can fix the test suite by placing the breakpoints on do_sys_openat2()
> instead since that isn't (currently) inlined. However do_sys_openat2() is
> a static function so we cannot simply use an addressof. Since we are
> testing debug machinery it is acceptable to use kallsyms to lookup a
> suitable address because this is more or less what kdb does in the same
> circumstances. Re-implement lookup_addr() to be based on kallsyms rather
> than function pointers.
> 
> Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>
> ---
> 
> Notes:
>     So less than a week ago I said I had nothing pending for kgdbts.
>     That was entirely true when I said it... but then this came up.

No worries, I'll take this too :)

thanks,

greg k-h