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From: Dave Hansen <dave.hansen@intel.com>
To: Nadav Amit <nadav.amit@gmail.com>, Borislav Petkov <bp@alien8.de>
Cc: Jiri Slaby <jirislaby@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] x86/lib: Do not use local symbols with SYM_CODE_START_LOCAL()
Date: Fri, 26 May 2023 14:17:20 -0700	[thread overview]
Message-ID: <e6cd1909-2776-28d2-ccc0-4b3d2d09e9ce@intel.com> (raw)
In-Reply-To: <D63AB9E6-BA52-4E24-B8EF-C7B9DB1595CC@gmail.com>

On 5/26/23 14:10, Nadav Amit wrote:
>>> I did not ask to make them global. Just to keep them as local after
>>> linkage in the executable, like all other functions in the kernel.
>> Ok, not global. But local and present in the symbol table:
>>
>> 105185: ffffffff81b89330    17 NOTYPE  LOCAL  DEFAULT    1 bad_get_user_clac
>>
>> And again, this helps how exactly?
> Allowing debuggers, tracers, disassemblers and instrumentation tools to
> work the same way they work as they work with any other piece of code in
> the kernel.
> 
> I personally work on code instrumentation and this makes my life hard for
> no good reason.
> 
> [ Perhaps the question should go the other way around: why addresses of
> code in these functions should not be mapped to any symbol? ]

Nadav, is there a chance you could give us a real-life example of how
this affects you as an end user?  What's a specific tool that you were
using or a specific problem that you were trying to solve where these
local symbols caused a problem?  How would the global symbol have helped?

I can certainly _imagine_ some, but I'm curious what you saw that
prompted you to send this patch.

  reply	other threads:[~2023-05-26 21:17 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-25 18:42 [PATCH v2] x86/lib: Do not use local symbols with SYM_CODE_START_LOCAL() Nadav Amit
2023-05-25 19:05 ` Dave Hansen
2023-05-25 19:39   ` Nadav Amit
2023-05-26  6:24     ` Jiri Slaby
2023-05-26 15:53     ` Borislav Petkov
2023-05-26 17:29       ` Nadav Amit
2023-05-26 20:45         ` Borislav Petkov
2023-05-26 21:10           ` Nadav Amit
2023-05-26 21:17             ` Dave Hansen [this message]
2023-05-26 21:55               ` Nadav Amit
2023-05-27  7:23                 ` Borislav Petkov
2023-05-27  9:17                   ` Nadav Amit
2023-05-27 12:29                     ` Borislav Petkov
2023-05-27 13:09                       ` Nadav Amit
2023-06-02  0:53                       ` Nadav Amit
2023-06-02  8:59 ` [tip: x86/misc] x86/lib: Make get/put_user() exception handling a visible symbol tip-bot2 for Nadav Amit

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