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Tue, 01 Sep 2026 00:23:41 -0700 (PDT) Date: Tue, 1 Sep 2026 09:23:37 +0200 From: Petr Mladek To: Steven Rostedt Cc: Sebastian Andrzej Siewior , Thomas Gleixner , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Andrew Morton , Andy Shevchenko , Kees Cook , Rasmus Villemoes , Sergey Senozhatsky , Tycho Andersen , Linus Torvalds Subject: Re: [PATCH v2 2/2] kallsyms: Document why unresolved symbols are revealed Message-ID: References: <20260821152614.2202196-1-bigeasy@linutronix.de> <20260821152614.2202196-3-bigeasy@linutronix.de> <20260827102411.NsziRXyJ@linutronix.de> <20260831133729.p5ylO7O6@linutronix.de> <20260831124928.22e163ab@gandalf.local.home> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260831124928.22e163ab@gandalf.local.home> On Mon 2026-08-31 12:49:28, Steven Rostedt wrote: > On Mon, 31 Aug 2026 15:37:29 +0200 > Sebastian Andrzej Siewior wrote: > > > Could someone yell here, please? I convinced myself that hiding > > unresolved pointers is the good thing to do here since a "wrong" pointer > > would be seen in backtrace anyway. > > > > Thread starts at > > https://lore.kernel.org/all/20260821152614.2202196-1-bigeasy@linutronix.de/ > > I wonder if we should just tagged hash values as such: > > | [ 1.498171] > | [ 1.498172] 00000000cb9bc262 [hash] > | [ 1.498174] ? 00000000eb5021dd [hash] > | [ 1.498176] 00000000ed1a9938 [hash] > | [ 1.498178] > > So that people will know that the value is just some random hash value and > not a real address. > > Although rather useless in call stacks, I like hash values because the same > address will show up the same. > > Having '[unknown]' may also be confusing because it doesn't really say > "why" it was unknown. But having a number goes back to what it always did. > Hashing it with a "[hash]" marker will also let people know the value was > hashed. I like this idea. I just wonder whether it might confuse some parsers who expect that symbol name is one string. %ps, %pS, %pB are used in various context. I think about adding the hint into the hashed value, e.g. by using 'h' instead of the highest number, something like: [ 1.498171] [ 1.498172] h0000000cb9bc262 [ 1.498174] ? h0000000eb5021dd [ 1.498176] h0000000ed1a9938 [ 1.498178] But 'h' is not a valid number number so it might confuse parsers as well. And it is not that user friedly either. So, I still like more Steven's variant with [hash]. Best Regards, Petr