From: David Laight <david.laight.linux@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Josh Poimboeuf" <jpoimboe@kernel.org>,
"Arnd Bergmann" <arnd@kernel.org>,
"Masahiro Yamada" <masahiroy@kernel.org>,
"Rae Moar" <rmoar@google.com>,
"Shuah Khan" <skhan@linuxfoundation.org>,
"Sergio González Collado" <sergio.collado@gmail.com>,
"David Gow" <davidgow@google.com>,
"Nathan Chancellor" <nathan@kernel.org>,
"Nicolas Schier" <nicolas.schier@linux.dev>,
"Mostafa Saleh" <smostafa@google.com>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] scripts/mksysmap: skip objtool __pfx_ symbols
Date: Tue, 15 Apr 2025 18:39:34 +0100 [thread overview]
Message-ID: <20250415183934.46f4ed6f@pumpkin> (raw)
In-Reply-To: <20250412102218.560196c0@batman.local.home>
On Sat, 12 Apr 2025 10:22:18 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
...
> I just hit this on my allyesconfig build:
>
> NM .tmp_vmlinux1.syms
> KSYMS .tmp_vmlinux1.kallsyms.S
> Symbol __cfi_snnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7n too long for kallsyms (517 >= 512).
> Please increase KSYM_NAME_LEN both in kernel and kallsyms.c
...
>
> I grepped for that symbol and it lives in: lib/tests/longest_symbol_kunit.o
Looks like it is carefully counted to be 511 characters.
And then the compiler adds __cfi_ making 517.
I guess the test could be changed?
Is it possible to remove the __cfi_ symbols (to save kernel memory) and then
use a single bit to indicate that the previous few bytes (the same number for
all such symbols) belong to the following symbol?
Then stack backtraces would say "foo-n" instead "__cfi_foo+n".
David
prev parent reply other threads:[~2025-04-15 17:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-28 10:48 [PATCH] scripts/mksysmap: skip objtool __pfx_ symbols Arnd Bergmann
2025-04-09 1:58 ` Josh Poimboeuf
2025-04-11 6:50 ` Peter Zijlstra
2025-04-11 7:47 ` Arnd Bergmann
2025-04-11 10:58 ` Peter Zijlstra
2025-04-12 14:22 ` Steven Rostedt
2025-04-13 2:22 ` Nathan Chancellor
2025-04-15 17:39 ` David Laight [this message]
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