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From: Arnd Bergmann <arnd@kernel.org>
To: linux-kbuild@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
	David Brazdil <dbrazdil@google.com>,
	Marc Zyngier <maz@kernel.org>,
	Mikhail Petrov <Mikhail.Petrov@mir.dev>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] kallsyms: fix nonconverging kallsyms table with lld
Date: Thu,  4 Feb 2021 16:29:47 +0100	[thread overview]
Message-ID: <20210204152957.1288448-1-arnd@kernel.org> (raw)

From: Arnd Bergmann <arnd@arndb.de>

ARM randconfig builds with lld sometimes show a build failure
from kallsyms:

  Inconsistent kallsyms data
  Try make KALLSYMS_EXTRA_PASS=1 as a workaround

The problem is the veneers/thunks getting added by the linker extend
the symbol table, which in turn leads to more veneers being needed,
so it may take a few extra iterations to converge.

This bug has been fixed multiple times before, but comes back every time
a new symbol name is used. lld uses a different set of idenitifiers from
ld.bfd, so the additional ones need to be added as well.

I looked through the sources and found that arm64 and mips define similar
prefixes, so I'm adding those as well, aside from the ones I observed. I'm
not sure about powerpc64, which seems to already be handled through a
section match, but if it comes back, the "__long_branch_" and "__plt_"
prefixes would have to get added as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 scripts/kallsyms.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 7ecd2ccba531..54ad86d13784 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -112,6 +112,12 @@ static bool is_ignored_symbol(const char *name, char type)
 		"__crc_",		/* modversions */
 		"__efistub_",		/* arm64 EFI stub namespace */
 		"__kvm_nvhe_",		/* arm64 non-VHE KVM namespace */
+		"__AArch64ADRPThunk_",	/* arm64 lld */
+		"__ARMV5PILongThunk_",	/* arm lld */
+		"__ARMV7PILongThunk_",
+		"__ThumbV7PILongThunk_",
+		"__LA25Thunk_",		/* mips lld */
+		"__microLA25Thunk_",
 		NULL
 	};
 
-- 
2.29.2


             reply	other threads:[~2021-02-04 15:32 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-04 15:29 Arnd Bergmann [this message]
2021-02-05  8:41 ` [PATCH] kallsyms: fix nonconverging kallsyms table with lld Masahiro Yamada
2021-06-09 11:05 ` Guenter Roeck
2021-06-09 11:24   ` Arnd Bergmann
2021-06-09 15:16     ` Guenter Roeck
2021-06-09 15:23       ` Arnd Bergmann
2021-06-09 19:15       ` Guenter Roeck
2021-06-09 20:30         ` Arnd Bergmann
2021-06-10 12:05           ` Guenter Roeck
2021-06-10 12:26             ` Arnd Bergmann
2021-06-21 11:47               ` Guenter Roeck

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