linux-kernel - [PATCH v3] modpost: Skip .llvm.call-graph-profile section check

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Message-ID: <20230825072744.1322656-1-denik@chromium.org>
Date:   Fri, 25 Aug 2023 00:27:43 -0700
From:   Denis Nikitin <denik@...omium.org>
To:     linux-kbuild@...r.kernel.org
Cc:     denik@...omium.org, Fangrui Song <maskray@...gle.com>,
        Douglas Anderson <dianders@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nicolas Schier <nicolas@...sle.eu>, Tom Rix <trix@...hat.com>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH v3] modpost: Skip .llvm.call-graph-profile section check

.llvm.call-graph-profile section is added by clang when the kernel is
built with profiles (e.g. -fprofile-sample-use= or -fprofile-use=).
Note that .llvm.call-graph-profile intentionally uses REL relocations
to decrease the object size, for more details see
https://reviews.llvm.org/D104080.

The section contains edge information derived from text sections,
so .llvm.call-graph-profile itself doesn't need more analysis as
the text sections have been analyzed.

This change fixes the kernel build with clang and a sample profile
which currently fails with:

"FATAL: modpost: Please add code to calculate addend for this architecture"

Signed-off-by: Denis Nikitin <denik@...omium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Reviewed-by: Fangrui Song <maskray@...gle.com>
---
 scripts/mod/modpost.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index b29b29707f10..64bd13f7199c 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -761,6 +761,7 @@ static const char *const section_white_list[] =
 	".fmt_slot*",			/* EZchip */
 	".gnu.lto*",
 	".discard.*",
+	".llvm.call-graph-profile",	/* call graph */
 	NULL
 };
 
-- 
2.42.0.rc1.204.g551eb34607-goog