Building the Linux kernel with Clang and LLVM
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From: Rosen Penev <rosenp@gmail.com>
To: sparclinux@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
	Andreas Larsson <andreas@gaisler.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	linux-kernel@vger.kernel.org (open list),
	llvm@lists.linux.dev (open list:CLANG/LLVM BUILD
	SUPPORT:Keyword:\b(?i:clang|llvm)\b)
Subject: [PATCH] sparc: Export mcount for Clang-built modules
Date: Thu,  7 May 2026 19:11:19 -0700	[thread overview]
Message-ID: <20260508021119.1635054-1-rosenp@gmail.com> (raw)

Clang emits calls to mcount for -pg on sparc64, while the
existing ftrace support only exports the _mcount name. With
FUNCTION_TRACER enabled, modules can therefore keep relocations
against mcount and fail during modpost:

  ERROR: modpost: "mcount" [arch/sparc/kernel/chmc.ko] undefined!

_mcount and mcount are aliases in arch/sparc/lib/mcount.S. Export
the plain mcount alias as well so Clang-built modules can resolve
their profiling call target.

Assisted-by: Codex:GPT-5
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 arch/sparc/lib/mcount.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sparc/lib/mcount.S b/arch/sparc/lib/mcount.S
index f7f7910eb41e..0309ba2c4712 100644
--- a/arch/sparc/lib/mcount.S
+++ b/arch/sparc/lib/mcount.S
@@ -21,6 +21,7 @@
 	EXPORT_SYMBOL(_mcount)
 	.globl		mcount
 	.type		mcount,#function
+	EXPORT_SYMBOL(mcount)
 _mcount:
 mcount:
 #ifdef CONFIG_FUNCTION_TRACER
-- 
2.54.0


                 reply	other threads:[~2026-05-08  2:11 UTC|newest]

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