linux-kernel - [PATCH 3/4] drivers/xen/xenbus: Fix split() section placement with AutoFDO

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Message-ID: <92a194234a0f757765e275b288bb1a7236c2c35c.1762991150.git.jpoimboe@kernel.org>
Date: Wed, 12 Nov 2025 15:47:50 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	live-patching@...r.kernel.org,
	Juergen Gross <jgross@...e.com>
Subject: [PATCH 3/4] drivers/xen/xenbus: Fix split() section placement with AutoFDO

When compiling the kernel with -ffunction-sections enabled, the split()
function gets compiled into the .text.split section.  In some cases it
can even be cloned into .text.split.constprop.0 or .text.split.isra.0.

However, .text.split.* is already reserved for use by the Clang
-fsplit-machine-functions flag, which is used by AutoFDO.  That may
place part of a function's code in a .text.split.<func> section.

This naming conflict causes the vmlinux linker script to wrongly place
split() with other .text.split.* code, rather than where it belongs with
regular text.

Fix it by renaming split() to split_strings().

Cc: Juergen Gross <jgross@...e.com>
Fixes: 6568f14cb5ae ("vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN")
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 drivers/xen/xenbus/xenbus_xs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index 528682bf0c7f..f794014814be 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -410,7 +410,7 @@ static char *join(const char *dir, const char *name)
 	return (!buffer) ? ERR_PTR(-ENOMEM) : buffer;
 }
 
-static char **split(char *strings, unsigned int len, unsigned int *num)
+static char **split_strings(char *strings, unsigned int len, unsigned int *num)
 {
 	char *p, **ret;
 
@@ -448,7 +448,7 @@ char **xenbus_directory(struct xenbus_transaction t,
 	if (IS_ERR(strings))
 		return ERR_CAST(strings);
 
-	return split(strings, len, num);
+	return split_strings(strings, len, num);
 }
 EXPORT_SYMBOL_GPL(xenbus_directory);
 
-- 
2.51.1