linux-kernel - [tip: objtool/core] drivers/xen/xenbus: Fix namespace collision and split() section placement with AutoFDO

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Message-ID: <176301773408.498.8502811332308425737.tip-bot2@tip-bot2>
Date: Thu, 13 Nov 2025 07:08:54 -0000
From: "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Josh Poimboeuf <jpoimboe@...nel.org>, Ingo Molnar <mingo@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>, live-patching@...r.kernel.org,
 Juergen Gross <jgross@...e.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: objtool/core] drivers/xen/xenbus: Fix namespace collision and
 split() section placement with AutoFDO

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     0330b7fbbf313b35470306a492b9e7a703b5af56
Gitweb:        https://git.kernel.org/tip/0330b7fbbf313b35470306a492b9e7a703b5af56
Author:        Josh Poimboeuf <jpoimboe@...nel.org>
AuthorDate:    Wed, 12 Nov 2025 15:47:50 -08:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Thu, 13 Nov 2025 08:03:10 +01:00

drivers/xen/xenbus: Fix namespace collision and 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().

Fixes: 6568f14cb5ae ("vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN")
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: live-patching@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Link: https://patch.msgid.link/92a194234a0f757765e275b288bb1a7236c2c35c.1762991150.git.jpoimboe@kernel.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 528682b..f794014 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);