linux-kernel - [PATCH v2 01/62] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text

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Message-ID: <5547e8efe2291df0c8acf06a9bbc8f3129cbe229.1746821544.git.jpoimboe@kernel.org>
Date: Fri,  9 May 2025 13:16:25 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Petr Mladek <pmladek@...e.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	live-patching@...r.kernel.org,
	Song Liu <song@...nel.org>,
	laokz <laokz@...mail.com>,
	Jiri Kosina <jikos@...nel.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Weinan Liu <wnliu@...gle.com>,
	Fazla Mehrab <a.mehrab@...edance.com>,
	Chen Zhongjin <chenzhongjin@...wei.com>,
	Puranjay Mohan <puranjay@...nel.org>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>
Subject: [PATCH v2 01/62] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text

The s390 indirect thunks are placed in the .text.__s390_indirect_jump_*
sections.

Certain config options which enable -ffunction-sections have a custom
version of the TEXT_TEXT macro:

  .text.[0-9a-zA-Z_]*

That unintentionally matches the thunk sections, causing them to get
grouped with normal text rather than being handled by their intended
rule later in the script:

  *(.text.*_indirect_*)

Fix that by adding another period to the thunk section names, following
the kernel's general convention for distinguishing code-generated text
sections from compiler-generated ones.

Cc: Heiko Carstens <hca@...ux.ibm.com>
Cc: Vasily Gorbik <gor@...ux.ibm.com>
Cc: Alexander Gordeev <agordeev@...ux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/s390/include/asm/nospec-insn.h | 2 +-
 arch/s390/kernel/vmlinux.lds.S      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/nospec-insn.h b/arch/s390/include/asm/nospec-insn.h
index cb15dd25bf21..84372c3f313a 100644
--- a/arch/s390/include/asm/nospec-insn.h
+++ b/arch/s390/include/asm/nospec-insn.h
@@ -18,7 +18,7 @@
 #ifdef CONFIG_EXPOLINE_EXTERN
 	SYM_CODE_START(\name)
 #else
-	.pushsection .text.\name,"axG",@progbits,\name,comdat
+	.pushsection .text..\name,"axG",@progbits,\name,comdat
 	.globl \name
 	.hidden \name
 	.type \name,@function
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index ff1ddba96352..fbd6d1f83b67 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -51,7 +51,7 @@ SECTIONS
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
 		FTRACE_HOTPATCH_TRAMPOLINES_TEXT
-		*(.text.*_indirect_*)
+		*(.text..*_indirect_*)
 		*(.gnu.warning)
 		. = ALIGN(PAGE_SIZE);
 		_etext = .;		/* End of text section */
-- 
2.49.0