linux-kernel - [PATCH 04/33] x86/stacktool: Add STACKTOOL_IGNORE

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Message-Id: <6b0446091a9cc4ceefef7845cf660a755e0d4239.1453405861.git.jpoimboe@redhat.com>
Date:	Thu, 21 Jan 2016 16:49:08 -0600
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:	linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
	Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Pedro Alves <palves@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
	Chris J Arges <chris.j.arges@...onical.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: [PATCH 04/33] x86/stacktool: Add STACKTOOL_IGNORE_FUNC macro

Add a new stacktool ignore macro, STACKTOOL_IGNORE_FUNC, which can be
used to tell stacktool to skip validation of a function.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 MAINTAINERS                   |  1 +
 arch/x86/kernel/vmlinux.lds.S |  5 ++++-
 include/linux/stacktool.h     | 23 +++++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 include/linux/stacktool.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 7ecbea9..80b26ec 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10190,6 +10190,7 @@ STACK METADATA VALIDATION
 M:	Josh Poimboeuf <jpoimboe@...hat.com>
 S:	Supported
 F:	tools/stacktool/
+F:	include/linux/stacktool.h
 
 STAGING SUBSYSTEM
 M:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 4f19942..c08c283c 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -333,7 +333,10 @@ SECTIONS
 
 	/* Sections to be discarded */
 	DISCARDS
-	/DISCARD/ : { *(.eh_frame) }
+	/DISCARD/ : {
+		*(.eh_frame)
+		*(__stacktool_ignore_*)
+	}
 }
 
 
diff --git a/include/linux/stacktool.h b/include/linux/stacktool.h
new file mode 100644
index 0000000..0d90db7
--- /dev/null
+++ b/include/linux/stacktool.h
@@ -0,0 +1,23 @@
+#ifndef _LINUX_STACKTOOL_H
+#define _LINUX_STACKTOOL_H
+
+#ifdef CONFIG_STACK_VALIDATION
+/*
+ * This C macro tells stacktool to ignore the function when doing stack
+ * metadata validation.  It should only be used in special cases where you're
+ * 100% sure it won't affect the reliability of frame pointers and kernel stack
+ * traces.
+ *
+ * For more information, see tools/stacktool/Documentation/stack-validation.txt.
+ */
+#define STACKTOOL_IGNORE_FUNC(_func) \
+	static void __used __section(__stacktool_ignore_func) \
+		*__stacktool_ignore_func_##_func = _func
+
+#else /* !CONFIG_STACK_VALIDATION */
+
+#define STACKTOOL_IGNORE_FUNC(_func)
+
+#endif /* CONFIG_STACK_VALIDATION */
+
+#endif /* _LINUX_STACKTOOL_H */
-- 
2.4.3