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Subject[PATCH v12 06/21] x86/stacktool: Add ignore macros
Date
Add new stacktool ignore macros: STACKTOOL_IGNORE_INSN and
STACKTOOL_IGNORE_FUNC. These can be used to tell stacktool to skip
validation of an instruction or a function, respectively.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/include/asm/stacktool.h | 45 ++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/vmlinux.lds.S | 5 ++++-
include/linux/stacktool.h | 29 ++++++++++++++++++++++++++
3 files changed, 78 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/include/asm/stacktool.h
create mode 100644 include/linux/stacktool.h

diff --git a/arch/x86/include/asm/stacktool.h b/arch/x86/include/asm/stacktool.h
new file mode 100644
index 0000000..250a37e
--- /dev/null
+++ b/arch/x86/include/asm/stacktool.h
@@ -0,0 +1,45 @@
+#ifndef _ASM_X86_STACKTOOL_H
+#define _ASM_X86_STACKTOOL_H
+
+#include <asm/asm.h>
+
+#ifdef __ASSEMBLY__
+
+/*
+ * This asm macro tells stacktool to ignore the instruction immediately after
+ * the macro 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.
+ */
+.macro STACKTOOL_IGNORE_INSN
+#ifdef CONFIG_STACK_VALIDATION
+ .Lstacktool_ignore_\@:
+ .pushsection __stacktool_ignore_insn, "a"
+ _ASM_ALIGN
+ .long .Lstacktool_ignore_\@ - .
+ .popsection
+#endif
+.endm
+
+#else /* !__ASSEMBLY__ */
+
+#ifdef CONFIG_STACK_VALIDATION
+
+#define STACKTOOL_IGNORE_INSN \
+ "1:\n" \
+ ".pushsection __stacktool_ignore_insn, \"a\"\n" \
+ _ASM_ALIGN "\n" \
+ ".long 1b - .\n" \
+ ".popsection\n"
+
+#else /* !CONFIG_STACK_VALIDATION */
+
+#define STACKTOOL_IGNORE_INSN ""
+
+#endif /* CONFIG_STACK_VALIDATION */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_STACKTOOL_H */
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 00bf300..4891aeb 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -332,7 +332,10 @@ 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..c1e151b
--- /dev/null
+++ b/include/linux/stacktool.h
@@ -0,0 +1,29 @@
+#ifndef _LINUX_STACKTOOL_H
+#define _LINUX_STACKTOOL_H
+
+#include <asm/stacktool.h>
+
+#ifndef __ASSEMBLY__
+
+#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 /* !__ASSEMBLY__ */
+
+#endif /* _LINUX_STACKTOOL_H */
--
2.4.3


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