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Message-ID: <2325294d8e67f7a71fcb65f39c9418c2b0034657.1758067943.git.jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:54 -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>,
Dylan Hatch <dylanbhatch@...gle.com>,
Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH v4 46/63] objtool: Add ANNOTATE_DATA_SPECIAL
In preparation for the objtool klp diff subcommand, add an
ANNOTATE_DATA_SPECIAL macro which annotates special section entries so
that objtool can determine their size and location and extract them
when needed.
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
include/linux/annotate.h | 49 ++++++++++++++++++++++-------
include/linux/objtool_types.h | 2 ++
tools/include/linux/objtool_types.h | 2 ++
3 files changed, 41 insertions(+), 12 deletions(-)
diff --git a/include/linux/annotate.h b/include/linux/annotate.h
index ccb445496331c..7c10d34d198cf 100644
--- a/include/linux/annotate.h
+++ b/include/linux/annotate.h
@@ -8,34 +8,52 @@
#ifndef __ASSEMBLY__
-#define __ASM_ANNOTATE(label, type) \
- ".pushsection .discard.annotate_insn,\"M\",@progbits,8\n\t" \
+#define __ASM_ANNOTATE(section, label, type) \
+ ".pushsection " section ",\"M\", @progbits, 8\n\t" \
".long " __stringify(label) " - .\n\t" \
".long " __stringify(type) "\n\t" \
".popsection\n\t"
+#define ASM_ANNOTATE_LABEL(label, type) \
+ __ASM_ANNOTATE(".discard.annotate_insn", label, type)
+
#define ASM_ANNOTATE(type) \
"911:\n\t" \
- __ASM_ANNOTATE(911b, type)
+ ASM_ANNOTATE_LABEL(911b, type)
+
+#define ASM_ANNOTATE_DATA(type) \
+ "912:\n\t" \
+ __ASM_ANNOTATE(".discard.annotate_data", 912b, type)
#else /* __ASSEMBLY__ */
-.macro ANNOTATE type:req
+.macro __ANNOTATE section, type
.Lhere_\@:
- .pushsection .discard.annotate_insn,"M",@progbits,8
+ .pushsection \section, "M", @progbits, 8
.long .Lhere_\@ - .
.long \type
.popsection
.endm
+.macro ANNOTATE type
+ __ANNOTATE ".discard.annotate_insn", \type
+.endm
+
+.macro ANNOTATE_DATA type
+ __ANNOTATE ".discard.annotate_data", \type
+.endm
+
#endif /* __ASSEMBLY__ */
#else /* !CONFIG_OBJTOOL */
#ifndef __ASSEMBLY__
-#define __ASM_ANNOTATE(label, type) ""
+#define ASM_ANNOTATE_LABEL(label, type) ""
#define ASM_ANNOTATE(type)
+#define ASM_ANNOTATE_DATA(type)
#else /* __ASSEMBLY__ */
-.macro ANNOTATE type:req
+.macro ANNOTATE type
+.endm
+.macro ANNOTATE_DATA type
.endm
#endif /* __ASSEMBLY__ */
#endif /* !CONFIG_OBJTOOL */
@@ -47,7 +65,7 @@
* these relocations will never be used for indirect calls.
*/
#define ANNOTATE_NOENDBR ASM_ANNOTATE(ANNOTYPE_NOENDBR)
-#define ANNOTATE_NOENDBR_SYM(sym) asm(__ASM_ANNOTATE(sym, ANNOTYPE_NOENDBR))
+#define ANNOTATE_NOENDBR_SYM(sym) asm(ASM_ANNOTATE_LABEL(sym, ANNOTYPE_NOENDBR))
/*
* This should be used immediately before an indirect jump/call. It tells
@@ -58,8 +76,8 @@
/*
* See linux/instrumentation.h
*/
-#define ANNOTATE_INSTR_BEGIN(label) __ASM_ANNOTATE(label, ANNOTYPE_INSTR_BEGIN)
-#define ANNOTATE_INSTR_END(label) __ASM_ANNOTATE(label, ANNOTYPE_INSTR_END)
+#define ANNOTATE_INSTR_BEGIN(label) ASM_ANNOTATE_LABEL(label, ANNOTYPE_INSTR_BEGIN)
+#define ANNOTATE_INSTR_END(label) ASM_ANNOTATE_LABEL(label, ANNOTYPE_INSTR_END)
/*
* objtool annotation to ignore the alternatives and only consider the original
* instruction(s).
@@ -83,7 +101,7 @@
* terminating, like a noreturn CALL or UD2 when we know they are not -- eg
* WARN using UD2.
*/
-#define ANNOTATE_REACHABLE(label) __ASM_ANNOTATE(label, ANNOTYPE_REACHABLE)
+#define ANNOTATE_REACHABLE(label) ASM_ANNOTATE_LABEL(label, ANNOTYPE_REACHABLE)
/*
* This should not be used; it annotates away CFI violations. There are a few
* valid use cases like kexec handover to the next kernel image, and there is
@@ -92,7 +110,13 @@
* There are also a few real issues annotated away, like EFI because we can't
* control the EFI code.
*/
-#define ANNOTATE_NOCFI_SYM(sym) asm(__ASM_ANNOTATE(sym, ANNOTYPE_NOCFI))
+#define ANNOTATE_NOCFI_SYM(sym) asm(ASM_ANNOTATE_LABEL(sym, ANNOTYPE_NOCFI))
+
+/*
+ * Annotate a special section entry. This emables livepatch module generation
+ * to find and extract individual special section entries as needed.
+ */
+#define ANNOTATE_DATA_SPECIAL ASM_ANNOTATE_DATA(ANNOTYPE_DATA_SPECIAL)
#else /* __ASSEMBLY__ */
#define ANNOTATE_NOENDBR ANNOTATE type=ANNOTYPE_NOENDBR
@@ -104,6 +128,7 @@
#define ANNOTATE_UNRET_BEGIN ANNOTATE type=ANNOTYPE_UNRET_BEGIN
#define ANNOTATE_REACHABLE ANNOTATE type=ANNOTYPE_REACHABLE
#define ANNOTATE_NOCFI_SYM ANNOTATE type=ANNOTYPE_NOCFI
+#define ANNOTATE_DATA_SPECIAL ANNOTATE_DATA type=ANNOTYPE_DATA_SPECIAL
#endif /* __ASSEMBLY__ */
#endif /* _LINUX_ANNOTATE_H */
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index aceac94632c8a..c6def4049b1ae 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -67,4 +67,6 @@ struct unwind_hint {
#define ANNOTYPE_REACHABLE 8
#define ANNOTYPE_NOCFI 9
+#define ANNOTYPE_DATA_SPECIAL 1
+
#endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index aceac94632c8a..c6def4049b1ae 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -67,4 +67,6 @@ struct unwind_hint {
#define ANNOTYPE_REACHABLE 8
#define ANNOTYPE_NOCFI 9
+#define ANNOTYPE_DATA_SPECIAL 1
+
#endif /* _LINUX_OBJTOOL_TYPES_H */
--
2.50.0
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