[PATCH 3/8] LoongArch: Add special section entry sizes for KLP support

George Guo <[email protected]> Thu, 4 Jun 2026 14:53:12 +0800
Newsgroups	org.kernel.vger.live-patching,dev.linux.lists.llvm,dev.linux.lists.loongarch,org.kernel.vger.linux-kernel
Message-ID	<[email protected]>
From: George Guo <[email protected]>

Define entry sizes for .altinstructions, __ex_table, __bug_table, and
__jump_table sections to enable objtool to process livepatch modules
on LoongArch.

Co-developed-by: Kexin Liu <[email protected]>
Signed-off-by: Kexin Liu <[email protected]>
Signed-off-by: George Guo <[email protected]>
---
 arch/loongarch/include/asm/alternative-asm.h |  5 +--
 arch/loongarch/include/asm/alternative.h     |  6 ++--
 arch/loongarch/include/asm/asm-extable.h     | 10 ++++--
 arch/loongarch/include/asm/bug.h             | 15 +++++++-
 arch/loongarch/include/asm/jump_label.h      |  9 ++++-
 arch/loongarch/kernel/asm-offsets.c          | 36 ++++++++++++++++++++
 arch/loongarch/kernel/head.S                 |  1 +
 7 files changed, 74 insertions(+), 8 deletions(-)

diff --git a/arch/loongarch/include/asm/alternative-asm.h b/arch/loongarch/include/asm/alternative-asm.h
index 7dc29bd9b2f0..d940d9d2c0e1 100644
--- a/arch/loongarch/include/asm/alternative-asm.h
+++ b/arch/loongarch/include/asm/alternative-asm.h
@@ -5,6 +5,7 @@
 #ifdef __ASSEMBLER__
 
 #include <asm/asm.h>
+#include <generated/asm-offsets.h>
 
 /*
  * Issue one struct alt_instr descriptor entry (need to put it into
@@ -33,7 +34,7 @@
 	.fill - (((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)) / 4, 4, 0x03400000
 142 :
 
-	.pushsection .altinstructions, "a"
+	.pushsection .altinstructions, "aM", @progbits, ALT_INSTR_SIZE
 	altinstruction_entry 140b, 143f, \feature, 142b-140b, 144f-143f
 	.popsection
 
@@ -63,7 +64,7 @@
 		(alt_max_short(new_len1, new_len2) - (old_len)) / 4, 4, 0x03400000
 142 :
 
-	.pushsection .altinstructions, "a"
+	.pushsection .altinstructions, "aM", @progbits, ALT_INSTR_SIZE
 	altinstruction_entry 140b, 143f, \feature1, 142b-140b, 144f-143f, 142b-141b
 	altinstruction_entry 140b, 144f, \feature2, 142b-140b, 145f-144f, 142b-141b
 	.popsection
diff --git a/arch/loongarch/include/asm/alternative.h b/arch/loongarch/include/asm/alternative.h
index b5bae21fb3c8..8f7712ed2f4e 100644
--- a/arch/loongarch/include/asm/alternative.h
+++ b/arch/loongarch/include/asm/alternative.h
@@ -70,7 +70,8 @@ extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
 /* alternative assembly primitive: */
 #define ALTERNATIVE(oldinstr, newinstr, feature)			\
 	OLDINSTR(oldinstr, 1)						\
-	".pushsection .altinstructions,\"a\"\n"				\
+	".pushsection .altinstructions, \"aM\", @progbits, "            \
+		 __stringify(ALT_INSTR_SIZE) "\n"                       \
 	ALTINSTR_ENTRY(feature, 1)					\
 	".popsection\n"							\
 	".subsection 1\n" \
@@ -79,7 +80,8 @@ extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
 
 #define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\
 	OLDINSTR_2(oldinstr, 1, 2)					\
-	".pushsection .altinstructions,\"a\"\n"				\
+	".pushsection .altinstructions, \"aM\", @progbits, "            \
+			__stringify(ALT_INSTR_SIZE) "\n"                \
 	ALTINSTR_ENTRY(feature1, 1)					\
 	ALTINSTR_ENTRY(feature2, 2)					\
 	".popsection\n"							\
diff --git a/arch/loongarch/include/asm/asm-extable.h b/arch/loongarch/include/asm/asm-extable.h
index d60bdf2e6377..2d7eef7c0b39 100644
--- a/arch/loongarch/include/asm/asm-extable.h
+++ b/arch/loongarch/include/asm/asm-extable.h
@@ -7,10 +7,15 @@
 #define EX_TYPE_UACCESS_ERR_ZERO	2
 #define EX_TYPE_BPF			3
 
+#ifndef COMPILE_OFFSETS
+#include <asm/asm-offsets.h>
+#endif
+
 #ifdef __ASSEMBLER__
 
 #define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
-	.pushsection	__ex_table, "a";		\
+	.pushsection    __ex_table, "aM", @progbits,    \
+			EXTABLE_SIZE;                   \
 	.balign		4;				\
 	.long		((insn) - .);			\
 	.long		((fixup) - .);			\
@@ -29,7 +34,8 @@
 #include <asm/gpr-num.h>
 
 #define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
-	".pushsection	__ex_table, \"a\"\n"		\
+	".pushsection   __ex_table, \"aM\", @progbits, "\
+	 __stringify(EXTABLE_SIZE) "\n"                 \
 	".balign	4\n"				\
 	".long		((" insn ") - .)\n"		\
 	".long		((" fixup ") - .)\n"		\
diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
index d090a5bec5eb..c067c858b918 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h
@@ -22,8 +22,20 @@
 #ifndef CONFIG_GENERIC_BUG
 #define __BUG_ENTRY(cond_str, flags)
 #else
+
+#ifdef COMPILE_OFFSETS
+#define __BUG_ENTRY(cond_str, flags)				\
+		.pushsection __bug_table, "awM", @progbits, 0;	\
+		.align 2;					\
+	10000:	.long 10001f - .;				\
+		_BUGVERBOSE_LOCATION(WARN_CONDITION_STR(cond_str) __FILE__, __LINE__) \
+		.short flags;					\
+		.popsection;					\
+	10001:
+#else
+#include <generated/asm-offsets.h>
 #define __BUG_ENTRY(cond_str, flags)				\
-		.pushsection __bug_table, "aw";			\
+		.pushsection __bug_table, "awM", @progbits, BUG_ENTRY_SIZE; \
 		.align 2;					\
 	10000:	.long 10001f - .;				\
 		_BUGVERBOSE_LOCATION(WARN_CONDITION_STR(cond_str) __FILE__, __LINE__) \
@@ -31,6 +43,7 @@
 		.popsection;					\
 	10001:
 #endif
+#endif
 
 #define ASM_BUG_FLAGS(cond_str, flags)				\
 	__BUG_ENTRY(cond_str, flags)				\
diff --git a/arch/loongarch/include/asm/jump_label.h b/arch/loongarch/include/asm/jump_label.h
index 7ef4ae3abf08..26ae644755ea 100644
--- a/arch/loongarch/include/asm/jump_label.h
+++ b/arch/loongarch/include/asm/jump_label.h
@@ -23,9 +23,16 @@
 #define JUMP_LABEL_TYPE		".quad "
 #endif
 
+#ifdef COMPILE_OFFSETS
+#define JUMP_ENTRY_SIZE 0
+#else
+#include <generated/asm-offsets.h>
+#endif
+
 /* This macro is also expanded on the Rust side. */
 #define JUMP_TABLE_ENTRY(key, label)			\
-	 ".pushsection	__jump_table, \"aw\"	\n\t"	\
+	 ".pushsection	__jump_table, \"awM\", @progbits, " \
+			__stringify(JUMP_ENTRY_SIZE) "\n\t" \
 	 ".align	" __stringify(PTRLOG) "	\n\t"	\
 	 ".long		1b - ., " label " - .	\n\t"	\
 	 JUMP_LABEL_TYPE  key " - .		\n\t"	\
diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c
index 2cc953f113ac..42f16e5da06d 100644
--- a/arch/loongarch/kernel/asm-offsets.c
+++ b/arch/loongarch/kernel/asm-offsets.c
@@ -18,6 +18,10 @@
 #include <asm/ftrace.h>
 #include <asm/sigframe.h>
 #include <vdso/datapage.h>
+#include <asm/alternative.h>
+#include <asm/extable.h>
+#include <asm/bug.h>
+#include <asm/jump_label.h>
 
 static void __used output_ptreg_defines(void)
 {
@@ -323,3 +327,35 @@ static void __used output_vdso_defines(void)
 	DEFINE(__VDSO_PAGES, VDSO_NR_PAGES);
 	BLANK();
 }
+
+static void __used output_extable_defines(void)
+{
+	COMMENT("LoongArch exception table entry offsets.");
+
+	DEFINE(EXTABLE_SIZE, sizeof(struct exception_table_entry));
+	BLANK();
+}
+
+static void __used output_alt_instr_defines(void)
+{
+	COMMENT("LoongArch alternative instructions offsets.");
+
+	DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
+	BLANK();
+}
+
+static void __used output_bug_defines(void)
+{
+	COMMENT("LoongArch bug entry offsets.");
+
+	DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));
+	BLANK();
+}
+
+static void __used output_jump_label_defines(void)
+{
+	COMMENT("LoongArch jump entry offsets.");
+
+	DEFINE(JUMP_ENTRY_SIZE, sizeof(struct jump_entry));
+	BLANK();
+}
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index 4eed7bc312a8..a8a2a98e0a5c 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -12,6 +12,7 @@
 #include <asm/regdef.h>
 #include <asm/loongarch.h>
 #include <asm/stackframe.h>
+#include <generated/asm-offsets.h>
 
 #ifdef CONFIG_EFI_STUB
 
-- 
2.25.1