[PATCH v3 02/12] LoongArch: Mark special sections for KLP support
From: George Guo <hidden>
Date: 2026-07-07 07:21:49
Also in:
lkml, llvm, loongarch
Subsystem:
loongarch, static branch/call, the rest · Maintainers:
Huacai Chen, Peter Zijlstra, Josh Poimboeuf, Jason Baron, Alice Ryhl, Linus Torvalds
From: George Guo <redacted> objtool needs to split the kernel's special sections into per-entry symbols when generating livepatch modules. Mark them so it can: - .altinstructions and __ex_table are read-only, so set an explicit entry size via SHF_MERGE (ALT_INSTR_SIZE / EXTABLE_SIZE). - __bug_table and __jump_table are writable. SHF_MERGE cannot be combined with SHF_WRITE (Clang rejects it), so annotate each entry with ANNOTATE_DATA_SPECIAL instead, mirroring x86/arm64. Co-developed-by: Kexin Liu <redacted> Signed-off-by: Kexin Liu <redacted> Signed-off-by: George Guo <redacted> --- 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 | 1 + arch/loongarch/include/asm/jump_label.h | 2 ++ arch/loongarch/kernel/asm-offsets.c | 20 ++++++++++++++++++++ 6 files changed, 38 insertions(+), 6 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..14e3acbaad8d 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h@@ -25,6 +25,7 @@ #define __BUG_ENTRY(cond_str, flags) \ .pushsection __bug_table, "aw"; \ .align 2; \ + __ANNOTATE_DATA_SPECIAL; \ 10000: .long 10001f - .; \ _BUGVERBOSE_LOCATION(WARN_CONDITION_STR(cond_str) __FILE__, __LINE__) \ .short flags; \
diff --git a/arch/loongarch/include/asm/jump_label.h b/arch/loongarch/include/asm/jump_label.h
index 7ef4ae3abf08..d20f0fa24b6b 100644
--- a/arch/loongarch/include/asm/jump_label.h
+++ b/arch/loongarch/include/asm/jump_label.h@@ -12,6 +12,7 @@ #include <linux/types.h> #include <linux/stringify.h> #include <asm/asm.h> +#include <linux/objtool.h> #define HAVE_JUMP_LABEL_BATCH
@@ -27,6 +28,7 @@ #define JUMP_TABLE_ENTRY(key, label) \ ".pushsection __jump_table, \"aw\" \n\t" \ ".align " __stringify(PTRLOG) " \n\t" \ + ANNOTATE_DATA_SPECIAL "\n\t" \ ".long 1b - ., " label " - . \n\t" \ JUMP_LABEL_TYPE key " - . \n\t" \ ".popsection \n\t"
diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c
index 2cc953f113ac..470323aa022c 100644
--- a/arch/loongarch/kernel/asm-offsets.c
+++ b/arch/loongarch/kernel/asm-offsets.c@@ -18,6 +18,8 @@ #include <asm/ftrace.h> #include <asm/sigframe.h> #include <vdso/datapage.h> +#include <asm/alternative.h> +#include <asm/extable.h> static void __used output_ptreg_defines(void) {
@@ -323,3 +325,21 @@ 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(); +} + +
--
2.25.1