Live Patching
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From: George Guo <dongtai.guo@linux.dev>
To: chenhuacai@kernel.org, jpoimboe@kernel.org, peterz@infradead.org,
	jikos@kernel.org, mbenes@suse.cz, pmladek@suse.com
Cc: kernel@xen0n.name, joe.lawrence@redhat.com, rostedt@goodmis.org,
	ardb@kernel.org, nathan@kernel.org,
	nick.desaulniers+lkml@gmail.com, yangtiezhu@loongson.cn,
	jiaxun.yang@flygoat.com, wangrui@loongson.cn,
	liukexin@kylinos.cn, guodongtai@kylinos.cn, xry111@xry111.site,
	wangyuli@aosc.io, loongarch@lists.linux.dev,
	live-patching@vger.kernel.org, llvm@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 12/14] objtool/LoongArch: Enable inline alternative cloning for KLP
Date: Fri, 24 Jul 2026 19:41:25 +0800	[thread overview]
Message-ID: <20260724114128.31451-13-dongtai.guo@linux.dev> (raw)
In-Reply-To: <20260724114128.31451-1-dongtai.guo@linux.dev>

From: George Guo <guodongtai@kylinos.cn>

An ALTERNATIVE() emits its replacement instructions into a .subsection 1
placed after the patched function.  When objtool clones the function into
a livepatch module, clone_inline_alternatives() clones that replacement
block too, but only for architectures that define ARCH_HAS_INLINE_ALTS.

LoongArch uses the same .subsection layout as arm64, and its alternative
macros now mark the replacement with ANNOTATE_DATA_SPECIAL (see "LoongArch:
Mark special sections for KLP support").  Define ARCH_HAS_INLINE_ALTS so
the replacement is cloned; otherwise a livepatch for a function containing
an ALTERNATIVE() fails to build with "can't find new instruction".

Reproduced by building a livepatch for a function containing an
ALTERNATIVE() (the base-vmlinux test).
Link: https://lore.kernel.org/all/ak7QBSm3mmDlB-4u@redhat.com

Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
 tools/objtool/arch/loongarch/include/arch/elf.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/objtool/arch/loongarch/include/arch/elf.h b/tools/objtool/arch/loongarch/include/arch/elf.h
index 0103f27fccfc..e2843679f24e 100644
--- a/tools/objtool/arch/loongarch/include/arch/elf.h
+++ b/tools/objtool/arch/loongarch/include/arch/elf.h
@@ -46,6 +46,7 @@
 #define R_TEXT32		R_LARCH_32_PCREL
 #define R_TEXT64		R_LARCH_32_PCREL
 
+#define ARCH_HAS_INLINE_ALTS	1
 #define ARCH_HAS_PAIRED_RELOCS	1
 
 struct elf;
-- 
2.53.0


  parent reply	other threads:[~2026-07-24 11:45 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-24 11:41 [PATCH v4 00/14] LoongArch: Add livepatch build (KLP) support George Guo
2026-07-24 11:41 ` [PATCH v4 01/14] objtool/LoongArch: Add arch_adjusted_addend() for KLP support George Guo
2026-07-24 11:41 ` [PATCH v4 02/14] LoongArch: Mark special sections " George Guo
2026-07-24 11:41 ` [PATCH v4 03/14] livepatch/klp-build: use -fPIC and drop direct-extern-access on LoongArch George Guo
2026-07-24 11:41 ` [PATCH v4 04/14] LoongArch: Fix EFI linking with -fdata-sections George Guo
2026-07-24 11:41 ` [PATCH v4 05/14] objtool/klp: Add LoongArch jump opcode bytes support George Guo
2026-07-24 11:41 ` [PATCH v4 06/14] klp-build: Add LoongArch syscall patching macro George Guo
2026-07-24 11:41 ` [PATCH v4 07/14] LoongArch: Add livepatch build (KLP) support George Guo
2026-07-24 11:41 ` [PATCH v4 08/14] LoongArch: Select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY George Guo
2026-07-24 11:41 ` [PATCH v4 09/14] objtool/klp: Convert local label references George Guo
2026-07-24 11:41 ` [PATCH v4 10/14] objtool/klp: Fix ANNOTATE_DATA_SPECIAL parsing for " George Guo
2026-07-24 11:41 ` [PATCH v4 11/14] objtool/klp: Fold LoongArch paired ADD/SUB relocations into PCREL George Guo
2026-07-24 11:41 ` George Guo [this message]
2026-07-24 11:41 ` [PATCH v4 13/14] objtool/klp: Keep LoongArch tablejump annotation table entries George Guo
2026-07-24 11:41 ` [PATCH v4 14/14] objtool/klp: Rewrite PC-relative data references to GOT on LoongArch George Guo

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