Add LoongArch support for kpatch v2

README.md

@@ -42,6 +42,7 @@ Supported Architectures
 - [x] ppc64le
 - [x] arm64
 - [x] s390 [upstream prerequisites](doc/s390-upstream-prerequisites.md)
+- [x] loongarch64
 
 Installation
 ------------

kpatch-build/Makefile

@@ -21,7 +21,7 @@ PLUGIN_CFLAGS := $(filter-out -std=gnu11 -Wconversion, $(CFLAGS))
 PLUGIN_CFLAGS += -shared -I$(GCC_PLUGINS_DIR)/include \
 		   -Igcc-plugins -fPIC -fno-rtti -O2 -Wall
 endif
-ifeq ($(filter $(ARCH),s390x x86_64 ppc64le aarch64),)
+ifeq ($(filter $(ARCH),s390x x86_64 ppc64le aarch64 loongarch64),)
 $(error Unsupported architecture ${ARCH}, check https://github.com/dynup/kpatch/#supported-architectures)
 endif
 

kpatch-build/create-diff-object.c

@@ -182,6 +182,8 @@ static bool is_gcc6_localentry_bundled_sym(struct kpatch_elf *kelf,
 		return false;
 	case S390:
 		return false;
+	case LOONGARCH64:
+		return false;
 	default:
 		ERROR("unsupported arch");
 	}
@@ -247,6 +249,7 @@ static bool kpatch_is_mapping_symbol(struct kpatch_elf *kelf, struct symbol *sym
 	case X86_64:
 	case PPC64:
 	case S390:
+	case LOONGARCH64:
 		return false;
 	default:
 		ERROR("unsupported arch");
@@ -771,6 +774,11 @@ static bool insn_is_load_immediate(struct kpatch_elf *kelf, void *addr)
 
 		break;
 
+	case LOONGARCH64:
+		/* to be done */
+
+		break;
+
 	case S390:
 		/* arg2: lghi %r3, imm */
 		if (insn[0] == 0xa7 && insn[1] == 0x39)
@@ -2598,22 +2606,22 @@ static bool static_call_sites_group_filter(struct lookup_table *lookup,
 static struct special_section special_sections[] = {
 	{
 		.name		= "__bug_table",
-		.arch		= AARCH64 | X86_64 | PPC64 | S390,
+		.arch		= AARCH64 | X86_64 | PPC64 | S390 | LOONGARCH64,
 		.group_size	= bug_table_group_size,
 	},
 	{
 		.name		= ".fixup",
-		.arch		= AARCH64 | X86_64 | PPC64 | S390,
+		.arch		= AARCH64 | X86_64 | PPC64 | S390 | LOONGARCH64,
 		.group_size	= fixup_group_size,
 	},
 	{
 		.name		= "__ex_table", /* must come after .fixup */
-		.arch		= AARCH64 | X86_64 | PPC64 | S390,
+		.arch		= AARCH64 | X86_64 | PPC64 | S390 | LOONGARCH64,
 		.group_size	= ex_table_group_size,
 	},
 	{
 		.name		= "__jump_table",
-		.arch		= AARCH64 | X86_64 | PPC64 | S390,
+		.arch		= AARCH64 | X86_64 | PPC64 | S390 | LOONGARCH64,
 		.group_size	= jump_table_group_size,
 		.group_filter	= jump_table_group_filter,
 	},
@@ -2634,7 +2642,7 @@ static struct special_section special_sections[] = {
 	},
 	{
 		.name		= ".altinstructions",
-		.arch		= AARCH64 | X86_64 | S390,
+		.arch		= AARCH64 | X86_64 | S390 | LOONGARCH64,
 		.group_size	= altinstructions_group_size,
 	},
 	{
@@ -3057,6 +3065,11 @@ static void kpatch_mark_ignored_sections(struct kpatch_elf *kelf)
 			    !strcmp(sec->name, "__patchable_function_entries"))
 				sec->ignore = 1;
 		}
+
+		if (kelf->arch == LOONGARCH64) {
+			if (!strncmp(sec->name, ".rela.orc_unwind_ip", 19))
+				sec->ignore = 1;
+		}
 	}
 
 	sec = find_section_by_name(&kelf->sections, ".kpatch.ignore.sections");
@@ -4059,6 +4072,21 @@ static void kpatch_create_ftrace_callsite_sections(struct kpatch_elf *kelf)
 			insn_offset = sym->sym.st_value;
 			break;
 		}
+		case LOONGARCH64: {
+			bool found = false;
+			unsigned char *insn = sym->sec->data->d_buf + sym->sym.st_value;
+
+			/* 0x03400000 is NOP instruction for LoongArch. */
+			if (insn[0] == 0x00 && insn[1] == 0x00 && insn[2] == 0x40 && insn[3] == 0x03 &&
+			    insn[4] == 0x00 && insn[5] == 0x00 && insn[6] == 0x40 && insn[7] == 0x03)
+				found = true;
+
+			if (!found)
+				ERROR("%s: unexpected instruction at the start of the function", sym->name);
+
+			insn_offset = 0;
+			break;
+		}
 		default:
 			ERROR("unsupported arch");
 		}
@@ -4317,6 +4345,7 @@ static void kpatch_find_func_profiling_calls(struct kpatch_elf *kelf)
 				sym->has_func_profiling = 1;
 			break;
 		case AARCH64:
+		case LOONGARCH64:
 			if (kpatch_symbol_has_pfe_entry(kelf, sym))
 				sym->has_func_profiling = 1;
 			break;

kpatch-build/kpatch-build

@@ -319,6 +319,17 @@ find_core_symvers() {
 	[[ -e "$SYMVERSFILE" ]]
 }
 
+cc_option_check() {
+	local compiler="$1"
+	local option="$2"
+
+	if "$compiler" -Werror "$option" -c -x c /dev/null -o /dev/null 2>/dev/null; then
+		return 0
+	fi
+
+	return 1
+}
+
 gcc_version_from_file() {
 	"$READELF" -p .comment "$1" | grep -m 1 -o 'GCC:.*'
 }
@@ -341,6 +352,11 @@ gcc_version_check() {
 		return 1
 	fi
 
+	if [[ "$ARCH" = "loongarch64" ]]; then
+		cc_option_check "$GCC" "-mno-direct-extern-access" || \
+			die "gcc version ($gccver) doesn't support -mno-direct-extern-access"
+	fi
+
 	out="$("$GCC" -c -gz=none -o "$o" "$c" 2>&1)"
 	if [[ -z "$out" ]]; then
 		DEBUG_KCFLAGS="-gz=none"
@@ -371,6 +387,11 @@ clang_version_check() {
 	clangver=$("$CLANG" --version | grep -m 1 -Eo 'clang version [0-9.]+')
 	kclangver="$(clang_version_from_file "$target")"
 
+	if [[ "$ARCH" = "loongarch64" ]]; then
+		cc_option_check "$CLANG" "-fno-direct-access-external-data" || \
+			die "clang version ($clangver) doesn't support -fno-direct-access-external-data"
+	fi
+
 	# ensure clang version matches that used to build the kernel
 	if [[ "$clangver" != "$kclangver" ]]; then
 		warn "clang/kernel version mismatch"
@@ -407,6 +428,9 @@ find_special_section_data() {
 		"aarch64")
 			check[a]=true					# alt_instr
 			;;
+		"loongarch64")
+			check[a]=true					# alt_instr
+			;;
 	esac
 
 	# Kernel CONFIG_ features
@@ -1255,6 +1279,7 @@ remove_patches
 cp -LR "$DATADIR/patch" "$TEMPDIR" || die
 chmod -R u+rw "$TEMPDIR" || die
 
+declare -a ARCH_MAKEVARS
 if [[ "$ARCH" = "ppc64le" ]]; then
 	ARCH_KCFLAGS="-mcmodel=large -fplugin=$PLUGINDIR/ppc64le-plugin.so"
 fi
@@ -1264,6 +1289,15 @@ if [[ "$ARCH" = "s390x" ]]; then
 	! kernel_version_gte 6.10.0 && ARCH_KCFLAGS+=" -fPIE"
 fi
 
+if [[ "$ARCH" = "loongarch64" ]]; then
+	ARCH_KCFLAGS="-fPIC"
+	if [[ -n "$CONFIG_CC_IS_CLANG" ]]; then
+		ARCH_MAKEVARS+=("KBUILD_CFLAGS_KERNEL+=-fno-direct-access-external-data")
+	else
+		ARCH_MAKEVARS+=("KBUILD_CFLAGS_KERNEL+=-mno-direct-extern-access")
+	fi
+fi
+
 export KCFLAGS="-I$DATADIR/patch -ffunction-sections -fdata-sections \
 		$ARCH_KCFLAGS $DEBUG_KCFLAGS"
 
@@ -1302,7 +1336,7 @@ fi
 
 # $TARGETS used as list, no quotes.
 # shellcheck disable=SC2086
-make "${MAKEVARS[@]}" "-j$CPUS" $TARGETS 2>&1 | logger || die
+make "${ARCH_MAKEVARS[@]}" "${MAKEVARS[@]}" "-j$CPUS" $TARGETS 2>&1 | logger || die
 
 # Save original module symvers
 cp -f "$BUILDDIR/Module.symvers" "$TEMPDIR/Module.symvers" || die
@@ -1315,7 +1349,7 @@ export KPATCH_GCC_SRCDIR="$BUILDDIR"
 save_env
 # $TARGETS used as list, no quotes.
 # shellcheck disable=SC2086
-KBUILD_MODPOST_WARN=1 make "${MAKEVARS[@]}" "-j$CPUS" $TARGETS 2>&1 | logger || die
+KBUILD_MODPOST_WARN=1 make "${ARCH_MAKEVARS[@]}" "${MAKEVARS[@]}" "-j$CPUS" $TARGETS 2>&1 | logger || die
 
 # source.c:(.section+0xFF): undefined reference to `symbol'
 grep "undefined reference" "$LOGFILE" | sed -r "s/^.*\`(.*)'$/\\1/" \

kpatch-build/kpatch-cc

@@ -43,6 +43,7 @@ if [[ "$TOOLCHAINCMD" =~ ^(.*-)?gcc$ || "$TOOLCHAINCMD" =~ ^(.*-)?clang$ ]] ; th
 				arch/s390/boot/*|\
 				arch/s390/purgatory/*|\
 				arch/s390/kernel/vdso64/*|\
+				arch/loongarch/vdso/*|\
 				drivers/firmware/efi/libstub/*|\
 				init/version.o|\
 				init/version-timestamp.o|\

kpatch-build/kpatch-elf.c

@@ -156,6 +156,8 @@ unsigned int absolute_rela_type(struct kpatch_elf *kelf)
 		return R_390_64;
 	case AARCH64:
 		return R_AARCH64_ABS64;
+	case LOONGARCH64:
+		return R_LARCH_64;
 	default:
 		ERROR("unsupported arch");
 	}
@@ -221,6 +223,7 @@ long rela_target_offset(struct kpatch_elf *kelf, struct section *relasec,
 	switch(kelf->arch) {
 	case PPC64:
 	case AARCH64:
+	case LOONGARCH64:
 		add_off = 0;
 		break;
 	case X86_64:
@@ -278,6 +281,7 @@ unsigned int insn_length(struct kpatch_elf *kelf, void *addr)
 		return decoded_insn.length;
 
 	case PPC64:
+	case LOONGARCH64:
 		return 4;
 
 	case S390:
@@ -349,6 +353,21 @@ static void kpatch_create_rela_list(struct kpatch_elf *kelf,
 				      rela->sym->name, rela->addend);
 		}
 
+		if (kelf->arch == LOONGARCH64) {
+			/*
+			 * LoongArch GCC creates local labels such as .LBB7266,
+			 * replace them with section symbols.
+			 */
+			if (rela->sym->sec && rela->sym->type == STT_NOTYPE &&
+			    rela->sym->bind == STB_LOCAL) {
+				log_debug("local label: %s -> ", rela->sym->name);
+				rela->addend += rela->sym->sym.st_value;
+				rela->sym = rela->sym->sec->secsym;
+				log_debug("section symbol: %s\n", rela->sym->name);
+			}
+		}
+
+
 		if (skip)
 			continue;
 		log_debug("offset %d, type %d, %s %s %ld", rela->offset,
@@ -614,6 +633,9 @@ struct kpatch_elf *kpatch_elf_open(const char *name)
 	case EM_AARCH64:
 		kelf->arch = AARCH64;
 		break;
+	case EM_LOONGARCH:
+		kelf->arch = LOONGARCH64;
+		break;
 	default:
 		ERROR("Unsupported target architecture");
 	}
@@ -647,6 +669,18 @@ struct kpatch_elf *kpatch_elf_open(const char *name)
 		}
 	}
 
+	if (kelf->arch == LOONGARCH64) {
+		struct symbol *sym, *tmp;
+
+		/* Delete local labels created by LoongArch GCC */
+		list_for_each_entry_safe(sym, tmp, &kelf->symbols, list) {
+			if (sym->sec && !is_rela_section(sym->sec) &&
+			    sym->type == STT_NOTYPE &&
+			    sym->bind == STB_LOCAL)
+				list_del(&sym->list);
+		}
+	}
+
 	return kelf;
 }
 

kpatch-build/kpatch-elf.h

@@ -31,6 +31,11 @@
 #define SHF_RELA_LIVEPATCH	0x00100000
 #define SHN_LIVEPATCH		0xff20
 
+#ifndef __loongarch__
+#define EM_LOONGARCH		258     /* LoongArch */
+#define R_LARCH_64              2
+#endif
+
 /*******************
  * Data structures
  * ****************/
@@ -117,6 +122,7 @@ enum architecture {
 	X86_64 = 0x1 << 1,
 	S390   = 0x1 << 2,
 	AARCH64  = 0x1 << 3,
+	LOONGARCH64 = 0x1 << 4,
 };
 
 struct kpatch_elf {

test/unit/Makefile

@@ -1,4 +1,4 @@
-ARCHES ?= aarch64 ppc64le x86_64
+ARCHES ?= loongarch64 aarch64 ppc64le x86_64
 
 .PHONY: all clean submodule-check