[linux-6.6.y] LoongArch: Fix objtool issues and add jump table feature

arch/loongarch/Kconfig

@@ -135,7 +135,7 @@ config LOONGARCH
 	select HAVE_KVM
 	select HAVE_MOD_ARCH_SPECIFIC
 	select HAVE_NMI
-	select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && !CC_IS_CLANG
+	select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB
 	select HAVE_PCI
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
@@ -262,7 +262,7 @@ config AS_HAS_FCSR_CLASS
 	def_bool $(as-instr,movfcsr2gr \$t0$(comma)\$fcsr0)
 
 config AS_HAS_THIN_ADD_SUB
-	def_bool $(cc-option,-Wa$(comma)-mthin-add-sub)
+	def_bool $(cc-option,-Wa$(comma)-mthin-add-sub) || AS_IS_LLVM
 
 config AS_HAS_LSX_EXTENSION
 	def_bool $(as-instr,vld \$vr0$(comma)\$a0$(comma)0)
@@ -276,6 +276,9 @@ config AS_HAS_LBT_EXTENSION
 config AS_HAS_LVZ_EXTENSION
 	def_bool $(as-instr,hvcl 0)
 
+config CC_HAS_ANNOTATE_TABLEJUMP
+	def_bool $(cc-option,-mannotate-tablejump)
+
 menu "Kernel type and options"
 
 source "kernel/Kconfig.hz"

arch/loongarch/Makefile

@@ -94,7 +94,11 @@ KBUILD_AFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)
 KBUILD_CFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
 
 ifdef CONFIG_OBJTOOL
-KBUILD_CFLAGS			+= -fno-jump-tables
+ifdef CONFIG_CC_HAS_ANNOTATE_TABLEJUMP
+KBUILD_CFLAGS			+= $(call cc-option,-mannotate-tablejump)
+else
+KBUILD_CFLAGS			+= -fno-jump-tables # keep compatibility with older compilers
+endif
 endif
 
 ifeq ($(CONFIG_RELOCATABLE),y)

arch/loongarch/configs/deepin_loongarch_desktop_defconfig

@@ -6010,3 +6010,4 @@ CONFIG_RV_MON_WIP=y
 CONFIG_RV_MON_WWNR=y
 # CONFIG_STRICT_DEVMEM is not set
 # CONFIG_RUNTIME_TESTING_MENU is not set
+CONFIG_UNWINDER_ORC=y

arch/loongarch/configs/loongson3_defconfig

@@ -2203,3 +2203,4 @@ CONFIG_RCU_CPU_STALL_TIMEOUT=60
 # CONFIG_RCU_TRACE is not set
 # CONFIG_STRICT_DEVMEM is not set
 # CONFIG_RUNTIME_TESTING_MENU is not set
+CONFIG_UNWINDER_ORC=y

arch/loongarch/kernel/fpu.S

@@ -530,6 +530,10 @@ SYM_FUNC_END(_restore_lasx_context)
 
 #ifdef CONFIG_CPU_HAS_LBT
 STACK_FRAME_NON_STANDARD _restore_fp
+#ifdef CONFIG_CPU_HAS_LSX
 STACK_FRAME_NON_STANDARD _restore_lsx
+#endif
+#ifdef CONFIG_CPU_HAS_LASX
 STACK_FRAME_NON_STANDARD _restore_lasx
 #endif
+#endif

include/linux/compiler.h

@@ -133,7 +133,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #define annotate_unreachable() __annotate_unreachable(__COUNTER__)
 
 /* Annotate a C jump table to allow objtool to follow the code flow */
-#define __annotate_jump_table __section(".rodata..c_jump_table")
+#define __annotate_jump_table __section(".rodata..c_jump_table,\"a\",@progbits #")
 
 #else /* !CONFIG_OBJTOOL */
 #define annotate_reachable()

tools/objtool/arch/loongarch/decode.c

@@ -122,7 +122,7 @@ static bool decode_insn_reg2i12_fomat(union loongarch_instruction inst,
 	switch (inst.reg2i12_format.opcode) {
 	case addid_op:
 		if ((inst.reg2i12_format.rd == CFI_SP) || (inst.reg2i12_format.rj == CFI_SP)) {
-			/* addi.d sp,sp,si12 or addi.d fp,sp,si12 */
+			/* addi.d sp,sp,si12 or addi.d fp,sp,si12 or addi.d sp,fp,si12 */
 			insn->immediate = sign_extend64(inst.reg2i12_format.immediate, 11);
 			ADD_OP(op) {
 				op->src.type = OP_SRC_ADD;
@@ -132,6 +132,15 @@ static bool decode_insn_reg2i12_fomat(union loongarch_instruction inst,
 				op->dest.reg = inst.reg2i12_format.rd;
 			}
 		}
+		if ((inst.reg2i12_format.rd == CFI_SP) && (inst.reg2i12_format.rj == CFI_FP)) {
+			/* addi.d sp,fp,si12 */
+			struct symbol *func = find_func_containing(insn->sec, insn->offset);
+
+			if (!func)
+				return false;
+
+			func->frame_pointer = true;
+		}
 		break;
 	case ldd_op:
 		if (inst.reg2i12_format.rj == CFI_SP) {

tools/objtool/arch/loongarch/special.c

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
+#include <string.h>
 #include <objtool/special.h>
+#include <objtool/warn.h>
 
 bool arch_support_alt_relocation(struct special_alt *special_alt,
 				 struct instruction *insn,
@@ -8,8 +10,160 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
 	return false;
 }
 
+struct table_info {
+	struct list_head jump_info;
+	unsigned long insn_offset;
+	unsigned long rodata_offset;
+};
+
+static void get_rodata_table_size_by_table_annotate(struct objtool_file *file,
+						    struct instruction *insn)
+{
+	struct section *rsec;
+	struct reloc *reloc;
+	struct list_head table_list;
+	struct table_info *orig_table;
+	struct table_info *next_table;
+	unsigned long tmp_insn_offset;
+	unsigned long tmp_rodata_offset;
+
+	rsec = find_section_by_name(file->elf, ".rela.discard.tablejump_annotate");
+	if (!rsec)
+		return;
+
+	INIT_LIST_HEAD(&table_list);
+
+	for_each_reloc(rsec, reloc) {
+		if (reloc->sym->type != STT_SECTION)
+			return;
+
+		orig_table = malloc(sizeof(struct table_info));
+		if (!orig_table) {
+			WARN("malloc failed");
+			return;
+		}
+
+		orig_table->insn_offset = reloc_addend(reloc);
+		reloc++;
+		orig_table->rodata_offset = reloc_addend(reloc);
+
+		list_add_tail(&orig_table->jump_info, &table_list);
+
+		if (reloc_idx(reloc) + 1 == sec_num_entries(rsec))
+			break;
+	}
+
+	list_for_each_entry(orig_table, &table_list, jump_info) {
+		next_table = list_next_entry(orig_table, jump_info);
+		list_for_each_entry_from(next_table, &table_list, jump_info) {
+			if (next_table->rodata_offset < orig_table->rodata_offset) {
+				tmp_insn_offset = next_table->insn_offset;
+				tmp_rodata_offset = next_table->rodata_offset;
+				next_table->insn_offset = orig_table->insn_offset;
+				next_table->rodata_offset = orig_table->rodata_offset;
+				orig_table->insn_offset = tmp_insn_offset;
+				orig_table->rodata_offset = tmp_rodata_offset;
+			}
+		}
+	}
+
+	list_for_each_entry(orig_table, &table_list, jump_info) {
+		if (insn->offset == orig_table->insn_offset) {
+			next_table = list_next_entry(orig_table, jump_info);
+			if (&next_table->jump_info == &table_list)
+				break;
+
+			while (next_table->rodata_offset == orig_table->rodata_offset)
+				next_table = list_next_entry(next_table, jump_info);
+
+			insn->table_size = next_table->rodata_offset - orig_table->rodata_offset;
+		}
+	}
+}
+
+static struct reloc *find_reloc_by_table_annotate(struct objtool_file *file,
+						  struct instruction *insn)
+{
+	struct section *rsec;
+	struct reloc *reloc;
+	unsigned long offset;
+
+	rsec = find_section_by_name(file->elf, ".rela.discard.tablejump_annotate");
+	if (!rsec)
+		return NULL;
+
+	for_each_reloc(rsec, reloc) {
+		if (reloc->sym->sec->rodata)
+			continue;
+
+		if (strcmp(insn->sec->name, reloc->sym->sec->name))
+			continue;
+
+		if (reloc->sym->type == STT_SECTION)
+			offset = reloc_addend(reloc);
+		else
+			offset = reloc->sym->offset;
+
+		if (insn->offset == offset) {
+			get_rodata_table_size_by_table_annotate(file, insn);
+			reloc++;
+			return reloc;
+		}
+	}
+
+	return NULL;
+}
+
+static struct reloc *find_reloc_of_rodata_c_jump_table(struct section *sec,
+						       unsigned long offset)
+{
+	struct section *rsec;
+	struct reloc *reloc;
+
+	rsec = sec->rsec;
+	if (!rsec)
+		return NULL;
+
+	for_each_reloc(rsec, reloc) {
+		if (reloc_offset(reloc) > offset)
+			break;
+
+		if (!strncmp(reloc->sym->sec->name, ".rodata..c_jump_table", 21))
+			return reloc;
+	}
+
+	return NULL;
+}
+
 struct reloc *arch_find_switch_table(struct objtool_file *file,
 				     struct instruction *insn)
 {
-	return NULL;
+	struct reloc *annotate_reloc;
+	struct reloc *rodata_reloc;
+	struct section *table_sec;
+	unsigned long table_offset;
+
+	annotate_reloc = find_reloc_by_table_annotate(file, insn);
+	if (!annotate_reloc) {
+		annotate_reloc = find_reloc_of_rodata_c_jump_table(insn->sec, insn->offset);
+		if (!annotate_reloc)
+			return NULL;
+	}
+
+	table_sec = annotate_reloc->sym->sec;
+	if (annotate_reloc->sym->type == STT_SECTION)
+		table_offset = reloc_addend(annotate_reloc);
+	else
+		table_offset = annotate_reloc->sym->offset;
+
+	/*
+	 * Each table entry has a rela associated with it.  The rela
+	 * should reference text in the same function as the original
+	 * instruction.
+	 */
+	rodata_reloc = find_reloc_by_dest(file->elf, table_sec, table_offset);
+	if (!rodata_reloc)
+		return NULL;
+
+	return rodata_reloc;
 }