[RFC,04/17] objtool: arm64: Add base definition for arm64 backend

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 92ce4fce7bc7..d5cfbec87c02 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -47,6 +47,11 @@  ifeq ($(SRCARCH),x86)
 	SUBCMD_ORC := y
 endif
 
+ifeq ($(SRCARCH),arm64)
+	SUBCMD_CHECK := y
+	CFLAGS  += -Wno-nested-externs
+endif
+
 export SUBCMD_CHECK SUBCMD_ORC
 export srctree OUTPUT CFLAGS SRCARCH AWK
 include $(srctree)/tools/build/Makefile.include
diff --git a/tools/objtool/arch/arm64/Build b/tools/objtool/arch/arm64/Build
new file mode 100644
index 000000000000..f3de3a50d541
--- /dev/null
+++ b/tools/objtool/arch/arm64/Build
@@ -0,0 +1,8 @@ 
+objtool-y += special.o
+objtool-y += decode.o
+
+objtool-y += libhweight.o
+
+$(OUTPUT)arch/arm64/libhweight.o: ../lib/hweight.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)
diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c
new file mode 100644
index 000000000000..8ae822f553ca
--- /dev/null
+++ b/tools/objtool/arch/arm64/decode.c
@@ -0,0 +1,130 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+/* Hack needed to avoid depending on brk-imm.h */
+#define FAULT_BRK_IMM	0x100
+
+#include <asm/aarch64-insn.h>
+
+#include <objtool/check.h>
+#include <objtool/arch.h>
+#include <objtool/elf.h>
+#include <objtool/warn.h>
+
+#include <arch/cfi_regs.h>
+
+/* Hack needed to avoid depending on kprobes.h */
+#ifndef __kprobes
+#define __kprobes
+#endif
+
+#include "../../../arch/arm64/lib/aarch64-insn.c"
+
+bool arch_callee_saved_reg(unsigned char reg)
+{
+	switch (reg) {
+	case AARCH64_INSN_REG_19:
+	case AARCH64_INSN_REG_20:
+	case AARCH64_INSN_REG_21:
+	case AARCH64_INSN_REG_22:
+	case AARCH64_INSN_REG_23:
+	case AARCH64_INSN_REG_24:
+	case AARCH64_INSN_REG_25:
+	case AARCH64_INSN_REG_26:
+	case AARCH64_INSN_REG_27:
+	case AARCH64_INSN_REG_28:
+	case AARCH64_INSN_REG_FP:
+	case AARCH64_INSN_REG_LR:
+		return true;
+	default:
+		return false;
+	}
+}
+
+void arch_initial_func_cfi_state(struct cfi_init_state *state)
+{
+	int i;
+
+	for (i = 0; i < CFI_NUM_REGS; i++) {
+		state->regs[i].base = CFI_UNDEFINED;
+		state->regs[i].offset = 0;
+	}
+
+	/* initial CFA (call frame address) */
+	state->cfa.base = CFI_SP;
+	state->cfa.offset = 0;
+}
+
+unsigned long arch_dest_reloc_offset(int addend)
+{
+	return addend;
+}
+
+unsigned long arch_jump_destination(struct instruction *insn)
+{
+	return insn->offset + insn->immediate;
+}
+
+const char *arch_nop_insn(int len)
+{
+	static u32 nop = 0;
+
+	if (len != AARCH64_INSN_SIZE)
+		WARN("invalid NOP size: %d\n", len);
+
+	if (!nop)
+		nop = aarch64_insn_gen_nop();
+
+	return (const char*)&nop;
+}
+
+static int is_arm64(const struct elf *elf)
+{
+	switch (elf->ehdr.e_machine) {
+	case EM_AARCH64: //0xB7
+		return 1;
+	default:
+		WARN("unexpected ELF machine type %x",
+		     elf->ehdr.e_machine);
+		return 0;
+	}
+}
+
+int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg)
+{
+	return -1;
+}
+
+int arch_decode_instruction(const struct elf *elf, const struct section *sec,
+			    unsigned long offset, unsigned int maxlen,
+			    unsigned int *len, enum insn_type *type,
+			    unsigned long *immediate,
+			    struct list_head *ops_list)
+{
+	u32 insn;
+
+	if (!is_arm64(elf))
+		return -1;
+
+	if (maxlen < AARCH64_INSN_SIZE)
+		return 0;
+
+	*len = AARCH64_INSN_SIZE;
+	*immediate = 0;
+
+	insn = *(u32 *)(sec->data->d_buf + offset);
+
+	switch (aarch64_get_insn_class(insn)) {
+	case AARCH64_INSN_CLS_UNKNOWN:
+		WARN("can't decode instruction at %s:0x%lx", sec->name, offset);
+		return -1;
+	default:
+		*type = INSN_OTHER;
+		break;
+	}
+
+	return 0;
+}
diff --git a/tools/objtool/arch/arm64/include/arch/cfi_regs.h b/tools/objtool/arch/arm64/include/arch/cfi_regs.h
new file mode 100644
index 000000000000..43ad56b6c3f9
--- /dev/null
+++ b/tools/objtool/arch/arm64/include/arch/cfi_regs.h
@@ -0,0 +1,14 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _OBJTOOL_CFI_REGS_H
+#define _OBJTOOL_CFI_REGS_H
+
+#include <asm/aarch64-insn.h>
+
+#define CFI_BP			AARCH64_INSN_REG_FP
+#define CFI_RA			AARCH64_INSN_REG_LR
+#define CFI_SP			AARCH64_INSN_REG_SP
+
+#define CFI_NUM_REGS		32
+
+#endif /* _OBJTOOL_CFI_REGS_H */
diff --git a/tools/objtool/arch/arm64/include/arch/elf.h b/tools/objtool/arch/arm64/include/arch/elf.h
new file mode 100644
index 000000000000..a31a29b1a386
--- /dev/null
+++ b/tools/objtool/arch/arm64/include/arch/elf.h
@@ -0,0 +1,6 @@ 
+#ifndef _OBJTOOL_ARCH_ELF
+#define _OBJTOOL_ARCH_ELF
+
+#define R_NONE R_AARCH64_NONE
+
+#endif /* _OBJTOOL_ARCH_ELF */
diff --git a/tools/objtool/arch/arm64/include/arch/endianness.h b/tools/objtool/arch/arm64/include/arch/endianness.h
new file mode 100644
index 000000000000..7c362527da20
--- /dev/null
+++ b/tools/objtool/arch/arm64/include/arch/endianness.h
@@ -0,0 +1,9 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _ARCH_ENDIANNESS_H
+#define _ARCH_ENDIANNESS_H
+
+#include <endian.h>
+
+#define __TARGET_BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* _ARCH_ENDIANNESS_H */
diff --git a/tools/objtool/arch/arm64/include/arch/special.h b/tools/objtool/arch/arm64/include/arch/special.h
new file mode 100644
index 000000000000..a82a9b3e51df
--- /dev/null
+++ b/tools/objtool/arch/arm64/include/arch/special.h
@@ -0,0 +1,21 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _ARM64_ARCH_SPECIAL_H
+#define _ARM64_ARCH_SPECIAL_H
+
+#define EX_ENTRY_SIZE		8
+#define EX_ORIG_OFFSET		0
+#define EX_NEW_OFFSET		4
+
+#define JUMP_ENTRY_SIZE		16
+#define JUMP_ORIG_OFFSET	0
+#define JUMP_NEW_OFFSET		4
+
+#define ALT_ENTRY_SIZE		12
+#define ALT_ORIG_OFFSET		0
+#define ALT_NEW_OFFSET		4
+#define ALT_FEATURE_OFFSET	8
+#define ALT_ORIG_LEN_OFFSET	10
+#define ALT_NEW_LEN_OFFSET	11
+
+#endif /* _ARM64_ARCH_SPECIAL_H */
diff --git a/tools/objtool/arch/arm64/special.c b/tools/objtool/arch/arm64/special.c
new file mode 100644
index 000000000000..45f283283091
--- /dev/null
+++ b/tools/objtool/arch/arm64/special.c
@@ -0,0 +1,21 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <objtool/special.h>
+
+void arch_handle_alternative(unsigned short feature, struct special_alt *alt)
+{
+}
+
+bool arch_support_alt_relocation(struct special_alt *special_alt,
+				 struct instruction *insn,
+				 struct reloc *reloc)
+{
+	return false;
+}
+
+
+struct reloc *arch_find_switch_table(struct objtool_file *file,
+				     struct instruction *insn)
+{
+	return NULL;
+}
diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
index 606a4b5e929f..69e7ebe8911b 100755
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -21,6 +21,11 @@  arch/x86/include/asm/insn.h     -I '^#include [\"<]\(asm/\)*inat.h[\">]'
 arch/x86/lib/inat.c             -I '^#include [\"<]\(../include/\)*asm/insn.h[\">]'
 arch/x86/lib/insn.c             -I '^#include [\"<]\(../include/\)*asm/in\(at\|sn\).h[\">]' -I '^#include [\"<]\(../include/\)*asm/emulate_prefix.h[\">]'
 "
+elif [ "$SRCARCH" = "arm64" ]; then
+FILES="$FILES
+arch/arm64/include/asm/aarch64-insn.h -I '^#include [\"<]\(asm/\)*brk-imm.h[\">]'
+arch/arm64/lib/aarch64-insn.c         -I '^#include [\"<]\(asm/\)*kprobes.h[\">]'
+"
 fi
 
 check_2 () {