[RFC PATCH v1 09/23] objtool: LoongArch: Add base definition for LoongArch

[Youling Tang]

Provide needed definitions for a new architecture instruction decoder.
No proper decoding is done yet.

There is currently no unwind hint implementation added, the unwind_hints.h
file is added only to avoid build errors.

Co-developed-by: Jinyang He <hejinyang@xxxxxxxxxxx>
Signed-off-by: Jinyang He <hejinyang@xxxxxxxxxxx>
Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
---
 .../arch/loongarch/include/asm/unwind_hints.h |  24 ++++
 tools/objtool/Makefile                        |   4 +
 tools/objtool/arch/loongarch/Build            |   2 +
 tools/objtool/arch/loongarch/decode.c         | 125 ++++++++++++++++++
 .../arch/loongarch/include/arch/cfi_regs.h    |  14 ++
 .../objtool/arch/loongarch/include/arch/elf.h |  15 +++
 .../arch/loongarch/include/arch/special.h     |  21 +++
 tools/objtool/arch/loongarch/special.c        |  20 +++
 8 files changed, 225 insertions(+)
 create mode 100644 tools/arch/loongarch/include/asm/unwind_hints.h
 create mode 100644 tools/objtool/arch/loongarch/Build
 create mode 100644 tools/objtool/arch/loongarch/decode.c
 create mode 100644 tools/objtool/arch/loongarch/include/arch/cfi_regs.h
 create mode 100644 tools/objtool/arch/loongarch/include/arch/elf.h
 create mode 100644 tools/objtool/arch/loongarch/include/arch/special.h
 create mode 100644 tools/objtool/arch/loongarch/special.c

diff --git a/tools/arch/loongarch/include/asm/unwind_hints.h b/tools/arch/loongarch/include/asm/unwind_hints.h
new file mode 100644
index 000000000000..ac48ee34bf7b
--- /dev/null
+++ b/tools/arch/loongarch/include/asm/unwind_hints.h
@@ -0,0 +1,24 @@
+#ifndef _ASM_LOONGARCH_UNWIND_HINTS_H
+#define _ASM_LOONGARCH_UNWIND_HINTS_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+
+/*
+ * This struct is used by asm and inline asm code to manually annotate the
+ * location of registers on the stack.
+ */
+struct unwind_hint {
+	u32		ip;
+	s16		sp_offset;
+	u8		sp_reg;
+	u8		type;
+	u8		signal;
+	u8		end;
+};
+#endif
+
+#include <linux/objtool.h>
+
+#endif /* _ASM_LOONGARCH_UNWIND_HINTS_H */
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 2262b49691b8..034fbd9f3f13 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -58,6 +58,10 @@ ifeq ($(SRCARCH),x86)
 	STATIC_CHECK := y
 endif
 
+ifeq ($(SRCARCH),loongarch)
+	STATIC_CHECK := y
+endif
+
 export BUILD_ORC STATIC_CHECK
 export srctree OUTPUT CFLAGS SRCARCH AWK
 include $(srctree)/tools/build/Makefile.include
diff --git a/tools/objtool/arch/loongarch/Build b/tools/objtool/arch/loongarch/Build
new file mode 100644
index 000000000000..d24d5636a5b8
--- /dev/null
+++ b/tools/objtool/arch/loongarch/Build
@@ -0,0 +1,2 @@
+objtool-y += decode.o
+objtool-y += special.o
diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
new file mode 100644
index 000000000000..3f795f57e914
--- /dev/null
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <asm/inst.h>
+
+#include <objtool/check.h>
+#include <objtool/elf.h>
+#include <objtool/arch.h>
+#include <objtool/warn.h>
+#include <objtool/builtin.h>
+#include <objtool/endianness.h>
+#include <arch/cfi_regs.h>
+
+int arch_ftrace_match(char *name)
+{
+	return !strcmp(name, "_mcount");
+}
+
+static int is_loongarch(const struct elf *elf)
+{
+	if (elf->ehdr.e_machine == EM_LOONGARCH)
+		return 1;
+
+	WARN("unexpected ELF machine type %d", elf->ehdr.e_machine);
+	return 0;
+}
+
+unsigned long arch_dest_reloc_offset(int addend)
+{
+	return addend;
+}
+
+bool arch_callee_saved_reg(unsigned char reg)
+{
+	switch (reg) {
+	case LOONGARCH_GPR_S0 ... LOONGARCH_GPR_S8:
+	case LOONGARCH_GPR_FP:
+	case LOONGARCH_GPR_RA:
+		return true;
+	default:
+		return false;
+	}
+}
+
+int arch_decode_hint_reg(u8 sp_reg, int *base)
+{
+	exit(-1);
+}
+
+const char *arch_nop_insn(int len)
+{
+	static u32 nop;
+
+	if (len != LOONGARCH_INSN_SIZE)
+		WARN("invalid NOP size: %d\n", len);
+
+	nop = LOONGARCH_INSN_NOP;
+
+	return (const char *)&nop;
+}
+
+const char *arch_ret_insn(int len)
+{
+	static u32 ret;
+
+	if (len != LOONGARCH_INSN_SIZE)
+		WARN("invalid RET size: %d\n", len);
+
+	emit_jirl((union loongarch_instruction *)&ret, LOONGARCH_GPR_RA,
+		  LOONGARCH_GPR_ZERO, 0);
+
+	return (const char *)&ret;
+}
+
+int arch_decode_instruction(struct objtool_file *file, const struct section *sec,
+			    unsigned long offset, unsigned int maxlen,
+			    struct instruction *insn)
+{
+	const struct elf *elf = file->elf;
+	union loongarch_instruction inst;
+
+	if (!is_loongarch(elf))
+		return -1;
+
+	if (maxlen < LOONGARCH_INSN_SIZE)
+		return 0;
+
+	insn->len = LOONGARCH_INSN_SIZE;
+	insn->type = INSN_OTHER;
+	insn->immediate = 0;
+
+	inst = *(union loongarch_instruction *)(sec->data->d_buf + offset);
+
+	/* For some where we .fill 0 and we cannot execute it. */
+	if (inst.word == 0)
+		insn->type = INSN_NOP;
+
+	return 0;
+}
+
+unsigned long arch_jump_destination(struct instruction *insn)
+{
+	return insn->offset + insn->immediate * 4;
+}
+
+bool arch_pc_relative_reloc(struct reloc *reloc)
+{
+	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;
+}
diff --git a/tools/objtool/arch/loongarch/include/arch/cfi_regs.h b/tools/objtool/arch/loongarch/include/arch/cfi_regs.h
new file mode 100644
index 000000000000..8077287066af
--- /dev/null
+++ b/tools/objtool/arch/loongarch/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/inst.h>
+
+#define CFI_RA		LOONGARCH_GPR_RA
+#define CFI_SP		LOONGARCH_GPR_SP
+#define CFI_FP		LOONGARCH_GPR_FP
+#define CFI_BP		CFI_FP
+#define CFI_NUM_REGS	32
+
+#endif /* _OBJTOOL_CFI_REGS_H */
diff --git a/tools/objtool/arch/loongarch/include/arch/elf.h b/tools/objtool/arch/loongarch/include/arch/elf.h
new file mode 100644
index 000000000000..6a3ec9bf3fd2
--- /dev/null
+++ b/tools/objtool/arch/loongarch/include/arch/elf.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _OBJTOOL_ARCH_ELF
+#define _OBJTOOL_ARCH_ELF
+
+#ifndef R_LARCH_32_PCREL
+#define R_LARCH_32_PCREL 99
+#endif
+
+#define R_NONE R_LARCH_NONE
+#define R_ABS64 R_LARCH_64
+#define R_ABS32 R_LARCH_32
+#define R_PCREL R_LARCH_32_PCREL
+
+#endif /* _OBJTOOL_ARCH_ELF */
diff --git a/tools/objtool/arch/loongarch/include/arch/special.h b/tools/objtool/arch/loongarch/include/arch/special.h
new file mode 100644
index 000000000000..fa07a3616288
--- /dev/null
+++ b/tools/objtool/arch/loongarch/include/arch/special.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _LOONGARCH_ARCH_SPECIAL_H
+#define _LOONGARCH_ARCH_SPECIAL_H
+
+#define EX_ENTRY_SIZE 12
+#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 JUMP_KEY_OFFSET 8
+
+#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 /* _LOONGARCH_ARCH_SPECIAL_H */
diff --git a/tools/objtool/arch/loongarch/special.c b/tools/objtool/arch/loongarch/special.c
new file mode 100644
index 000000000000..8669dbe44459
--- /dev/null
+++ b/tools/objtool/arch/loongarch/special.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <string.h>
+#include <stdlib.h>
+#include <objtool/special.h>
+#include <objtool/builtin.h>
+
+
+bool arch_support_alt_relocation(struct special_alt *special_alt,
+				 struct instruction *insn,
+				 struct reloc *reloc)
+{
+	return NULL;
+}
+
+struct reloc *arch_find_switch_table(struct objtool_file *file,
+				    struct instruction *insn)
+{
+	return NULL;
+}
-- 
2.39.2