[RFC PATCH v4 15/37] objtool: arm64: Add unwind_hint support

[Chen Zhongjin]

From: Julien Thierry <jthierry@xxxxxxxxxx>

Provide unwind hint defines for arm64 and objtool hint decoding.

Signed-off-by: Julien Thierry <jthierry@xxxxxxxxxx>
Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
---
 arch/arm64/include/asm/unwind_hints.h       | 27 +++++++++++++++++++++
 tools/arch/arm64/include/asm/unwind_hints.h | 27 +++++++++++++++++++++
 tools/objtool/arch/arm64/decode.c           |  8 +++++-
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/include/asm/unwind_hints.h
 create mode 100644 tools/arch/arm64/include/asm/unwind_hints.h

diff --git a/arch/arm64/include/asm/unwind_hints.h b/arch/arm64/include/asm/unwind_hints.h
new file mode 100644
index 000000000000..60f866e4e12c
--- /dev/null
+++ b/arch/arm64/include/asm/unwind_hints.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_UNWIND_HINTS_H
+#define __ASM_UNWIND_HINTS_H
+
+#include <linux/objtool.h>
+
+#define UNWIND_HINT_REG_UNDEFINED	0xff
+#define UNWIND_HINT_REG_SP		31
+
+#ifdef __ASSEMBLY__
+
+.macro UNWIND_HINT_EMPTY
+	UNWIND_HINT sp_reg=UNWIND_HINT_REG_UNDEFINED type=UNWIND_HINT_TYPE_CALL
+.endm
+
+.macro UNWIND_HINT_FUNC sp_offset=0
+	UNWIND_HINT sp_reg=UNWIND_HINT_REG_SP sp_offset=\sp_offset type=UNWIND_HINT_TYPE_CALL
+.endm
+
+.macro UNWIND_HINT_REGS base=UNWIND_HINT_REG_SP offset=0
+	UNWIND_HINT sp_reg=\base sp_offset=\offset type=UNWIND_HINT_TYPE_REGS
+.endm
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_UNWIND_HINTS_H */
diff --git a/tools/arch/arm64/include/asm/unwind_hints.h b/tools/arch/arm64/include/asm/unwind_hints.h
new file mode 100644
index 000000000000..60f866e4e12c
--- /dev/null
+++ b/tools/arch/arm64/include/asm/unwind_hints.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_UNWIND_HINTS_H
+#define __ASM_UNWIND_HINTS_H
+
+#include <linux/objtool.h>
+
+#define UNWIND_HINT_REG_UNDEFINED	0xff
+#define UNWIND_HINT_REG_SP		31
+
+#ifdef __ASSEMBLY__
+
+.macro UNWIND_HINT_EMPTY
+	UNWIND_HINT sp_reg=UNWIND_HINT_REG_UNDEFINED type=UNWIND_HINT_TYPE_CALL
+.endm
+
+.macro UNWIND_HINT_FUNC sp_offset=0
+	UNWIND_HINT sp_reg=UNWIND_HINT_REG_SP sp_offset=\sp_offset type=UNWIND_HINT_TYPE_CALL
+.endm
+
+.macro UNWIND_HINT_REGS base=UNWIND_HINT_REG_SP offset=0
+	UNWIND_HINT sp_reg=\base sp_offset=\offset type=UNWIND_HINT_TYPE_REGS
+.endm
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_UNWIND_HINTS_H */
diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c
index d2522ef43101..2e7affca1ec9 100644
--- a/tools/objtool/arch/arm64/decode.c
+++ b/tools/objtool/arch/arm64/decode.c
@@ -5,6 +5,7 @@
 #include <stdint.h>
 
 #include <asm/insn.h>
+#include <asm/unwind_hints.h>
 
 #include <objtool/check.h>
 #include <objtool/arch.h>
@@ -176,7 +177,12 @@ static int is_arm64(const struct elf *elf)
 
 int arch_decode_hint_reg(u8 sp_reg, int *base)
 {
-	return -1;
+	if (sp_reg == UNWIND_HINT_REG_UNDEFINED)
+		*base = CFI_UNDEFINED;
+	else
+		*base = sp_reg;
+
+	return 0;
 }
 
 static struct stack_op *arm_make_store_op(enum aarch64_insn_register base,
-- 
2.17.1