[RFC PATCH v3 10/12] objtool/powerpc: Add --mcount specific implementation

[Sathvika Vasireddy <sv@linux.ibm.com>]

This patch enables objtool --mcount on powerpc, and
adds implementation specific to powerpc.

Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
---
 arch/powerpc/Kconfig                          |  1 +
 tools/objtool/arch/powerpc/decode.c           | 22 +++++++++++++++++++
 tools/objtool/arch/powerpc/include/arch/elf.h |  2 ++
 3 files changed, 25 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 732a3f91ee5e..3373d44a1298 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -233,6 +233,7 @@ config PPC
 	select HAVE_NMI				if PERF_EVENTS || (PPC64 && PPC_BOOK3S)
 	select HAVE_OPTPROBES
 	select HAVE_OBJTOOL			if PPC64
+	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_EVENTS_NMI		if PPC64
 	select HAVE_PERF_REGS
diff --git a/tools/objtool/arch/powerpc/decode.c b/tools/objtool/arch/powerpc/decode.c
index 8b6a14680da7..06fc0206bf8e 100644
--- a/tools/objtool/arch/powerpc/decode.c
+++ b/tools/objtool/arch/powerpc/decode.c
@@ -9,6 +9,14 @@
 #include <objtool/builtin.h>
 #include <objtool/endianness.h>
 
+bool arch_ftrace_match(char *name)
+{
+	if ((!strcmp(name, "_mcount")) || (!strcmp(name, "._mcount")))
+		return true;
+
+	return false;
+}
+
 unsigned long arch_dest_reloc_offset(int addend)
 {
 	return addend;
@@ -41,12 +49,26 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 			    struct list_head *ops_list)
 {
 	u32 insn;
+	unsigned int opcode;
 
 	*immediate = 0;
 	insn = bswap_if_needed(file->elf, *(u32 *)(sec->data->d_buf + offset));
 	*len = 4;
 	*type = INSN_OTHER;
 
+	opcode = insn >> 26;
+
+	switch (opcode) {
+	case 18: /* bl */
+		if ((insn & 3) == 1) {
+			*type = INSN_CALL;
+			*immediate = insn & 0x3fffffc;
+			if (*immediate & 0x2000000)
+				*immediate -= 0x4000000;
+		}
+		break;
+	}
+
 	return 0;
 }
 
diff --git a/tools/objtool/arch/powerpc/include/arch/elf.h b/tools/objtool/arch/powerpc/include/arch/elf.h
index 3c8ebb7d2a6b..73f9ae172fe5 100644
--- a/tools/objtool/arch/powerpc/include/arch/elf.h
+++ b/tools/objtool/arch/powerpc/include/arch/elf.h
@@ -4,5 +4,7 @@
 #define _OBJTOOL_ARCH_ELF
 
 #define R_NONE R_PPC_NONE
+#define R_ABS64 R_PPC64_ADDR64
+#define R_ABS32 R_PPC_ADDR32
 
 #endif /* _OBJTOOL_ARCH_ELF */
-- 
2.25.1