linux-kernel - [PATCH v3 16/16] objtool/powerpc: Add --mcount specific implementation

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Date:   Mon, 12 Sep 2022 13:50:20 +0530
From:   Sathvika Vasireddy <sv@...ux.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     jpoimboe@...hat.com, peterz@...radead.org,
        linux-kernel@...r.kernel.org, aik@...abs.ru, mpe@...erman.id.au,
        mingo@...hat.com, christophe.leroy@...roup.eu, rostedt@...dmis.org,
        mbenes@...e.cz, npiggin@...il.com, chenzhongjin@...wei.com,
        naveen.n.rao@...ux.vnet.ibm.com, sv@...ux.ibm.com
Subject: [PATCH v3 16/16] objtool/powerpc: Add --mcount specific implementation

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

Signed-off-by: Sathvika Vasireddy <sv@...ux.ibm.com>
---
 arch/powerpc/Kconfig                          |  1 +
 tools/objtool/arch/powerpc/decode.c           | 16 ++++++++++++++++
 tools/objtool/arch/powerpc/include/arch/elf.h |  2 ++
 3 files changed, 19 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index dc05cd23c233..6be2e68fa9eb 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -238,6 +238,7 @@ config PPC
 	select HAVE_NMI				if PERF_EVENTS || (PPC64 && PPC_BOOK3S)
 	select HAVE_OPTPROBES
 	select HAVE_OBJTOOL			if PPC32 || MPROFILE_KERNEL
+	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 dcd0975cad6b..ea2b1968f0ee 100644
--- a/tools/objtool/arch/powerpc/decode.c
+++ b/tools/objtool/arch/powerpc/decode.c
@@ -9,6 +9,11 @@
 #include <objtool/builtin.h>
 #include <objtool/endianness.h>
 
+int arch_ftrace_match(char *name)
+{
+	return !strcmp(name, "_mcount");
+}
+
 unsigned long arch_dest_reloc_offset(int addend)
 {
 	return addend;
@@ -50,6 +55,17 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 	typ = INSN_OTHER;
 	imm = 0;
 
+	switch (opcode) {
+	case 18: /* b[l][a] */
+		if (insn & 1)  /* bl[a] */
+			typ = INSN_CALL;
+
+		imm = insn & 0x3fffffc;
+		if (imm & 0x2000000)
+			imm -= 0x4000000;
+		break;
+	}
+
 	if (opcode == 1)
 		*len = 8;
 	else
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 */
-- 
2.31.1