[RFC PATCH 0/3] objtool: Add mcount sub-command

@@ -12,6 +12,7 @@ objtool-y += builtin-check.o
 objtool-y += builtin-orc.o
 objtool-y += elf.o
 objtool-y += objtool.o
+objtool-y += utils.o
 
 objtool-y += libstring.o
 objtool-y += libctype.o

@@ -12,6 +12,7 @@
 #include <objtool/cfi.h>
 #include <objtool/arch.h>
 #include <objtool/check.h>
+#include <objtool/utils.h>
 #include <objtool/special.h>
 #include <objtool/warn.h>
 #include <objtool/endianness.h>

@@ -33,19 +34,6 @@ static struct cfi_init_state initial_func_cfi;
 static struct cfi_state init_cfi;
 static struct cfi_state func_cfi;
 
-struct instruction *find_insn(struct objtool_file *file,
-			      struct section *sec, unsigned long offset)
-{
-	struct instruction *insn;
-
-	hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
-		if (insn->sec == sec && insn->offset == offset)
-			return insn;
-	}
-
-	return NULL;
-}
-
 static struct instruction *next_insn_same_sec(struct objtool_file *file,
 					      struct instruction *insn)
 {

@@ -342,86 +330,8 @@ static void *cfi_hash_alloc(unsigned long size)
 	return cfi_hash;
 }
 
-static unsigned long nr_insns;
 static unsigned long nr_insns_visited;
 
-/*
- * Call the arch-specific instruction decoder for all the instructions and add
- * them to the global instruction list.
- */
-static int decode_instructions(struct objtool_file *file)
-{
-	struct section *sec;
-	struct symbol *func;
-	unsigned long offset;
-	struct instruction *insn;
-	int ret;
-
-	for_each_sec(file, sec) {
-
-		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
-			continue;
-
-		if (strcmp(sec->name, ".altinstr_replacement") &&
-		    strcmp(sec->name, ".altinstr_aux") &&
-		    strncmp(sec->name, ".discard.", 9))
-			sec->text = true;
-
-		if (!strcmp(sec->name, ".noinstr.text") ||
-		    !strcmp(sec->name, ".entry.text"))
-			sec->noinstr = true;
-
-		for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
-			insn = malloc(sizeof(*insn));
-			if (!insn) {
-				WARN("malloc failed");
-				return -1;
-			}
-			memset(insn, 0, sizeof(*insn));
-			INIT_LIST_HEAD(&insn->alts);
-			INIT_LIST_HEAD(&insn->stack_ops);
-
-			insn->sec = sec;
-			insn->offset = offset;
-
-			ret = arch_decode_instruction(file, sec, offset,
-						      sec->sh.sh_size - offset,
-						      &insn->len, &insn->type,
-						      &insn->immediate,
-						      &insn->stack_ops);
-			if (ret)
-				goto err;
-
-			hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
-			list_add_tail(&insn->list, &file->insn_list);
-			nr_insns++;
-		}
-
-		list_for_each_entry(func, &sec->symbol_list, list) {
-			if (func->type != STT_FUNC || func->alias != func)
-				continue;
-
-			if (!find_insn(file, sec, func->offset)) {
-				WARN("%s(): can't find starting instruction",
-				     func->name);
-				return -1;
-			}
-
-			sym_for_each_insn(file, func, insn)
-				insn->func = func;
-		}
-	}
-
-	if (stats)
-		printf("nr_insns: %lu\n", nr_insns);
-
-	return 0;
-
-err:
-	free(insn);
-	return ret;
-}
-
 /*
  * Read the pv_ops[] .data table to find the static initialized values.
  */

@@ -731,49 +641,6 @@ static int create_retpoline_sites_sections(struct objtool_file *file)
 	return 0;
 }
 
-static int create_mcount_loc_sections(struct objtool_file *file)
-{
-	struct section *sec;
-	unsigned long *loc;
-	struct instruction *insn;
-	int idx;
-
-	sec = find_section_by_name(file->elf, "__mcount_loc");
-	if (sec) {
-		INIT_LIST_HEAD(&file->mcount_loc_list);
-		WARN("file already has __mcount_loc section, skipping");
-		return 0;
-	}
-
-	if (list_empty(&file->mcount_loc_list))
-		return 0;
-
-	idx = 0;
-	list_for_each_entry(insn, &file->mcount_loc_list, call_node)
-		idx++;
-
-	sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
-	if (!sec)
-		return -1;
-
-	idx = 0;
-	list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
-
-		loc = (unsigned long *)sec->data->d_buf + idx;
-		memset(loc, 0, sizeof(unsigned long));
-
-		if (elf_add_reloc_to_insn(file->elf, sec,
-					  idx * sizeof(unsigned long),
-					  R_X86_64_64,
-					  insn->sec, insn->offset))
-			return -1;
-
-		idx++;
-	}
-
-	return 0;
-}
-
 /*
  * Warnings shouldn't be reported for ignored functions.
  */

@@ -1013,38 +880,6 @@ __weak bool arch_is_retpoline(struct symbol *sym)
 	return false;
 }
 
-#define NEGATIVE_RELOC	((void *)-1L)
-
-static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
-{
-	if (insn->reloc == NEGATIVE_RELOC)
-		return NULL;
-
-	if (!insn->reloc) {
-		if (!file)
-			return NULL;
-
-		insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
-						       insn->offset, insn->len);
-		if (!insn->reloc) {
-			insn->reloc = NEGATIVE_RELOC;
-			return NULL;
-		}
-	}
-
-	return insn->reloc;
-}
-
-static void remove_insn_ops(struct instruction *insn)
-{
-	struct stack_op *op, *tmp;
-
-	list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
-		list_del(&op->list);
-		free(op);
-	}
-}
-
 static void annotate_call_site(struct objtool_file *file,
 			       struct instruction *insn, bool sibling)
 {

@@ -1256,17 +1091,6 @@ static int add_jump_destinations(struct objtool_file *file)
 	return 0;
 }
 
-static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
-{
-	struct symbol *call_dest;
-
-	call_dest = find_func_by_offset(sec, offset);
-	if (!call_dest)
-		call_dest = find_symbol_by_offset(sec, offset);
-
-	return call_dest;
-}
-
 /*
  * Find the destination instructions for all calls.
  */

@@ -79,8 +79,6 @@ static inline bool is_jump(struct instruction *insn)
 	return is_static_jump(insn) || is_dynamic_jump(insn);
 }
 
-struct instruction *find_insn(struct objtool_file *file,
-			      struct section *sec, unsigned long offset);
 
 #define for_each_insn(file, insn)					\
 	list_for_each_entry(insn, &file->insn_list, list)

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef UTILS_H
+#define UTILS_H
+
+#include <stdbool.h>
+#include <objtool/cfi.h>
+#include <objtool/arch.h>
+
+int decode_instructions(struct objtool_file *file);
+struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn);
+void remove_insn_ops(struct instruction *insn);
+struct symbol *find_call_destination(struct section *sec, unsigned long offset);
+int create_mcount_loc_sections(struct objtool_file *file);
+struct instruction *find_insn(struct objtool_file *file,
+			      struct section *sec, unsigned long offset);
+
+#define sym_for_each_insn(file, sym, insn)                              \
+	for (insn = find_insn(file, sym->sec, sym->offset);             \
+	     insn && &insn->list != &file->insn_list &&                 \
+		insn->sec == sym->sec &&                                \
+		insn->offset < sym->offset + sym->len;                  \
+	     insn = list_next_entry(insn, list))
+
+#endif /* UTILS_H */

@@ -10,6 +10,7 @@
 #include <asm/orc_types.h>
 
 #include <objtool/check.h>
+#include <objtool/utils.h>
 #include <objtool/warn.h>
 #include <objtool/endianness.h>
 

@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+
+#include <objtool/builtin.h>
+#include <objtool/check.h>
+#include <objtool/utils.h>
+#include <objtool/warn.h>
+
+#include <linux/objtool.h>
+#include <linux/hashtable.h>
+#include <linux/kernel.h>
+#include <linux/static_call_types.h>
+
+struct instruction *find_insn(struct objtool_file *file,
+			      struct section *sec, unsigned long offset)
+{
+	struct instruction *insn;
+
+	hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
+		if (insn->sec == sec && insn->offset == offset)
+			return insn;
+	}
+
+	return NULL;
+}
+
+#define NEGATIVE_RELOC  ((void *)-1L)
+
+struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
+{
+	if (insn->reloc == NEGATIVE_RELOC)
+		return NULL;
+
+	if (!insn->reloc) {
+		if (!file)
+			return NULL;
+
+		insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
+						       insn->offset, insn->len);
+		if (!insn->reloc) {
+			insn->reloc = NEGATIVE_RELOC;
+			return NULL;
+		}
+	}
+
+	return insn->reloc;
+}
+void remove_insn_ops(struct instruction *insn)
+{
+	struct stack_op *op, *tmp;
+
+	list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
+		list_del(&op->list);
+		free(op);
+	}
+}
+
+
+struct symbol *find_call_destination(struct section *sec, unsigned long offset)
+{
+	struct symbol *call_dest;
+
+	call_dest = find_func_by_offset(sec, offset);
+	if (!call_dest)
+		call_dest = find_symbol_by_offset(sec, offset);
+
+	return call_dest;
+}
+
+static unsigned long nr_insns;
+
+int decode_instructions(struct objtool_file *file)
+{
+	struct section *sec;
+	struct symbol *func;
+	unsigned long offset;
+	struct instruction *insn;
+	int ret;
+
+	for_each_sec(file, sec) {
+
+		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+			continue;
+
+		if (strcmp(sec->name, ".altinstr_replacement") &&
+		    strcmp(sec->name, ".altinstr_aux") &&
+		    strncmp(sec->name, ".discard.", 9))
+			sec->text = true;
+
+		if (!strcmp(sec->name, ".noinstr.text") ||
+		    !strcmp(sec->name, ".entry.text"))
+			sec->noinstr = true;
+
+		for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
+			insn = malloc(sizeof(*insn));
+			if (!insn) {
+				WARN("malloc failed");
+				return -1;
+			}
+			memset(insn, 0, sizeof(*insn));
+			INIT_LIST_HEAD(&insn->alts);
+			INIT_LIST_HEAD(&insn->stack_ops);
+
+			insn->sec = sec;
+			insn->offset = offset;
+
+			ret = arch_decode_instruction(file, sec, offset,
+						      sec->sh.sh_size - offset,
+						      &insn->len, &insn->type,
+						      &insn->immediate,
+						      &insn->stack_ops);
+			if (ret)
+				goto err;
+
+			hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
+			list_add_tail(&insn->list, &file->insn_list);
+			nr_insns++;
+		}
+
+		list_for_each_entry(func, &sec->symbol_list, list) {
+			if (func->type != STT_FUNC || func->alias != func)
+				continue;
+
+			if (!find_insn(file, sec, func->offset)) {
+				WARN("%s(): can't find starting instruction",
+				     func->name);
+				return -1;
+			}
+
+			sym_for_each_insn(file, func, insn)
+				insn->func = func;
+		}
+	}
+
+	if (stats)
+		printf("nr_insns: %lu\n", nr_insns);
+
+	return 0;
+
+err:
+	free(insn);
+	return ret;
+}
+
+int create_mcount_loc_sections(struct objtool_file *file)
+{
+	struct section *sec;
+	unsigned long *loc;
+	struct instruction *insn;
+	int idx;
+
+	sec = find_section_by_name(file->elf, "__mcount_loc");
+	if (sec) {
+		INIT_LIST_HEAD(&file->mcount_loc_list);
+		WARN("file already has __mcount_loc section, skipping");
+		return 0;
+	}
+
+	if (list_empty(&file->mcount_loc_list))
+		return 0;
+
+	idx = 0;
+	list_for_each_entry(insn, &file->mcount_loc_list, call_node)
+		idx++;
+
+	sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
+	if (!sec)
+		return -1;
+
+	idx = 0;
+	list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
+
+		loc = (unsigned long *)sec->data->d_buf + idx;
+		memset(loc, 0, sizeof(unsigned long));
+
+		if (elf_add_reloc_to_insn(file->elf, sec,
+					  idx * sizeof(unsigned long),
+					  R_X86_64_64,
+					  insn->sec, insn->offset))
+			return -1;
+
+		idx++;
+	}
+
+	return 0;
+}

@@ -846,7 +846,9 @@ ifdef CONFIG_FTRACE_MCOUNT_USE_CC
   endif
 endif
 ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+ ifdef CONFIG_HAVE_NOP_MCOUNT
   CC_FLAGS_USING	+= -DCC_USING_NOP_MCOUNT
+ endif
 endif
 ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
   ifdef CONFIG_HAVE_C_RECORDMCOUNT

@@ -1303,6 +1305,10 @@ ifdef CONFIG_STACK_VALIDATION
 prepare: tools/objtool
 endif
 
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+prepare: tools/objtool
+endif
+
 ifdef CONFIG_BPF
 ifdef CONFIG_DEBUG_INFO_BTF
 prepare: tools/bpf/resolve_btfids

@@ -185,7 +185,8 @@ config X86
 	select HAVE_CONTEXT_TRACKING		if X86_64
 	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
 	select HAVE_C_RECORDMCOUNT
-	select HAVE_OBJTOOL_MCOUNT		if STACK_VALIDATION
+	select HAVE_OBJTOOL_MCOUNT
+	select HAVE_NOP_MCOUNT			if HAVE_OBJTOOL_MCOUNT
 	select HAVE_BUILDTIME_MCOUNT_SORT
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS

@@ -242,6 +242,18 @@ cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(o
 
 endif # CONFIG_STACK_VALIDATION
 
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+
+objtool := $(objtree)/tools/objtool/objtool
+
+objtool_args := mcount
+objtool_args += $(if $(CONFIG_HAVE_NOP_MCOUNT), --mnop)
+
+cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
+cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
+
+endif # CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+
 ifdef CONFIG_LTO_CLANG
 
 # Skip objtool for LLVM bitcode

@@ -2,12 +2,14 @@ objtool-y += arch/$(SRCARCH)/
 
 objtool-y += weak.o
 
+objtool-$(SUBCMD_MCOUNT) += mcount.o
 objtool-$(SUBCMD_CHECK) += check.o
 objtool-$(SUBCMD_CHECK) += special.o
 objtool-$(SUBCMD_ORC) += check.o
 objtool-$(SUBCMD_ORC) += orc_gen.o
 objtool-$(SUBCMD_ORC) += orc_dump.o
 
+objtool-y += builtin-mcount.o
 objtool-y += builtin-check.o
 objtool-y += builtin-orc.o
 objtool-y += elf.o

@@ -41,13 +41,15 @@ AWK = awk
 
 SUBCMD_CHECK := n
 SUBCMD_ORC := n
+SUBCMD_MCOUNT := n
 
 ifeq ($(SRCARCH),x86)
 	SUBCMD_CHECK := y
 	SUBCMD_ORC := y
+	SUBCMD_MCOUNT := y
 endif
 
-export SUBCMD_CHECK SUBCMD_ORC
+export SUBCMD_CHECK SUBCMD_ORC SUBCMD_MCOUNT
 export srctree OUTPUT CFLAGS SRCARCH AWK
 include $(srctree)/tools/build/Makefile.include
 

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <subcmd/parse-options.h>
+#include <string.h>
+#include <stdlib.h>
+#include <objtool/builtin.h>
+#include <objtool/objtool.h>
+
+bool mnop;
+
+static const char * const mcount_usage[] = {
+	"objtool mcount [<options>] file.o",
+	NULL,
+};
+
+static const char * const env_usage[] = {
+	"OBJTOOL_ARGS=\"<options>\"",
+	NULL,
+};
+
+const struct option mcount_options[] = {
+	OPT_BOOLEAN('N', "mnop", &mnop, "nop mcount call sites"),
+	OPT_END(),
+};
+
+int cmd_parse_options_mcount(int argc, const char **argv, const char * const usage[])
+{
+	const char *envv[16] = { };
+	char *env;
+	int envc;
+
+	env = getenv("OBJTOOL_ARGS");
+	if (env) {
+		envv[0] = "OBJTOOL_ARGS";
+		for (envc = 1; envc < ARRAY_SIZE(envv); ) {
+			envv[envc++] = env;
+			env = strchr(env, ' ');
+			if (!env)
+				break;
+			*env = '\0';
+			env++;
+		}
+
+		parse_options(envc, envv, mcount_options, env_usage, 0);
+	}
+
+	argc = parse_options(argc, argv, mcount_options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, mcount_options);
+	return argc;
+}
+
+int cmd_mcount(int argc, const char **argv)
+{
+	const char *objname;
+	struct objtool_file *file;
+	int ret;
+
+	argc = cmd_parse_options_mcount(argc, argv, mcount_usage);
+	objname = argv[0];
+
+	file = objtool_open_read(objname);
+	if (!file)
+		return 1;
+
+	ret = objtool_mcount(file);
+	if (ret)
+		return ret;
+
+	if (file->elf->changed)
+		return elf_write(file->elf);
+
+	return 0;
+}

@@ -9,11 +9,13 @@
 
 extern const struct option check_options[];
 extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
-            validate_dup, vmlinux, mcount, noinstr, backup, sls;
+	    validate_dup, vmlinux, mcount, noinstr, backup, sls, mnop;
 
 extern int cmd_parse_options(int argc, const char **argv, const char * const usage[]);
+extern int cmd_parse_options_mcount(int argc, const char **argv, const char * const usage[]);
 
 extern int cmd_check(int argc, const char **argv);
 extern int cmd_orc(int argc, const char **argv);
+extern int cmd_mcount(int argc, const char **argv);
 
 #endif /* _BUILTIN_H */

@@ -41,5 +41,6 @@ void objtool_pv_add(struct objtool_file *file, int idx, struct symbol *func);
 int check(struct objtool_file *file);
 int orc_dump(const char *objname);
 int orc_create(struct objtool_file *file);
+int objtool_mcount(struct objtool_file *file);
 
 #endif /* _OBJTOOL_H */

@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <string.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+
+#include <arch/elf.h>
+#include <objtool/builtin.h>
+#include <objtool/cfi.h>
+#include <objtool/arch.h>
+#include <objtool/check.h>
+#include <objtool/utils.h>
+#include <objtool/special.h>
+#include <objtool/warn.h>
+
+#include <linux/objtool.h>
+#include <linux/hashtable.h>
+#include <linux/kernel.h>
+#include <linux/static_call_types.h>
+
+static int classify_symbols(struct objtool_file *file)
+{
+	struct section *sec;
+	struct symbol *func;
+
+	for_each_sec(file, sec) {
+		list_for_each_entry(func, &sec->symbol_list, list) {
+			if (func->bind != STB_GLOBAL)
+				continue;
+			if ((!strcmp(func->name, "__fentry__")) || (!strcmp(func->name, "_mcount")))
+				func->fentry = true;
+		}
+	}
+
+	return 0;
+}
+
+static void annotate_call_site(struct objtool_file *file,
+							   struct instruction *insn, bool sibling)
+{
+	struct reloc *reloc = insn_reloc(file, insn);
+	struct symbol *sym = insn->call_dest;
+
+	if (!sym)
+		sym = reloc->sym;
+
+	if (sym->fentry) {
+		if (sibling)
+			WARN_FUNC("Tail call to _mcount !?!?", insn->sec, insn->offset);
+		if (mnop) {
+			if (reloc) {
+				reloc->type = R_NONE;
+				elf_write_reloc(file->elf, reloc);
+			}
+			elf_write_insn(file->elf, insn->sec,
+				       insn->offset, insn->len,
+				       arch_nop_insn(insn->len));
+
+			insn->type = INSN_NOP;
+		}
+
+		list_add_tail(&insn->call_node, &file->mcount_loc_list);
+		return;
+	}
+}
+
+static void add_call_dest(struct objtool_file *file, struct instruction *insn,
+						  struct symbol *dest, bool sibling)
+{
+	insn->call_dest = dest;
+	if (!dest)
+		return;
+
+	remove_insn_ops(insn);
+
+	annotate_call_site(file, insn, sibling);
+}
+static int add_call_destinations(struct objtool_file *file)
+{
+	struct instruction *insn;
+	unsigned long dest_off;
+	struct symbol *dest;
+	struct reloc *reloc;
+
+	for_each_insn(file, insn) {
+		if (insn->type != INSN_CALL)
+			continue;
+
+		reloc = insn_reloc(file, insn);
+		if (!reloc) {
+			dest_off = arch_jump_destination(insn);
+			dest = find_call_destination(insn->sec, dest_off);
+
+			add_call_dest(file, insn, dest, false);
+
+
+		} else {
+			add_call_dest(file, insn, reloc->sym, false);
+		}
+	}
+
+	return 0;
+}
+
+static int decode_sections(struct objtool_file *file)
+{
+	int ret;
+
+	ret = decode_instructions(file);
+	if (ret)
+		return ret;
+
+	ret = classify_symbols(file);
+	if (ret)
+		return ret;
+
+	ret = add_call_destinations(file);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+
+int objtool_mcount(struct objtool_file *file)
+{
+	int ret, warnings = 0;
+
+	ret = decode_sections(file);
+	if (ret < 0)
+		return 0;
+
+	ret = create_mcount_loc_sections(file);
+	if (ret < 0)
+		return 0;
+	warnings += ret;
+	return 0;
+}

@@ -37,6 +37,7 @@ static const char objtool_usage_string[] =
 
 static struct cmd_struct objtool_cmds[] = {
 	{"check",	cmd_check,	"Perform stack metadata validation on an object file" },
+	{"mcount",      cmd_mcount,    "Generate __mcount_loc section" },
 	{"orc",		cmd_orc,	"Generate in-place ORC unwind tables for an object file" },
 };
 

@@ -29,3 +29,8 @@ int __weak orc_create(struct objtool_file *file)
 {
 	UNSUPPORTED("orc");
 }
+
+int __weak objtool_mcount(struct objtool_file *file)
+{
+	UNSUPPORTED("mcount subcommand");
+}

@@ -225,6 +225,7 @@ config PPC
 	select HAVE_MOD_ARCH_SPECIFIC
 	select HAVE_NMI				if PERF_EVENTS || (PPC64 && PPC_BOOK3S)
 	select HAVE_OPTPROBES
+	select HAVE_OBJTOOL_MCOUNT
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_EVENTS_NMI		if PPC64
 	select HAVE_PERF_REGS

@@ -49,6 +49,10 @@ ifeq ($(SRCARCH),x86)
 	SUBCMD_MCOUNT := y
 endif
 
+ifeq ($(SRCARCH),powerpc)
+        SUBCMD_MCOUNT := y
+endif
+
 export SUBCMD_CHECK SUBCMD_ORC SUBCMD_MCOUNT
 export srctree OUTPUT CFLAGS SRCARCH AWK
 include $(srctree)/tools/build/Makefile.include

@@ -0,0 +1 @@
+objtool-y += decode.o

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <objtool/check.h>
+#include <objtool/elf.h>
+#include <objtool/arch.h>
+#include <objtool/warn.h>
+#include <objtool/builtin.h>
+
+int arch_decode_instruction(struct objtool_file *file, 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;
+	unsigned int opcode;
+	u64 imm;
+
+	*immediate = imm = 0;
+	memcpy(&insn, sec->data->d_buf+offset, 4);
+	*len = 4;
+	*type = INSN_OTHER;
+
+	opcode = (insn >> 26);
+
+	switch (opcode) {
+	case 18: /* bl */
+		*type = INSN_CALL;
+		break;
+	}
+	*immediate = imm;
+	return 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)
+{
+	return NULL;
+}

@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _OBJTOOL_CFI_REGS_H
+#define _OBJTOOL_CFI_REGS_H
+
+#define CFI_SP                  1
+#define CFI_TOC                 2
+#define CFI_R3                  3
+#define CFI_R4                  4
+#define CFI_R5                  5
+#define CFI_R6                  6
+#define CFI_R7                  7
+#define CFI_R8                  8
+#define CFI_R9                  9
+#define CFI_R10                 10
+#define CFI_R14                 14
+#define CFI_R15                 15
+#define CFI_R16                 16
+#define CFI_R17                 17
+#define CFI_R18                 18
+#define CFI_R19                 19
+#define CFI_R20                 20
+#define CFI_R21                 21
+#define CFI_R22                 22
+#define CFI_R23                 23
+#define CFI_R24                 24
+#define CFI_R25                 25
+#define CFI_R26                 26
+#define CFI_R27                 27
+#define CFI_R28                 28
+#define CFI_R29                 29
+#define CFI_R30                 30
+#define CFI_R31                 31
+#define CFI_LR                  32
+#define CFI_NUM_REGS            33
+
+#endif

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _OBJTOOL_ARCH_ELF
+#define _OBJTOOL_ARCH_ELF
+
+#define R_NONE R_PPC_NONE
+
+#endif /* _OBJTOOL_ARCH_ELF */

@@ -179,11 +179,29 @@ int create_mcount_loc_sections(struct objtool_file *file)
 		loc = (unsigned long *)sec->data->d_buf + idx;
 		memset(loc, 0, sizeof(unsigned long));
 
-		if (elf_add_reloc_to_insn(file->elf, sec,
-					  idx * sizeof(unsigned long),
-					  R_X86_64_64,
-					  insn->sec, insn->offset))
-			return -1;
+		if (file->elf->ehdr.e_machine == EM_X86_64) {
+			if (elf_add_reloc_to_insn(file->elf, sec,
+						  idx * sizeof(unsigned long),
+						  R_X86_64_64,
+						  insn->sec, insn->offset))
+				return -1;
+		}
+
+		if (file->elf->ehdr.e_machine == EM_PPC64) {
+			if (elf_add_reloc_to_insn(file->elf, sec,
+						  idx * sizeof(unsigned long),
+						  R_PPC64_ADDR64,
+						  insn->sec, insn->offset))
+				return -1;
+		}
+
+		if (file->elf->ehdr.e_machine == EM_PPC) {
+			if (elf_add_reloc_to_insn(file->elf, sec,
+						  idx * sizeof(unsigned long),
+						  R_PPC_ADDR32,
+						  insn->sec, insn->offset))
+				return -1;
+		}
 
 		idx++;
 	}