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authorSami Tolvanen <samitolvanen@google.com>2020-09-25 16:43:53 -0700
committerKees Cook <keescook@chromium.org>2021-02-23 12:46:57 -0800
commit22c8542d7b220ffc53816d47b371b1fe34341d4a (patch)
tree55e578bad8de1fb1142b4f4f694a33ab5485dcfe
parent0e731dbc18241d68318e0a7d2c2c0087c9073fb9 (diff)
downloadlinux-22c8542d7b220ffc53816d47b371b1fe34341d4a.tar.gz
tracing: add support for objtool mcount
This change adds build support for using objtool to generate
__mcount_loc sections.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
-rw-r--r--Makefile7
-rw-r--r--kernel/trace/Kconfig13
-rw-r--r--scripts/Makefile.build3
3 files changed, 23 insertions, 0 deletions
diff --git a/Makefile b/Makefile
index 2233951666f7..3189eacf3185 100644
--- a/Makefile
+++ b/Makefile
@@ -860,6 +860,9 @@ ifdef CONFIG_FTRACE_MCOUNT_USE_CC
     endif
   endif
 endif
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+  CC_FLAGS_USING	+= -DCC_USING_NOP_MCOUNT
+endif
 ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
   ifdef CONFIG_HAVE_C_RECORDMCOUNT
     BUILD_C_RECORDMCOUNT := y
@@ -1236,6 +1239,10 @@ uapi-asm-generic:
 PHONY += prepare-objtool prepare-resolve_btfids
 prepare-objtool: $(objtool_target)
 ifeq ($(SKIP_STACK_VALIDATION),1)
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+	@echo "error: Cannot generate __mcount_loc for CONFIG_DYNAMIC_FTRACE=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
+	@false
+endif
 ifdef CONFIG_UNWINDER_ORC
 	@echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
 	@false
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 3985a31a49b7..936ccab1b938 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -60,6 +60,11 @@ config HAVE_NOP_MCOUNT
 	help
 	  Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
 
+config HAVE_OBJTOOL_MCOUNT
+	bool
+	help
+	  Arch supports objtool --mcount
+
 config HAVE_C_RECORDMCOUNT
 	bool
 	help
@@ -612,10 +617,18 @@ config FTRACE_MCOUNT_USE_CC
 	depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
 	depends on FTRACE_MCOUNT_RECORD
 
+config FTRACE_MCOUNT_USE_OBJTOOL
+	def_bool y
+	depends on HAVE_OBJTOOL_MCOUNT
+	depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
+	depends on !FTRACE_MCOUNT_USE_CC
+	depends on FTRACE_MCOUNT_RECORD
+
 config FTRACE_MCOUNT_USE_RECORDMCOUNT
 	def_bool y
 	depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
 	depends on !FTRACE_MCOUNT_USE_CC
+	depends on !FTRACE_MCOUNT_USE_OBJTOOL
 	depends on FTRACE_MCOUNT_RECORD
 
 config TRACING_MAP
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index d94fc9ab819d..59fabd9685ee 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -238,6 +238,9 @@ endif
 ifdef CONFIG_X86_SMAP
   objtool_args += --uaccess
 endif
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+  objtool_args += --mcount
+endif
 
 # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file