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tracing: add support for objtool mcount

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This change adds build support for using objtool to generate
__mcount_loc sections.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Sami Tolvanen 2020-09-25 16:43:53 -07:00 committed by Kees Cook
parent 0e731dbc18
commit 22c8542d7b
3 changed files with 23 additions and 0 deletions
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7
Makefile
View File

@ -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

13
kernel/trace/Kconfig
View File

@ -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

3
scripts/Makefile.build
View File

@ -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