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Date: Mon, 12 Oct 2020 17:31:43 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Masahiro Yamada <masahiroy@...nel.org>, Steven Rostedt <rostedt@...dmis.org>
Cc: Will Deacon <will@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Paul E. McKenney" <paulmck@...nel.org>,
Kees Cook <keescook@...omium.org>, Nick Desaulniers <ndesaulniers@...gle.com>,
clang-built-linux@...glegroups.com, kernel-hardening@...ts.openwall.com,
linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, x86@...nel.org,
Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v6 05/25] 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@...gle.com>
---
Makefile | 12 ++++++++++--
kernel/trace/Kconfig | 13 +++++++++++++
scripts/Makefile.build | 3 +++
3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile
index 129001b38357..fda1f8a0b1c7 100644
--- a/Makefile
+++ b/Makefile
@@ -850,6 +850,9 @@ 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
@@ -1209,11 +1212,16 @@ uapi-asm-generic:
PHONY += prepare-objtool prepare-resolve_btfids
prepare-objtool: $(objtool_target)
ifeq ($(SKIP_STACK_VALIDATION),1)
+objtool-lib-prompt := "please install libelf-dev, libelf-devel or elfutils-libelf-devel"
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+ @echo "error: Cannot generate __mcount_loc for CONFIG_DYNAMIC_FTRACE=y, $(objtool-lib-prompt)" >&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
+ @echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, $(objtool-lib-prompt)" >&2
@false
else
- @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
+ @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, $(objtool-lib-prompt)" >&2
endif
endif
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 927ad004888a..89263210ab26 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -51,6 +51,11 @@ 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
@@ -605,10 +610,18 @@ 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 a4634aae1506..cd4294435fef 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -228,6 +228,9 @@ 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
--
2.28.0.1011.ga647a8990f-goog
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