Sathvika Vasireddy wrote:
Some architectures (powerpc) may not support ftrace locations being nop'ed
out at build time. Introduce CONFIG_HAVE_OBJTOOL_NOP_MCOUNT for objtool, as
a means for architectures to enable nop'ing of ftrace locations. Add --mnop
as an option to objtool --mcount, to indicate support for the same.
Also, make sure that --mnop can be passed as an option to objtool only when
--mcount is passed.
Signed-off-by: Sathvika Vasireddy <s...@linux.ibm.com>
---
Makefile | 4 +++-
arch/x86/Kconfig | 1 +
kernel/trace/Kconfig | 7 +++++++
scripts/Makefile.lib | 1 +
tools/objtool/builtin-check.c | 14 ++++++++++++++
tools/objtool/check.c | 19 ++++++++++---------
tools/objtool/include/objtool/builtin.h | 1 +
7 files changed, 37 insertions(+), 10 deletions(-)
diff --git a/Makefile b/Makefile
index a5e9d9388649..b2230ad14748 100644
--- a/Makefile
+++ b/Makefile
@@ -857,7 +857,9 @@ ifdef CONFIG_FTRACE_MCOUNT_USE_CC
endif
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
- CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
+ ifdef CONFIG_HAVE_OBJTOOL_NOP_MCOUNT
+ CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
+ endif
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
ifdef CONFIG_HAVE_C_RECORDMCOUNT
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f9920f1341c8..2a79a05c4402 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -189,6 +189,7 @@ config X86
select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if
HAVE_CONTEXT_TRACKING_USER
select HAVE_C_RECORDMCOUNT
select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
+ select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
select HAVE_BUILDTIME_MCOUNT_SORT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 1052126bdca2..9c696cb24756 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -76,6 +76,13 @@ config HAVE_OBJTOOL_MCOUNT
help
Arch supports objtool --mcount
+config HAVE_OBJTOOL_NOP_MCOUNT
+ bool
+ help
+ Arch supports the objtool options --mcount with --mnop.
+ An architecture can select this if it wants to enable nop'ing
+ of ftrace locations.
+
config HAVE_C_RECORDMCOUNT
bool
help
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 3fb6a99e78c4..ce14e3b8577f 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -234,6 +234,7 @@ objtool_args =
\
$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
$(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
+ $(if $(CONFIG_HAVE_OBJTOOL_NOP_MCOUNT), --mnop) \
This still won't help: for instance, if CONFIG_FTRACE itself is
disabled. I think we should make this depend on
CONFIG_FTRACE_MCOUNT_USE_OBJTOOL. The below change works for me:
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 54d2d6451bdacc..fd3f55a1fdb7bb 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -245,8 +245,8 @@ objtool_args =
\
$(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \
$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
$(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
- $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
- $(if $(CONFIG_HAVE_OBJTOOL_NOP_MCOUNT), --mnop) \
+ $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), \
+ $(if $(CONFIG_HAVE_OBJTOOL_NOP_MCOUNT), --mcount --mnop,
--mcount)) \
$(if $(CONFIG_UNWINDER_ORC), --orc) \
$(if $(CONFIG_RETPOLINE), --retpoline) \
$(if $(CONFIG_RETHUNK), --rethunk) \
- Naveen
