Messages in this thread Patch in this message | | | Date | Mon, 10 Oct 2022 17:07:46 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [PATCH v4 11/16] objtool: Add --mnop as an option to --mcount |
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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 <sv@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
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