| Message ID | 20201118220731.925424-17-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add support for Clang LTO | expand |
On Wed, Nov 18, 2020 at 02:07:30PM -0800, Sami Tolvanen wrote: > DYNAMIC_FTRACE_WITH_REGS uses -fpatchable-function-entry, which makes > running recordmcount unnecessary as there are no mcount calls in object > files, and __mcount_loc doesn't need to be generated. > > While there's normally no harm in running recordmcount even when it's > not strictly needed, this won't work with LTO as we have LLVM bitcode > instead of ELF objects. > > This change selects FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY, which > disables recordmcount when patchable function entries are used instead. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- > arch/arm64/Kconfig | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 1515f6f153a0..c7f07978f5b6 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -158,6 +158,8 @@ config ARM64 > select HAVE_DYNAMIC_FTRACE > select HAVE_DYNAMIC_FTRACE_WITH_REGS \ > if $(cc-option,-fpatchable-function-entry=2) > + select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \ > + if DYNAMIC_FTRACE_WITH_REGS I don't really understand why this is in the arch header file, rather than have the core code check for "fpatchable-function-entry=2" and expose a CC_HAS_PATCHABLE_FUNCTION_ENTRY, but in the interest of making some progress on this series: Acked-by: Will Deacon <will@kernel.org> Will
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1515f6f153a0..c7f07978f5b6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -158,6 +158,8 @@ config ARM64 select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_REGS \ if $(cc-option,-fpatchable-function-entry=2) + select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \ + if DYNAMIC_FTRACE_WITH_REGS select HAVE_EFFICIENT_UNALIGNED_ACCESS select HAVE_FAST_GUP select HAVE_FTRACE_MCOUNT_RECORD
DYNAMIC_FTRACE_WITH_REGS uses -fpatchable-function-entry, which makes running recordmcount unnecessary as there are no mcount calls in object files, and __mcount_loc doesn't need to be generated. While there's normally no harm in running recordmcount even when it's not strictly needed, this won't work with LTO as we have LLVM bitcode instead of ELF objects. This change selects FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY, which disables recordmcount when patchable function entries are used instead. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/Kconfig | 2 ++ 1 file changed, 2 insertions(+)