Commit a31d793d authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Kees Cook
Browse files

arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS 



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: default avatarSami Tolvanen <samitolvanen@google.com>
Acked-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-16-samitolvanen@google.com
parent 004d53f8

arch/arm64/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -162,6 +162,8 @@ 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