ftrace: Add arm64 support to recordmcount

Recordmcount utility under scripts is run, after compiling each object,
to find out all the locations of calling _mcount() and put them into
specific seciton named __mcount_loc.
Then linker collects all such information into a table in the kernel image
(between __start_mcount_loc and __stop_mcount_loc) for later use by ftrace.

This patch adds arm64 specific definitions to identify such locations.
There are two types of implementation, C and Perl. On arm64, only C version
is used to build the kernel now that CONFIG_HAVE_C_RECORDMCOUNT is on.
But Perl version is also maintained.

This patch also contains a workaround just in case where a header file,
elf.h, on host machine doesn't have definitions of EM_AARCH64 nor
R_AARCH64_ABS64. Without them, compiling C version of recordmcount will
fail.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 78b356d079dd..c7022a9d5eeb 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -30,12 +30,14 @@ config ARM64
         select HAVE_ARCH_JUMP_LABEL
         select HAVE_ARCH_KGDB
         select HAVE_ARCH_TRACEHOOK
+        select HAVE_C_RECORDMCOUNT
         select HAVE_DEBUG_BUGVERBOSE
         select HAVE_DEBUG_KMEMLEAK
         select HAVE_DMA_API_DEBUG
         select HAVE_DMA_ATTRS
         select HAVE_DMA_CONTIGUOUS
         select HAVE_EFFICIENT_UNALIGNED_ACCESS
+        select HAVE_FTRACE_MCOUNT_RECORD
         select HAVE_GENERIC_DMA_COHERENT
         select HAVE_HW_BREAKPOINT if PERF_EVENTS
         select HAVE_MEMBLOCK