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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-11-20 17:41:30 +0000
committerWill Deacon <will.deacon@arm.com>2017-12-01 13:04:59 +0000
commitbe0f272bfc83797f70d44faca86954df62e2bbc0 (patch)
treecc30988986ef959c80ad89912f5dc342f99f0be5 /arch/arm64/kernel/Makefile
parent7e8b9c1d2e2f5f45db7d40b50d14f606097c25de (diff)
downloadlinux-be0f272bfc83797f70d44faca86954df62e2bbc0.tar.bz2
arm64: ftrace: emit ftrace-mod.o contents through code
When building the arm64 kernel with both CONFIG_ARM64_MODULE_PLTS and CONFIG_DYNAMIC_FTRACE enabled, the ftrace-mod.o object file is built with the kernel and contains a trampoline that is linked into each module, so that modules can be loaded far away from the kernel and still reach the ftrace entry point in the core kernel with an ordinary relative branch, as is emitted by the compiler instrumentation code dynamic ftrace relies on. In order to be able to build out of tree modules, this object file needs to be included into the linux-headers or linux-devel packages, which is undesirable, as it makes arm64 a special case (although a precedent does exist for 32-bit PPC). Given that the trampoline essentially consists of a PLT entry, let's not bother with a source or object file for it, and simply patch it in whenever the trampoline is being populated, using the existing PLT support routines. Cc: <stable@vger.kernel.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/Makefile')
-rw-r--r--arch/arm64/kernel/Makefile3
1 files changed, 0 insertions, 3 deletions
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 8265dd790895..067baace74a0 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -61,6 +61,3 @@ extra-y += $(head-y) vmlinux.lds
ifeq ($(CONFIG_DEBUG_EFI),y)
AFLAGS_head.o += -DVMLINUX_PATH="\"$(realpath $(objtree)/vmlinux)\""
endif
-
-# will be included by each individual module but not by the core kernel itself
-extra-$(CONFIG_DYNAMIC_FTRACE) += ftrace-mod.o