[PATCH] arm64/efi: move arm64 specific stub C code to libstub

[Ard Biesheuvel]

On 27 October 2015 at 06:11, Matt Fleming <matt at codeblueprint.co.uk> wrote:
> On Fri, 23 Oct, at 04:48:14PM, Ard Biesheuvel wrote:
>> Now that we added special handling to the C files in libstub, move
>> the one remaining arm64 specific EFI stub C file to libstub as
>> well, so that it gets the same treatment. This should prevent future
>> changes from resulting in binaries that may execute incorrectly in
>> UEFI context.
>
> Sorry, I'm coming at this cache-cold: What special handling was added
> to libstub that you want to make use of here?
>

This is about the libstub patches that you reviewed ~2 weeks ago and
that have been queued in Catalin's arm64 tree for 4.4

>> With efi-entry.S the only remaining EFI stub source file under
>> arch/arm64, we can also simplify the Makefile logic somewhat.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>> ---
>>
>> I would like to suggest that this be taken on top of the stuff that is
>> queued for 4.4 at the moment (if it is not too late already).
>
> That's upto the tip folks (Cc'd). Ingo, would you consider applying
> a minimal build cleanup patch like this for v4.4?
>

Actually, the suggestion was aimed at Catalin, who has all the libstub
and KASAN patches queued that this patch depends on.
Apologies for the confusion.

Thanks,
Ard.


>>  arch/arm64/kernel/Makefile                                                | 9 ++-------
>>  drivers/firmware/efi/libstub/Makefile                                     | 3 +++
>>  arch/arm64/kernel/efi-stub.c => drivers/firmware/efi/libstub/arm64-stub.c | 0
>>  3 files changed, 5 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
>> index 1b6bda2ff102..474691f8b13a 100644
>> --- a/arch/arm64/kernel/Makefile
>> +++ b/arch/arm64/kernel/Makefile
>> @@ -4,11 +4,8 @@
>>
>>  CPPFLAGS_vmlinux.lds := -DTEXT_OFFSET=$(TEXT_OFFSET)
>>  AFLAGS_head.o                := -DTEXT_OFFSET=$(TEXT_OFFSET)
>> -CFLAGS_efi-stub.o    := -DTEXT_OFFSET=$(TEXT_OFFSET)
>>  CFLAGS_armv8_deprecated.o := -I$(src)
>>
>> -KASAN_SANITIZE_efi-stub.o    := n
>> -
>>  CFLAGS_REMOVE_ftrace.o = -pg
>>  CFLAGS_REMOVE_insn.o = -pg
>>  CFLAGS_REMOVE_return_address.o = -pg
>> @@ -22,9 +19,7 @@ arm64-obj-y         := debug-monitors.o entry.o irq.o fpsimd.o              \
>>                          cpufeature.o alternative.o cacheinfo.o               \
>>                          smp.o smp_spin_table.o topology.o
>>
>> -stub-obj                             := efi-stub.o efi-entry.o
>> -extra-y                                      := $(stub-obj)
>> -stub-obj                             := $(patsubst %.o,%.stub.o,$(stub-obj))
>> +extra-$(CONFIG_EFI)                  := efi-entry.o
>>
>>  OBJCOPYFLAGS := --prefix-symbols=__efistub_
>>  $(obj)/%.stub.o: $(obj)/%.o FORCE
>> @@ -42,7 +37,7 @@ arm64-obj-$(CONFIG_CPU_PM)          += sleep.o suspend.o
>>  arm64-obj-$(CONFIG_CPU_IDLE)         += cpuidle.o
>>  arm64-obj-$(CONFIG_JUMP_LABEL)               += jump_label.o
>>  arm64-obj-$(CONFIG_KGDB)             += kgdb.o
>> -arm64-obj-$(CONFIG_EFI)                      += efi.o $(stub-obj)
>> +arm64-obj-$(CONFIG_EFI)                      += efi.o efi-entry.stub.o
>>  arm64-obj-$(CONFIG_PCI)                      += pci.o
>>  arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o
>>  arm64-obj-$(CONFIG_ACPI)             += acpi.o
>> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
>> index bca9a76cbd33..92ae557abbbc 100644
>> --- a/drivers/firmware/efi/libstub/Makefile
>> +++ b/drivers/firmware/efi/libstub/Makefile
>> @@ -34,6 +34,9 @@ $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
>>  lib-$(CONFIG_EFI_ARMSTUB)    += arm-stub.o fdt.o string.o \
>>                                  $(patsubst %.c,lib-%.o,$(arm-deps))
>>
>> +lib-$(CONFIG_ARM64)          += arm64-stub.o
>> +CFLAGS_arm64-stub.o          := -DTEXT_OFFSET=$(TEXT_OFFSET)
>> +
>>  #
>>  # arm64 puts the stub in the kernel proper, which will unnecessarily retain all
>>  # code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
>> diff --git a/arch/arm64/kernel/efi-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
>> similarity index 100%
>> rename from arch/arm64/kernel/efi-stub.c
>> rename to drivers/firmware/efi/libstub/arm64-stub.c
>> --
>> 2.1.4
>>