arm64/efi: move arm64 specific stub C code to libstub

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.

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 <[email protected]>

---

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).

 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(-)

arch/arm64/kernel/Makefile +2 -7

index 1b6bda2ff102..474691f8b13a 100644
@@ -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

drivers/firmware/efi/libstub/Makefile +3 -0

index bca9a76cbd33..92ae557abbbc 100644
@@ -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.

drivers/firmware/efi/libstub/arm64-stub.c renamed from arch/arm64/kernel/efi-stub.c +0 -0

similarity index 100%
rename from arch/arm64/kernel/efi-stub.c
rename to drivers/firmware/efi/libstub/arm64-stub.c

Signature · 1 line

2.1.4

Quoted 5 lines · Ard Biesheuvel

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?

Quoted 8 lines

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 <[email protected]>

---

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?

Quoted 62 lines

 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(-)

arch/arm64/kernel/Makefile +2 -7

index 1b6bda2ff102..474691f8b13a 100644
@@ -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

drivers/firmware/efi/libstub/Makefile +3 -0

index bca9a76cbd33..92ae557abbbc 100644
@@ -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.

drivers/firmware/efi/libstub/arm64-stub.c renamed from arch/arm64/kernel/efi-stub.c +0 -1

similarity index 100%
rename from arch/arm64/kernel/efi-stub.c
rename to drivers/firmware/efi/libstub/arm64-stub.c
--

2.1.4

Quoted 10 lines · Matt Fleming

Quoted 5 lines · Ard Biesheuvel

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

Quoted 9 lines

Quoted 8 lines

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 <[email protected]>

---

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).

Quoted 3 lines

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.

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.

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 <[email protected]>

---

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).

Quoted 9 lines · Ard Biesheuvel

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.

With efi-entry.S the only remaining EFI stub source file under arch/arm64, we can also simplify the Makefile logic somewhat.

Quoted 5 lines

Signed-off-by Ard Biesheuvel <[email protected]>

---

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).

Applied. Thanks.

Quoted 13 lines · Catalin Marinas

Quoted 12 lines · Ard Biesheuvel

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.

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 <[email protected]>

---

Quoted 4 lines

Quoted 2 lines

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).

Applied. Thanks.

Please note (before you push it out), that Will just pulled a 4.3-rc fix that changes arch/arm64/kernel/efi-stub.c

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.

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 <[email protected]>