This ensures all stub component are freed when the kernel proper is
done booting, by prefixing the names of all ELF sections that have
the SHF_ALLOC attribute with ".init". This approach ensures that even
implicitly emitted allocated data (like initializer values and string
literals) are covered.
At the same time, remove some __init annotations in the stub that have
now become redundant, and add the __init annotation to handle_kernel_image
which will now trigger a section mismatch warning without it.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
v2: fixed an issue with spurious rebuilding of object files, now setting
$(extra-y) correctly, which also allows the .PRECIOUS: to be dropped.
arch/arm64/kernel/efi-stub.c | 14 +++++++-------
drivers/firmware/efi/libstub/Makefile | 14 ++++++++++++++
drivers/firmware/efi/libstub/arm-stub.c | 8 ++++----
drivers/firmware/efi/libstub/efi-stub-helper.c | 2 +-
4 files changed, 26 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
index d27dd982ff26..f5374065ad53 100644
--- a/arch/arm64/kernel/efi-stub.c
+++ b/arch/arm64/kernel/efi-stub.c
@@ -13,13 +13,13 @@
#include <asm/efi.h>
#include <asm/sections.h>
-efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
- unsigned long *image_addr,
- unsigned long *image_size,
- unsigned long *reserve_addr,
- unsigned long *reserve_size,
- unsigned long dram_base,
- efi_loaded_image_t *image)
+efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
+ unsigned long *image_addr,
+ unsigned long *image_size,
+ unsigned long *reserve_addr,
+ unsigned long *reserve_size,
+ unsigned long dram_base,
+ efi_loaded_image_t *image)
{
efi_status_t status;
unsigned long kernel_size, kernel_memsize = 0;
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index b14bc2b9fb4d..8902f52e0998 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -24,3 +24,17 @@ lib-y := efi-stub-helper.o
lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o
CFLAGS_fdt.o += -I$(srctree)/scripts/dtc/libfdt/
+
+#
+# arm64 puts the stub in the kernel proper, which will unnecessarily retain all
+# code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
+# So let's apply the __init annotations at the section level, by prefixing
+# the section names directly. This will ensure that even all the inline string
+# literals are covered.
+#
+extra-$(CONFIG_ARM64) := $(lib-y)
+lib-$(CONFIG_ARM64) := $(patsubst %.o,%.init.o,$(lib-y))
+
+OBJCOPYFLAGS := --prefix-alloc-sections=.init
+$(obj)/%.init.o: $(obj)/%.o FORCE
+ $(call if_changed,objcopy)
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index e2432b39b6df..dcae482a9a17 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -17,10 +17,10 @@
#include "efistub.h"
-static int __init efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
+static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
{
- static efi_guid_t const var_guid __initconst = EFI_GLOBAL_VARIABLE_GUID;
- static efi_char16_t const var_name[] __initconst = {
+ static efi_guid_t const var_guid = EFI_GLOBAL_VARIABLE_GUID;
+ static efi_char16_t const var_name[] = {
'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 };
efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable;
@@ -164,7 +164,7 @@ efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
* for both archictectures, with the arch-specific code provided in the
* handle_kernel_image() function.
*/
-unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table,
+unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
unsigned long *image_addr)
{
efi_loaded_image_t *image;
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index e766df60fbfb..2fe195002021 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -110,7 +110,7 @@ fail:
}
-unsigned long __init get_dram_base(efi_system_table_t *sys_table_arg)
+unsigned long get_dram_base(efi_system_table_t *sys_table_arg)
{
efi_status_t status;
unsigned long map_size;
--
1.8.3.2
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