The following commit has been merged into the efi/core branch of tip:
Commit-ID: 688eb28211abdf82a3f51e8997f1c8137947227d
Gitweb: https://git.kernel.org/tip/688eb28211abdf82a3f51e8997f1c8137947227d
Author: Arvind Sankar <nivedita@xxxxxxxxxxxx>
AuthorDate: Sun, 11 Oct 2020 10:20:12 -04:00
Committer: Ard Biesheuvel <ardb@xxxxxxxxxx>
CommitterDate: Mon, 26 Oct 2020 08:06:36 +01:00
efi/x86: Only copy the compressed kernel image in efi_relocate_kernel()
The image_size argument to efi_relocate_kernel() is currently specified
as init_size, but this is unnecessarily large. The compressed kernel is
much smaller, in fact, its image only extends up to the start of _bss,
since at this point, the .bss section is still uninitialized.
Depending on compression level, this can reduce the amount of data
copied by 4-5x.
Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201011142012.96493-1-nivedita@xxxxxxxxxxxx
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
drivers/firmware/efi/libstub/x86-stub.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index 3672539..f14c4ff 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -715,8 +715,11 @@ unsigned long efi_main(efi_handle_t handle,
(IS_ENABLED(CONFIG_X86_32) && buffer_end > KERNEL_IMAGE_SIZE) ||
(IS_ENABLED(CONFIG_X86_64) && buffer_end > MAXMEM_X86_64_4LEVEL) ||
(image_offset == 0)) {
+ extern char _bss[];
+
status = efi_relocate_kernel(&bzimage_addr,
- hdr->init_size, hdr->init_size,
+ (unsigned long)_bss - bzimage_addr,
+ hdr->init_size,
hdr->pref_address,
hdr->kernel_alignment,
LOAD_PHYSICAL_ADDR);
|