From 688eb28211abdf82a3f51e8997f1c8137947227d Mon Sep 17 00:00:00 2001 From: Arvind Sankar Date: Sun, 11 Oct 2020 10:20:12 -0400 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/20201011142012.96493-1-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel --- 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 3672539cb96e..f14c4ff5839f 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);