diff options
| author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-03-08 09:08:47 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-03-08 09:58:19 +0100 |
| commit | 1887c9b653f99577c0f8ec413b0921a32b6129e2 (patch) | |
| tree | a6a31605952088bd1a3aeceab795d0d96e980153 /arch/x86/boot/compressed/head_64.S | |
| parent | 8ef44be393113dca5cece65bc142ebb8ef013af0 (diff) | |
efi/x86: Decompress at start of PE image load address
When booted via PE loader, define image_offset to hold the offset of
startup_32() from the start of the PE image, and use it as the start of
the decompression buffer.
[ mingo: Fixed the grammar in the comments. ]
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200303221205.4048668-3-nivedita@alum.mit.edu
Link: https://lore.kernel.org/r/20200308080859.21568-17-ardb@kernel.org
Diffstat (limited to 'arch/x86/boot/compressed/head_64.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 42 |
1 files changed, 39 insertions, 3 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 5d8338a693ce..d4657d38e884 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -99,6 +99,19 @@ SYM_FUNC_START(startup_32) #ifdef CONFIG_RELOCATABLE movl %ebp, %ebx + +#ifdef CONFIG_EFI_STUB +/* + * If we were loaded via the EFI LoadImage service, startup_32 will be at an + * offset to the start of the space allocated for the image. efi_pe_entry will + * set up image_offset to tell us where the image actually starts, so that we + * can use the full available buffer. + * image_offset = startup_32 - image_base + * Otherwise image_offset will be zero and has no effect on the calculations. + */ + subl image_offset(%ebp), %ebx +#endif + movl BP_kernel_alignment(%esi), %eax decl %eax addl %eax, %ebx @@ -111,9 +124,8 @@ SYM_FUNC_START(startup_32) 1: /* Target address to relocate to for decompression */ - movl BP_init_size(%esi), %eax - subl $_end, %eax - addl %eax, %ebx + addl BP_init_size(%esi), %ebx + subl $_end, %ebx /* * Prepare for entering 64 bit mode @@ -299,6 +311,20 @@ SYM_CODE_START(startup_64) /* Start with the delta to where the kernel will run at. */ #ifdef CONFIG_RELOCATABLE leaq startup_32(%rip) /* - $startup_32 */, %rbp + +#ifdef CONFIG_EFI_STUB +/* + * If we were loaded via the EFI LoadImage service, startup_32 will be at an + * offset to the start of the space allocated for the image. efi_pe_entry will + * set up image_offset to tell us where the image actually starts, so that we + * can use the full available buffer. + * image_offset = startup_32 - image_base + * Otherwise image_offset will be zero and has no effect on the calculations. + */ + movl image_offset(%rip), %eax + subq %rax, %rbp +#endif + movl BP_kernel_alignment(%rsi), %eax decl %eax addq %rax, %rbp @@ -647,6 +673,10 @@ SYM_DATA_START_LOCAL(gdt) .quad 0x0000000000000000 /* TS continued */ SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end) +#ifdef CONFIG_EFI_STUB +SYM_DATA(image_offset, .long 0) +#endif + #ifdef CONFIG_EFI_MIXED SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0) SYM_DATA(efi_is64, .byte 1) @@ -712,6 +742,12 @@ SYM_FUNC_START(efi32_pe_entry) movl -4(%ebp), %esi // loaded_image movl LI32_image_base(%esi), %esi // loaded_image->image_base movl %ebx, %ebp // startup_32 for efi32_pe_stub_entry + /* + * We need to set the image_offset variable here since startup_32() will + * use it before we get to the 64-bit efi_pe_entry() in C code. + */ + subl %esi, %ebx + movl %ebx, image_offset(%ebp) // save image_offset jmp efi32_pe_stub_entry 2: popl %edi // restore callee-save registers |