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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2014-10-08 16:11:27 +0200
committerKees Cook <keescook@google.com>2015-10-07 13:12:27 -0700
commit7564cb6558d035d402ad5cefe3f41a26b9b365e3 (patch)
treec62f6d66486fc76088e61a72014d83842725f262
parent88b0c7958bb652acd4ce90aededc8365276a3c8b (diff)
downloadlinux-linaro-stable-7564cb6558d035d402ad5cefe3f41a26b9b365e3.tar.gz
UPSTREAM: arm64/efi: efistub: jump to 'stext' directly, not through the header
After the EFI stub has done its business, it jumps into the kernel by branching to offset #0 of the loaded Image, which is where it expects to find the header containing a 'branch to stext' instruction. However, the UEFI spec 2.1.1 states the following regarding PE/COFF image loading: "A UEFI image is loaded into memory through the LoadImage() Boot Service. This service loads an image with a PE32+ format into memory. This PE32+ loader is required to load all sections of the PE32+ image into memory." In other words, it is /not/ required to load parts of the image that are not covered by a PE/COFF section, so it may not have loaded the header at the expected offset, as it is not covered by any PE/COFF section. So instead, jump to 'stext' directly, which is at the base of the PE/COFF .text section, by supplying a symbol 'stext_offset' to efi-entry.o which contains the relative offset of stext into the Image. Also replace other open coded calculations of the same value with a reference to 'stext_offset' Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Roy Franz <roy.franz@linaro.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> (cherry picked from commit 95b395963fed02cca8849137b375528a5fc94e35) Signed-off-by: Tomasz Figa <tfiga@chromium.org> Bug: 24475017 Change-Id: I21548ced434a5c6eab6d763821b3ca733827d66e Signed-off-by: Kees Cook <keescook@google.com>
-rw-r--r--arch/arm64/kernel/efi-entry.S3
-rw-r--r--arch/arm64/kernel/head.S10
2 files changed, 8 insertions, 5 deletions
diff --git a/arch/arm64/kernel/efi-entry.S b/arch/arm64/kernel/efi-entry.S
index d18a44940968..8ce9b0577442 100644
--- a/arch/arm64/kernel/efi-entry.S
+++ b/arch/arm64/kernel/efi-entry.S
@@ -61,7 +61,8 @@ ENTRY(efi_stub_entry)
*/
mov x20, x0 // DTB address
ldr x0, [sp, #16] // relocated _text address
- mov x21, x0
+ ldr x21, =stext_offset
+ add x21, x0, x21
/*
* Calculate size of the kernel Image (same for original and copy).
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 22c55501c341..ad57e21ccda2 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -132,6 +132,8 @@ efi_head:
#endif
#ifdef CONFIG_EFI
+ .globl stext_offset
+ .set stext_offset, stext - efi_head
.align 3
pe_header:
.ascii "PE"
@@ -155,7 +157,7 @@ optional_header:
.long 0 // SizeOfInitializedData
.long 0 // SizeOfUninitializedData
.long efi_stub_entry - efi_head // AddressOfEntryPoint
- .long stext - efi_head // BaseOfCode
+ .long stext_offset // BaseOfCode
extra_header_fields:
.quad 0 // ImageBase
@@ -172,7 +174,7 @@ extra_header_fields:
.long _end - efi_head // SizeOfImage
// Everything before the kernel image is considered part of the header
- .long stext - efi_head // SizeOfHeaders
+ .long stext_offset // SizeOfHeaders
.long 0 // CheckSum
.short 0xa // Subsystem (EFI application)
.short 0 // DllCharacteristics
@@ -217,9 +219,9 @@ section_table:
.byte 0
.byte 0 // end of 0 padding of section name
.long _end - stext // VirtualSize
- .long stext - efi_head // VirtualAddress
+ .long stext_offset // VirtualAddress
.long _edata - stext // SizeOfRawData
- .long stext - efi_head // PointerToRawData
+ .long stext_offset // PointerToRawData
.long 0 // PointerToRelocations (0 for executables)
.long 0 // PointerToLineNumbers (0 for executables)