@@ -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
/*
* Flush dcache covering current runtime addresses
@@ -129,6 +129,8 @@ efi_head:
#endif
#ifdef CONFIG_EFI
+ .globl stext_offset
+ .set stext_offset, stext - efi_head
.align 3
pe_header:
.ascii "PE"
@@ -152,7 +154,7 @@ 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
@@ -169,7 +171,7 @@ extra_header_fields:
.long _edata - 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
@@ -214,9 +216,9 @@ section_table:
.byte 0
.byte 0 // end of 0 padding of section name
.long _edata - 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)
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 header is not covered by any PE/COFF section, so the header may not actually be loaded at the expected offset. 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' Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm64/kernel/efi-entry.S | 3 ++- arch/arm64/kernel/head.S | 10 ++++++---- 2 files changed, 8 insertions(+), 5 deletions(-)