From: Ard Biesheuvel <ardb@xxxxxxxxxx>
[ Commit 1ad55cecf22f05f1c884adf63cc09d3c3e609ebf upstream ]
The .compat section is a dummy PE section that contains the address of
the 32-bit entrypoint of the 64-bit kernel image if it is bootable from
32-bit firmware (i.e., CONFIG_EFI_MIXED=y)
This section is only 8 bytes in size and is only referenced from the
loader, and so it is placed at the end of the memory view of the image,
to avoid the need for padding it to 4k, which is required for sections
appearing in the middle of the image.
Unfortunately, this violates the PE/COFF spec, and even if most EFI
loaders will work correctly (including the Tianocore reference
implementation), PE loaders do exist that reject such images, on the
basis that both the file and memory views of the file contents should be
described by the section headers in a monotonically increasing manner
without leaving any gaps.
So reorganize the sections to avoid this issue. This results in a slight
padding overhead (< 4k) which can be avoided if desired by disabling
CONFIG_EFI_MIXED (which is only needed in rare cases these days)
Fixes: 3e3eabe26dc8 ("x86/boot: Increase section and file alignment to 4k/512")
Reported-by: Mike Beaton <mjsbeaton@xxxxxxxxx>
Link: https://lkml.kernel.org/r/CAHzAAWQ6srV6LVNdmfbJhOwhBw5ZzxxZZ07aHt9oKkfYAdvuQQ%40mail.gmail.com
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
arch/x86/boot/header.S | 14 ++++++--------
arch/x86/boot/setup.ld | 6 +++---
2 files changed, 9 insertions(+), 11 deletions(-)
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 6264bbf54fbc..7593339b529a 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -105,8 +105,7 @@ extra_header_fields:
.word 0 # MinorSubsystemVersion
.long 0 # Win32VersionValue
- .long setup_size + ZO__end + pecompat_vsize
- # SizeOfImage
+ .long setup_size + ZO__end # SizeOfImage
.long salign # SizeOfHeaders
.long 0 # CheckSum
@@ -142,7 +141,7 @@ section_table:
.ascii ".setup"
.byte 0
.byte 0
- .long setup_size - salign # VirtualSize
+ .long pecompat_fstart - salign # VirtualSize
.long salign # VirtualAddress
.long pecompat_fstart - salign # SizeOfRawData
.long salign # PointerToRawData
@@ -155,8 +154,8 @@ section_table:
#ifdef CONFIG_EFI_MIXED
.asciz ".compat"
- .long 8 # VirtualSize
- .long setup_size + ZO__end # VirtualAddress
+ .long pecompat_fsize # VirtualSize
+ .long pecompat_fstart # VirtualAddress
.long pecompat_fsize # SizeOfRawData
.long pecompat_fstart # PointerToRawData
@@ -171,17 +170,16 @@ section_table:
* modes this image supports.
*/
.pushsection ".pecompat", "a", @progbits
- .balign falign
- .set pecompat_vsize, salign
+ .balign salign
.globl pecompat_fstart
pecompat_fstart:
.byte 0x1 # Version
.byte 8 # Size
.word IMAGE_FILE_MACHINE_I386 # PE machine type
.long setup_size + ZO_efi32_pe_entry # Entrypoint
+ .byte 0x0 # Sentinel
.popsection
#else
- .set pecompat_vsize, 0
.set pecompat_fstart, setup_size
#endif
.ascii ".text"
diff --git a/arch/x86/boot/setup.ld b/arch/x86/boot/setup.ld
index 83bb7efad8ae..3a2d1360abb0 100644
--- a/arch/x86/boot/setup.ld
+++ b/arch/x86/boot/setup.ld
@@ -24,6 +24,9 @@ SECTIONS
.text : { *(.text .text.*) }
.text32 : { *(.text32) }
+ .pecompat : { *(.pecompat) }
+ PROVIDE(pecompat_fsize = setup_size - pecompat_fstart);
+
. = ALIGN(16);
.rodata : { *(.rodata*) }
@@ -36,9 +39,6 @@ SECTIONS
. = ALIGN(16);
.data : { *(.data*) }
- .pecompat : { *(.pecompat) }
- PROVIDE(pecompat_fsize = setup_size - pecompat_fstart);
-
.signature : {
setup_sig = .;
LONG(0x5a5aaa55)
--
2.44.0.769.g3c40516874-goog
