On 09/07/14 22:41, Michael Brown wrote:
The PE/COFF headers currently describe only the initialised-data
portions of the image, and result in no space being allocated for the
uninitialised-data portions. Consequently, the EFI boot stub will end
up overwriting unexpected areas of memory, with unpredictable results.
Fix by including a .bss section in the PE/COFF headers (functionally
equivalent to the init_size field in the bzImage header).
Following on from this: hpa mentioned via IRC that we should also take
alignment into account. I am unsure if init_size already includes
padding for alignment; on my sample kernel init_size is >16MB (with 16MB
alignment), so it looks plausible to me that alignment is already
accounted for.
If not, then the following trivial patch exposes the desired alignment
via the PE/COFF headers:
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 7a6d43a..16ef025 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -154,7 +154,7 @@ extra_header_fields:
#else
.quad 0 # ImageBase
#endif
- .long 0x20 # SectionAlignment
+ .long CONFIG_PHYSICAL_ALIGN # SectionAlignment
.long 0x20 # FileAlignment
.word 0 # MajorOperatingSystemVersion
.word 0 # MinorOperatingSystemVersion
--
1.8.4.5
Michael
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