Michael Brown <mbrown@...> writes: > > The kernel will align itself to the nearest boundary specified by the > kernel_alignment field in the bzImage header. If the kernel is loaded > to an address which is not sufficiently aligned, it will therefore use > memory beyond that indicated solely by the init_size field. > > The PE/COFF headers now include a .bss section to describe the > requirements of the init_size field, but do not currently expose the > alignment requirement. Consequently, a kernel loaded via the PE entry > point may still end up overwriting unexpected areas of memory. > > Fix by exposing the desired alignment via the SectionAlignment field > in the PE/COFF headers. Despite its name, this field provides an > overall alignment requirement for the loaded file. (Naturally, the > FileAlignment field describes the alignment for individual sections.) > > There is no way in the PE/COFF headers to express the concept of > min_alignment; we therefore do not expose the minimum (as opposed to > preferred) alignment. > > Signed-off-by: Michael Brown <mbrown@...> > --- > arch/x86/boot/header.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > 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 > <at> <at> -154,7 +154,7 <at> <at> 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 There may be a problem with this change. The specification says that the SizeOfImage field must be a multiple of SectionAlignment. That was the case when SectionAlignment was 0x20, but now that it is so large it would require quite an increase in the last section to comply. A kernel I am looking at now has: Alignment of sections: 0x1000000 Size of image: 0x105a000 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
