forked from Minki/linux
f2a9e1dec2
This patch updates x86_64 linker script to pack any .note.* sections into a PT_NOTE segment in the output file. To do this, we tell ld that we need a PT_NOTE segment. This requires us to start explicitly mapping sections to segments, so we also need to explicitly create PT_LOAD segments for text and data, and map the sections to them appropriately. Fortunately, each section will default to its previous section's segment, so it doesn't take many changes to vmlinux.lds.S. The corresponding change is already made for i386 in -mm and I'd like this patch to join it. The section to segment mappings do change as do the segment flags so some time in -mm would be good for that reason as well, just in case. In particular .data and .bss move from the text segment to the data segment and .data.cacheline_aligned .data.read_mostly are put in the data segment instead of a separate one. I think that it would be possible to exactly match the existing section to segment mapping and flags but it would be a more intrusive change and I'm not sure there is a reason for the existing layout other than it is what you get by default if you don't explicitly specify something else. If there is a reason for the existing layout then I will of course make the more intrusive change. If there is no reason we could probably drop the executable or writable flags from some segments but I don't know how much attention is paid to them anyway so it might not be worth the effort. The vsyscall related sections need to go in a different segment to the normal data segment and so I invented a "user" segment to contain them. I believe this should appear to be another data segment as far as the kernel is concerned so the flags are setup accordingly. The notes will be used in the Xen paravirt_ops backend to provide additional information to the domain builder. I am in the process of converting the xen-unstable kernels and tools over to this scheme at the moment to support this in the future. It has been suggested to me that the notes segment should have flags 0 (i.e. not readable) since it is only used by the loader and is not used at runtime. For now I went with a readable segment since that is what the i386 patch uses. AK: dropped NOTES addition right now because the needed infrastructure for that is not merged yet Signed-off-by: Ian Campbell <ian.campbell@xensource.com> Signed-off-by: Andi Kleen <ak@suse.de> |
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