tree 5a505c3f47a36b8e71247278c9f95d844764d5e3
parent 8f75582a2fb6e2c5afc5252b6d6932f61a79c939
author Vasily Gorbik <gor@linux.ibm.com> 1532011885 +0200
committer Martin Schwidefsky <schwidefsky@de.ibm.com> 1539076862 +0200

s390/decompressor: rework uncompressed image info collection

The kernel decompressor has to know several bits of information about
uncompressed image. Currently this info is collected by running "nm" on
uncompressed vmlinux + "sed" and producing sizes.h file. This method
worked well, but it has several disadvantages. Obscure symbols name
pattern matching is fragile. Adding new values makes pattern even
longer. Logic is spread across code and make file. Limited ability to
adjust symbols values (currently magic lma value of 0x100000 is always
subtracted). Apart from that same pieces of information (and more)
would be needed for early memory detection and features like KASLR
outside of boot/compressed/ folder where sizes.h is generated.

To overcome limitations new "struct vmlinux_info" has been introduced
to include values needed for the decompressor and the rest of the
boot code. The only static instance of vmlinux_info is produced during
vmlinux link step by filling in struct fields by the linker (like it is
done with input_data in boot/compressed/vmlinux.scr.lds.S). This way
individual values could be adjusted with all the knowledge linker has
and arithmetic it supports. Later .vmlinux.info section (which contains
struct vmlinux_info) is transplanted into the decompressor image and
dropped from uncompressed image altogether.

While doing that replace "compressed/vmlinux.scr.lds.S" linker
script (whose purpose is to rename .data section in piggy.o to
.rodata.compressed) with plain objcopy command. And simplify
decompressor's linker script.

Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>