x86/boot: Simplify calculation of output address

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Condense the calculation of decompressed kernel start a little.

Committer notes:

before:

ebp = ebx - (init_size - _end)

after:

eax = (ebx + _end) - init_size

where in both ebx contains the temporary address the kernel is moved to
for in-place decompression.

The before and after difference in register state is %eax and %ebp
but that is immaterial because the compressed image is not built with
-mregparm, i.e., all arguments of the following extract_kernel() call
are passed on the stack.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200107194436.2166846-1-nivedita@alum.mit.edu

...

This commit is contained in:

Arvind Sankar 2020-01-07 14:44:34 -05:00 • committed by Borislav Petkov

parent b2b1d94cdf

commit 183ef7adf4

1 changed files with 3 additions and 5 deletions

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arch/x86/boot/compressed/head_32.S

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