x86/decompressor: Call trampoline as a normal function

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commit e8972a76aa upstream.

Move the long return to switch to 32-bit mode into the trampoline code
so it can be called as an ordinary function. This will allow it to be
called directly from C code in a subsequent patch.

While at it, reorganize the code somewhat to keep the prologue and
epilogue of the function together, making the code a bit easier to
follow. Also, given that the trampoline is now entered in 64-bit mode, a
simple RIP-relative reference can be used to take the address of the
exit point.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20230807162720.545787-10-ardb@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Ard Biesheuvel 2023-08-07 18:27:06 +02:00 • committed by Greg Kroah-Hartman

parent 99a20f5891

commit 640f27fc2e

2 changed files with 36 additions and 45 deletions

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79

arch/x86/boot/compressed/head_64.S

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2

arch/x86/boot/compressed/pgtable.h

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