x86/boot/compressed: Fix reloading of GDTR post-relocation

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The following commit:

  ef5a7b5eb1 ("efi/x86: Remove GDT setup from efi_main")

introduced GDT setup into the 32-bit kernel's startup_32, and reloads
the GDTR after relocating the kernel for paranoia's sake.

A followup commit:

   32d009137a ("x86/boot: Reload GDTR after copying to the end of the buffer")

introduced a similar GDTR reload in the 64-bit kernel as well.

The GDTR is adjusted by (init_size-_end), however this may not be the
correct offset to apply if the kernel was loaded at a misaligned address
or below LOAD_PHYSICAL_ADDR, as in that case the decompression buffer
has an additional offset from the original load address.

This should never happen for a conformant bootloader, but we're being
paranoid anyway, so just store the new GDT address in there instead of
adding any offsets, which is simpler as well.

Fixes: ef5a7b5eb1 ("efi/x86: Remove GDT setup from efi_main")
Fixes: 32d009137a ("x86/boot: Reload GDTR after copying to the end of the buffer")
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: https://lore.kernel.org/r/20200226230031.3011645-2-nivedita@alum.mit.edu

...

This commit is contained in:

Arvind Sankar 2020-02-26 18:00:31 -05:00 • committed by Ingo Molnar

parent 3e03dca500

commit c98a76eabb

2 changed files with 6 additions and 7 deletions

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9

arch/x86/boot/compressed/head_32.S

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4

arch/x86/boot/compressed/head_64.S

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