Re: [PATCHv2 1/2] x86/boot/compressed/64: Set up GOT for paging_prepare() and cleanup_trampoline()
- Date: Wed, 16 May 2018 11:52:42 +0200 (CEST)
- From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
- Subject: Re: [PATCHv2 1/2] x86/boot/compressed/64: Set up GOT for paging_prepare() and cleanup_trampoline()
On Wed, 16 May 2018, Kirill A. Shutemov wrote:
> Eric and Hugh have reported instant reboot due to my recent changes in
> decompression code.
> The root cause is that I didn't realize that we need to adjust GOT to be
> able to run C code that early.
> The problem is only visible with an older toolchain. Binutils >= 2.24 is
> able to eliminate GOT references by replacing them with RIP-relative
> address loads.
> We need to adjust GOT two times:
> - before calling paging_prepare() using the initial load address
> - before calling C code from the relocated kernel
>  https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;h=80d873266dec
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Fixes: 194a9749c73d ("x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G")
> Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Reported-by: Hugh Dickins <hughd@xxxxxxxxxx>
Very nice and well done!
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>