tree 290511dcb5901f8f621032c01ee7b78fb2c43ebf
parent 9d4fc09b9e77f06a45a6762b116e867c3614a39d
author James Morse <james.morse@arm.com> 1637754018 +0000
committer Greg Kroah-Hartman <gregkh@google.com> 1647532824 +0100

UPSTREAM: arm64: entry: Allow tramp_alias to access symbols after the 4K boundary

commit 6c5bf79b69f911560fbf82214c0971af6e58e682 upstream.

Systems using kpti enter and exit the kernel through a trampoline mapping
that is always mapped, even when the kernel is not. tramp_valias is a macro
to find the address of a symbol in the trampoline mapping.

Adding extra sets of vectors will expand the size of the entry.tramp.text
section to beyond 4K. tramp_valias will be unable to generate addresses
for symbols beyond 4K as it uses the 12 bit immediate of the add
instruction.

As there are now two registers available when tramp_alias is called,
use the extra register to avoid the 4K limit of the 12 bit immediate.

Bug: 215557547
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ic7a70f79baeacb3c8d12c396009968e563a2e69a