x86/setup: Fix low identity map for >= 2GB kernel range
x86/setup: Fix low identity map for >= 2GB kernel range

The commit f5f3497cad8c extended the low identity mapping. However, if
the kernel uses more than 2 GB (VMSPLIT_2G_OPT or VMSPLIT_1G memory
split), the normal memory mapping is overwritten by the low identity
mapping causing a crash. To avoid overwritting, limit the low identity
map to cover only memory before kernel range (PAGE_OFFSET).

Fixes: f5f3497cad8c "x86/setup: Extend low identity map to cover whole kernel range
Signed-off-by: Krzysztof Mazur <ac4f352566d26649578fb9202213e9e6cf800c73@podlesie.net>
Cc: Andy Lutomirski <2cc0d0d76de2e6f37b92deeb83c85cb306fc5dc1@amacapital.net>
Cc: Borislav Petkov <0691a664b24b6f15b20cd5aee64b72271db08be1@alien8.de>
Cc: Laszlo Ersek <7437296077edea1cb64451c122c4dac071f0cfbc@redhat.com>
Cc: Matt Fleming <b02f0790d66a0f0a6b369873bf6df37420fbe5dd@intel.com>
Cc: Paolo Bonzini <69d3ebcf5ee4e7f05a50dc23cd96655b730804b4@redhat.com>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org
Link: http://lkml.kernel.org/r/1446815916-22105-1-git-send-email-ac4f352566d26649578fb9202213e9e6cf800c73@podlesie.net
Signed-off-by: Thomas Gleixner <00e4cf8f46a57000a44449bf9dd8cbbcc209fd2a@linutronix.de>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs