Commits
Jason Andryuk committed 36104cb9012
x86/xen: Delay get_cpu_cap until stack canary is established
Commit 2cc42bac1c79 ("x86-64/Xen: eliminate W+X mappings") introduced a
call to get_cpu_cap, which is fstack-protected. This is works on x86-64
as commit 4f277295e54c ("x86/xen: init %gs very early to avoid page
faults with stack protector") ensures the stack protector is configured,
but it it did not cover x86-32.
Delay calling get_cpu_cap until after xen_setup_gdt has initialized the
stack canary. Without this, a 32bit PV machine crashes early
in boot.
(XEN) Domain 0 (vcpu#0) crashed on cpu#0:
(XEN) ----[ Xen-4.6.6-xc x86_64 debug=n Tainted: C ]----
(XEN) CPU: 0
(XEN) RIP: e019:[<00000000c10362f8>]
And the PV kernel IP corresponds to init_scattered_cpuid_features
0xc10362f8 <+24>: mov %gs:0x14,%eax
Fixes 2cc42bac1c79 ("x86-64/Xen: eliminate W+X mappings")
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>