Commit 287e0131 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar

x86/vdso: Make the PER_CPU segment 32 bits

IMO users ought not to be able to use 16-bit segments without
using modify_ldt.  Fortunately, it's impossible to break
espfix64 by loading the PER_CPU segment into SS because it's
PER_CPU is marked read-only and SS cannot contain an RO segment,
but marking PER_CPU as 32-bit is less fragile.
Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/179f490d659307873eefd09206bebd417e2ab5ad.1411494540.git.luto@amacapital.netSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9c0080ef
...@@ -268,6 +268,7 @@ static void vsyscall_set_cpu(int cpu) ...@@ -268,6 +268,7 @@ static void vsyscall_set_cpu(int cpu)
.dpl = 3, /* Visible to user code */ .dpl = 3, /* Visible to user code */
.s = 1, /* Not a system segment */ .s = 1, /* Not a system segment */
.p = 1, /* Present */ .p = 1, /* Present */
.d = 1, /* 32-bit */
}; };
write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S); write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
......
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