From: Dave Hansen <dave.han...@linux.intel.com> The IDT is another structure which the CPU references via a virtual address. It also obviously needs these to handle an interrupt in userspace, so these need to be mapped into the user copy of the page tables.
Signed-off-by: Dave Hansen <dave.han...@linux.intel.com> Cc: Moritz Lipp <moritz.l...@iaik.tugraz.at> Cc: Daniel Gruss <daniel.gr...@iaik.tugraz.at> Cc: Michael Schwarz <michael.schw...@iaik.tugraz.at> Cc: Richard Fellner <richard.fell...@student.tugraz.at> Cc: Andy Lutomirski <l...@kernel.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Kees Cook <keesc...@google.com> Cc: Hugh Dickins <hu...@google.com> Cc: x...@kernel.org --- b/arch/x86/mm/kaiser.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff -puN arch/x86/mm/kaiser.c~kaiser-user-map-trace-and-debug-idt arch/x86/mm/kaiser.c --- a/arch/x86/mm/kaiser.c~kaiser-user-map-trace-and-debug-idt 2017-11-10 11:22:14.332244936 -0800 +++ b/arch/x86/mm/kaiser.c 2017-11-10 11:22:14.336244936 -0800 @@ -286,6 +286,14 @@ int kaiser_add_user_map_ptrs(const void flags); } +static int kaiser_user_map_ptr_early(const void *start_addr, unsigned long size, + unsigned long flags) +{ + int ret = kaiser_add_user_map(start_addr, size, flags); + WARN_ON(ret); + return ret; +} + /* * Ensure that the top level of the (shadow) page tables are * entirely populated. This ensures that all processes that get @@ -374,6 +382,10 @@ void __init kaiser_init(void) sizeof(gate_desc) * NR_VECTORS, __PAGE_KERNEL_RO | _PAGE_GLOBAL); + kaiser_user_map_ptr_early(&debug_idt_table, + sizeof(gate_desc) * NR_VECTORS, + __PAGE_KERNEL | _PAGE_GLOBAL); + /* * We could theoretically do this in setup_fixmap_gdt(). * But, we would need to rewrite the above page table _