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Subject[PATCH 17/30] x86, kaiser: map debug IDT tables
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From: Dave Hansen <dave.hansen@linux.intel.com>

The IDT table it references are another structure where the
CPU references 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.hansen@linux.intel.com>
Cc: Moritz Lipp <moritz.lipp@iaik.tugraz.at>
Cc: Daniel Gruss <daniel.gruss@iaik.tugraz.at>
Cc: Michael Schwarz <michael.schwarz@iaik.tugraz.at>
Cc: Richard Fellner <richard.fellner@student.tugraz.at>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <keescook@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: x86@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 2017-11-08 10:45:35.124681380 -0800
+++ b/arch/x86/mm/kaiser.c 2017-11-08 10:45:35.127681380 -0800
@@ -275,6 +275,14 @@ 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
@@ -363,6 +371,10 @@ 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
_
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