x86/mpx, selftests: Add MPX self test

I've had this code for a while, but never submitted it upstream.  Now
that Skylake hardware is out in the wild, folks can actually run this
for real.  It tests the following:

	1. The MPX hardware is enabled by the kernel and doing what it
	   is supposed to
	2. The MPX management code is present and enabled in the kernel
	3. MPX Signal handling
	4. The MPX bounds table population code (on-demand population)
	5. The MPX bounds table unmapping code (kernel-initiated freeing
	   when unused)

This has also caught bugs in the XSAVE code because MPX state is
saved/restored with XSAVE.

I'm submitting it now because it would have caught the recent issues
with the compat_siginfo code not being properly augmented when new
siginfo state is added.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160608172535.5B40B0EE@viggo.jf.intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

tools/testing/selftests/x86/Makefile

@@ -5,7 +5,7 @@ include ../lib.mk
 .PHONY: all all_32 all_64 warn_32bit_failure clean
 
 TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall \
-			check_initial_reg_state sigreturn ldt_gdt iopl
+			check_initial_reg_state sigreturn ldt_gdt iopl mpx-mini-test
 TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
 			test_FCMOV test_FCOMI test_FISTTP \
 			vdso_restorer

tools/testing/selftests/x86/mpx-debug.h

+#ifndef _MPX_DEBUG_H
+#define _MPX_DEBUG_H
+
+#ifndef DEBUG_LEVEL
+#define DEBUG_LEVEL 0
+#endif
+#define dprintf_level(level, args...) do { if(level <= DEBUG_LEVEL) printf(args); } while(0)
+#define dprintf1(args...) dprintf_level(1, args)
+#define dprintf2(args...) dprintf_level(2, args)
+#define dprintf3(args...) dprintf_level(3, args)
+#define dprintf4(args...) dprintf_level(4, args)
+#define dprintf5(args...) dprintf_level(5, args)
+
+#endif /* _MPX_DEBUG_H */

tools/testing/selftests/x86/mpx-hw.h

+#ifndef _MPX_HW_H
+#define _MPX_HW_H
+
+#include <assert.h>
+
+/* Describe the MPX Hardware Layout in here */
+
+#define NR_MPX_BOUNDS_REGISTERS 4
+
+#ifdef __i386__
+
+#define MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES	16 /* 4 * 32-bits */
+#define MPX_BOUNDS_TABLE_SIZE_BYTES		(1ULL << 14) /* 16k */
+#define MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES		4
+#define MPX_BOUNDS_DIR_SIZE_BYTES		(1ULL << 22) /* 4MB */
+
+#define MPX_BOUNDS_TABLE_BOTTOM_BIT		2
+#define MPX_BOUNDS_TABLE_TOP_BIT		11
+#define MPX_BOUNDS_DIR_BOTTOM_BIT		12
+#define MPX_BOUNDS_DIR_TOP_BIT			31
+
+#else
+
+/*
+ * Linear Address of "pointer" (LAp)
+ *   0 ->  2: ignored
+ *   3 -> 19: index in to bounds table
+ *  20 -> 47: index in to bounds directory
+ *  48 -> 63: ignored
+ */
+
+#define MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES	32
+#define MPX_BOUNDS_TABLE_SIZE_BYTES		(1ULL << 22) /* 4MB */
+#define MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES		8
+#define MPX_BOUNDS_DIR_SIZE_BYTES		(1ULL << 31) /* 2GB */
+
+#define MPX_BOUNDS_TABLE_BOTTOM_BIT		3
+#define MPX_BOUNDS_TABLE_TOP_BIT		19
+#define MPX_BOUNDS_DIR_BOTTOM_BIT		20
+#define MPX_BOUNDS_DIR_TOP_BIT			47
+
+#endif
+
+#define MPX_BOUNDS_DIR_NR_ENTRIES	\
+	(MPX_BOUNDS_DIR_SIZE_BYTES/MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES)
+#define MPX_BOUNDS_TABLE_NR_ENTRIES	\
+	(MPX_BOUNDS_TABLE_SIZE_BYTES/MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES)
+
+#define MPX_BOUNDS_TABLE_ENTRY_VALID_BIT	0x1
+
+struct mpx_bd_entry {
+	union {
+		char x[MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES];
+		void *contents[1];
+	};
+} __attribute__((packed));
+
+struct mpx_bt_entry {
+	union {
+		char x[MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES];
+		unsigned long contents[1];
+	};
+} __attribute__((packed));
+
+struct mpx_bounds_dir {
+	struct mpx_bd_entry entries[MPX_BOUNDS_DIR_NR_ENTRIES];
+} __attribute__((packed));
+
+struct mpx_bounds_table {
+	struct mpx_bt_entry entries[MPX_BOUNDS_TABLE_NR_ENTRIES];
+} __attribute__((packed));
+
+static inline unsigned long GET_BITS(unsigned long val, int bottombit, int topbit)
+{
+	int total_nr_bits = topbit - bottombit;
+	unsigned long mask = (1UL << total_nr_bits)-1;
+	return (val >> bottombit) & mask;
+}
+
+static inline unsigned long __vaddr_bounds_table_index(void *vaddr)
+{
+	return GET_BITS((unsigned long)vaddr, MPX_BOUNDS_TABLE_BOTTOM_BIT,
+					      MPX_BOUNDS_TABLE_TOP_BIT);
+}
+
+static inline unsigned long __vaddr_bounds_directory_index(void *vaddr)
+{
+	return GET_BITS((unsigned long)vaddr, MPX_BOUNDS_DIR_BOTTOM_BIT,
+					      MPX_BOUNDS_DIR_TOP_BIT);
+}
+
+static inline struct mpx_bd_entry *mpx_vaddr_to_bd_entry(void *vaddr,
+		struct mpx_bounds_dir *bounds_dir)
+{
+	unsigned long index = __vaddr_bounds_directory_index(vaddr);
+	return &bounds_dir->entries[index];
+}
+
+static inline int bd_entry_valid(struct mpx_bd_entry *bounds_dir_entry)
+{
+	unsigned long __bd_entry = (unsigned long)bounds_dir_entry->contents;
+	return (__bd_entry & MPX_BOUNDS_TABLE_ENTRY_VALID_BIT);
+}
+
+static inline struct mpx_bounds_table *
+__bd_entry_to_bounds_table(struct mpx_bd_entry *bounds_dir_entry)
+{
+	unsigned long __bd_entry = (unsigned long)bounds_dir_entry->contents;
+	assert(__bd_entry & MPX_BOUNDS_TABLE_ENTRY_VALID_BIT);
+	__bd_entry &= ~MPX_BOUNDS_TABLE_ENTRY_VALID_BIT;
+	return (struct mpx_bounds_table *)__bd_entry;
+}
+
+static inline struct mpx_bt_entry *
+mpx_vaddr_to_bt_entry(void *vaddr, struct mpx_bounds_dir *bounds_dir)
+{
+	struct mpx_bd_entry *bde = mpx_vaddr_to_bd_entry(vaddr, bounds_dir);
+	struct mpx_bounds_table *bt = __bd_entry_to_bounds_table(bde);
+	unsigned long index = __vaddr_bounds_table_index(vaddr);
+	return &bt->entries[index];
+}
+
+#endif /* _MPX_HW_H */

tools/testing/selftests/x86/mpx-mm.h

+#ifndef _MPX_MM_H
+#define _MPX_MM_H
+
+#define PAGE_SIZE 4096
+#define MB (1UL<<20)
+
+extern long nr_incore(void *ptr, unsigned long size_bytes);
+
+#endif /* _MPX_MM_H */