x86/pkeys: Add self-tests
This code should be a good demonstration of how to use the new
system calls as well as how to use protection keys in general.
This code shows how to:
1. Manipulate the Protection Keys Rights User (PKRU) register
2. Set a protection key on memory
3. Fetch and/or modify PKRU from the signal XSAVE state
4. Read the kernel-provided protection key in the siginfo
5. Set up an execute-only mapping
There are currently 13 tests:
test_read_of_write_disabled_region
test_read_of_access_disabled_region
test_write_of_write_disabled_region
test_write_of_access_disabled_region
test_kernel_write_of_access_disabled_region
test_kernel_write_of_write_disabled_region
test_kernel_gup_of_access_disabled_region
test_kernel_gup_write_to_write_disabled_region
test_executing_on_unreadable_memory
test_ptrace_of_child
test_pkey_syscalls_on_non_allocated_pkey
test_pkey_syscalls_bad_args
test_pkey_alloc_exhaust
Each of the tests is run with plain memory (via mmap(MAP_ANON)),
transparent huge pages, and hugetlb.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-arch@vger.kernel.org
Cc: Dave Hansen <dave@sr71.net>
Cc: mgorman@techsingularity.net
Cc: arnd@arndb.de
Cc: linux-api@vger.kernel.org
Cc: shuahkh@osg.samsung.com
Cc: linux-mm@kvack.org
Cc: luto@kernel.org
Cc: akpm@linux-foundation.org
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/20160729163024.FC5A0C2D@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/tools/testing/selftests/x86/pkey-helpers.h b/tools/testing/selftests/x86/pkey-helpers.h
new file mode 100644
index 0000000..b202939
--- /dev/null
+++ b/tools/testing/selftests/x86/pkey-helpers.h
@@ -0,0 +1,219 @@
+#ifndef _PKEYS_HELPER_H
+#define _PKEYS_HELPER_H
+#define _GNU_SOURCE
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ucontext.h>
+#include <sys/mman.h>
+
+#define NR_PKEYS 16
+#define PKRU_BITS_PER_PKEY 2
+
+#ifndef DEBUG_LEVEL
+#define DEBUG_LEVEL 0
+#endif
+#define DPRINT_IN_SIGNAL_BUF_SIZE 4096
+extern int dprint_in_signal;
+extern char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
+static inline void sigsafe_printf(const char *format, ...)
+{
+ va_list ap;
+
+ va_start(ap, format);
+ if (!dprint_in_signal) {
+ vprintf(format, ap);
+ } else {
+ int len = vsnprintf(dprint_in_signal_buffer,
+ DPRINT_IN_SIGNAL_BUF_SIZE,
+ format, ap);
+ /*
+ * len is amount that would have been printed,
+ * but actual write is truncated at BUF_SIZE.
+ */
+ if (len > DPRINT_IN_SIGNAL_BUF_SIZE)
+ len = DPRINT_IN_SIGNAL_BUF_SIZE;
+ write(1, dprint_in_signal_buffer, len);
+ }
+ va_end(ap);
+}
+#define dprintf_level(level, args...) do { \
+ if (level <= DEBUG_LEVEL) \
+ sigsafe_printf(args); \
+ fflush(NULL); \
+} while (0)
+#define dprintf0(args...) dprintf_level(0, args)
+#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)
+
+extern unsigned int shadow_pkru;
+static inline unsigned int __rdpkru(void)
+{
+ unsigned int eax, edx;
+ unsigned int ecx = 0;
+ unsigned int pkru;
+
+ asm volatile(".byte 0x0f,0x01,0xee\n\t"
+ : "=a" (eax), "=d" (edx)
+ : "c" (ecx));
+ pkru = eax;
+ return pkru;
+}
+
+static inline unsigned int _rdpkru(int line)
+{
+ unsigned int pkru = __rdpkru();
+
+ dprintf4("rdpkru(line=%d) pkru: %x shadow: %x\n",
+ line, pkru, shadow_pkru);
+ assert(pkru == shadow_pkru);
+
+ return pkru;
+}
+
+#define rdpkru() _rdpkru(__LINE__)
+
+static inline void __wrpkru(unsigned int pkru)
+{
+ unsigned int eax = pkru;
+ unsigned int ecx = 0;
+ unsigned int edx = 0;
+
+ dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
+ asm volatile(".byte 0x0f,0x01,0xef\n\t"
+ : : "a" (eax), "c" (ecx), "d" (edx));
+ assert(pkru == __rdpkru());
+}
+
+static inline void wrpkru(unsigned int pkru)
+{
+ dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
+ /* will do the shadow check for us: */
+ rdpkru();
+ __wrpkru(pkru);
+ shadow_pkru = pkru;
+ dprintf4("%s(%08x) pkru: %08x\n", __func__, pkru, __rdpkru());
+}
+
+/*
+ * These are technically racy. since something could
+ * change PKRU between the read and the write.
+ */
+static inline void __pkey_access_allow(int pkey, int do_allow)
+{
+ unsigned int pkru = rdpkru();
+ int bit = pkey * 2;
+
+ if (do_allow)
+ pkru &= (1<<bit);
+ else
+ pkru |= (1<<bit);
+
+ dprintf4("pkru now: %08x\n", rdpkru());
+ wrpkru(pkru);
+}
+
+static inline void __pkey_write_allow(int pkey, int do_allow_write)
+{
+ long pkru = rdpkru();
+ int bit = pkey * 2 + 1;
+
+ if (do_allow_write)
+ pkru &= (1<<bit);
+ else
+ pkru |= (1<<bit);
+
+ wrpkru(pkru);
+ dprintf4("pkru now: %08x\n", rdpkru());
+}
+
+#define PROT_PKEY0 0x10 /* protection key value (bit 0) */
+#define PROT_PKEY1 0x20 /* protection key value (bit 1) */
+#define PROT_PKEY2 0x40 /* protection key value (bit 2) */
+#define PROT_PKEY3 0x80 /* protection key value (bit 3) */
+
+#define PAGE_SIZE 4096
+#define MB (1<<20)
+
+static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
+ unsigned int *ecx, unsigned int *edx)
+{
+ /* ecx is often an input as well as an output. */
+ asm volatile(
+ "cpuid;"
+ : "=a" (*eax),
+ "=b" (*ebx),
+ "=c" (*ecx),
+ "=d" (*edx)
+ : "0" (*eax), "2" (*ecx));
+}
+
+/* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx) */
+#define X86_FEATURE_PKU (1<<3) /* Protection Keys for Userspace */
+#define X86_FEATURE_OSPKE (1<<4) /* OS Protection Keys Enable */
+
+static inline int cpu_has_pku(void)
+{
+ unsigned int eax;
+ unsigned int ebx;
+ unsigned int ecx;
+ unsigned int edx;
+
+ eax = 0x7;
+ ecx = 0x0;
+ __cpuid(&eax, &ebx, &ecx, &edx);
+
+ if (!(ecx & X86_FEATURE_PKU)) {
+ dprintf2("cpu does not have PKU\n");
+ return 0;
+ }
+ if (!(ecx & X86_FEATURE_OSPKE)) {
+ dprintf2("cpu does not have OSPKE\n");
+ return 0;
+ }
+ return 1;
+}
+
+#define XSTATE_PKRU_BIT (9)
+#define XSTATE_PKRU 0x200
+
+int pkru_xstate_offset(void)
+{
+ unsigned int eax;
+ unsigned int ebx;
+ unsigned int ecx;
+ unsigned int edx;
+ int xstate_offset;
+ int xstate_size;
+ unsigned long XSTATE_CPUID = 0xd;
+ int leaf;
+
+ /* assume that XSTATE_PKRU is set in XCR0 */
+ leaf = XSTATE_PKRU_BIT;
+ {
+ eax = XSTATE_CPUID;
+ ecx = leaf;
+ __cpuid(&eax, &ebx, &ecx, &edx);
+
+ if (leaf == XSTATE_PKRU_BIT) {
+ xstate_offset = ebx;
+ xstate_size = eax;
+ }
+ }
+
+ if (xstate_size == 0) {
+ printf("could not find size/offset of PKRU in xsave state\n");
+ return 0;
+ }
+
+ return xstate_offset;
+}
+
+#endif /* _PKEYS_HELPER_H */