selftests/vm/pkeys: introduce a sub-page allocator

This introduces a new allocator that allocates 4K hardware pages to back
64K linux pages.  This allocator is available only on powerpc.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "Desnes A. Nunes do Rosario" <desnesn@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Suchanek <msuchanek@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Link: http://lkml.kernel.org/r/c4a82fa962ec71015b994fab1aaf83bdfd091553.1585646528.git.sandipan@linux.ibm.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/vm/pkey-helpers.h

@@ -28,6 +28,9 @@
 extern int dprint_in_signal;
 extern char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
 
+extern int test_nr;
+extern int iteration_nr;
+
 #ifdef __GNUC__
 __attribute__((format(printf, 1, 2)))
 #endif
@@ -78,6 +81,9 @@ __attribute__((noinline)) int read_ptr(int *ptr);
 void expected_pkey_fault(int pkey);
 int sys_pkey_alloc(unsigned long flags, unsigned long init_val);
 int sys_pkey_free(unsigned long pkey);
+int mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey);
+void record_pkey_malloc(void *ptr, long size, int prot);
 
 #if defined(__i386__) || defined(__x86_64__) /* arch */
 #include "pkey-x86.h"

tools/testing/selftests/vm/pkey-powerpc.h

@@ -107,4 +107,29 @@ void expect_fault_on_read_execonly_key(void *p1, int pkey)
 /* 4-byte instructions * 16384 = 64K page */
 #define __page_o_noops() asm(".rept 16384 ; nop; .endr")
 
+void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int ret;
+
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	pkey_assert(pkey < NR_PKEYS);
+	ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+
+	ret = syscall(__NR_subpage_prot, ptr, size, NULL);
+	if (ret) {
+		perror("subpage_perm");
+		return PTR_ERR_ENOTSUP;
+	}
+
+	ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
+	pkey_assert(!ret);
+	record_pkey_malloc(ptr, size, prot);
+
+	dprintf1("%s() for pkey %d @ %p\n", __func__, pkey, ptr);
+	return ptr;
+}
+
 #endif /* _PKEYS_POWERPC_H */

tools/testing/selftests/vm/pkey-x86.h

@@ -173,4 +173,9 @@ void expect_fault_on_read_execonly_key(void *p1, int pkey)
 	expected_pkey_fault(pkey);
 }
 
+void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
+{
+	return PTR_ERR_ENOTSUP;
+}
+
 #endif /* _PKEYS_X86_H */

tools/testing/selftests/vm/protection_keys.c

@@ -845,6 +845,7 @@ void *malloc_pkey_mmap_dax(long size, int prot, u16 pkey)
 void *(*pkey_malloc[])(long size, int prot, u16 pkey) = {
 
 	malloc_pkey_with_mprotect,
+	malloc_pkey_with_mprotect_subpage,
 	malloc_pkey_anon_huge,
 	malloc_pkey_hugetlb
 /* can not do direct with the pkey_mprotect() API: