selftests/powerpc: Add pkey helpers for rights

This adds some new pkey-related helper to print
access rights of a pkey in the "rwx" format and
to generate different valid combinations of pkey
rights starting from a given combination.

Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/6cc1c7d1f686618668a3e090f1d0c2a4cd9dea3f.1595821792.git.sandipan@linux.ibm.com

tools/testing/selftests/powerpc/include/pkeys.h

@@ -105,4 +105,32 @@ int siginfo_pkey(siginfo_t *si)
 #endif
 }
 
+#define pkey_rights(r) ({						\
+	static char buf[4] = "rwx";					\
+	unsigned int amr_bits;						\
+	if ((r) & PKEY_DISABLE_EXECUTE)					\
+		buf[2] = '-';						\
+	amr_bits = (r) & PKEY_BITS_MASK;				\
+	if (amr_bits & PKEY_DISABLE_WRITE)				\
+		buf[1] = '-';						\
+	if (amr_bits & PKEY_DISABLE_ACCESS & ~PKEY_DISABLE_WRITE)	\
+		buf[0] = '-';						\
+	buf;								\
+})
+
+unsigned long next_pkey_rights(unsigned long rights)
+{
+	if (rights == PKEY_DISABLE_ACCESS)
+		return PKEY_DISABLE_EXECUTE;
+	else if (rights == (PKEY_DISABLE_ACCESS | PKEY_DISABLE_EXECUTE))
+		return 0;
+
+	if ((rights & PKEY_BITS_MASK) == 0)
+		rights |= PKEY_DISABLE_WRITE;
+	else if ((rights & PKEY_BITS_MASK) == PKEY_DISABLE_WRITE)
+		rights |= PKEY_DISABLE_ACCESS;
+
+	return rights;
+}
+
 #endif /* _SELFTESTS_POWERPC_PKEYS_H */

tools/testing/selftests/powerpc/mm/pkey_exec_prot.c

@@ -102,6 +102,7 @@ static void segv_handler(int signum, siginfo_t *sinfo, void *ctx)
 static int test(void)
 {
 	struct sigaction segv_act, trap_act;
+	unsigned long rights;
 	int pkey, ret, i;
 
 	ret = pkeys_unsupported();
@@ -150,7 +151,8 @@ static int test(void)
 	insns[numinsns - 1] = PPC_INST_BLR;
 
 	/* Allocate a pkey that restricts execution */
-	pkey = sys_pkey_alloc(0, PKEY_DISABLE_EXECUTE);
+	rights = PKEY_DISABLE_EXECUTE;
+	pkey = sys_pkey_alloc(0, rights);
 	FAIL_IF(pkey < 0);
 
 	/*
@@ -175,8 +177,8 @@ static int test(void)
 	 */
 	remaining_faults = 0;
 	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
-	printf("read from %p, pkey is execute-disabled, access-enabled\n",
-	       (void *) fault_addr);
+	printf("read from %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
 	i = *fault_addr;
 	FAIL_IF(remaining_faults != 0);
 
@@ -192,12 +194,13 @@ static int test(void)
 	 */
 	remaining_faults = 1;
 	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
-	printf("write to %p, pkey is execute-disabled, access-enabled\n",
-	       (void *) fault_addr);
+	printf("write to %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
 	*fault_addr = PPC_INST_TRAP;
 	FAIL_IF(remaining_faults != 0 || fault_code != SEGV_ACCERR);
 
 	/* The following three cases will generate SEGV_PKUERR */
+	rights |= PKEY_DISABLE_ACCESS;
 	fault_type = PKEY_DISABLE_ACCESS;
 	fault_pkey = pkey;
 
@@ -211,9 +214,9 @@ static int test(void)
 	 */
 	remaining_faults = 1;
 	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
-	printf("read from %p, pkey is execute-disabled, access-disabled\n",
-	       (void *) fault_addr);
-	pkey_set_rights(pkey, PKEY_DISABLE_ACCESS);
+	pkey_set_rights(pkey, rights);
+	printf("read from %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
 	i = *fault_addr;
 	FAIL_IF(remaining_faults != 0 || fault_code != SEGV_PKUERR);
 
@@ -228,9 +231,9 @@ static int test(void)
 	 */
 	remaining_faults = 2;
 	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
-	printf("write to %p, pkey is execute-disabled, access-disabled\n",
-	       (void *) fault_addr);
-	pkey_set_rights(pkey, PKEY_DISABLE_ACCESS);
+	pkey_set_rights(pkey, rights);
+	printf("write to %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
 	*fault_addr = PPC_INST_NOP;
 	FAIL_IF(remaining_faults != 0 || fault_code != SEGV_ACCERR);
 
@@ -251,8 +254,8 @@ static int test(void)
 	remaining_faults = 1;
 	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
 	pkey_set_rights(pkey, PKEY_DISABLE_ACCESS);
-	printf("execute at %p, pkey is execute-disabled, access-disabled\n",
-	       (void *) fault_addr);
+	printf("execute at %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
 	asm volatile("mtctr	%0; bctrl" : : "r"(insns));
 	FAIL_IF(remaining_faults != 0 || fault_code != SEGV_PKUERR);
 
@@ -261,7 +264,8 @@ static int test(void)
 	 * fully permissive.
 	 */
 	sys_pkey_free(pkey);
-	pkey = sys_pkey_alloc(0, 0);
+	rights = 0;
+	pkey = sys_pkey_alloc(0, rights);
 
 	/*
 	 * Jump to the executable region when AMR bits are not set
@@ -274,8 +278,8 @@ static int test(void)
 	fault_pkey = pkey;
 	remaining_faults = 0;
 	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
-	printf("execute at %p, pkey is execute-enabled, access-enabled\n",
-	       (void *) fault_addr);
+	printf("execute at %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
 	asm volatile("mtctr	%0; bctrl" : : "r"(insns));
 	FAIL_IF(remaining_faults != 0);