selftests/powerpc/dexcr: Add DEXCR prctl interface test

Some basic tests of the prctl interface of the DEXCR.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
[mpe: Add missing SPDX tag]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240417112325.728010-6-bgray@linux.ibm.com

tools/testing/selftests/powerpc/dexcr/.gitignore

@@ -1,2 +1,3 @@
+dexcr_test
 hashchk_test
 lsdexcr

tools/testing/selftests/powerpc/dexcr/Makefile

@@ -1,9 +1,11 @@
-TEST_GEN_PROGS := hashchk_test
+TEST_GEN_PROGS := dexcr_test hashchk_test
 TEST_GEN_FILES := lsdexcr
 
 include ../../lib.mk
 include ../flags.mk
 
+CFLAGS += $(KHDR_INCLUDES)
+
 $(OUTPUT)/hashchk_test: CFLAGS += -fno-pie -no-pie $(call cc-option,-mno-rop-protect)
 
 $(TEST_GEN_PROGS): ../harness.c ../utils.c ./dexcr.c

tools/testing/selftests/powerpc/dexcr/dexcr.c

@@ -3,6 +3,7 @@
 #include <errno.h>
 #include <setjmp.h>
 #include <signal.h>
+#include <sys/prctl.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 
@@ -43,6 +44,45 @@ out:
 	return exists;
 }
 
+unsigned int pr_which_to_aspect(unsigned long which)
+{
+	switch (which) {
+	case PR_PPC_DEXCR_SBHE:
+		return DEXCR_PR_SBHE;
+	case PR_PPC_DEXCR_IBRTPD:
+		return DEXCR_PR_IBRTPD;
+	case PR_PPC_DEXCR_SRAPD:
+		return DEXCR_PR_SRAPD;
+	case PR_PPC_DEXCR_NPHIE:
+		return DEXCR_PR_NPHIE;
+	default:
+		FAIL_IF_EXIT_MSG(true, "unknown PR aspect");
+	}
+}
+
+int pr_get_dexcr(unsigned long which)
+{
+	return prctl(PR_PPC_GET_DEXCR, which, 0UL, 0UL, 0UL);
+}
+
+int pr_set_dexcr(unsigned long which, unsigned long ctrl)
+{
+	return prctl(PR_PPC_SET_DEXCR, which, ctrl, 0UL, 0UL);
+}
+
+bool pr_dexcr_aspect_supported(unsigned long which)
+{
+	if (pr_get_dexcr(which) == -1)
+		return errno == ENODEV;
+
+	return true;
+}
+
+bool pr_dexcr_aspect_editable(unsigned long which)
+{
+	return pr_get_dexcr(which) & PR_PPC_DEXCR_CTRL_EDITABLE;
+}
+
 /*
  * Just test if a bad hashchk triggers a signal, without checking
  * for support or if the NPHIE aspect is enabled.

tools/testing/selftests/powerpc/dexcr/dexcr.h

@@ -28,6 +28,16 @@
 
 bool dexcr_exists(void);
 
+bool pr_dexcr_aspect_supported(unsigned long which);
+
+bool pr_dexcr_aspect_editable(unsigned long which);
+
+int pr_get_dexcr(unsigned long pr_aspect);
+
+int pr_set_dexcr(unsigned long pr_aspect, unsigned long ctrl);
+
+unsigned int pr_which_to_aspect(unsigned long which);
+
 bool hashchk_triggers(void);
 
 enum dexcr_source {

tools/testing/selftests/powerpc/dexcr/dexcr_test.c

@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/prctl.h>
+#include <unistd.h>
+
+#include "dexcr.h"
+#include "utils.h"
+
+/*
+ * Helper function for testing the behaviour of a newly exec-ed process
+ */
+static int dexcr_prctl_onexec_test_child(unsigned long which, const char *status)
+{
+	unsigned long dexcr = mfspr(SPRN_DEXCR_RO);
+	unsigned long aspect = pr_which_to_aspect(which);
+	int ctrl = pr_get_dexcr(which);
+
+	if (!strcmp(status, "set")) {
+		FAIL_IF_EXIT_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_SET),
+				 "setting aspect across exec not applied");
+
+		FAIL_IF_EXIT_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC),
+				 "setting aspect across exec not inherited");
+
+		FAIL_IF_EXIT_MSG(!(aspect & dexcr), "setting aspect across exec did not take effect");
+	} else if (!strcmp(status, "clear")) {
+		FAIL_IF_EXIT_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR),
+				 "clearing aspect across exec not applied");
+
+		FAIL_IF_EXIT_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC),
+				 "clearing aspect across exec not inherited");
+
+		FAIL_IF_EXIT_MSG(aspect & dexcr, "clearing aspect across exec did not take effect");
+	} else {
+		FAIL_IF_EXIT_MSG(true, "unknown expected status");
+	}
+
+	return 0;
+}
+
+/*
+ * Test that the given prctl value can be manipulated freely
+ */
+static int dexcr_prctl_aspect_test(unsigned long which)
+{
+	unsigned long aspect = pr_which_to_aspect(which);
+	pid_t pid;
+	int ctrl;
+	int err;
+	int errno_save;
+
+	SKIP_IF_MSG(!dexcr_exists(), "DEXCR not supported");
+	SKIP_IF_MSG(!pr_dexcr_aspect_supported(which), "DEXCR aspect not supported");
+	SKIP_IF_MSG(!pr_dexcr_aspect_editable(which), "DEXCR aspect not editable with prctl");
+
+	/* We reject invalid combinations of arguments */
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_SET | PR_PPC_DEXCR_CTRL_CLEAR);
+	errno_save = errno;
+	FAIL_IF_MSG(err != -1, "simultaneous set and clear should be rejected");
+	FAIL_IF_MSG(errno_save != EINVAL, "simultaneous set and clear should be rejected with EINVAL");
+
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_SET_ONEXEC | PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC);
+	errno_save = errno;
+	FAIL_IF_MSG(err != -1, "simultaneous set and clear on exec should be rejected");
+	FAIL_IF_MSG(errno_save != EINVAL, "simultaneous set and clear on exec should be rejected with EINVAL");
+
+	/* We set the aspect */
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_SET);
+	FAIL_IF_MSG(err, "PR_PPC_DEXCR_CTRL_SET failed");
+
+	ctrl = pr_get_dexcr(which);
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_SET), "config value not PR_PPC_DEXCR_CTRL_SET");
+	FAIL_IF_MSG(ctrl & PR_PPC_DEXCR_CTRL_CLEAR, "config value unexpected clear flag");
+	FAIL_IF_MSG(!(aspect & mfspr(SPRN_DEXCR_RO)), "setting aspect did not take effect");
+
+	/* We clear the aspect */
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_CLEAR);
+	FAIL_IF_MSG(err, "PR_PPC_DEXCR_CTRL_CLEAR failed");
+
+	ctrl = pr_get_dexcr(which);
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR), "config value not PR_PPC_DEXCR_CTRL_CLEAR");
+	FAIL_IF_MSG(ctrl & PR_PPC_DEXCR_CTRL_SET, "config value unexpected set flag");
+	FAIL_IF_MSG(aspect & mfspr(SPRN_DEXCR_RO), "clearing aspect did not take effect");
+
+	/* We make it set on exec (doesn't change our current value) */
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_SET_ONEXEC);
+	FAIL_IF_MSG(err, "PR_PPC_DEXCR_CTRL_SET_ONEXEC failed");
+
+	ctrl = pr_get_dexcr(which);
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR), "process aspect should still be cleared");
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC), "config value not PR_PPC_DEXCR_CTRL_SET_ONEXEC");
+	FAIL_IF_MSG(ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC, "config value unexpected clear on exec flag");
+	FAIL_IF_MSG(aspect & mfspr(SPRN_DEXCR_RO), "scheduling aspect to set on exec should not change it now");
+
+	/* We make it clear on exec (doesn't change our current value) */
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC);
+	FAIL_IF_MSG(err, "PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC failed");
+
+	ctrl = pr_get_dexcr(which);
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR), "process aspect config should still be cleared");
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC), "config value not PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC");
+	FAIL_IF_MSG(ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC, "config value unexpected set on exec flag");
+	FAIL_IF_MSG(aspect & mfspr(SPRN_DEXCR_RO), "process aspect should still be cleared");
+
+	/* We allow setting the current and on-exec value in a single call */
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_SET | PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC);
+	FAIL_IF_MSG(err, "PR_PPC_DEXCR_CTRL_SET | PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC failed");
+
+	ctrl = pr_get_dexcr(which);
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_SET), "config value not PR_PPC_DEXCR_CTRL_SET");
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC), "config value not PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC");
+	FAIL_IF_MSG(!(aspect & mfspr(SPRN_DEXCR_RO)), "process aspect should be set");
+
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_CLEAR | PR_PPC_DEXCR_CTRL_SET_ONEXEC);
+	FAIL_IF_MSG(err, "PR_PPC_DEXCR_CTRL_CLEAR | PR_PPC_DEXCR_CTRL_SET_ONEXEC failed");
+
+	ctrl = pr_get_dexcr(which);
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR), "config value not PR_PPC_DEXCR_CTRL_CLEAR");
+	FAIL_IF_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC), "config value not PR_PPC_DEXCR_CTRL_SET_ONEXEC");
+	FAIL_IF_MSG(aspect & mfspr(SPRN_DEXCR_RO), "process aspect should be clear");
+
+	/* Verify the onexec value is applied across exec */
+	pid = fork();
+	if (!pid) {
+		char which_str[32] = {};
+		char *args[] = { "dexcr_prctl_onexec_test_child", which_str, "set", NULL };
+		unsigned int ctrl = pr_get_dexcr(which);
+
+		sprintf(which_str, "%lu", which);
+
+		FAIL_IF_EXIT_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC),
+				 "setting aspect on exec not copied across fork");
+
+		FAIL_IF_EXIT_MSG(mfspr(SPRN_DEXCR_RO) & aspect,
+				 "setting aspect on exec wrongly applied to fork");
+
+		execve("/proc/self/exe", args, NULL);
+		_exit(errno);
+	}
+	await_child_success(pid);
+
+	err = pr_set_dexcr(which, PR_PPC_DEXCR_CTRL_SET | PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC);
+	FAIL_IF_MSG(err, "PR_PPC_DEXCR_CTRL_SET | PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC failed");
+
+	pid = fork();
+	if (!pid) {
+		char which_str[32] = {};
+		char *args[] = { "dexcr_prctl_onexec_test_child", which_str, "clear", NULL };
+		unsigned int ctrl = pr_get_dexcr(which);
+
+		sprintf(which_str, "%lu", which);
+
+		FAIL_IF_EXIT_MSG(!(ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC),
+				 "clearing aspect on exec not copied across fork");
+
+		FAIL_IF_EXIT_MSG(!(mfspr(SPRN_DEXCR_RO) & aspect),
+				 "clearing aspect on exec wrongly applied to fork");
+
+		execve("/proc/self/exe", args, NULL);
+		_exit(errno);
+	}
+	await_child_success(pid);
+
+	return 0;
+}
+
+static int dexcr_prctl_ibrtpd_test(void)
+{
+	return dexcr_prctl_aspect_test(PR_PPC_DEXCR_IBRTPD);
+}
+
+static int dexcr_prctl_srapd_test(void)
+{
+	return dexcr_prctl_aspect_test(PR_PPC_DEXCR_SRAPD);
+}
+
+static int dexcr_prctl_nphie_test(void)
+{
+	return dexcr_prctl_aspect_test(PR_PPC_DEXCR_NPHIE);
+}
+
+int main(int argc, char *argv[])
+{
+	int err = 0;
+
+	/*
+	 * Some tests require checking what happens across exec, so we may be
+	 * invoked as the child of a particular test
+	 */
+	if (argc > 1) {
+		if (argc == 3 && !strcmp(argv[0], "dexcr_prctl_onexec_test_child")) {
+			unsigned long which;
+
+			err = parse_ulong(argv[1], strlen(argv[1]), &which, 10);
+			FAIL_IF_MSG(err, "failed to parse which value for child");
+
+			return dexcr_prctl_onexec_test_child(which, argv[2]);
+		}
+
+		FAIL_IF_MSG(true, "unknown test case");
+	}
+
+	/*
+	 * Otherwise we are the main test invocation and run the full suite
+	 */
+	err |= test_harness(dexcr_prctl_ibrtpd_test, "dexcr_prctl_ibrtpd");
+	err |= test_harness(dexcr_prctl_srapd_test, "dexcr_prctl_srapd");
+	err |= test_harness(dexcr_prctl_nphie_test, "dexcr_prctl_nphie");
+
+	return err;
+}