1 files changed, 518 insertions, 0 deletions
diff --git a/tools/testing/selftests/x86/amx.c b/tools/testing/selftests/x86/amx.c
new file mode 100644
index 000000000000..40769c16de1b
--- /dev/null
+++ b/tools/testing/selftests/x86/amx.c
@@ -0,0 +1,518 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <setjmp.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <x86intrin.h>
+
+#include <sys/auxv.h>
+#include <sys/mman.h>
+#include <sys/shm.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+
+#include "helpers.h"
+#include "xstate.h"
+
+#ifndef __x86_64__
+# error This test is 64-bit only
+#endif
+
+/* err() exits and will not return */
+#define fatal_error(msg, ...)	err(1, "[FAIL]\t" msg, ##__VA_ARGS__)
+
+#define XFEATURE_MASK_XTILECFG	(1 << XFEATURE_XTILECFG)
+#define XFEATURE_MASK_XTILEDATA	(1 << XFEATURE_XTILEDATA)
+#define XFEATURE_MASK_XTILE	(XFEATURE_MASK_XTILECFG | XFEATURE_MASK_XTILEDATA)
+
+struct xstate_info xtiledata;
+
+/* The helpers for managing XSAVE buffer and tile states: */
+
+struct xsave_buffer *stashed_xsave;
+
+static void init_stashed_xsave(void)
+{
+	stashed_xsave = alloc_xbuf();
+	if (!stashed_xsave)
+		fatal_error("failed to allocate stashed_xsave\n");
+	clear_xstate_header(stashed_xsave);
+}
+
+static void free_stashed_xsave(void)
+{
+	free(stashed_xsave);
+}
+
+/* Work around printf() being unsafe in signals: */
+#define SIGNAL_BUF_LEN 1000
+char signal_message_buffer[SIGNAL_BUF_LEN];
+void sig_print(char *msg)
+{
+	int left = SIGNAL_BUF_LEN - strlen(signal_message_buffer) - 1;
+
+	strncat(signal_message_buffer, msg, left);
+}
+
+static volatile bool noperm_signaled;
+static int noperm_errs;
+/*
+ * Signal handler for when AMX is used but
+ * permission has not been obtained.
+ */
+static void handle_noperm(int sig, siginfo_t *si, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t *)ctx_void;
+	void *xbuf = ctx->uc_mcontext.fpregs;
+	struct _fpx_sw_bytes *sw_bytes;
+	uint64_t features;
+
+	/* Reset the signal message buffer: */
+	signal_message_buffer[0] = '\0';
+	sig_print("\tAt SIGILL handler,\n");
+
+	if (si->si_code != ILL_ILLOPC) {
+		noperm_errs++;
+		sig_print("[FAIL]\tInvalid signal code.\n");
+	} else {
+		sig_print("[OK]\tValid signal code (ILL_ILLOPC).\n");
+	}
+
+	sw_bytes = get_fpx_sw_bytes(xbuf);
+	/*
+	 * Without permission, the signal XSAVE buffer should not
+	 * have room for AMX register state (aka. xtiledata).
+	 * Check that the size does not overlap with where xtiledata
+	 * will reside.
+	 *
+	 * This also implies that no state components *PAST*
+	 * XTILEDATA (features >=19) can be present in the buffer.
+	 */
+	if (sw_bytes->xstate_size <= xtiledata.xbuf_offset) {
+		sig_print("[OK]\tValid xstate size\n");
+	} else {
+		noperm_errs++;
+		sig_print("[FAIL]\tInvalid xstate size\n");
+	}
+
+	features = get_fpx_sw_bytes_features(xbuf);
+	/*
+	 * Without permission, the XTILEDATA feature
+	 * bit should not be set.
+	 */
+	if ((features & XFEATURE_MASK_XTILEDATA) == 0) {
+		sig_print("[OK]\tValid xstate mask\n");
+	} else {
+		noperm_errs++;
+		sig_print("[FAIL]\tInvalid xstate mask\n");
+	}
+
+	noperm_signaled = true;
+	ctx->uc_mcontext.gregs[REG_RIP] += 3; /* Skip the faulting XRSTOR */
+}
+
+/* Return true if XRSTOR is successful; otherwise, false. */
+static inline bool xrstor_safe(struct xsave_buffer *xbuf, uint64_t mask)
+{
+	noperm_signaled = false;
+	xrstor(xbuf, mask);
+
+	/* Print any messages produced by the signal code: */
+	printf("%s", signal_message_buffer);
+	/*
+	 * Reset the buffer to make sure any future printing
+	 * only outputs new messages:
+	 */
+	signal_message_buffer[0] = '\0';
+
+	if (noperm_errs)
+		fatal_error("saw %d errors in noperm signal handler\n", noperm_errs);
+
+	return !noperm_signaled;
+}
+
+/*
+ * Use XRSTOR to populate the XTILEDATA registers with
+ * random data.
+ *
+ * Return true if successful; otherwise, false.
+ */
+static inline bool load_rand_tiledata(struct xsave_buffer *xbuf)
+{
+	clear_xstate_header(xbuf);
+	set_xstatebv(xbuf, XFEATURE_MASK_XTILEDATA);
+	set_rand_data(&xtiledata, xbuf);
+	return xrstor_safe(xbuf, XFEATURE_MASK_XTILEDATA);
+}
+
+enum expected_result { FAIL_EXPECTED, SUCCESS_EXPECTED };
+
+/* arch_prctl() and sigaltstack() test */
+
+#define ARCH_GET_XCOMP_SUPP	0x1021
+#define ARCH_GET_XCOMP_PERM	0x1022
+#define ARCH_REQ_XCOMP_PERM	0x1023
+
+static void req_xtiledata_perm(void)
+{
+	syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_PERM, XFEATURE_XTILEDATA);
+}
+
+static void validate_req_xcomp_perm(enum expected_result exp)
+{
+	unsigned long bitmask, expected_bitmask;
+	long rc;
+
+	rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask);
+	if (rc) {
+		fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc);
+	} else if (!(bitmask & XFEATURE_MASK_XTILECFG)) {
+		fatal_error("ARCH_GET_XCOMP_PERM returns XFEATURE_XTILECFG off.");
+	}
+
+	rc = syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_PERM, XFEATURE_XTILEDATA);
+	if (exp == FAIL_EXPECTED) {
+		if (rc) {
+			printf("[OK]\tARCH_REQ_XCOMP_PERM saw expected failure..\n");
+			return;
+		}
+
+		fatal_error("ARCH_REQ_XCOMP_PERM saw unexpected success.\n");
+	} else if (rc) {
+		fatal_error("ARCH_REQ_XCOMP_PERM saw unexpected failure.\n");
+	}
+
+	expected_bitmask = bitmask | XFEATURE_MASK_XTILEDATA;
+
+	rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask);
+	if (rc) {
+		fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc);
+	} else if (bitmask != expected_bitmask) {
+		fatal_error("ARCH_REQ_XCOMP_PERM set a wrong bitmask: %lx, expected: %lx.\n",
+			    bitmask, expected_bitmask);
+	} else {
+		printf("\tARCH_REQ_XCOMP_PERM is successful.\n");
+	}
+}
+
+static void validate_xcomp_perm(enum expected_result exp)
+{
+	bool load_success = load_rand_tiledata(stashed_xsave);
+
+	if (exp == FAIL_EXPECTED) {
+		if (load_success) {
+			noperm_errs++;
+			printf("[FAIL]\tLoad tiledata succeeded.\n");
+		} else {
+			printf("[OK]\tLoad tiledata failed.\n");
+		}
+	} else if (exp == SUCCESS_EXPECTED) {
+		if (load_success) {
+			printf("[OK]\tLoad tiledata succeeded.\n");
+		} else {
+			noperm_errs++;
+			printf("[FAIL]\tLoad tiledata failed.\n");
+		}
+	}
+}
+
+#ifndef AT_MINSIGSTKSZ
+#  define AT_MINSIGSTKSZ	51
+#endif
+
+static void *alloc_altstack(unsigned int size)
+{
+	void *altstack;
+
+	altstack = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+
+	if (altstack == MAP_FAILED)
+		fatal_error("mmap() for altstack");
+
+	return altstack;
+}
+
+static void setup_altstack(void *addr, unsigned long size, enum expected_result exp)
+{
+	stack_t ss;
+	int rc;
+
+	memset(&ss, 0, sizeof(ss));
+	ss.ss_size = size;
+	ss.ss_sp = addr;
+
+	rc = sigaltstack(&ss, NULL);
+
+	if (exp == FAIL_EXPECTED) {
+		if (rc) {
+			printf("[OK]\tsigaltstack() failed.\n");
+		} else {
+			fatal_error("sigaltstack() succeeded unexpectedly.\n");
+		}
+	} else if (rc) {
+		fatal_error("sigaltstack()");
+	}
+}
+
+static void test_dynamic_sigaltstack(void)
+{
+	unsigned int small_size, enough_size;
+	unsigned long minsigstksz;
+	void *altstack;
+
+	minsigstksz = getauxval(AT_MINSIGSTKSZ);
+	printf("\tAT_MINSIGSTKSZ = %lu\n", minsigstksz);
+	/*
+	 * getauxval() itself can return 0 for failure or
+	 * success.  But, in this case, AT_MINSIGSTKSZ
+	 * will always return a >=0 value if implemented.
+	 * Just check for 0.
+	 */
+	if (minsigstksz == 0) {
+		printf("no support for AT_MINSIGSTKSZ, skipping sigaltstack tests\n");
+		return;
+	}
+
+	enough_size = minsigstksz * 2;
+
+	altstack = alloc_altstack(enough_size);
+	printf("\tAllocate memory for altstack (%u bytes).\n", enough_size);
+
+	/*
+	 * Try setup_altstack() with a size which can not fit
+	 * XTILEDATA.  ARCH_REQ_XCOMP_PERM should fail.
+	 */
+	small_size = minsigstksz - xtiledata.size;
+	printf("\tAfter sigaltstack() with small size (%u bytes).\n", small_size);
+	setup_altstack(altstack, small_size, SUCCESS_EXPECTED);
+	validate_req_xcomp_perm(FAIL_EXPECTED);
+
+	/*
+	 * Try setup_altstack() with a size derived from
+	 * AT_MINSIGSTKSZ.  It should be more than large enough
+	 * and thus ARCH_REQ_XCOMP_PERM should succeed.
+	 */
+	printf("\tAfter sigaltstack() with enough size (%u bytes).\n", enough_size);
+	setup_altstack(altstack, enough_size, SUCCESS_EXPECTED);
+	validate_req_xcomp_perm(SUCCESS_EXPECTED);
+
+	/*
+	 * Try to coerce setup_altstack() to again accept a
+	 * too-small altstack.  This ensures that big-enough
+	 * sigaltstacks can not shrink to a too-small value
+	 * once XTILEDATA permission is established.
+	 */
+	printf("\tThen, sigaltstack() with small size (%u bytes).\n", small_size);
+	setup_altstack(altstack, small_size, FAIL_EXPECTED);
+}
+
+static void test_dynamic_state(void)
+{
+	pid_t parent, child, grandchild;
+
+	parent = fork();
+	if (parent < 0) {
+		/* fork() failed */
+		fatal_error("fork");
+	} else if (parent > 0) {
+		int status;
+		/* fork() succeeded.  Now in the parent. */
+
+		wait(&status);
+		if (!WIFEXITED(status) || WEXITSTATUS(status))
+			fatal_error("arch_prctl test parent exit");
+		return;
+	}
+	/* fork() succeeded.  Now in the child . */
+
+	printf("[RUN]\tCheck ARCH_REQ_XCOMP_PERM around process fork() and sigaltack() test.\n");
+
+	printf("\tFork a child.\n");
+	child = fork();
+	if (child < 0) {
+		fatal_error("fork");
+	} else if (child > 0) {
+		int status;
+
+		wait(&status);
+		if (!WIFEXITED(status) || WEXITSTATUS(status))
+			fatal_error("arch_prctl test child exit");
+		_exit(0);
+	}
+
+	/*
+	 * The permission request should fail without an
+	 * XTILEDATA-compatible signal stack
+	 */
+	printf("\tTest XCOMP_PERM at child.\n");
+	validate_xcomp_perm(FAIL_EXPECTED);
+
+	/*
+	 * Set up an XTILEDATA-compatible signal stack and
+	 * also obtain permission to populate XTILEDATA.
+	 */
+	printf("\tTest dynamic sigaltstack at child:\n");
+	test_dynamic_sigaltstack();
+
+	/* Ensure that XTILEDATA can be populated. */
+	printf("\tTest XCOMP_PERM again at child.\n");
+	validate_xcomp_perm(SUCCESS_EXPECTED);
+
+	printf("\tFork a grandchild.\n");
+	grandchild = fork();
+	if (grandchild < 0) {
+		/* fork() failed */
+		fatal_error("fork");
+	} else if (!grandchild) {
+		/* fork() succeeded.  Now in the (grand)child. */
+		printf("\tTest XCOMP_PERM at grandchild.\n");
+
+		/*
+		 * Ensure that the grandchild inherited
+		 * permission and a compatible sigaltstack:
+		 */
+		validate_xcomp_perm(SUCCESS_EXPECTED);
+	} else {
+		int status;
+		/* fork() succeeded.  Now in the parent. */
+
+		wait(&status);
+		if (!WIFEXITED(status) || WEXITSTATUS(status))
+			fatal_error("fork test grandchild");
+	}
+
+	_exit(0);
+}
+
+static inline int __compare_tiledata_state(struct xsave_buffer *xbuf1, struct xsave_buffer *xbuf2)
+{
+	return memcmp(&xbuf1->bytes[xtiledata.xbuf_offset],
+		      &xbuf2->bytes[xtiledata.xbuf_offset],
+		      xtiledata.size);
+}
+
+/*
+ * Save current register state and compare it to @xbuf1.'
+ *
+ * Returns false if @xbuf1 matches the registers.
+ * Returns true  if @xbuf1 differs from the registers.
+ */
+static inline bool __validate_tiledata_regs(struct xsave_buffer *xbuf1)
+{
+	struct xsave_buffer *xbuf2;
+	int ret;
+
+	xbuf2 = alloc_xbuf();
+	if (!xbuf2)
+		fatal_error("failed to allocate XSAVE buffer\n");
+
+	xsave(xbuf2, XFEATURE_MASK_XTILEDATA);
+	ret = __compare_tiledata_state(xbuf1, xbuf2);
+
+	free(xbuf2);
+
+	if (ret == 0)
+		return false;
+	return true;
+}
+
+static inline void validate_tiledata_regs_changed(struct xsave_buffer *xbuf)
+{
+	int ret = __validate_tiledata_regs(xbuf);
+
+	if (ret == 0)
+		fatal_error("TILEDATA registers did not change");
+}
+
+/* tiledata inheritance test */
+
+static void test_fork(void)
+{
+	pid_t child, grandchild;
+
+	child = fork();
+	if (child < 0) {
+		/* fork() failed */
+		fatal_error("fork");
+	} else if (child > 0) {
+		/* fork() succeeded.  Now in the parent. */
+		int status;
+
+		wait(&status);
+		if (!WIFEXITED(status) || WEXITSTATUS(status))
+			fatal_error("fork test child");
+		return;
+	}
+	/* fork() succeeded.  Now in the child. */
+	printf("[RUN]\tCheck tile data inheritance.\n\tBefore fork(), load tiledata\n");
+
+	load_rand_tiledata(stashed_xsave);
+
+	grandchild = fork();
+	if (grandchild < 0) {
+		/* fork() failed */
+		fatal_error("fork");
+	} else if (grandchild > 0) {
+		/* fork() succeeded.  Still in the first child. */
+		int status;
+
+		wait(&status);
+		if (!WIFEXITED(status) || WEXITSTATUS(status))
+			fatal_error("fork test grand child");
+		_exit(0);
+	}
+	/* fork() succeeded.  Now in the (grand)child. */
+
+	/*
+	 * TILEDATA registers are not preserved across fork().
+	 * Ensure that their value has changed:
+	 */
+	validate_tiledata_regs_changed(stashed_xsave);
+
+	_exit(0);
+}
+
+int main(void)
+{
+	unsigned long features;
+	long rc;
+
+	rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_SUPP, &features);
+	if (rc || (features & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE) {
+		ksft_print_msg("no AMX support\n");
+		return KSFT_SKIP;
+	}
+
+	xtiledata = get_xstate_info(XFEATURE_XTILEDATA);
+	if (!xtiledata.size || !xtiledata.xbuf_offset) {
+		fatal_error("xstate cpuid: invalid tile data size/offset: %d/%d",
+			    xtiledata.size, xtiledata.xbuf_offset);
+	}
+
+	init_stashed_xsave();
+	sethandler(SIGILL, handle_noperm, 0);
+
+	test_dynamic_state();
+
+	/* Request permission for the following tests */
+	req_xtiledata_perm();
+
+	test_fork();
+
+	/*
+	 * Perform generic xstate tests for context switching, ptrace,
+	 * and signal.
+	 */
+	test_xstate(XFEATURE_XTILEDATA);
+
+	clearhandler(SIGILL);
+	free_stashed_xsave();
+
+	return 0;
+}