selftests/powerpc: Add a rtas_filter selftest

Add a selftest to test the basic functionality of CONFIG_RTAS_FILTER.

Signed-off-by: Andrew Donnellan <[e-mail]>
[mpe: Change rmo_start/end to 32-bit to avoid build errors on ppc64]
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/powerpc/syscalls/Makefile

···
 # SPDX-License-Identifier: GPL-2.0-only
-TEST_GEN_PROGS := ipc_unmuxed
+TEST_GEN_PROGS := ipc_unmuxed rtas_filter
 
 CFLAGS += -I../../../../../usr/include
 

tools/testing/selftests/powerpc/syscalls/rtas_filter.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2005-2020 IBM Corporation.
+ *
+ * Includes code from librtas (https://github.com/ibm-power-utilities/librtas/)
+ */
+
+#include <byteswap.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <errno.h>
+#include "utils.h"
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define cpu_to_be32(x)		bswap_32(x)
+#define be32_to_cpu(x)		bswap_32(x)
+#else
+#define cpu_to_be32(x)		(x)
+#define be32_to_cpu(x)		(x)
+#endif
+
+#define RTAS_IO_ASSERT	-1098	/* Unexpected I/O Error */
+#define RTAS_UNKNOWN_OP -1099	/* No Firmware Implementation of Function */
+#define BLOCK_SIZE 4096
+#define PAGE_SIZE 4096
+#define MAX_PAGES 64
+
+static const char *ofdt_rtas_path = "/proc/device-tree/rtas";
+
+typedef __be32 uint32_t;
+struct rtas_args {
+	__be32 token;
+	__be32 nargs;
+	__be32 nret;
+	__be32 args[16];
+	__be32 *rets;	  /* Pointer to return values in args[]. */
+};
+
+struct region {
+	uint64_t addr;
+	uint32_t size;
+	struct region *next;
+};
+
+int read_entire_file(int fd, char **buf, size_t *len)
+{
+	size_t buf_size = 0;
+	size_t off = 0;
+	int rc;
+
+	*buf = NULL;
+	do {
+		buf_size += BLOCK_SIZE;
+		if (*buf == NULL)
+			*buf = malloc(buf_size);
+		else
+			*buf = realloc(*buf, buf_size);
+
+		if (*buf == NULL)
+			return -ENOMEM;
+
+		rc = read(fd, *buf + off, BLOCK_SIZE);
+		if (rc < 0)
+			return -EIO;
+
+		off += rc;
+	} while (rc == BLOCK_SIZE);
+
+	if (len)
+		*len = off;
+
+	return 0;
+}
+
+static int open_prop_file(const char *prop_path, const char *prop_name, int *fd)
+{
+	char *path;
+	int len;
+
+	/* allocate enough for two string, a slash and trailing NULL */
+	len = strlen(prop_path) + strlen(prop_name) + 1 + 1;
+	path = malloc(len);
+	if (path == NULL)
+		return -ENOMEM;
+
+	snprintf(path, len, "%s/%s", prop_path, prop_name);
+
+	*fd = open(path, O_RDONLY);
+	free(path);
+	if (*fd < 0)
+		return -errno;
+
+	return 0;
+}
+
+static int get_property(const char *prop_path, const char *prop_name,
+			char **prop_val, size_t *prop_len)
+{
+	int rc, fd;
+
+	rc = open_prop_file(prop_path, prop_name, &fd);
+	if (rc)
+		return rc;
+
+	rc = read_entire_file(fd, prop_val, prop_len);
+	close(fd);
+
+	return rc;
+}
+
+int rtas_token(const char *call_name)
+{
+	char *prop_buf = NULL;
+	size_t len;
+	int rc;
+
+	rc = get_property(ofdt_rtas_path, call_name, &prop_buf, &len);
+	if (rc < 0) {
+		rc = RTAS_UNKNOWN_OP;
+		goto err;
+	}
+
+	rc = be32_to_cpu(*(int *)prop_buf);
+
+err:
+	free(prop_buf);
+	return rc;
+}
+
+static int read_kregion_bounds(struct region *kregion)
+{
+	char *buf;
+	int fd;
+	int rc;
+
+	fd = open("/proc/ppc64/rtas/rmo_buffer", O_RDONLY);
+	if (fd < 0) {
+		printf("Could not open rmo_buffer file\n");
+		return RTAS_IO_ASSERT;
+	}
+
+	rc = read_entire_file(fd, &buf, NULL);
+	close(fd);
+	if (rc) {
+		free(buf);
+		return rc;
+	}
+
+	sscanf(buf, "%" SCNx64 " %x", &kregion->addr, &kregion->size);
+	free(buf);
+
+	if (!(kregion->size && kregion->addr) ||
+	    (kregion->size > (PAGE_SIZE * MAX_PAGES))) {
+		printf("Unexpected kregion bounds\n");
+		return RTAS_IO_ASSERT;
+	}
+
+	return 0;
+}
+
+static int rtas_call(const char *name, int nargs,
+		     int nrets, ...)
+{
+	struct rtas_args args;
+	__be32 *rets[16];
+	int i, rc, token;
+	va_list ap;
+
+	va_start(ap, nrets);
+
+	token = rtas_token(name);
+	if (token == RTAS_UNKNOWN_OP) {
+		// We don't care if the call doesn't exist
+		printf("call '%s' not available, skipping...", name);
+		rc = RTAS_UNKNOWN_OP;
+		goto err;
+	}
+
+	args.token = cpu_to_be32(token);
+	args.nargs = cpu_to_be32(nargs);
+	args.nret = cpu_to_be32(nrets);
+
+	for (i = 0; i < nargs; i++)
+		args.args[i] = (__be32) va_arg(ap, unsigned long);
+
+	for (i = 0; i < nrets; i++)
+		rets[i] = (__be32 *) va_arg(ap, unsigned long);
+
+	rc = syscall(__NR_rtas, &args);
+	if (rc) {
+		rc = -errno;
+		goto err;
+	}
+
+	if (nrets) {
+		*(rets[0]) = be32_to_cpu(args.args[nargs]);
+
+		for (i = 1; i < nrets; i++) {
+			*(rets[i]) = args.args[nargs + i];
+		}
+	}
+
+err:
+	va_end(ap);
+	return rc;
+}
+
+static int test(void)
+{
+	struct region rmo_region;
+	uint32_t rmo_start;
+	uint32_t rmo_end;
+	__be32 rets[1];
+	int rc;
+
+	// Test a legitimate harmless call
+	// Expected: call succeeds
+	printf("Test a permitted call, no parameters... ");
+	rc = rtas_call("get-time-of-day", 0, 1, rets);
+	printf("rc: %d\n", rc);
+	FAIL_IF(rc != 0 && rc != RTAS_UNKNOWN_OP);
+
+	// Test a prohibited call
+	// Expected: call returns -EINVAL
+	printf("Test a prohibited call... ");
+	rc = rtas_call("nvram-fetch", 0, 1, rets);
+	printf("rc: %d\n", rc);
+	FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);
+
+	// Get RMO
+	rc = read_kregion_bounds(&rmo_region);
+	if (rc) {
+		printf("Couldn't read RMO region bounds, skipping remaining cases\n");
+		return 0;
+	}
+	rmo_start = rmo_region.addr;
+	rmo_end = rmo_start + rmo_region.size - 1;
+	printf("RMO range: %08x - %08x\n", rmo_start, rmo_end);
+
+	// Test a permitted call, user-supplied size, buffer inside RMO
+	// Expected: call succeeds
+	printf("Test a permitted call, user-supplied size, buffer inside RMO... ");
+	rc = rtas_call("ibm,get-system-parameter", 3, 1, 0, cpu_to_be32(rmo_start),
+		       cpu_to_be32(rmo_end - rmo_start + 1), rets);
+	printf("rc: %d\n", rc);
+	FAIL_IF(rc != 0 && rc != RTAS_UNKNOWN_OP);
+
+	// Test a permitted call, user-supplied size, buffer start outside RMO
+	// Expected: call returns -EINVAL
+	printf("Test a permitted call, user-supplied size, buffer start outside RMO... ");
+	rc = rtas_call("ibm,get-system-parameter", 3, 1, 0, cpu_to_be32(rmo_end + 1),
+		       cpu_to_be32(4000), rets);
+	printf("rc: %d\n", rc);
+	FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);
+
+	// Test a permitted call, user-supplied size, buffer end outside RMO
+	// Expected: call returns -EINVAL
+	printf("Test a permitted call, user-supplied size, buffer end outside RMO... ");
+	rc = rtas_call("ibm,get-system-parameter", 3, 1, 0, cpu_to_be32(rmo_start),
+		       cpu_to_be32(rmo_end - rmo_start + 2), rets);
+	printf("rc: %d\n", rc);
+	FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);
+
+	// Test a permitted call, fixed size, buffer end outside RMO
+	// Expected: call returns -EINVAL
+	printf("Test a permitted call, fixed size, buffer end outside RMO... ");
+	rc = rtas_call("ibm,configure-connector", 2, 1, cpu_to_be32(rmo_end - 4000), 0, rets);
+	printf("rc: %d\n", rc);
+	FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	return test_harness(test, "rtas_filter");
+}