libc: Fix the alignment of the TCB to match rtld for several architectures.

[jhb]

Summary

• Use 16 byte alignment rather than 8 for aarch64, powerpc64, and RISC-V.

• Use 8 byte alignment rather than 4 for 32-bit arm, mips, and powerpc.

I suspect that mips64 should be using 16 byte alignment, but both libc
and rtld currently use 8 byte alignment.

Sponsored by: The University of Cambridge, Google Inc.

lib/libc/gen/tls.c

+/*-
+ * Copyright (c) 2020
+ *      Alexander V. Chernikov <[e-mail]>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+
+struct fib_data;
+struct fib_dp;
+enum flm_op_result {
+        FLM_SUCCESS,    /* No errors, operation successful */
+        FLM_REBUILD,    /* Operation cannot be completed, schedule algorithm rebuild */
+        FLM_ERROR,      /* Operation failed, this algo cannot be used */
+};
+
+struct rib_rtable_info {
+        uint32_t num_prefixes;
+        uint32_t num_nhops;
+        uint32_t num_nhgrp;
+};
+
+struct flm_lookup_key {
+        union {
+                const struct in6_addr *addr6;
+                struct in_addr addr4;
+        };
+};
+
+typedef struct nhop_object *flm_lookup_t(void *algo_data,
+    const struct flm_lookup_key key, uint32_t scopeid);
+typedef enum flm_op_result flm_init_t (uint32_t fibnum, struct fib_data *fd,
+    void *_old_data, void **new_data);
+typedef void flm_destroy_t(void *data);
+typedef enum flm_op_result flm_dump_t(struct rtentry *rt, void *data);
+typedef enum flm_op_result flm_dump_end_t(void *data, struct fib_dp *dp);
+typedef enum flm_op_result flm_change_t(struct rib_head *rnh,
+    struct rib_cmd_info *rc, void *data);
+typedef uint8_t flm_get_pref_t(const struct rib_rtable_info *rinfo);
+
+struct fib_lookup_module {
+        char            *flm_name;              /* algo name */
+        int             flm_family;             /* address family this module supports */
+        int             flm_refcount;           /* # of references */
+        uint32_t        flm_flags;              /* flags */
+        uint8_t         flm_index;              /* internal algo index */
+        flm_init_t      *flm_init_cb;           /* instance init */
+        flm_destroy_t   *flm_destroy_cb;                /* destroy instance */
+        flm_change_t    *flm_change_rib_item_cb;/* routing table change hook */
+        flm_dump_t      *flm_dump_rib_item_cb;  /* routing table dump cb */
+        flm_dump_end_t  *flm_dump_end_cb;       /* end of dump */
+        flm_lookup_t    *flm_lookup;            /* lookup function */
+        flm_get_pref_t  *flm_get_pref;          /* get algo preference */
+        TAILQ_ENTRY(fib_lookup_module)  entries;
+};
+
+/* Datapath lookup data */
+struct fib_dp {
+        flm_lookup_t    *f;
+        void            *arg;
+};
+
+VNET_DECLARE(struct fib_dp *, inet_dp);
+#define V_inet_dp       VNET(inet_dp)
+VNET_DECLARE(struct fib_dp *, inet6_dp);
+#define V_inet6_dp      VNET(inet6_dp)
+
+#define FIB_PRINTF(_l, _fd, _fmt, ...)  fib_printf(_l, _fd, __func__, _fmt, ##__VA_ARGS__)
+
+void fib_printf(int level, struct fib_data *fd, const char *func, char *fmt, ...);
+int fib_module_init(struct fib_lookup_module *flm, uint32_t fibnum,
+    int family);
+int fib_module_clone(const struct fib_lookup_module *flm_orig,
+    struct fib_lookup_module *flm, bool waitok);
+int fib_module_dumptree(struct fib_lookup_module *flm,
+    enum rib_subscription_type subscription_type);
+int fib_module_register(struct fib_lookup_module *flm);
+int fib_module_unregister(struct fib_lookup_module *flm);
+
+uint32_t fib_get_nhop_idx(struct fib_data *fd, struct nhop_object *nh);
+struct nhop_object **fib_get_nhop_array(struct fib_data *fd);
+void fib_get_rtable_info(struct rib_head *rh, struct rib_rtable_info *rinfo);
+struct rib_head *fib_get_rh(struct fib_data *fd);
+
+