RISC-V: Linux ABI

Linux-specific code that is required for maintaining ABI compatibility.
This doesn't contain the actual system call interface, that is split out
in order to avoid having a patch that's too big.

2018-01-29  Palmer Dabbelt  <palmer@sifive.com>

        * sysdeps/riscv/nptl/pthread-offsets.h: New file.
        * sysdeps/riscv/nptl/pthreaddef.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/bits/fcntl.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/bits/mman.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/bits/sigcontext.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/dl-cache.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/flush-icache.c: Likewise.
        * sysdeps/unix/sysv/linux/riscv/getcontext.S: Likewise.
        * sysdeps/unix/sysv/linux/riscv/init-first.c: Likewise.
        * sysdeps/unix/sysv/linux/riscv/libc-vdso.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/makecontext.c: Likewise.
        * sysdeps/unix/sysv/linux/riscv/readelflib.c: Likewise.
        * sysdeps/unix/sysv/linux/riscv/register-dump.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/setcontext.S: Likewise.
        * sysdeps/unix/sysv/linux/riscv/sigcontextinfo.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/swapcontext.S: Likewise.
        * sysdeps/unix/sysv/linux/riscv/sys/cachectl.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/sys/procfs.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/sys/ucontext.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/sys/user.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/ucontext-macros.h: Likewise.
        * sysdeps/unix/sysv/linux/riscv/ucontext_i.sym: Likewise.

sysdeps/unix/sysv/linux/riscv/sys/ucontext.h

@@ -0,0 +1,110 @@
+/* struct ucontext definition, RISC-V version.
+   Copyright (C) 1997-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Don't rely on this, the interface is currently messed up and may need to
+   be broken to be fixed.  */
+#ifndef _SYS_UCONTEXT_H
+#define _SYS_UCONTEXT_H	1
+
+#include <features.h>
+
+#include <bits/types/sigset_t.h>
+#include <bits/types/stack_t.h>
+
+typedef unsigned long int __riscv_mc_gp_state[32];
+
+#ifdef __USE_MISC
+# define NGREG	32
+
+# define REG_PC 0
+# define REG_RA 1
+# define REG_SP 2
+# define REG_TP 4
+# define REG_S0 8
+# define REG_S1 9
+# define REG_A0 10
+# define REG_S2 18
+# define REG_NARGS 8
+
+typedef unsigned long int greg_t;
+
+/* Container for all general registers.  */
+typedef __riscv_mc_gp_state gregset_t;
+
+/* Container for floating-point state.  */
+typedef union __riscv_mc_fp_state fpregset_t;
+#endif
+
+struct __riscv_mc_f_ext_state
+  {
+    unsigned int __f[32];
+    unsigned int __fcsr;
+  };
+
+struct __riscv_mc_d_ext_state
+  {
+    unsigned long long int __f[32];
+    unsigned int __fcsr;
+  };
+
+struct __riscv_mc_q_ext_state
+  {
+    unsigned long long int __f[64] __attribute__ ((__aligned__ (16)));
+    unsigned int __fcsr;
+    /* Reserved for expansion of sigcontext structure.  Currently zeroed
+       upon signal, and must be zero upon sigreturn.  */
+    unsigned int __glibc_reserved[3];
+  };
+
+union __riscv_mc_fp_state
+  {
+    struct __riscv_mc_f_ext_state __f;
+    struct __riscv_mc_d_ext_state __d;
+    struct __riscv_mc_q_ext_state __q;
+  };
+
+typedef struct mcontext_t
+  {
+    __riscv_mc_gp_state __gregs;
+    union  __riscv_mc_fp_state __fpregs;
+  } mcontext_t;
+
+/* Userlevel context.  */
+typedef struct ucontext_t
+  {
+    unsigned long int  __uc_flags;
+    struct ucontext_t *uc_link;
+    stack_t            uc_stack;
+    sigset_t           uc_sigmask;
+    /* There's some padding here to allow sigset_t to be expanded in the
+       future.  Though this is unlikely, other architectures put uc_sigmask
+       at the end of this structure and explicitly state it can be
+       expanded, so we didn't want to box ourselves in here.  */
+    char               __glibc_reserved[1024 / 8 - sizeof (sigset_t)];
+    /* We can't put uc_sigmask at the end of this structure because we need
+       to be able to expand sigcontext in the future.  For example, the
+       vector ISA extension will almost certainly add ISA state.  We want
+       to ensure all user-visible ISA state can be saved and restored via a
+       ucontext, so we're putting this at the end in order to allow for
+       infinite extensibility.  Since we know this will be extended and we
+       assume sigset_t won't be extended an extreme amount, we're
+       prioritizing this.  */
+    mcontext_t uc_mcontext;
+  } ucontext_t;
+
+#endif /* sys/ucontext.h */