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.

1 files changed, 73 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/riscv/flush-icache.c b/sysdeps/unix/sysv/linux/riscv/flush-icache.c
new file mode 100644
index 0000000000..d612ef4c6c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/flush-icache.c
@@ -0,0 +1,73 @@
+/* RISC-V instruction cache flushing VDSO calls
+   Copyright (C) 2017-2018 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/>.  */
+
+#include <dl-vdso.h>
+#include <stdlib.h>
+#include <atomic.h>
+#include <sys/cachectl.h>
+#include <asm/syscalls.h>
+
+typedef int (*func_type) (void *, void *, unsigned long int);
+
+static int
+__riscv_flush_icache_syscall (void *start, void *end, unsigned long int flags)
+{
+  return INLINE_SYSCALL (riscv_flush_icache, 3, start, end, flags);
+}
+
+static func_type
+__lookup_riscv_flush_icache (void)
+{
+  PREPARE_VERSION_KNOWN (linux_version, LINUX_4_15);
+
+  func_type func = _dl_vdso_vsym ("__vdso_flush_icache", &linux_version);
+
+  /* If there is no vDSO entry then call the system call directly.  All Linux
+     versions provide the vDSO entry, but QEMU's user-mode emulation doesn't
+     provide a vDSO.  */
+  if (!func)
+    func = &__riscv_flush_icache_syscall;
+
+  return func;
+}
+
+#ifdef SHARED
+
+# define INIT_ARCH()
+libc_ifunc (__riscv_flush_icache, __lookup_riscv_flush_icache ())
+
+#else
+
+int
+__riscv_flush_icache (void *start, void *end, unsigned long int flags)
+{
+  static volatile func_type cached_func;
+
+  func_type func = atomic_load_relaxed (&cached_func);
+
+  if (!func)
+    {
+      func = __lookup_riscv_flush_icache ();
+      atomic_store_relaxed (&cached_func, func);
+    }
+
+  return func (start, end, flags);
+}
+
+#endif