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, 78 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/riscv/makecontext.c b/sysdeps/unix/sysv/linux/riscv/makecontext.c
new file mode 100644
index 0000000000..b8054a29b0
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/makecontext.c
@@ -0,0 +1,78 @@
+/* Create new context.  RISC-V version.
+   Copyright (C) 2001-2018 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 <sysdep.h>
+#include <sys/asm.h>
+#include <sys/ucontext.h>
+#include <stdarg.h>
+#include <assert.h>
+
+void
+__makecontext (ucontext_t *ucp, void (*func) (void), int argc,
+	       long int a0, long int a1, long int a2, long int a3, long int a4,
+	       ...)
+{
+  extern void __start_context (void) attribute_hidden;
+  long int i, sp;
+
+  _Static_assert (REG_NARGS == 8, "__makecontext assumes 8 argument registers");
+
+  /* Set up the stack.  */
+  sp = ((long int) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ALMASK;
+
+  /* Set up the register context.
+     ra = s0 = 0, terminating the stack for backtracing purposes.
+     s1 = the function we must call.
+     s2 = the subsequent context to run.  */
+  ucp->uc_mcontext.__gregs[REG_RA] = 0;
+  ucp->uc_mcontext.__gregs[REG_S0] = 0;
+  ucp->uc_mcontext.__gregs[REG_S1] = (long int) func;
+  ucp->uc_mcontext.__gregs[REG_S2] = (long int) ucp->uc_link;
+  ucp->uc_mcontext.__gregs[REG_SP] = sp;
+  ucp->uc_mcontext.__gregs[REG_PC] = (long int) &__start_context;
+
+  /* Put args in a0-a7, then put any remaining args on the stack.  */
+  ucp->uc_mcontext.__gregs[REG_A0 + 0] = a0;
+  ucp->uc_mcontext.__gregs[REG_A0 + 1] = a1;
+  ucp->uc_mcontext.__gregs[REG_A0 + 2] = a2;
+  ucp->uc_mcontext.__gregs[REG_A0 + 3] = a3;
+  ucp->uc_mcontext.__gregs[REG_A0 + 4] = a4;
+
+  if (__glibc_unlikely (argc > 5))
+    {
+      va_list vl;
+      va_start (vl, a4);
+
+      long reg_args = argc < REG_NARGS ? argc : REG_NARGS;
+      for (i = 5; i < reg_args; i++)
+        ucp->uc_mcontext.__gregs[REG_A0 + i] = va_arg (vl, long);
+
+      long int stack_args = argc - reg_args;
+      if (stack_args > 0)
+	{
+	  sp = (sp - stack_args * sizeof (long int)) & ALMASK;
+	  ucp->uc_mcontext.__gregs[REG_SP] = sp;
+	  for (i = 0; i < stack_args; i++)
+	    ((long int *) sp)[i] = va_arg (vl, long int);
+	}
+
+      va_end (vl);
+    }
+}
+
+weak_alias (__makecontext, makecontext)