Patchwork [03/12] RISC-V: Startup and Dynamic Loading Code

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Submitter Palmer Dabbelt
Date June 14, 2017, 6:30 p.m.
Message ID <20170614183048.11040-4-palmer@dabbelt.com>
Download mbox | patch
Permalink /patch/21016/
State New
Headers show

Comments

Palmer Dabbelt - June 14, 2017, 6:30 p.m.
This patch contains the various bits of support used by the C startup
code and the dynamic loader when running on a RISC-V system.  This
contains the implementation of our PLT entries, various ld.so hooks, and
_start.  This does not contain any Linux-specific code.
---
 sysdeps/riscv/bits/link.h   |  56 ++++++++
 sysdeps/riscv/crti.S        |  14 ++
 sysdeps/riscv/dl-machine.h  | 317 ++++++++++++++++++++++++++++++++++++++++++++
 sysdeps/riscv/ldsodefs.h    |  48 +++++++
 sysdeps/riscv/linkmap.h     |   4 +
 sysdeps/riscv/sotruss-lib.c |  51 +++++++
 sysdeps/riscv/start.S       |  82 ++++++++++++
 sysdeps/riscv/tst-audit.h   |  26 ++++
 8 files changed, 598 insertions(+)
 create mode 100644 sysdeps/riscv/bits/link.h
 create mode 100644 sysdeps/riscv/crti.S
 create mode 100644 sysdeps/riscv/dl-machine.h
 create mode 100644 sysdeps/riscv/ldsodefs.h
 create mode 100644 sysdeps/riscv/linkmap.h
 create mode 100644 sysdeps/riscv/sotruss-lib.c
 create mode 100644 sysdeps/riscv/start.S
 create mode 100644 sysdeps/riscv/tst-audit.h
Joseph Myers - June 14, 2017, 8:43 p.m.
On Wed, 14 Jun 2017, Palmer Dabbelt wrote:

> diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h

> +#define EM_RISCV 243
> +
> +/* Relocs. */
> +#define R_RISCV_NONE          0
> +#define R_RISCV_32            1
> +#define R_RISCV_64            2
> +#define R_RISCV_RELATIVE      3
> +#define R_RISCV_COPY          4
> +#define R_RISCV_JUMP_SLOT     5
> +#define R_RISCV_TLS_DTPMOD32  6
> +#define R_RISCV_TLS_DTPMOD64  7
> +#define R_RISCV_TLS_DTPREL32  8
> +#define R_RISCV_TLS_DTPREL64  9
> +#define R_RISCV_TLS_TPREL32  10
> +#define R_RISCV_TLS_TPREL64  11

EM_* and relocation values go in elf/elf.h, not dl-machine.h.  EM_RISCV is 
already there.
Palmer Dabbelt - June 20, 2017, 9:14 p.m.
On Wed, 14 Jun 2017 13:43:52 PDT (-0700), joseph@codesourcery.com wrote:
> On Wed, 14 Jun 2017, Palmer Dabbelt wrote:
>
>> diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h
>
>> +#define EM_RISCV 243
>> +
>> +/* Relocs. */
>> +#define R_RISCV_NONE          0
>> +#define R_RISCV_32            1
>> +#define R_RISCV_64            2
>> +#define R_RISCV_RELATIVE      3
>> +#define R_RISCV_COPY          4
>> +#define R_RISCV_JUMP_SLOT     5
>> +#define R_RISCV_TLS_DTPMOD32  6
>> +#define R_RISCV_TLS_DTPMOD64  7
>> +#define R_RISCV_TLS_DTPREL32  8
>> +#define R_RISCV_TLS_DTPREL64  9
>> +#define R_RISCV_TLS_TPREL32  10
>> +#define R_RISCV_TLS_TPREL64  11
>
> EM_* and relocation values go in elf/elf.h, not dl-machine.h.  EM_RISCV is
> already there.

OK, we'll move these as part of the v2 patch set.

Thanks!

Patch

diff --git a/sysdeps/riscv/bits/link.h b/sysdeps/riscv/bits/link.h
new file mode 100644
index 0000000000..4e0cd96553
--- /dev/null
+++ b/sysdeps/riscv/bits/link.h
@@ -0,0 +1,56 @@ 
+/* Copyright (C) 2005, 2009, 2017 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef	_LINK_H
+# error "Never include <bits/link.h> directly; use <link.h> instead."
+#endif
+
+typedef struct La_riscv_regs
+{
+  unsigned long lr_reg[8]; /* a0 - a7 */
+  double lr_fpreg[8]; /* fa0 - fa7 */
+  unsigned long lr_ra;
+  unsigned long lr_sp;
+} La_riscv_regs;
+
+/* Return values for calls from PLT on RISC-V.  */
+typedef struct La_riscv_retval
+{
+  unsigned long lrv_a0;
+  unsigned long lrv_a1;
+  double lrv_fa0;
+  double lrv_fa1;
+} La_riscv_retval;
+
+__BEGIN_DECLS
+
+extern ElfW(Addr) la_riscv_gnu_pltenter (ElfW(Sym) *__sym, unsigned int __ndx,
+					 uintptr_t *__refcook,
+					 uintptr_t *__defcook,
+					 La_riscv_regs *__regs,
+					 unsigned int *__flags,
+					 const char *__symname,
+					 long int *__framesizep);
+extern unsigned int la_riscv_gnu_pltexit (ElfW(Sym) *__sym, unsigned int __ndx,
+					  uintptr_t *__refcook,
+					  uintptr_t *__defcook,
+					  const La_riscv_regs *__inregs,
+					  La_riscv_retval *__outregs,
+					  const char *__symname);
+
+__END_DECLS
diff --git a/sysdeps/riscv/crti.S b/sysdeps/riscv/crti.S
new file mode 100644
index 0000000000..a4332d2d64
--- /dev/null
+++ b/sysdeps/riscv/crti.S
@@ -0,0 +1,14 @@ 
+/* Facilitate pthread initialization using init_array.  */
+
+#include <sys/asm.h>
+
+#ifdef PREINIT_FUNCTION
+
+#if PREINIT_FUNCTION_WEAK
+# error PREINIT_FUNCTION_WEAK is unsupported
+#endif
+
+	.section .init_array, "aw"
+	.dc.a PREINIT_FUNCTION
+
+#endif
diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h
new file mode 100644
index 0000000000..b93f088765
--- /dev/null
+++ b/sysdeps/riscv/dl-machine.h
@@ -0,0 +1,317 @@ 
+/* Machine-dependent ELF dynamic relocation inline functions.  RISC-V version.
+   Copyright (C) 2011-2017 Free Software Foundation, Inc.
+   Contributed by Andrew Waterman (andrew@sifive.com).
+   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/>.  */
+
+#ifndef dl_machine_h
+#define dl_machine_h
+
+#define ELF_MACHINE_NAME "RISC-V"
+#define EM_RISCV 243
+
+/* Relocs. */
+#define R_RISCV_NONE          0
+#define R_RISCV_32            1
+#define R_RISCV_64            2
+#define R_RISCV_RELATIVE      3
+#define R_RISCV_COPY          4
+#define R_RISCV_JUMP_SLOT     5
+#define R_RISCV_TLS_DTPMOD32  6
+#define R_RISCV_TLS_DTPMOD64  7
+#define R_RISCV_TLS_DTPREL32  8
+#define R_RISCV_TLS_DTPREL64  9
+#define R_RISCV_TLS_TPREL32  10
+#define R_RISCV_TLS_TPREL64  11
+
+#include <entry.h>
+
+#include <sys/asm.h>
+#include <dl-tls.h>
+
+#ifndef _RTLD_PROLOGUE
+# define _RTLD_PROLOGUE(entry)						\
+	".globl\t" __STRING(entry) "\n\t"				\
+	".type\t" __STRING(entry) ", @function\n"			\
+	__STRING(entry) ":\n\t"
+#endif
+
+#ifndef _RTLD_EPILOGUE
+# define _RTLD_EPILOGUE(entry)						\
+	".size\t" __STRING(entry) ", . - " __STRING(entry) "\n\t"
+#endif
+
+#define ELF_MACHINE_JMP_SLOT R_RISCV_JUMP_SLOT
+
+#define elf_machine_type_class(type)				\
+  ((ELF_RTYPE_CLASS_PLT * ((type) == ELF_MACHINE_JMP_SLOT	\
+     || (__WORDSIZE == 32 && (type) == R_RISCV_TLS_DTPREL32)	\
+     || (__WORDSIZE == 32 && (type) == R_RISCV_TLS_DTPMOD32)	\
+     || (__WORDSIZE == 32 && (type) == R_RISCV_TLS_TPREL32)	\
+     || (__WORDSIZE == 64 && (type) == R_RISCV_TLS_DTPREL64)	\
+     || (__WORDSIZE == 64 && (type) == R_RISCV_TLS_DTPMOD64)	\
+     || (__WORDSIZE == 64 && (type) == R_RISCV_TLS_TPREL64)))	\
+   | (ELF_RTYPE_CLASS_COPY * ((type) == R_RISCV_COPY)))
+
+#define ELF_MACHINE_NO_REL 1
+#define ELF_MACHINE_NO_RELA 0
+
+/* Return nonzero iff ELF header is compatible with the running host.  */
+static inline int __attribute_used__
+elf_machine_matches_host (const ElfW(Ehdr) *ehdr)
+{
+  return ehdr->e_machine == EM_RISCV;
+}
+
+/* Return the link-time address of _DYNAMIC.  */
+static inline ElfW(Addr)
+elf_machine_dynamic (void)
+{
+  extern ElfW(Addr) _GLOBAL_OFFSET_TABLE_ __attribute__((visibility("hidden")));
+  return _GLOBAL_OFFSET_TABLE_;
+}
+
+#define STRINGXP(X) __STRING(X)
+#define STRINGXV(X) STRINGV_(X)
+#define STRINGV_(...) # __VA_ARGS__
+
+/* Return the run-time load address of the shared object.  */
+static inline ElfW(Addr)
+elf_machine_load_address (void)
+{
+  ElfW(Addr) load_addr;
+  asm ("lla %0, _DYNAMIC" : "=r"(load_addr));
+  return load_addr - elf_machine_dynamic ();
+}
+
+/* Initial entry point code for the dynamic linker.
+   The C function `_dl_start' is the real entry point;
+   its return value is the user program's entry point. */
+
+#define RTLD_START asm (\
+	".text\n\
+	" _RTLD_PROLOGUE(ENTRY_POINT) "\
+	mv a0, sp\n\
+	jal _dl_start\n\
+	# Stash user entry point in s0.\n\
+	mv s0, a0\n\
+	# See if we were run as a command with the executable file\n\
+	# name as an extra leading argument.\n\
+	lw a0, _dl_skip_args\n\
+	# Load the original argument count.\n\
+	" STRINGXP(REG_L) " a1, 0(sp)\n\
+	# Subtract _dl_skip_args from it.\n\
+	sub a1, a1, a0\n\
+	# Adjust the stack pointer to skip _dl_skip_args words.\n\
+	sll a0, a0, " STRINGXP (PTRLOG) "\n\
+	add sp, sp, a0\n\
+	# Save back the modified argument count.\n\
+	" STRINGXP(REG_S) " a1, 0(sp)\n\
+	# Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env) \n\
+	" STRINGXP(REG_L) " a0, _rtld_local\n\
+	add a2, sp, " STRINGXP (SZREG) "\n\
+	sll a3, a1, " STRINGXP (PTRLOG) "\n\
+	add a3, a3, a2\n\
+	add a3, a3, " STRINGXP (SZREG) "\n\
+	# Call the function to run the initializers.\n\
+	jal _dl_init\n\
+	# Pass our finalizer function to _start.\n\
+	lla a0, _dl_fini\n\
+	# Jump to the user entry point.\n\
+	jr s0\n\
+	" _RTLD_EPILOGUE(ENTRY_POINT) "\
+	.previous" \
+);
+
+/* Names of the architecture-specific auditing callback functions.  */
+#define ARCH_LA_PLTENTER riscv_gnu_pltenter
+#define ARCH_LA_PLTEXIT riscv_gnu_pltexit
+
+/* Bias .got.plt entry by the offset requested by the PLT header. */
+#define elf_machine_plt_value(map, reloc, value) (value)
+#define elf_machine_fixup_plt(map, t, reloc, reloc_addr, value) \
+  (*(ElfW(Addr) *)(reloc_addr) = (value))
+
+#endif /* !dl_machine_h */
+
+#ifdef RESOLVE_MAP
+
+/* Perform a relocation described by R_INFO at the location pointed to
+   by RELOC_ADDR.  SYM is the relocation symbol specified by R_INFO and
+   MAP is the object containing the reloc.  */
+
+auto inline void
+__attribute__ ((always_inline))
+elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
+		  const ElfW(Sym) *sym, const struct r_found_version *version,
+		  void *const reloc_addr, int skip_ifunc)
+{
+  ElfW(Addr) r_info = reloc->r_info;
+  const unsigned long int r_type = ELFW(R_TYPE) (r_info);
+  ElfW(Addr) *addr_field = (ElfW(Addr) *) reloc_addr;
+  const ElfW(Sym) *const __attribute__((unused)) refsym = sym;
+  struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
+  ElfW(Addr) value = 0;
+  if (sym_map != NULL)
+    value = sym_map->l_addr + sym->st_value + reloc->r_addend;
+
+  switch (r_type)
+    {
+#ifndef RTLD_BOOTSTRAP
+    case __WORDSIZE == 64 ? R_RISCV_TLS_DTPMOD64 : R_RISCV_TLS_DTPMOD32:
+      if (sym_map)
+	*addr_field = sym_map->l_tls_modid;
+      break;
+
+    case __WORDSIZE == 64 ? R_RISCV_TLS_DTPREL64 : R_RISCV_TLS_DTPREL32:
+      if (sym != NULL)
+	*addr_field = TLS_DTPREL_VALUE (sym) + reloc->r_addend;
+      break;
+
+    case __WORDSIZE == 64 ? R_RISCV_TLS_TPREL64 : R_RISCV_TLS_TPREL32:
+      if (sym != NULL)
+	{
+	  CHECK_STATIC_TLS (map, sym_map);
+	  *addr_field = TLS_TPREL_VALUE (sym_map, sym) + reloc->r_addend;
+	}
+      break;
+
+    case R_RISCV_COPY:
+      {
+	if (__builtin_expect (sym == NULL, 0))
+	  /* This can happen in trace mode if an object could not be
+	     found.  */
+	  break;
+
+	/* Handle TLS copy relocations.  */
+	if (__glibc_unlikely (ELFW(ST_TYPE) (sym->st_info) == STT_TLS))
+	  {
+	    /* There's nothing to do if the symbol is in .tbss.  */
+	    if (__glibc_likely (sym->st_value >= sym_map->l_tls_initimage_size))
+	      break;
+	    value += (ElfW(Addr)) sym_map->l_tls_initimage - sym_map->l_addr;
+	  }
+
+	size_t size = sym->st_size;
+	if (__builtin_expect (sym->st_size != refsym->st_size, 0))
+	  {
+	    const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
+	    if (sym->st_size > refsym->st_size)
+	      size = refsym->st_size;
+	    if (sym->st_size > refsym->st_size || GLRO(dl_verbose))
+	      _dl_error_printf ("\
+  %s: Symbol `%s' has different size in shared object, consider re-linking\n",
+				rtld_progname ?: "<program name unknown>",
+				strtab + refsym->st_name);
+	  }
+
+	memcpy (reloc_addr, (void *)value, size);
+	break;
+      }
+#endif
+
+#if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
+    case R_RISCV_RELATIVE:
+      {
+# if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
+	/* This is defined in rtld.c, but nowhere in the static libc.a;
+	   make the reference weak so static programs can still link.
+	   This declaration cannot be done when compiling rtld.c
+	   (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
+	   common defn for _dl_rtld_map, which is incompatible with a
+	   weak decl in the same file.  */
+#  ifndef SHARED
+	weak_extern (GL(dl_rtld_map));
+#  endif
+	if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
+# endif
+	  *addr_field = map->l_addr + reloc->r_addend;
+      break;
+    }
+#endif
+
+    case R_RISCV_JUMP_SLOT:
+    case __WORDSIZE == 64 ? R_RISCV_64 : R_RISCV_32:
+      *addr_field = value;
+      break;
+
+    case R_RISCV_NONE:
+      break;
+
+    default:
+      _dl_reloc_bad_type (map, r_type, 0);
+      break;
+    }
+}
+
+auto inline void
+__attribute__((always_inline))
+elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc,
+			  void *const reloc_addr)
+{
+  *(ElfW(Addr) *)reloc_addr = l_addr + reloc->r_addend;
+}
+
+auto inline void
+__attribute__((always_inline))
+elf_machine_lazy_rel (struct link_map *map, ElfW(Addr) l_addr,
+		      const ElfW(Rela) *reloc, int skip_ifunc)
+{
+  ElfW(Addr) *const reloc_addr = (void *) (l_addr + reloc->r_offset);
+  const unsigned int r_type = ELFW(R_TYPE) (reloc->r_info);
+
+  /* Check for unexpected PLT reloc type.  */
+  if (__builtin_expect (r_type == R_RISCV_JUMP_SLOT, 1))
+    {
+      if (__builtin_expect (map->l_mach.plt, 0) == 0)
+	{
+	  if (l_addr)
+	    *reloc_addr += l_addr;
+	}
+      else
+	*reloc_addr = map->l_mach.plt;
+    }
+  else
+    _dl_reloc_bad_type (map, r_type, 1);
+}
+
+/* Set up the loaded object described by L so its stub function
+   will jump to the on-demand fixup code __dl_runtime_resolve.  */
+
+auto inline int
+__attribute__((always_inline))
+elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
+{
+#ifndef RTLD_BOOTSTRAP
+  /* If using PLTs, fill in the first two entries of .got.plt.  */
+  if (l->l_info[DT_JMPREL])
+    {
+      extern void _dl_runtime_resolve (void) __attribute__((visibility("hidden")));
+      ElfW(Addr) *gotplt = (ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]);
+      /* If a library is prelinked but we have to relocate anyway,
+	 we have to be able to undo the prelinking of .got.plt.
+	 The prelinker saved the address of .plt for us here.  */
+      if (gotplt[1])
+	l->l_mach.plt = gotplt[1] + l->l_addr;
+      gotplt[0] = (ElfW(Addr)) &_dl_runtime_resolve;
+      gotplt[1] = (ElfW(Addr)) l;
+    }
+#endif
+
+  return lazy;
+}
+
+#endif /* RESOLVE_MAP */
diff --git a/sysdeps/riscv/ldsodefs.h b/sysdeps/riscv/ldsodefs.h
new file mode 100644
index 0000000000..794871a4f6
--- /dev/null
+++ b/sysdeps/riscv/ldsodefs.h
@@ -0,0 +1,48 @@ 
+/* Run-time dynamic linker data structures for loaded ELF shared objects.
+   Copyright (C) 2011-2017 Free Software Foundation, Inc.
+   Contributed by Andrew Waterman (andrew@sifive.com).
+   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/>.  */
+
+#ifndef _RISCV_LDSODEFS_H
+#define _RISCV_LDSODEFS_H 1
+
+#include <elf.h>
+
+struct La_riscv_regs;
+struct La_riscv_retval;
+
+#define ARCH_PLTENTER_MEMBERS						\
+    Elf64_Addr (*riscv_gnu_pltenter) (Elf64_Sym *, unsigned int,	\
+				      uintptr_t *, uintptr_t *,		\
+				      const struct La_riscv_regs *,	\
+				      unsigned int *, const char *name,	\
+				      long int *framesizep);
+
+#define ARCH_PLTEXIT_MEMBERS						\
+    unsigned int (*riscv_gnu_pltexit) (Elf64_Sym *, unsigned int,	\
+				       uintptr_t *, uintptr_t *,	\
+				       const struct La_riscv_regs *,	\
+				       struct La_riscv_retval *,	\
+				       const char *);
+
+/* The RISC-V ABI specifies that the dynamic section has to be read-only.  */
+
+#define DL_RO_DYN_SECTION 1
+
+#include_next <ldsodefs.h>
+
+#endif
diff --git a/sysdeps/riscv/linkmap.h b/sysdeps/riscv/linkmap.h
new file mode 100644
index 0000000000..a6df7821e6
--- /dev/null
+++ b/sysdeps/riscv/linkmap.h
@@ -0,0 +1,4 @@ 
+struct link_map_machine
+  {
+    ElfW(Addr) plt; /* Address of .plt */
+  };
diff --git a/sysdeps/riscv/sotruss-lib.c b/sysdeps/riscv/sotruss-lib.c
new file mode 100644
index 0000000000..ef57f6885a
--- /dev/null
+++ b/sysdeps/riscv/sotruss-lib.c
@@ -0,0 +1,51 @@ 
+/* Override generic sotruss-lib.c to define actual functions for RISC-V.
+   Copyright (C) 2012-2017 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/>.  */
+
+#define HAVE_ARCH_PLTENTER
+#define HAVE_ARCH_PLTEXIT
+
+#include <elf/sotruss-lib.c>
+
+ElfW(Addr)
+la_riscv_gnu_pltenter (ElfW(Sym) *sym __attribute__ ((unused)),
+		       unsigned int ndx __attribute__ ((unused)),
+		       uintptr_t *refcook, uintptr_t *defcook,
+		       La_riscv_regs *regs, unsigned int *flags,
+		       const char *symname, long int *framesizep)
+{
+  print_enter (refcook, defcook, symname,
+	       regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
+	       *flags);
+
+  /* No need to copy anything, we will not need the parameters in any case.  */
+  *framesizep = 0;
+
+  return sym->st_value;
+}
+
+unsigned int
+la_riscv_gnu_pltexit (ElfW(Sym) *sym, unsigned int ndx, uintptr_t *refcook,
+		      uintptr_t *defcook,
+		      const struct La_riscv_regs *inregs,
+		      struct La_riscv_retval *outregs,
+		      const char *symname)
+{
+  print_exit (refcook, defcook, symname, outregs->lrv_a0);
+
+  return 0;
+}
diff --git a/sysdeps/riscv/start.S b/sysdeps/riscv/start.S
new file mode 100644
index 0000000000..dcb20e4500
--- /dev/null
+++ b/sysdeps/riscv/start.S
@@ -0,0 +1,82 @@ 
+/* Startup code compliant to the ELF RISC-V ABI.
+   Copyright (C) 1995, 1997, 2000-2004, 2017
+	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.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.
+
+   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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#define __ASSEMBLY__ 1
+#include <entry.h>
+#include <sysdep.h>
+#include <sys/asm.h>
+
+/* The entry point's job is to call __libc_start_main.  Per the ABI,
+   a0 contains the address of a function to be passed to atexit.
+   __libc_start_main wants this in a5.  */
+
+ENTRY(ENTRY_POINT)
+	call  .Lload_gp
+	mv    a5, a0  /* rtld_fini */
+	lla   a0, main
+	REG_L a1, 0(sp)      /* argc */
+	addi  a2, sp, SZREG  /* argv */
+	andi  sp, sp, ALMASK /* Align stack. */
+	lla   a3, __libc_csu_init
+	lla   a4, __libc_csu_fini
+	mv    a6, sp  /* stack_end */
+
+	tail  __libc_start_main@plt
+END(ENTRY_POINT)
+
+/* Dynamic links need the global pointer to be initialized prior to calling
+   any shared library's initializers, so we use preinit_array to load it.
+   This doesn't cut it for static links, though, since the global pointer
+   needs to be initialized before calling __libc_start_main in that case.
+   So we redundantly initialize it at the beginning of _start.  */
+
+.Lload_gp:
+.option push
+.option norelax
+	lla   gp, __global_pointer$
+.option pop
+	ret
+
+	.section .preinit_array,"aw"
+	.dc.a .Lload_gp
+
+/* Define a symbol for the first piece of initialized data.  */
+	.data
+	.globl __data_start
+__data_start:
+	.weak data_start
+	data_start = __data_start
diff --git a/sysdeps/riscv/tst-audit.h b/sysdeps/riscv/tst-audit.h
new file mode 100644
index 0000000000..44a4107460
--- /dev/null
+++ b/sysdeps/riscv/tst-audit.h
@@ -0,0 +1,26 @@ 
+/* Definitions for testing PLT entry/exit auditing.  RISC-V version.
+
+   Copyright (C) 2005, 2017 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#define pltenter la_riscv_gnu_pltenter
+#define pltexit la_riscv_gnu_pltexit
+#define La_regs La_riscv_regs
+#define La_retval La_riscv_retval
+#define int_retval lrv_a0