Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 326 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/mips/dl-machine-reject-phdr.h b/REORG.TODO/sysdeps/mips/dl-machine-reject-phdr.h
new file mode 100644
index 0000000000..3dde936e3b
--- /dev/null
+++ b/REORG.TODO/sysdeps/mips/dl-machine-reject-phdr.h
@@ -0,0 +1,326 @@
+/* Machine-dependent program header inspection for the ELF loader.
+   Copyright (C) 2014-2017 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/>.  */
+
+#ifndef _DL_MACHINE_REJECT_PHDR_H
+#define _DL_MACHINE_REJECT_PHDR_H 1
+
+#include <unistd.h>
+#include <sys/prctl.h>
+
+#if defined PR_GET_FP_MODE && defined PR_SET_FP_MODE
+# define HAVE_PRCTL_FP_MODE 1
+#else
+# define HAVE_PRCTL_FP_MODE 0
+#endif
+
+/* Reject an object with a debug message.  */
+#define REJECT(str, args...)						      \
+  {									      \
+    if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))		      \
+      _dl_debug_printf (str, ##args);					      \
+    return true;							      \
+  }
+
+/* Search the program headers for the ABI Flags.  */
+
+static inline const ElfW(Phdr) *
+find_mips_abiflags (const ElfW(Phdr) *phdr, ElfW(Half) phnum)
+{
+  const ElfW(Phdr) *ph;
+
+  for (ph = phdr; ph < &phdr[phnum]; ++ph)
+    if (ph->p_type == PT_MIPS_ABIFLAGS)
+      return ph;
+  return NULL;
+}
+
+/* Cache the FP ABI value from the PT_MIPS_ABIFLAGS program header.  */
+
+static bool
+cached_fpabi_reject_phdr_p (struct link_map *l)
+{
+  if (l->l_mach.fpabi == 0)
+    {
+      const ElfW(Phdr) *ph = find_mips_abiflags (l->l_phdr, l->l_phnum);
+
+      if (ph)
+	{
+	  Elf_MIPS_ABIFlags_v0 * mips_abiflags;
+	  if (ph->p_filesz < sizeof (Elf_MIPS_ABIFlags_v0))
+	    REJECT ("   %s: malformed PT_MIPS_ABIFLAGS found\n", l->l_name);
+
+	  mips_abiflags = (Elf_MIPS_ABIFlags_v0 *) (l->l_addr + ph->p_vaddr);
+
+	  if (__glibc_unlikely (mips_abiflags->flags2 != 0))
+	    REJECT ("   %s: unknown MIPS.abiflags flags2: %u\n", l->l_name,
+		    mips_abiflags->flags2);
+
+	  l->l_mach.fpabi = mips_abiflags->fp_abi;
+	  l->l_mach.odd_spreg = (mips_abiflags->flags1
+				 & MIPS_AFL_FLAGS1_ODDSPREG) != 0;
+	}
+      else
+	{
+	  l->l_mach.fpabi = -1;
+	  l->l_mach.odd_spreg = true;
+	}
+    }
+  return false;
+}
+
+/* Return a description of the specified floating-point ABI.  */
+
+static const char *
+fpabi_string (int fpabi)
+{
+  switch (fpabi)
+    {
+    case Val_GNU_MIPS_ABI_FP_ANY:
+      return "Hard or soft float";
+    case Val_GNU_MIPS_ABI_FP_DOUBLE:
+      return "Hard float (double precision)";
+    case Val_GNU_MIPS_ABI_FP_SINGLE:
+      return "Hard float (single precision)";
+    case Val_GNU_MIPS_ABI_FP_SOFT:
+      return "Soft float";
+    case Val_GNU_MIPS_ABI_FP_OLD_64:
+      return "Unsupported FP64";
+    case Val_GNU_MIPS_ABI_FP_XX:
+      return "Hard float (32-bit CPU, Any FPU)";
+    case Val_GNU_MIPS_ABI_FP_64:
+      return "Hard float (32-bit CPU, 64-bit FPU)";
+    case Val_GNU_MIPS_ABI_FP_64A:
+      return "Hard float compat (32-bit CPU, 64-bit FPU)";
+    case -1:
+      return "Double precision, single precision or soft float";
+    default:
+      return "Unknown FP ABI";
+    }
+}
+
+/* A structure to describe the requirements of each FP ABI extension.
+   Each field says whether the ABI can be executed in that mode.  The FR0 field
+   is actually overloaded and means 'default' FR mode for the ABI.  I.e. For
+   O32 it is FR0 and for N32/N64 it is actually FR1.  Since this logic is
+   focussed on the intricacies of mode management for O32 we call the field
+   FR0.  */
+
+struct abi_req
+{
+  bool single;
+  bool soft;
+  bool fr0;
+  bool fr1;
+  bool fre;
+};
+
+/* FP ABI requirements for all Val_GNU_MIPS_ABI_FP_* values.  */
+
+static const struct abi_req reqs[Val_GNU_MIPS_ABI_FP_MAX + 1] =
+    {{true,  true,  true,  true,  true},  /* Any */
+     {false, false, true,  false, true},  /* Double-float */
+     {true,  false, false, false, false}, /* Single-float */
+     {false, true,  false, false, false}, /* Soft-float */
+     {false, false, false, false, false}, /* old-FP64 */
+     {false, false, true,  true,  true},  /* FPXX */
+     {false, false, false, true,  false}, /* FP64 */
+     {false, false, false, true,  true}}; /* FP64A */
+
+/* FP ABI requirements for objects without a PT_MIPS_ABIFLAGS segment.  */
+
+static const struct abi_req none_req = { true, true, true, false, true };
+
+/* Return true iff ELF program headers are incompatible with the running
+   host.  This verifies that floating-point ABIs are compatible and
+   re-configures the hardware mode if necessary.  This code handles both the
+   DT_NEEDED libraries and the dlopen'ed libraries.  It also accounts for the
+   impact of dlclose.  */
+
+static bool __attribute_used__
+elf_machine_reject_phdr_p (const ElfW(Phdr) *phdr, uint_fast16_t phnum,
+			   const char *buf, size_t len, struct link_map *map,
+			   int fd)
+{
+  const ElfW(Phdr) *ph = find_mips_abiflags (phdr, phnum);
+  struct link_map *l;
+  Lmid_t nsid;
+  int in_abi = -1;
+  struct abi_req in_req;
+  Elf_MIPS_ABIFlags_v0 *mips_abiflags = NULL;
+  bool perfect_match = false;
+#if _MIPS_SIM == _ABIO32
+  unsigned int cur_mode = -1;
+# if HAVE_PRCTL_FP_MODE
+  bool cannot_mode_switch = false;
+
+  /* Get the current hardware mode.  */
+  cur_mode = __prctl (PR_GET_FP_MODE);
+# endif
+#endif
+
+  /* Read the attributes section.  */
+  if (ph != NULL)
+    {
+      ElfW(Addr) size = ph->p_filesz;
+
+      if (ph->p_offset + size <= len)
+	mips_abiflags = (Elf_MIPS_ABIFlags_v0 *) (buf + ph->p_offset);
+      else
+	{
+	  mips_abiflags = alloca (size);
+	  __lseek (fd, ph->p_offset, SEEK_SET);
+	  if (__libc_read (fd, (void *) mips_abiflags, size) != size)
+	    REJECT ("   unable to read PT_MIPS_ABIFLAGS\n");
+	}
+
+      if (size < sizeof (Elf_MIPS_ABIFlags_v0))
+	REJECT ("   contains malformed PT_MIPS_ABIFLAGS\n");
+
+      if (__glibc_unlikely (mips_abiflags->flags2 != 0))
+	REJECT ("   unknown MIPS.abiflags flags2: %u\n", mips_abiflags->flags2);
+
+      in_abi = mips_abiflags->fp_abi;
+    }
+
+  /* ANY is compatible with anything.  */
+  perfect_match |= (in_abi == Val_GNU_MIPS_ABI_FP_ANY);
+
+  /* Unknown ABIs are rejected.  */
+  if (in_abi != -1 && in_abi > Val_GNU_MIPS_ABI_FP_MAX)
+    REJECT ("   uses unknown FP ABI: %u\n", in_abi);
+
+  /* Obtain the initial requirements.  */
+  in_req = (in_abi == -1) ? none_req : reqs[in_abi];
+
+  /* Check that the new requirement does not conflict with any currently
+     loaded object.  */
+  for (nsid = 0; nsid < DL_NNS; ++nsid)
+    for (l = GL(dl_ns)[nsid]._ns_loaded; l != NULL; l = l->l_next)
+      {
+	struct abi_req existing_req;
+
+	if (cached_fpabi_reject_phdr_p (l))
+	  return true;
+
+#if _MIPS_SIM == _ABIO32
+	/* A special case arises for O32 FP64 and FP64A where the kernel
+	   pre-dates PT_MIPS_ABIFLAGS.  These ABIs will be blindly loaded even
+	   if the hardware mode is unavailable or disabled.  In this
+	   circumstance the prctl call to obtain the current mode will fail.
+	   Detect this situation here and reject everything.  This will
+	   effectively prevent dynamically linked applications from failing in
+	   unusual ways but there is nothing we can do to help static
+	   applications.  */
+	if ((l->l_mach.fpabi == Val_GNU_MIPS_ABI_FP_64A
+	     || l->l_mach.fpabi == Val_GNU_MIPS_ABI_FP_64)
+	    && cur_mode == -1)
+	  REJECT ("   found %s running in the wrong mode\n",
+		  fpabi_string (l->l_mach.fpabi));
+#endif
+
+	/* Found a perfect match, success.  */
+	perfect_match |= (in_abi == l->l_mach.fpabi);
+
+	/* Unknown ABIs are rejected.  */
+	if (l->l_mach.fpabi != -1 && l->l_mach.fpabi > Val_GNU_MIPS_ABI_FP_MAX)
+	  REJECT ("   found unknown FP ABI: %u\n", l->l_mach.fpabi);
+
+	existing_req = (l->l_mach.fpabi == -1 ? none_req
+			: reqs[l->l_mach.fpabi]);
+
+	/* Merge requirements.  */
+	in_req.soft &= existing_req.soft;
+	in_req.single &= existing_req.single;
+	in_req.fr0 &= existing_req.fr0;
+	in_req.fr1 &= existing_req.fr1;
+	in_req.fre &= existing_req.fre;
+
+	/* If there is at least one mode which is still usable then the new
+	   object can be loaded.  */
+	if (in_req.single || in_req.soft || in_req.fr1 || in_req.fr0
+	    || in_req.fre)
+	  {
+#if _MIPS_SIM == _ABIO32 && HAVE_PRCTL_FP_MODE
+	    /* Account for loaded ABIs which prohibit mode switching.  */
+	    if (l->l_mach.fpabi == Val_GNU_MIPS_ABI_FP_XX)
+	      cannot_mode_switch |= l->l_mach.odd_spreg;
+#endif
+	  }
+	else
+	  REJECT ("   uses %s, already loaded %s\n",
+		  fpabi_string (in_abi),
+		  fpabi_string (l->l_mach.fpabi));
+      }
+
+#if _MIPS_SIM == _ABIO32
+  /* At this point we know that the newly loaded object is compatible with all
+     existing objects but the hardware mode may not be correct.  */
+  if ((in_req.fr1 || in_req.fre || in_req.fr0)
+      && !perfect_match)
+    {
+      if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
+	_dl_debug_printf ("   needs %s%s mode\n", in_req.fr0 ? "FR0 or " : "",
+			  (in_req.fre && !in_req.fr1) ? "FRE" : "FR1");
+
+      /* If the PR_GET_FP_MODE is not supported then only FR0 is available.
+	 If the overall requirements cannot be met by FR0 then reject the
+	 object.  */
+      if (cur_mode == -1)
+	return !in_req.fr0;
+
+# if HAVE_PRCTL_FP_MODE
+      {
+	unsigned int fr1_mode = PR_FP_MODE_FR;
+
+	/* It is not possible to change the mode of a thread which may be
+	   executing FPXX code with odd-singles.  If an FPXX object with
+	   odd-singles is loaded then just check the current mode is OK. This
+	   can be either the FR1 mode or FR0 if the requirements are met by
+	   FR0.  */
+	if (cannot_mode_switch)
+	  return (!(in_req.fre && cur_mode == (PR_FP_MODE_FR | PR_FP_MODE_FRE))
+		  && !(in_req.fr1 && cur_mode == PR_FP_MODE_FR)
+		  && !(in_req.fr0 && cur_mode == 0));
+
+	/* If the overall requirements can be satisfied by FRE but not FR1 then
+	   fr1_mode must become FRE.  */
+	if (in_req.fre && !in_req.fr1)
+	  fr1_mode |= PR_FP_MODE_FRE;
+
+	/* Set the new mode.  Use fr1_mode if the requirements cannot be met by
+	   FR0.  */
+	if (!in_req.fr0)
+	  return __prctl (PR_SET_FP_MODE, fr1_mode) != 0;
+	else if (__prctl (PR_SET_FP_MODE, /* fr0_mode */ 0) != 0)
+	  {
+	    /* Setting FR0 can validly fail on an R6 core so retry with the FR1
+	       mode as a fall back.  */
+	    if (errno != ENOTSUP)
+	      return true;
+
+	    return __prctl (PR_SET_FP_MODE, fr1_mode) != 0;
+	  }
+      }
+# endif /* HAVE_PRCTL_FP_MODE */
+    }
+#endif /* _MIPS_SIM == _ABIO32 */
+
+  return false;
+}
+
+#endif /* dl-machine-reject-phdr.h */