Move _dl_important_hwcaps to dl-hwcaps.c

1 files changed, 279 insertions, 0 deletions

diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c
new file mode 100644
index 0000000000..d911548f2a
--- /dev/null
+++ b/elf/dl-hwcaps.c
@@ -0,0 +1,279 @@
+/* Hardware capability support for run-time dynamic loader.
+   Copyright (C) 2012 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 <assert.h>
+#include <elf.h>
+#include <errno.h>
+#include <libintl.h>
+#include <unistd.h>
+#include <ldsodefs.h>
+
+#include <dl-procinfo.h>
+
+#ifdef _DL_FIRST_PLATFORM
+# define _DL_FIRST_EXTRA (_DL_FIRST_PLATFORM + _DL_PLATFORMS_COUNT)
+#else
+# define _DL_FIRST_EXTRA _DL_HWCAP_COUNT
+#endif
+
+/* Return an array of useful/necessary hardware capability names.  */
+const struct r_strlenpair *
+internal_function
+_dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
+		      size_t *max_capstrlen)
+{
+  /* Determine how many important bits are set.  */
+  uint64_t masked = GLRO(dl_hwcap) & GLRO(dl_hwcap_mask);
+  size_t cnt = platform != NULL;
+  size_t n, m;
+  size_t total;
+  struct r_strlenpair *temp;
+  struct r_strlenpair *result;
+  struct r_strlenpair *rp;
+  char *cp;
+
+  /* Count the number of bits set in the masked value.  */
+  for (n = 0; (~((1ULL << n) - 1) & masked) != 0; ++n)
+    if ((masked & (1ULL << n)) != 0)
+      ++cnt;
+
+#if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
+  /* The system-supplied DSO can contain a note of type 2, vendor "GNU".
+     This gives us a list of names to treat as fake hwcap bits.  */
+
+  const char *dsocaps = NULL;
+  size_t dsocapslen = 0;
+  if (GLRO(dl_sysinfo_map) != NULL)
+    {
+      const ElfW(Phdr) *const phdr = GLRO(dl_sysinfo_map)->l_phdr;
+      const ElfW(Word) phnum = GLRO(dl_sysinfo_map)->l_phnum;
+      for (uint_fast16_t i = 0; i < phnum; ++i)
+	if (phdr[i].p_type == PT_NOTE)
+	  {
+	    const ElfW(Addr) start = (phdr[i].p_vaddr
+				      + GLRO(dl_sysinfo_map)->l_addr);
+	    const struct
+	    {
+	      ElfW(Word) vendorlen;
+	      ElfW(Word) datalen;
+	      ElfW(Word) type;
+	    } *note = (const void *) start;
+	    while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
+	      {
+#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
+		if (note->type == NT_GNU_HWCAP
+		    && note->vendorlen == sizeof "GNU"
+		    && !memcmp ((note + 1), "GNU", sizeof "GNU")
+		    && note->datalen > 2 * sizeof (ElfW(Word)) + 2)
+		  {
+		    const ElfW(Word) *p = ((const void *) (note + 1)
+					   + ROUND (sizeof "GNU"));
+		    cnt += *p++;
+		    ++p;	/* Skip mask word.  */
+		    dsocaps = (const char *) p;
+		    dsocapslen = note->datalen - sizeof *p * 2;
+		    break;
+		  }
+		note = ((const void *) (note + 1)
+			+ ROUND (note->vendorlen) + ROUND (note->datalen));
+#undef ROUND
+	      }
+	    if (dsocaps != NULL)
+	      break;
+	  }
+    }
+#endif
+
+  /* For TLS enabled builds always add 'tls'.  */
+  ++cnt;
+
+  /* Create temporary data structure to generate result table.  */
+  temp = (struct r_strlenpair *) alloca (cnt * sizeof (*temp));
+  m = 0;
+#if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
+  if (dsocaps != NULL)
+    {
+      const ElfW(Word) mask = ((const ElfW(Word) *) dsocaps)[-1];
+      GLRO(dl_hwcap) |= (uint64_t) mask << _DL_FIRST_EXTRA;
+      /* Note that we add the dsocaps to the set already chosen by the
+	 LD_HWCAP_MASK environment variable (or default HWCAP_IMPORTANT).
+	 So there is no way to request ignoring an OS-supplied dsocap
+	 string and bit like you can ignore an OS-supplied HWCAP bit.  */
+      GLRO(dl_hwcap_mask) |= (uint64_t) mask << _DL_FIRST_EXTRA;
+      size_t len;
+      for (const char *p = dsocaps; p < dsocaps + dsocapslen; p += len + 1)
+	{
+	  uint_fast8_t bit = *p++;
+	  len = strlen (p);
+
+	  /* Skip entries that are not enabled in the mask word.  */
+	  if (__builtin_expect (mask & ((ElfW(Word)) 1 << bit), 1))
+	    {
+	      temp[m].str = p;
+	      temp[m].len = len;
+	      ++m;
+	    }
+	  else
+	    --cnt;
+	}
+    }
+#endif
+  for (n = 0; masked != 0; ++n)
+    if ((masked & (1ULL << n)) != 0)
+      {
+	temp[m].str = _dl_hwcap_string (n);
+	temp[m].len = strlen (temp[m].str);
+	masked ^= 1ULL << n;
+	++m;
+      }
+  if (platform != NULL)
+    {
+      temp[m].str = platform;
+      temp[m].len = platform_len;
+      ++m;
+    }
+
+  temp[m].str = "tls";
+  temp[m].len = 3;
+  ++m;
+
+  assert (m == cnt);
+
+  /* Determine the total size of all strings together.  */
+  if (cnt == 1)
+    total = temp[0].len + 1;
+  else
+    {
+      total = temp[0].len + temp[cnt - 1].len + 2;
+      if (cnt > 2)
+	{
+	  total <<= 1;
+	  for (n = 1; n + 1 < cnt; ++n)
+	    total += temp[n].len + 1;
+	  if (cnt > 3
+	      && (cnt >= sizeof (size_t) * 8
+		  || total + (sizeof (*result) << 3)
+		     >= (1UL << (sizeof (size_t) * 8 - cnt + 3))))
+	    _dl_signal_error (ENOMEM, NULL, NULL,
+			      N_("cannot create capability list"));
+
+	  total <<= cnt - 3;
+	}
+    }
+
+  /* The result structure: we use a very compressed way to store the
+     various combinations of capability names.  */
+  *sz = 1 << cnt;
+  result = (struct r_strlenpair *) malloc (*sz * sizeof (*result) + total);
+  if (result == NULL)
+    _dl_signal_error (ENOMEM, NULL, NULL,
+		      N_("cannot create capability list"));
+
+  if (cnt == 1)
+    {
+      result[0].str = (char *) (result + *sz);
+      result[0].len = temp[0].len + 1;
+      result[1].str = (char *) (result + *sz);
+      result[1].len = 0;
+      cp = __mempcpy ((char *) (result + *sz), temp[0].str, temp[0].len);
+      *cp = '/';
+      *sz = 2;
+      *max_capstrlen = result[0].len;
+
+      return result;
+    }
+
+  /* Fill in the information.  This follows the following scheme
+     (indeces from TEMP for four strings):
+	entry #0: 0, 1, 2, 3	binary: 1111
+	      #1: 0, 1, 3		1101
+	      #2: 0, 2, 3		1011
+	      #3: 0, 3			1001
+     This allows the representation of all possible combinations of
+     capability names in the string.  First generate the strings.  */
+  result[1].str = result[0].str = cp = (char *) (result + *sz);
+#define add(idx) \
+      cp = __mempcpy (__mempcpy (cp, temp[idx].str, temp[idx].len), "/", 1);
+  if (cnt == 2)
+    {
+      add (1);
+      add (0);
+    }
+  else
+    {
+      n = 1 << (cnt - 1);
+      do
+	{
+	  n -= 2;
+
+	  /* We always add the last string.  */
+	  add (cnt - 1);
+
+	  /* Add the strings which have the bit set in N.  */
+	  for (m = cnt - 2; m > 0; --m)
+	    if ((n & (1 << m)) != 0)
+	      add (m);
+
+	  /* Always add the first string.  */
+	  add (0);
+	}
+      while (n != 0);
+    }
+#undef add
+
+  /* Now we are ready to install the string pointers and length.  */
+  for (n = 0; n < (1UL << cnt); ++n)
+    result[n].len = 0;
+  n = cnt;
+  do
+    {
+      size_t mask = 1 << --n;
+
+      rp = result;
+      for (m = 1 << cnt; m > 0; ++rp)
+	if ((--m & mask) != 0)
+	  rp->len += temp[n].len + 1;
+    }
+  while (n != 0);
+
+  /* The first half of the strings all include the first string.  */
+  n = (1 << cnt) - 2;
+  rp = &result[2];
+  while (n != (1UL << (cnt - 1)))
+    {
+      if ((--n & 1) != 0)
+	rp[0].str = rp[-2].str + rp[-2].len;
+      else
+	rp[0].str = rp[-1].str;
+      ++rp;
+    }
+
+  /* The second half starts right after the first part of the string of
+     the corresponding entry in the first half.  */
+  do
+    {
+      rp[0].str = rp[-(1 << (cnt - 1))].str + temp[cnt - 1].len + 1;
+      ++rp;
+    }
+  while (--n != 0);
+
+  /* The maximum string length.  */
+  *max_capstrlen = result[0].len;
+
+  return result;
+}