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-rw-r--r--elf/dl-hwcaps.c279
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;
+}
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