ff08fc59e3
Drop _dl_hwcap_mask when building with tunables. This completes the transition of hwcap_mask reading from _dl_hwcap_mask to tunables. * elf/dl-hwcaps.h: New file. * elf/dl-hwcaps.c: Include it. (_dl_important_hwcaps)[HAVE_TUNABLES]: Read and update glibc.tune.hwcap_mask. * elf/dl-cache.c: Include dl-hwcaps.h. (_dl_load_cache_lookup)[HAVE_TUNABLES]: Read glibc.tune.hwcap_mask. * sysdeps/sparc/sparc32/dl-machine.h: Likewise. * elf/dl-support.c (_dl_hwcap2)[HAVE_TUNABLES]: Drop _dl_hwcap_mask. * elf/rtld.c (rtld_global_ro)[HAVE_TUNABLES]: Drop _dl_hwcap_mask. (process_envvars)[HAVE_TUNABLES]: Likewise. * sysdeps/generic/ldsodefs.h (rtld_global_ro)[HAVE_TUNABLES]: Likewise. * sysdeps/x86/cpu-features.c (init_cpu_features): Don't initialize dl_hwcap_mask when tunables are enabled.
298 lines
8.5 KiB
C
298 lines
8.5 KiB
C
/* Hardware capability support for run-time dynamic loader.
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Copyright (C) 2012-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <elf.h>
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#include <errno.h>
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#include <libintl.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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#include <dl-procinfo.h>
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#include <dl-hwcaps.h>
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#ifdef _DL_FIRST_PLATFORM
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# define _DL_FIRST_EXTRA (_DL_FIRST_PLATFORM + _DL_PLATFORMS_COUNT)
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#else
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# define _DL_FIRST_EXTRA _DL_HWCAP_COUNT
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#endif
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/* Return an array of useful/necessary hardware capability names. */
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const struct r_strlenpair *
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internal_function
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_dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
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size_t *max_capstrlen)
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{
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uint64_t hwcap_mask = GET_HWCAP_MASK();
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/* Determine how many important bits are set. */
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uint64_t masked = GLRO(dl_hwcap) & hwcap_mask;
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size_t cnt = platform != NULL;
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size_t n, m;
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size_t total;
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struct r_strlenpair *result;
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struct r_strlenpair *rp;
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char *cp;
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/* Count the number of bits set in the masked value. */
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for (n = 0; (~((1ULL << n) - 1) & masked) != 0; ++n)
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if ((masked & (1ULL << n)) != 0)
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++cnt;
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#ifdef NEED_DL_SYSINFO_DSO
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/* The system-supplied DSO can contain a note of type 2, vendor "GNU".
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This gives us a list of names to treat as fake hwcap bits. */
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const char *dsocaps = NULL;
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size_t dsocapslen = 0;
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if (GLRO(dl_sysinfo_map) != NULL)
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{
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const ElfW(Phdr) *const phdr = GLRO(dl_sysinfo_map)->l_phdr;
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const ElfW(Word) phnum = GLRO(dl_sysinfo_map)->l_phnum;
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for (uint_fast16_t i = 0; i < phnum; ++i)
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if (phdr[i].p_type == PT_NOTE)
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{
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const ElfW(Addr) start = (phdr[i].p_vaddr
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+ GLRO(dl_sysinfo_map)->l_addr);
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/* The standard ELF note layout is exactly as the anonymous struct.
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The next element is a variable length vendor name of length
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VENDORLEN (with a real length rounded to ElfW(Word)), followed
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by the data of length DATALEN (with a real length rounded to
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ElfW(Word)). */
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const struct
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{
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ElfW(Word) vendorlen;
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ElfW(Word) datalen;
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ElfW(Word) type;
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} *note = (const void *) start;
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while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
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{
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#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
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/* The layout of the type 2, vendor "GNU" note is as follows:
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.long <Number of capabilities enabled by this note>
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.long <Capabilities mask> (as mask >> _DL_FIRST_EXTRA).
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.byte <The bit number for the next capability>
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.asciz <The name of the capability>. */
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if (note->type == NT_GNU_HWCAP
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&& note->vendorlen == sizeof "GNU"
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&& !memcmp ((note + 1), "GNU", sizeof "GNU")
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&& note->datalen > 2 * sizeof (ElfW(Word)) + 2)
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{
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const ElfW(Word) *p = ((const void *) (note + 1)
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+ ROUND (sizeof "GNU"));
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cnt += *p++;
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++p; /* Skip mask word. */
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dsocaps = (const char *) p; /* Pseudo-string "<b>name" */
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dsocapslen = note->datalen - sizeof *p * 2;
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break;
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}
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note = ((const void *) (note + 1)
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+ ROUND (note->vendorlen) + ROUND (note->datalen));
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#undef ROUND
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}
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if (dsocaps != NULL)
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break;
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}
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}
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#endif
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/* For TLS enabled builds always add 'tls'. */
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++cnt;
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/* Create temporary data structure to generate result table. */
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struct r_strlenpair temp[cnt];
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m = 0;
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#ifdef NEED_DL_SYSINFO_DSO
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if (dsocaps != NULL)
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{
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/* dsocaps points to the .asciz string, and -1 points to the mask
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.long just before the string. */
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const ElfW(Word) mask = ((const ElfW(Word) *) dsocaps)[-1];
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GLRO(dl_hwcap) |= (uint64_t) mask << _DL_FIRST_EXTRA;
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/* Note that we add the dsocaps to the set already chosen by the
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LD_HWCAP_MASK environment variable (or default HWCAP_IMPORTANT).
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So there is no way to request ignoring an OS-supplied dsocap
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string and bit like you can ignore an OS-supplied HWCAP bit. */
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hwcap_mask |= (uint64_t) mask << _DL_FIRST_EXTRA;
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#if HAVE_TUNABLES
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TUNABLE_SET (glibc, tune, hwcap_mask, uint64_t, hwcap_mask);
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#else
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GLRO(dl_hwcap_mask) = hwcap_mask;
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#endif
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size_t len;
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for (const char *p = dsocaps; p < dsocaps + dsocapslen; p += len + 1)
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{
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uint_fast8_t bit = *p++;
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len = strlen (p);
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/* Skip entries that are not enabled in the mask word. */
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if (__glibc_likely (mask & ((ElfW(Word)) 1 << bit)))
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{
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temp[m].str = p;
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temp[m].len = len;
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++m;
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}
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else
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--cnt;
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}
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}
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#endif
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for (n = 0; masked != 0; ++n)
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if ((masked & (1ULL << n)) != 0)
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{
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temp[m].str = _dl_hwcap_string (n);
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temp[m].len = strlen (temp[m].str);
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masked ^= 1ULL << n;
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++m;
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}
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if (platform != NULL)
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{
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temp[m].str = platform;
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temp[m].len = platform_len;
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++m;
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}
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temp[m].str = "tls";
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temp[m].len = 3;
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++m;
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assert (m == cnt);
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/* Determine the total size of all strings together. */
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if (cnt == 1)
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total = temp[0].len + 1;
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else
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{
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total = temp[0].len + temp[cnt - 1].len + 2;
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if (cnt > 2)
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{
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total <<= 1;
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for (n = 1; n + 1 < cnt; ++n)
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total += temp[n].len + 1;
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if (cnt > 3
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&& (cnt >= sizeof (size_t) * 8
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|| total + (sizeof (*result) << 3)
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>= (1UL << (sizeof (size_t) * 8 - cnt + 3))))
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_dl_signal_error (ENOMEM, NULL, NULL,
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N_("cannot create capability list"));
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total <<= cnt - 3;
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}
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}
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/* The result structure: we use a very compressed way to store the
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various combinations of capability names. */
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*sz = 1 << cnt;
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result = (struct r_strlenpair *) malloc (*sz * sizeof (*result) + total);
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if (result == NULL)
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_dl_signal_error (ENOMEM, NULL, NULL,
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N_("cannot create capability list"));
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if (cnt == 1)
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{
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result[0].str = (char *) (result + *sz);
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result[0].len = temp[0].len + 1;
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result[1].str = (char *) (result + *sz);
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result[1].len = 0;
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cp = __mempcpy ((char *) (result + *sz), temp[0].str, temp[0].len);
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*cp = '/';
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*sz = 2;
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*max_capstrlen = result[0].len;
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return result;
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}
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/* Fill in the information. This follows the following scheme
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(indices from TEMP for four strings):
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entry #0: 0, 1, 2, 3 binary: 1111
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#1: 0, 1, 3 1101
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#2: 0, 2, 3 1011
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#3: 0, 3 1001
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This allows the representation of all possible combinations of
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capability names in the string. First generate the strings. */
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result[1].str = result[0].str = cp = (char *) (result + *sz);
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#define add(idx) \
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cp = __mempcpy (__mempcpy (cp, temp[idx].str, temp[idx].len), "/", 1);
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if (cnt == 2)
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{
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add (1);
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add (0);
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}
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else
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{
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n = 1 << (cnt - 1);
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do
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{
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n -= 2;
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/* We always add the last string. */
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add (cnt - 1);
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/* Add the strings which have the bit set in N. */
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for (m = cnt - 2; m > 0; --m)
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if ((n & (1 << m)) != 0)
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add (m);
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/* Always add the first string. */
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add (0);
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}
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while (n != 0);
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}
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#undef add
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/* Now we are ready to install the string pointers and length. */
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for (n = 0; n < (1UL << cnt); ++n)
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result[n].len = 0;
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n = cnt;
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do
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{
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size_t mask = 1 << --n;
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rp = result;
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for (m = 1 << cnt; m > 0; ++rp)
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if ((--m & mask) != 0)
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rp->len += temp[n].len + 1;
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}
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while (n != 0);
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/* The first half of the strings all include the first string. */
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n = (1 << cnt) - 2;
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rp = &result[2];
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while (n != (1UL << (cnt - 1)))
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{
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if ((--n & 1) != 0)
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rp[0].str = rp[-2].str + rp[-2].len;
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else
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rp[0].str = rp[-1].str;
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++rp;
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}
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/* The second half starts right after the first part of the string of
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the corresponding entry in the first half. */
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do
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{
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rp[0].str = rp[-(1 << (cnt - 1))].str + temp[cnt - 1].len + 1;
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++rp;
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}
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while (--n != 0);
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/* The maximum string length. */
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*max_capstrlen = result[0].len;
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return result;
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}
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