[PATCH 18/30] elf: Add glibc-hwcaps support for LD_LIBRARY_PATH
Florian Weimer
fweimer@redhat.com
Mon Jun 22 15:14:32 GMT 2020
This hacks non-power-set processing into _dl_important_hwcaps.
Once the legacy hwcaps handling goes away, the subdirectory
handling needs to be reworked, but it is premature to do this
while both approaches are still supported.
---
elf/Makefile | 5 +-
elf/dl-hwcaps-subdirs.c | 29 ++++++++
elf/dl-hwcaps.c | 138 +++++++++++++++++++++++++++++++-----
elf/dl-hwcaps.h | 83 ++++++++++++++++++++++
elf/dl-hwcaps_split.c | 77 ++++++++++++++++++++
elf/dl-load.c | 7 +-
elf/dl-main.h | 11 ++-
elf/dl-support.c | 5 +-
elf/dl-usage.c | 68 +++++++++++++++++-
elf/rtld.c | 18 +++++
elf/tst-dl-hwcaps_split.c | 139 +++++++++++++++++++++++++++++++++++++
sysdeps/generic/ldsodefs.h | 20 ++++--
12 files changed, 570 insertions(+), 30 deletions(-)
create mode 100644 elf/dl-hwcaps-subdirs.c
create mode 100644 elf/dl-hwcaps_split.c
create mode 100644 elf/tst-dl-hwcaps_split.c
diff --git a/elf/Makefile b/elf/Makefile
index d2f58c8ce6..728cb3b734 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -59,7 +59,8 @@ elide-routines.os = $(all-dl-routines) dl-support enbl-secure dl-origin \
# ld.so uses those routines, plus some special stuff for being the program
# interpreter and operating independent of libc.
rtld-routines = rtld $(all-dl-routines) dl-sysdep dl-environ dl-minimal \
- dl-error-minimal dl-conflict dl-hwcaps dl-usage
+ dl-error-minimal dl-conflict dl-hwcaps dl-hwcaps_split dl-hwcaps-subdirs \
+ dl-usage
all-rtld-routines = $(rtld-routines) $(sysdep-rtld-routines)
CFLAGS-dl-runtime.c += -fexceptions -fasynchronous-unwind-tables
@@ -210,7 +211,7 @@ tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
tst-tls3 tst-tls6 tst-tls7 tst-tls8 tst-dlmopen2 \
tst-ptrguard1 tst-stackguard1 tst-libc_dlvsym \
- tst-create_format1
+ tst-create_format1 tst-dl-hwcaps_split
tests-container += tst-pldd tst-dlopen-tlsmodid-container \
tst-dlopen-self-container
test-srcs = tst-pathopt
diff --git a/elf/dl-hwcaps-subdirs.c b/elf/dl-hwcaps-subdirs.c
new file mode 100644
index 0000000000..b142a3b826
--- /dev/null
+++ b/elf/dl-hwcaps-subdirs.c
@@ -0,0 +1,29 @@
+/* Architecture-specific glibc-hwcaps subdirectories. Generic version.
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <dl-hwcaps.h>
+
+/* In the generic version, there are no subdirectories defined. */
+
+const char _dl_hwcaps_subdirs[] = "";
+
+int32_t
+_dl_hwcaps_subdirs_active (void)
+{
+ return 0;
+}
diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c
index 44dbac099f..4de94759a2 100644
--- a/elf/dl-hwcaps.c
+++ b/elf/dl-hwcaps.c
@@ -26,20 +26,97 @@
#include <dl-procinfo.h>
#include <dl-hwcaps.h>
+/* This is the result of counting the substrings in a colon-separated
+ hwcaps string. */
+struct count_hwcaps
+{
+ /* Number of substrings. */
+ size_t count;
+
+ /* Sum of the individual substring lengths (without separates or
+ null terminators). */
+ size_t total_length;
+
+ /* Maximum length of an individual substring. */
+ size_t maximum_length;
+};
+
+/* Update *COUNTS according to the contents of HWCAPS. Skip over
+ entries whose bit is not set in MASK. */
+static void
+count_hwcaps (struct count_hwcaps *counts, const char *hwcaps,
+ int32_t bitmask, const char *mask)
+{
+ struct dl_hwcaps_split_masked sp;
+ _dl_hwcaps_split_masked_init (&sp, hwcaps, bitmask, mask);
+ while (_dl_hwcaps_split_masked (&sp))
+ {
+ ++counts->count;
+ counts->total_length += sp.split.length;
+ if (sp.split.length > counts->maximum_length)
+ counts->maximum_length = sp.split.length;
+ }
+}
+
+/* State for copy_hwcaps. Must be initialized to point to
+ the storage areas for the array and the strings themselves. */
+struct copy_hwcaps
+{
+ struct r_strlenpair *next_pair;
+ char *next_string;
+};
+
+/* Copy HWCAPS into the string pairs and strings, advancing *TARGET.
+ Skip over entries whose bit is not set in MASK. */
+static void
+copy_hwcaps (struct copy_hwcaps *target, const char *hwcaps,
+ int32_t bitmask, const char *mask)
+{
+ struct dl_hwcaps_split_masked sp;
+ _dl_hwcaps_split_masked_init (&sp, hwcaps, bitmask, mask);
+ while (_dl_hwcaps_split_masked (&sp))
+ {
+ target->next_pair->str = target->next_string;
+ char *slash = __mempcpy (__mempcpy (target->next_string,
+ GLIBC_HWCAPS_PREFIX,
+ strlen (GLIBC_HWCAPS_PREFIX)),
+ sp.split.segment, sp.split.length);
+ *slash = '/';
+ target->next_pair->len
+ = strlen (GLIBC_HWCAPS_PREFIX) + sp.split.length + 1;
+ ++target->next_pair;
+ target->next_string = slash + 1;
+ }
+}
+
/* Return an array of useful/necessary hardware capability names. */
const struct r_strlenpair *
-_dl_important_hwcaps (size_t *sz, size_t *max_capstrlen)
+_dl_important_hwcaps (const char *glibc_hwcaps_prepend,
+ const char *glibc_hwcaps_mask,
+ size_t *sz, size_t *max_capstrlen)
{
uint64_t hwcap_mask = GET_HWCAP_MASK();
/* Determine how many important bits are set. */
uint64_t masked = GLRO(dl_hwcap) & hwcap_mask;
size_t cnt = GLRO (dl_platform) != NULL;
size_t n, m;
- size_t total;
struct r_strlenpair *result;
struct r_strlenpair *rp;
char *cp;
+ /* glibc-hwcaps subdirectories. These are exempted from the power
+ set construction below below. */
+ int32_t hwcaps_subdirs_active = _dl_hwcaps_subdirs_active ();
+ struct count_hwcaps hwcaps_counts = { 0, };
+ count_hwcaps (&hwcaps_counts, glibc_hwcaps_prepend, -1, NULL);
+ count_hwcaps (&hwcaps_counts, _dl_hwcaps_subdirs, hwcaps_subdirs_active,
+ glibc_hwcaps_mask);
+
+ /* Each hwcaps subdirectory has a GLIBC_HWCAPS_PREFIX string prefix
+ and a "/" suffix once stored in the result. */
+ size_t total = (hwcaps_counts.count * (strlen (GLIBC_HWCAPS_PREFIX) + 1)
+ + hwcaps_counts.total_length);
+
/* Count the number of bits set in the masked value. */
for (n = 0; (~((1ULL << n) - 1) & masked) != 0; ++n)
if ((masked & (1ULL << n)) != 0)
@@ -74,10 +151,10 @@ _dl_important_hwcaps (size_t *sz, size_t *max_capstrlen)
/* Determine the total size of all strings together. */
if (cnt == 1)
- total = temp[0].len + 1;
+ total += temp[0].len + 1;
else
{
- total = temp[0].len + temp[cnt - 1].len + 2;
+ total += temp[0].len + temp[cnt - 1].len + 2;
if (cnt > 2)
{
total <<= 1;
@@ -94,26 +171,48 @@ _dl_important_hwcaps (size_t *sz, size_t *max_capstrlen)
}
}
- /* 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)
+ *sz = hwcaps_counts.count + (1 << cnt);
+
+ /* This is the overall result, including both glibc-hwcaps
+ subdirectories and the legacy hwcaps subdirectories using the
+ power set construction. */
+ struct r_strlenpair *overall_result
+ = malloc (*sz * sizeof (*result) + total);
+ if (overall_result == NULL)
_dl_signal_error (ENOMEM, NULL, NULL,
N_("cannot create capability list"));
+ /* Fill in the glibc-hwcaps subdirectories. */
+ {
+ struct copy_hwcaps target;
+ target.next_pair = overall_result;
+ target.next_string = (char *) (overall_result + *sz);
+ copy_hwcaps (&target, glibc_hwcaps_prepend, -1, NULL);
+ copy_hwcaps (&target, _dl_hwcaps_subdirs,
+ hwcaps_subdirs_active, glibc_hwcaps_mask);
+ /* Set up the write target for the power set construction. */
+ result = target.next_pair;
+ cp = target.next_string;
+ }
+
+
+ /* Power set construction begins here. We use a very compressed way
+ to store the various combinations of capability names. */
+
if (cnt == 1)
{
- result[0].str = (char *) (result + *sz);
+ result[0].str = cp;
result[0].len = temp[0].len + 1;
- result[1].str = (char *) (result + *sz);
+ result[1].str = cp;
result[1].len = 0;
- cp = __mempcpy ((char *) (result + *sz), temp[0].str, temp[0].len);
+ cp = __mempcpy (cp, temp[0].str, temp[0].len);
*cp = '/';
- *sz = 2;
- *max_capstrlen = result[0].len;
+ if (result[0].len > hwcaps_counts.maximum_length)
+ *max_capstrlen = result[0].len;
+ else
+ *max_capstrlen = hwcaps_counts.maximum_length;
- return result;
+ return overall_result;
}
/* Fill in the information. This follows the following scheme
@@ -124,7 +223,7 @@ _dl_important_hwcaps (size_t *sz, size_t *max_capstrlen)
#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);
+ result[1].str = result[0].str = cp;
#define add(idx) \
cp = __mempcpy (__mempcpy (cp, temp[idx].str, temp[idx].len), "/", 1);
if (cnt == 2)
@@ -191,7 +290,10 @@ _dl_important_hwcaps (size_t *sz, size_t *max_capstrlen)
while (--n != 0);
/* The maximum string length. */
- *max_capstrlen = result[0].len;
+ if (result[0].len > hwcaps_counts.maximum_length)
+ *max_capstrlen = result[0].len;
+ else
+ *max_capstrlen = hwcaps_counts.maximum_length;
- return result;
+ return overall_result;
}
diff --git a/elf/dl-hwcaps.h b/elf/dl-hwcaps.h
index b66da59b89..a6453f15f3 100644
--- a/elf/dl-hwcaps.h
+++ b/elf/dl-hwcaps.h
@@ -16,6 +16,11 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
+#ifndef _DL_HWCAPS_H
+#define _DL_HWCAPS_H
+
+#include <stdint.h>
+
#include <elf/dl-tunables.h>
#if HAVE_TUNABLES
@@ -28,3 +33,81 @@
# define GET_HWCAP_MASK() (0)
# endif
#endif
+
+#define GLIBC_HWCAPS_SUBDIRECTORY "glibc-hwcaps"
+#define GLIBC_HWCAPS_PREFIX GLIBC_HWCAPS_SUBDIRECTORY "/"
+
+/* Used by _dl_hwcaps_split below, to split strings at ':'
+ separators. */
+struct dl_hwcaps_split
+{
+ const char *segment; /* Start of the current segment. */
+ size_t length; /* Number of bytes until ':' or NUL. */
+};
+
+/* Prepare *S to parse SUBJECT, for future _dl_hwcaps_split calls. If
+ SUBJECT is NULL, it is treated as the empty string. */
+static inline void
+_dl_hwcaps_split_init (struct dl_hwcaps_split *s, const char *subject)
+{
+ s->segment = subject;
+ /* The initial call to _dl_hwcaps_split will not skip anything. */
+ s->length = 0;
+}
+
+/* Extract the next non-empty string segment, up to ':' or the null
+ terminator. Return true if one more segment was found, or false if
+ the end of the string was reached. On success, S->segment is the
+ start of the segment found, and S->length is its length.
+ (Typically, S->segment[S->length] is not null.) */
+_Bool _dl_hwcaps_split (struct dl_hwcaps_split *s) attribute_hidden;
+
+/* Similar to dl_hwcaps_split, but with bit-based and name-based
+ masking. */
+struct dl_hwcaps_split_masked
+{
+ struct dl_hwcaps_split split;
+
+ /* For used by the iterator implementation. */
+ const char *mask;
+ int32_t bitmask;
+};
+
+/* Prepare *S for iteration with _dl_hwcaps_split_masked. Only HWCAP
+ names in SUBJECT whose bit is set in BITMASK and whose ane is in
+ MASK will be returned. SUBJECT must not contain empty HWCAP names.
+ If MASK is NULL, no name-based masking is applied. Likewise for
+ BITMASK if BITMASK is -1 (infinite number of bits). */
+static inline void
+_dl_hwcaps_split_masked_init (struct dl_hwcaps_split_masked *s,
+ const char *subject,
+ int32_t bitmask, const char *mask)
+{
+ _dl_hwcaps_split_init (&s->split, subject);
+ s->bitmask = bitmask;
+ s->mask = mask;
+}
+
+/* Like _dl_hwcaps_split, but apply masking. */
+_Bool _dl_hwcaps_split_masked (struct dl_hwcaps_split_masked *s)
+ attribute_hidden;
+
+/* Returns true if the colon-separated HWCAP list HWCAPS contains the
+ capability NAME (with length NAME_LENGTH). If HWCAPS is NULL, the
+ function returns true. */
+_Bool _dl_hwcaps_contains (const char *hwcaps, const char *name,
+ size_t name_length) attribute_hidden;
+
+/* Colon-separated string of glibc-hwcaps subdirectories, without the
+ "glibc-hwcaps/" prefix. The most preferred subdirectory needs to
+ be listed first. */
+extern const char _dl_hwcaps_subdirs[] attribute_hidden;
+
+/* Returns a bitmap of active subdirectories in _dl_hwcaps_subdirs.
+ Bit 0 (the LSB) corresponds to the first substring in
+ _dl_hwcaps_subdirs, bit 1 to the second substring, and so on.
+ There is no direct correspondence between HWCAP bitmasks and this
+ bitmask. */
+int32_t _dl_hwcaps_subdirs_active (void) attribute_hidden;
+
+#endif /* _DL_HWCAPS_H */
diff --git a/elf/dl-hwcaps_split.c b/elf/dl-hwcaps_split.c
new file mode 100644
index 0000000000..95225e9f40
--- /dev/null
+++ b/elf/dl-hwcaps_split.c
@@ -0,0 +1,77 @@
+/* Hardware capability support for run-time dynamic loader. String splitting.
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <dl-hwcaps.h>
+#include <stdbool.h>
+#include <string.h>
+
+_Bool
+_dl_hwcaps_split (struct dl_hwcaps_split *s)
+{
+ if (s->segment == NULL)
+ return false;
+
+ /* Skip over the previous segment. */
+ s->segment += s->length;
+
+ /* Consume delimiters. This also avoids returning an empty
+ segment. */
+ while (*s->segment == ':')
+ ++s->segment;
+ if (*s->segment == '\0')
+ return false;
+
+ /* This could use strchrnul, but we would have to link the function
+ into ld.so for that. */
+ const char *colon = strchr (s->segment, ':');
+ if (colon == NULL)
+ s->length = strlen (s->segment);
+ else
+ s->length = colon - s->segment;
+ return true;
+}
+
+_Bool
+_dl_hwcaps_split_masked (struct dl_hwcaps_split_masked *s)
+{
+ while (true)
+ {
+ if (!_dl_hwcaps_split (&s->split))
+ return false;
+ bool active = s->bitmask & 1;
+ s->bitmask >>= 1;
+ if (active && _dl_hwcaps_contains (s->mask,
+ s->split.segment, s->split.length))
+ return true;
+ }
+}
+
+_Bool
+_dl_hwcaps_contains (const char *hwcaps, const char *name, size_t name_length)
+{
+ if (hwcaps == NULL)
+ return true;
+
+ struct dl_hwcaps_split split;
+ _dl_hwcaps_split_init (&split, hwcaps);
+ while (_dl_hwcaps_split (&split))
+ if (split.length == name_length
+ && memcmp (split.segment, name, name_length) == 0)
+ return true;
+ return false;
+}
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 6e5fa2af13..f99d791edb 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -682,7 +682,9 @@ cache_rpath (struct link_map *l,
void
-_dl_init_paths (const char *llp, const char *source)
+_dl_init_paths (const char *llp, const char *source,
+ const char *glibc_hwcaps_prepend,
+ const char *glibc_hwcaps_mask)
{
size_t idx;
const char *strp;
@@ -697,7 +699,8 @@ _dl_init_paths (const char *llp, const char *source)
#ifdef SHARED
/* Get the capabilities. */
- capstr = _dl_important_hwcaps (&ncapstr, &max_capstrlen);
+ capstr = _dl_important_hwcaps (glibc_hwcaps_prepend, glibc_hwcaps_mask,
+ &ncapstr, &max_capstrlen);
#endif
/* First set up the rest of the default search directory entries. */
diff --git a/elf/dl-main.h b/elf/dl-main.h
index 0df849d3cd..710d29685b 100644
--- a/elf/dl-main.h
+++ b/elf/dl-main.h
@@ -80,6 +80,14 @@ struct dl_main_state
/* The preload list passed as a command argument. */
const char *preloadarg;
+ /* Additional glibc-hwcaps subdirectories to search first.
+ Colon-separated list. */
+ const char *glibc_hwcaps_prepend;
+
+ /* Mask for the internal glibc-hwcaps subdirectories.
+ Colon-separated list. */
+ const char *glibc_hwcaps_mask;
+
enum mode mode;
/* True if any of the debugging options is enabled. */
@@ -94,7 +102,8 @@ struct dl_main_state
static inline void
call_init_paths (const struct dl_main_state *state)
{
- _dl_init_paths (state->library_path, state->library_path_source);
+ _dl_init_paths (state->library_path, state->library_path_source,
+ state->glibc_hwcaps_prepend, state->glibc_hwcaps_mask);
}
/* Print ld.so usage information and exit. */
diff --git a/elf/dl-support.c b/elf/dl-support.c
index afbc94df54..3264262f4e 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -323,7 +323,10 @@ _dl_non_dynamic_init (void)
/* Initialize the data structures for the search paths for shared
objects. */
- _dl_init_paths (getenv ("LD_LIBRARY_PATH"), "LD_LIBRARY_PATH");
+ _dl_init_paths (getenv ("LD_LIBRARY_PATH"), "LD_LIBRARY_PATH",
+ /* No glibc-hwcaps selection support in statically
+ linked binaries. */
+ NULL, NULL);
/* Remember the last search directory added at startup. */
_dl_init_all_dirs = GL(dl_all_dirs);
diff --git a/elf/dl-usage.c b/elf/dl-usage.c
index 7ff642349c..e94334e877 100644
--- a/elf/dl-usage.c
+++ b/elf/dl-usage.c
@@ -82,7 +82,7 @@ print_search_path_for_help (struct dl_main_state *state)
{
if (__rtld_search_dirs.dirs == NULL)
/* The run-time search paths have not yet been initialized. */
- _dl_init_paths (state->library_path, state->library_path_source);
+ call_init_paths (state);
_dl_printf ("\nShared library search path:\n");
@@ -131,6 +131,67 @@ print_hwcap_1_finish (bool *first)
_dl_printf (")\n");
}
+/* Print the header for print_hwcaps_subdirectories. */
+static void
+print_hwcaps_subdirectories_header (bool *nothing_printed)
+{
+ if (*nothing_printed)
+ {
+ _dl_printf ("\n\
+Subdirectories of glibc-hwcaps directories, in priority order:\n");
+ *nothing_printed = false;
+ }
+}
+
+/* Print the HWCAP name itself, indented. */
+static void
+print_hwcaps_subdirectories_name (const struct dl_hwcaps_split *split)
+{
+ _dl_write (STDOUT_FILENO, " ", 2);
+ _dl_write (STDOUT_FILENO, split->segment, split->length);
+}
+
+/* Print the list of recognized glibc-hwcaps subdirectories. */
+static void
+print_hwcaps_subdirectories (const struct dl_main_state *state)
+{
+ bool nothing_printed = true;
+ struct dl_hwcaps_split split;
+
+ /* The prepended glibc-hwcaps subdirectories. */
+ _dl_hwcaps_split_init (&split, state->glibc_hwcaps_prepend);
+ while (_dl_hwcaps_split (&split))
+ {
+ print_hwcaps_subdirectories_header (¬hing_printed);
+ print_hwcaps_subdirectories_name (&split);
+ bool first = true;
+ print_hwcap_1 (&first, true, "searched");
+ print_hwcap_1_finish (&first);
+ }
+
+ /* The built-in glibc-hwcaps subdirectories. Do the filtering
+ manually, so that more precise diagnostics are possible. */
+ int32_t mask = _dl_hwcaps_subdirs_active ();
+ _dl_hwcaps_split_init (&split, _dl_hwcaps_subdirs);
+ while (_dl_hwcaps_split (&split))
+ {
+ print_hwcaps_subdirectories_header (¬hing_printed);
+ print_hwcaps_subdirectories_name (&split);
+ bool first = true;
+ print_hwcap_1 (&first, mask & 1, "supported");
+ bool listed = _dl_hwcaps_contains (state->glibc_hwcaps_mask,
+ split.segment, split.length);
+ print_hwcap_1 (&first, !listed, "masked");
+ print_hwcap_1 (&first, (mask & 1) && listed, "searched");
+ print_hwcap_1_finish (&first);
+ mask >>= 1;
+ }
+
+ if (nothing_printed)
+ _dl_printf ("\n\
+No subdirectories of glibc-hwcaps directories are searched.\n");
+}
+
/* Write a list of hwcap subdirectories to standard output. See
_dl_important_hwcaps in dl-hwcaps.c. */
static void
@@ -185,6 +246,10 @@ setting environment variables (which would be inherted by subprocesses).\n\
--inhibit-cache Do not use " LD_SO_CACHE "\n\
--library-path PATH use given PATH instead of content of the environment\n\
variable LD_LIBRARY_PATH\n\
+ --glibc-hwcaps-prepend LIST\n\
+ search glibc-hwcaps subdirectories in LIST\n\
+ --glibc-hwcaps-mask LIST\n\
+ only search built-in subdirectories if in LIST\n\
--inhibit-rpath LIST ignore RUNPATH and RPATH information in object names\n\
in LIST\n\
--audit LIST use objects named in LIST as auditors\n\
@@ -196,6 +261,7 @@ This program interpreter self-identifies as: " RTLD "\n\
",
argv0);
print_search_path_for_help (state);
+ print_hwcaps_subdirectories (state);
print_legacy_hwcap_directories ();
_exit (0);
}
diff --git a/elf/rtld.c b/elf/rtld.c
index 06bc8eca9a..b31597da3c 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -272,6 +272,8 @@ dl_main_state_init (struct dl_main_state *state)
state->library_path_source = NULL;
state->preloadlist = NULL;
state->preloadarg = NULL;
+ state->glibc_hwcaps_prepend = NULL;
+ state->glibc_hwcaps_mask = NULL;
state->mode = normal;
state->any_debug = false;
state->version_info = false;
@@ -1218,6 +1220,22 @@ dl_main (const ElfW(Phdr) *phdr,
_dl_argc -= 2;
_dl_argv += 2;
}
+ else if (strcmp (_dl_argv[1], "--glibc-hwcaps-prepend") == 0
+ && _dl_argc > 2)
+ {
+ state.glibc_hwcaps_prepend = _dl_argv[2];
+ _dl_skip_args += 2;
+ _dl_argc -= 2;
+ _dl_argv += 2;
+ }
+ else if (strcmp (_dl_argv[1], "--glibc-hwcaps-mask") == 0
+ && _dl_argc > 2)
+ {
+ state.glibc_hwcaps_mask = _dl_argv[2];
+ _dl_skip_args += 2;
+ _dl_argc -= 2;
+ _dl_argv += 2;
+ }
else if (strcmp (_dl_argv[1], "--help") == 0)
{
state.mode = rtld_help;
diff --git a/elf/tst-dl-hwcaps_split.c b/elf/tst-dl-hwcaps_split.c
new file mode 100644
index 0000000000..929c99a23b
--- /dev/null
+++ b/elf/tst-dl-hwcaps_split.c
@@ -0,0 +1,139 @@
+/* Unit tests for dl-hwcaps.c.
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <array_length.h>
+#include <dl-hwcaps.h>
+#include <string.h>
+#include <support/check.h>
+
+static void
+check_split_masked (const char *input, int32_t bitmask, const char *mask,
+ const char *expected[], size_t expected_length)
+{
+ struct dl_hwcaps_split_masked split;
+ _dl_hwcaps_split_masked_init (&split, input, bitmask, mask);
+ size_t index = 0;
+ while (_dl_hwcaps_split_masked (&split))
+ {
+ TEST_VERIFY_EXIT (index < expected_length);
+ TEST_COMPARE_BLOB (expected[index], strlen (expected[index]),
+ split.split.segment, split.split.length);
+ ++index;
+ }
+ TEST_COMPARE (index, expected_length);
+}
+
+static void
+check_split (const char *input,
+ const char *expected[], size_t expected_length)
+{
+ struct dl_hwcaps_split split;
+ _dl_hwcaps_split_init (&split, input);
+ size_t index = 0;
+ while (_dl_hwcaps_split (&split))
+ {
+ TEST_VERIFY_EXIT (index < expected_length);
+ TEST_COMPARE_BLOB (expected[index], strlen (expected[index]),
+ split.segment, split.length);
+ ++index;
+ }
+ TEST_COMPARE (index, expected_length);
+
+ /* Reuse the test cases with masking that does not actually remove
+ anything. */
+ check_split_masked (input, -1, NULL, expected, expected_length);
+ check_split_masked (input, -1, input, expected, expected_length);
+}
+
+static int
+do_test (void)
+{
+ /* Splitting tests, without masking. */
+ check_split (NULL, NULL, 0);
+ check_split ("", NULL, 0);
+ check_split (":", NULL, 0);
+ check_split ("::", NULL, 0);
+
+ {
+ const char *expected[] = { "first" };
+ check_split ("first", expected, array_length (expected));
+ check_split (":first", expected, array_length (expected));
+ check_split ("first:", expected, array_length (expected));
+ check_split (":first:", expected, array_length (expected));
+ }
+
+ {
+ const char *expected[] = { "first", "second" };
+ check_split ("first:second", expected, array_length (expected));
+ check_split ("first::second", expected, array_length (expected));
+ check_split (":first:second", expected, array_length (expected));
+ check_split ("first:second:", expected, array_length (expected));
+ check_split (":first:second:", expected, array_length (expected));
+ }
+
+ /* Splitting tests with masking. */
+ {
+ const char *expected[] = { "first" };
+ check_split_masked ("first", 3, "first:second",
+ expected, array_length (expected));
+ check_split_masked ("first:second", 3, "first:",
+ expected, array_length (expected));
+ check_split_masked ("first:second", 1, NULL,
+ expected, array_length (expected));
+ }
+ {
+ const char *expected[] = { "second" };
+ check_split_masked ("first:second", 3, "second",
+ expected, array_length (expected));
+ check_split_masked ("first:second:third", -1, "second:",
+ expected, array_length (expected));
+ check_split_masked ("first:second", 2, NULL,
+ expected, array_length (expected));
+ check_split_masked ("first:second:third", 2, "first:second",
+ expected, array_length (expected));
+ }
+
+ /* Tests for _dl_hwcaps_contains. */
+ TEST_VERIFY (_dl_hwcaps_contains (NULL, "first", strlen ("first")));
+ TEST_VERIFY (_dl_hwcaps_contains (NULL, "", 0));
+ TEST_VERIFY (! _dl_hwcaps_contains ("", "first", strlen ("first")));
+ TEST_VERIFY (! _dl_hwcaps_contains ("firs", "first", strlen ("first")));
+ TEST_VERIFY (_dl_hwcaps_contains ("firs", "first", strlen ("first") - 1));
+ for (int i = 0; i < strlen ("first"); ++i)
+ TEST_VERIFY (! _dl_hwcaps_contains ("first", "first", i));
+ TEST_VERIFY (_dl_hwcaps_contains ("first", "first", strlen ("first")));
+ TEST_VERIFY (_dl_hwcaps_contains ("first:", "first", strlen ("first")));
+ TEST_VERIFY (_dl_hwcaps_contains ("first:second",
+ "first", strlen ("first")));
+ TEST_VERIFY (_dl_hwcaps_contains (":first:second", "first",
+ strlen ("first")));
+ TEST_VERIFY (_dl_hwcaps_contains ("first:second", "second",
+ strlen ("second")));
+ TEST_VERIFY (_dl_hwcaps_contains ("first:second:", "second",
+ strlen ("second")));
+ for (int i = 0; i < strlen ("second"); ++i)
+ TEST_VERIFY (!_dl_hwcaps_contains ("first:second:", "sec", i));
+
+ return 0;
+}
+
+#include <support/test-driver.c>
+
+/* Rebuild the sources here because the object file is built for
+ inclusion into the dynamic loader. */
+#include "dl-hwcaps_split.c"
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 2de060848b..7e14650422 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -1035,8 +1035,13 @@ extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
attribute_hidden;
/* Initialize the basic data structure for the search paths. SOURCE
- is either "LD_LIBRARY_PATH" or "--library-path". */
-extern void _dl_init_paths (const char *library_path, const char *source)
+ is either "LD_LIBRARY_PATH" or "--library-path".
+ GLIBC_HWCAPS_PREPEND adds additional glibc-hwcaps subdirectories to
+ search. GLIBC_HWCAPS_MASK is used to filter the built-in
+ subdirectories if not NULL. */
+extern void _dl_init_paths (const char *library_path, const char *source,
+ const char *glibc_hwcaps_prepend,
+ const char *glibc_hwcaps_mask)
attribute_hidden;
/* Gather the information needed to install the profiling tables and start
@@ -1060,9 +1065,14 @@ extern void _dl_show_auxv (void) attribute_hidden;
extern char *_dl_next_ld_env_entry (char ***position) attribute_hidden;
/* Return an array with the names of the important hardware
- capabilities. The length of the array is written to *SZ, and the
- maximum of all strings length is written to *MAX_CAPSTRLEN. */
-const struct r_strlenpair *_dl_important_hwcaps (size_t *sz,
+ capabilities. PREPEND is a colon-separated list of glibc-hwcaps
+ directories to search first. MASK is a colon-separated list used
+ to filter the built-in glibc-hwcaps subdirectories. The length of
+ the array is written to *SZ, and the maximum of all strings length
+ is written to *MAX_CAPSTRLEN. */
+const struct r_strlenpair *_dl_important_hwcaps (const char *prepend,
+ const char *mask,
+ size_t *sz,
size_t *max_capstrlen)
attribute_hidden;
--
2.25.4
More information about the Libc-alpha
mailing list