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elf: Add glibc-hwcaps support for LD_LIBRARY_PATH

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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.

ld.so supports two new arguments, --glibc-hwcaps-prepend and
--glibc-hwcaps-mask.  Each accepts a colon-separated list of
glibc-hwcaps subdirectory names.  The prepend option adds additional
subdirectories that are searched first, in the specified order.  The
mask option restricts the automatically selected subdirectories to
those listed in the option argument.  For example, on systems where
/usr/lib64 is on the library search path,
--glibc-hwcaps-prepend=valgrind:debug causes the dynamic loader to
search the directories /usr/lib64/glibc-hwcaps/valgrind and
/usr/lib64/glibc-hwcaps/debug just before /usr/lib64 is searched.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2020-12-04 09:13:43 +01:00
parent c41d197ec4
commit dad90d5282
16 changed files with 784 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
elf/Makefile
View File

@ -61,7 +61,8 @@ 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
@ -212,14 +213,14 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-filterobj tst-filterobj-dlopen tst-auxobj tst-auxobj-dlopen \
tst-audit14 tst-audit15 tst-audit16 \
tst-single_threaded tst-single_threaded-pthread \
tst-tls-ie tst-tls-ie-dlmopen \
argv0test
tst-tls-ie tst-tls-ie-dlmopen argv0test \
tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask
# reldep9
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-tls-surplus
tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split
tests-container += tst-pldd tst-dlopen-tlsmodid-container \
tst-dlopen-self-container
test-srcs = tst-pathopt
@ -331,7 +332,10 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-single_threaded-mod3 tst-single_threaded-mod4 \
tst-tls-ie-mod0 tst-tls-ie-mod1 tst-tls-ie-mod2 \
tst-tls-ie-mod3 tst-tls-ie-mod4 tst-tls-ie-mod5 \
tst-tls-ie-mod6
tst-tls-ie-mod6 libmarkermod1-1 libmarkermod1-2 libmarkermod1-3 \
libmarkermod2-1 libmarkermod2-2 \
libmarkermod3-1 libmarkermod3-2 libmarkermod3-3 \
libmarkermod4-1 libmarkermod4-2 libmarkermod4-3 libmarkermod4-4 \
# Most modules build with _ISOMAC defined, but those filtered out
# depend on internal headers.
@ -1814,3 +1818,60 @@ $(objpfx)argv0test.out: tst-rtld-argv0.sh $(objpfx)ld.so \
'$(test-wrapper-env)' '$(run_program_env)' \
'$(rpath-link)' 'test-argv0' > $@; \
$(evaluate-test)
# A list containing the name of the most likely searched subdirectory
# of the glibc-hwcaps directory, for each supported architecture (in
# other words, the oldest hardware level recognized by the
# glibc-hwcaps mechanism for this architecture). Used to obtain test
# coverage for some glibc-hwcaps tests for the widest possible range
# of systems.
glibc-hwcaps-first-subdirs-for-tests =
# The test modules are parameterized by preprocessor macros.
LDFLAGS-libmarkermod1-1.so += -Wl,-soname,libmarkermod1.so
LDFLAGS-libmarkermod2-1.so += -Wl,-soname,libmarkermod2.so
LDFLAGS-libmarkermod3-1.so += -Wl,-soname,libmarkermod3.so
LDFLAGS-libmarkermod4-1.so += -Wl,-soname,libmarkermod4.so
$(objpfx)libmarkermod%.os : markermodMARKER-VALUE.c
$(compile-command.c) \
-DMARKER=marker$(firstword $(subst -, ,$*)) \
-DVALUE=$(lastword $(subst -, ,$*))
$(objpfx)libmarkermod1.so: $(objpfx)libmarkermod1-1.so
cp $< $@
$(objpfx)libmarkermod2.so: $(objpfx)libmarkermod2-1.so
cp $< $@
$(objpfx)libmarkermod3.so: $(objpfx)libmarkermod3-1.so
cp $< $@
$(objpfx)libmarkermod4.so: $(objpfx)libmarkermod4-1.so
cp $< $@
# tst-glibc-hwcaps-prepend checks that --glibc-hwcaps-prepend is
# preferred over auto-detected subdirectories.
$(objpfx)tst-glibc-hwcaps-prepend: $(objpfx)libmarkermod1-1.so
$(objpfx)glibc-hwcaps/prepend-markermod1/libmarkermod1.so: \
$(objpfx)libmarkermod1-2.so
$(make-target-directory)
cp $< $@
$(objpfx)glibc-hwcaps/%/libmarkermod1.so: $(objpfx)libmarkermod1-3.so
$(make-target-directory)
cp $< $@
$(objpfx)tst-glibc-hwcaps-prepend.out: \
$(objpfx)tst-glibc-hwcaps-prepend $(objpfx)libmarkermod1.so \
$(patsubst %,$(objpfx)glibc-hwcaps/%/libmarkermod1.so,prepend-markermod1 \
$(glibc-hwcaps-first-subdirs-for-tests))
$(test-wrapper) $(rtld-prefix) \
--glibc-hwcaps-prepend prepend-markermod1 \
$< > $@; \
$(evaluate-test)
# tst-glibc-hwcaps-mask checks that --glibc-hwcaps-mask can be used to
# suppress all auto-detected subdirectories.
$(objpfx)tst-glibc-hwcaps-mask: $(objpfx)libmarkermod1-1.so
$(objpfx)tst-glibc-hwcaps-mask.out: \
$(objpfx)tst-glibc-hwcaps-mask $(objpfx)libmarkermod1.so \
$(patsubst %,$(objpfx)glibc-hwcaps/%/libmarkermod1.so,\
$(glibc-hwcaps-first-subdirs-for-tests))
$(test-wrapper) $(rtld-prefix) \
--glibc-hwcaps-mask does-not-exist \
$< > $@; \
$(evaluate-test)

29
elf/dl-hwcaps-subdirs.c Normal file
View File

@ -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[] = "";
uint32_t
_dl_hwcaps_subdirs_active (void)
{
return 0;
}

138
elf/dl-hwcaps.c
View File

@ -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 hwcaps_counts
{
/* Number of substrings. */
size_t count;
/* Sum of the individual substring lengths (without separators 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
update_hwcaps_counts (struct hwcaps_counts *counts, const char *hwcaps,
uint32_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,
uint32_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. */
uint32_t hwcaps_subdirs_active = _dl_hwcaps_subdirs_active ();
struct hwcaps_counts hwcaps_counts = { 0, };
update_hwcaps_counts (&hwcaps_counts, glibc_hwcaps_prepend, -1, NULL);
update_hwcaps_counts (&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;
}

105
elf/dl-hwcaps.h
View File

@ -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 +33,103 @@
# 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;
uint32_t bitmask;
};
/* Prepare *S for iteration with _dl_hwcaps_split_masked. Only HWCAP
names in SUBJECT whose bit is set in BITMASK and whose name 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,
uint32_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. Up to 32 subdirectories are supported, limited by
the width of the uint32_t mask. */
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. */
uint32_t _dl_hwcaps_subdirs_active (void) attribute_hidden;
/* Returns a bitmask that marks the last ACTIVE subdirectories in a
_dl_hwcaps_subdirs_active string (containing SUBDIRS directories in
total) as active. Intended for use in _dl_hwcaps_subdirs_active
implementations (if a contiguous tail of the list in
_dl_hwcaps_subdirs is selected). */
static inline uint32_t
_dl_hwcaps_subdirs_build_bitmask (int subdirs, int active)
{
/* Leading subdirectories that are not active. */
int inactive = subdirs - active;
if (inactive == 32)
return 0;
uint32_t mask;
if (subdirs != 32)
mask = (1U << subdirs) - 1;
else
mask = -1;
return mask ^ ((1U << inactive) - 1);
}
#endif /* _DL_HWCAPS_H */

77
elf/dl-hwcaps_split.c Normal file
View File

@ -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;
}

7
elf/dl-load.c
View File

@ -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. */

11
elf/dl-main.h
View File

@ -84,6 +84,14 @@ 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 rtld_mode mode;
/* True if any of the debugging options is enabled. */
@ -98,7 +106,8 @@ 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. */

5
elf/dl-support.c
View File

@ -324,7 +324,10 @@ _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);

68
elf/dl-usage.c
View File

@ -83,7 +83,7 @@ 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");
@ -132,6 +132,67 @@ 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 (&nothing_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. */
uint32_t mask = _dl_hwcaps_subdirs_active ();
_dl_hwcaps_split_init (&split, _dl_hwcaps_subdirs);
while (_dl_hwcaps_split (&split))
{
print_hwcaps_subdirectories_header (&nothing_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
@ -186,6 +247,10 @@ setting environment variables (which would be inherited 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\
@ -198,6 +263,7 @@ This program interpreter self-identifies as: " RTLD "\n\
",
argv0);
print_search_path_for_help (state);
print_hwcaps_subdirectories (state);
print_legacy_hwcap_directories ();
_exit (EXIT_SUCCESS);
}

29
elf/markermodMARKER-VALUE.c Normal file
View File

@ -0,0 +1,29 @@
/* Source file template for building shared objects with marker functions.
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/>. */
/* MARKER and VALUE must be set on the compiler command line. */
#ifndef MARKER
# error MARKER not defined
#endif
int
MARKER (void)
{
return VALUE;
}

18
elf/rtld.c
View File

@ -290,6 +290,8 @@ 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 = rtld_mode_normal;
state->any_debug = false;
state->version_info = false;
@ -1253,6 +1255,22 @@ dl_main (const ElfW(Phdr) *phdr,
{
argv0 = _dl_argv[2];
_dl_skip_args += 2;
_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;

148
elf/tst-dl-hwcaps_split.c Normal file
View File

@ -0,0 +1,148 @@
/* 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")));
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", "second", i));
TEST_VERIFY (!_dl_hwcaps_contains ("first:second:", "second", i));
TEST_VERIFY (!_dl_hwcaps_contains ("first:second::", "second", i));
TEST_VERIFY (!_dl_hwcaps_contains ("first::second", "second", 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"

31
elf/tst-glibc-hwcaps-mask.c Normal file
View File

@ -0,0 +1,31 @@
/* Test that --glibc-hwcaps-mask works.
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 <support/check.h>
extern int marker1 (void);
static int
do_test (void)
{
/* The marker1 function in elf/markermod1.so returns 1. */
TEST_COMPARE (marker1 (), 1);
return 0;
}
#include <support/test-driver.c>

32
elf/tst-glibc-hwcaps-prepend.c Normal file
View File

@ -0,0 +1,32 @@
/* Test that --glibc-hwcaps-prepend works.
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 <support/check.h>
extern int marker1 (void);
static int
do_test (void)
{
/* The marker1 function in
glibc-hwcaps/prepend-markermod1/markermod1.so returns 2. */
TEST_COMPARE (marker1 (), 2);
return 0;
}
#include <support/test-driver.c>

28
elf/tst-glibc-hwcaps.c Normal file
View File

@ -0,0 +1,28 @@
/* Stub test for glibc-hwcaps.
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 <stdio.h>
static int
do_test (void)
{
puts ("info: generic tst-glibc-hwcaps (tests nothing)");
return 0;
}
#include <support/test-driver.c>

20
sysdeps/generic/ldsodefs.h
View File

@ -1055,8 +1055,13 @@ 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
@ -1080,9 +1085,14 @@ 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;