[PATCH 03/11] elf: Add glibc-hwcaps support for LD_LIBRARY_PATH
Adhemerval Zanella
adhemerval.zanella@linaro.org
Thu Nov 26 20:29:10 GMT 2020
On 09/11/2020 15:40, Florian Weimer via Libc-alpha wrote:
> 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.
Could you extend the commit message with the extra options you are adding
on ld.so and their expected semantic? I would be good to have some
documentation at least on the commit message.
Patch looks goods in general, some nits below.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> elf/Makefile | 67 ++++++++++++++--
> elf/dl-hwcaps-subdirs.c | 29 +++++++
> elf/dl-hwcaps.c | 138 +++++++++++++++++++++++++++-----
> elf/dl-hwcaps.h | 105 +++++++++++++++++++++++++
> 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/markermodMARKER-VALUE.c | 29 +++++++
> elf/rtld.c | 18 +++++
> elf/tst-dl-hwcaps_split.c | 139 +++++++++++++++++++++++++++++++++
> elf/tst-glibc-hwcaps-mask.c | 31 ++++++++
> elf/tst-glibc-hwcaps-prepend.c | 32 ++++++++
> elf/tst-glibc-hwcaps.c | 28 +++++++
> sysdeps/generic/ldsodefs.h | 20 +++--
> 16 files changed, 771 insertions(+), 33 deletions(-)
> create mode 100644 elf/dl-hwcaps-subdirs.c
> create mode 100644 elf/dl-hwcaps_split.c
> create mode 100644 elf/markermodMARKER-VALUE.c
> create mode 100644 elf/tst-dl-hwcaps_split.c
> create mode 100644 elf/tst-glibc-hwcaps-mask.c
> create mode 100644 elf/tst-glibc-hwcaps-prepend.c
> create mode 100644 elf/tst-glibc-hwcaps.c
>
> diff --git a/elf/Makefile b/elf/Makefile
> index f10cc59e7c..d2f7e99863 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
Ok.
> @@ -210,14 +211,14 @@ 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
Ok.
> @@ -329,7 +330,10 @@ 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.
Ok.
> @@ -1812,3 +1816,56 @@ $(objpfx)argv0test.out: tst-rtld-argv0.sh $(objpfx)ld.so \
> '$(test-wrapper-env)' '$(run_program_env)' \
> '$(rpath-link)' 'test-argv0' > $@; \
> $(evaluate-test)
> +
> +# Most likely search subdirectories, for each supported architecture.
> +# Used to obtain test coverage wide test coverage.
This comments sounds strange, specially the second line.
> +glibc-hwcaps-first-subdirs-for-tests =
> +
> +# The test modules are parameterized by preprocessor macros.
> +LDFLAGS-libmarkermod1-1.so += -Wl,-soname,libmarkermod1.so
> +LDFLAGS-libmarkermod2-1.so += -Wl,-soname,libmarkermod2.so
> +LDFLAGS-libmarkermod3-1.so += -Wl,-soname,libmarkermod3.so
> +LDFLAGS-libmarkermod4-1.so += -Wl,-soname,libmarkermod4.so
> +$(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 $< $@
> +
Ok.
> +# tst-glibc-hwcaps-prepend checks that --glibc-hwcaps-prepend is
> +# preferred over auto-detected subdirectories.
> +$(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 \
> + $< > $@; \
> + $(evaluate-test)
> +
Ok.
> +# tst-glibc-hwcaps-mask checks that --glibc-hwcaps-mask can be used to
> +# suppress all auto-detected subdirectories.
> +$(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)
Ok.
> diff --git a/elf/dl-hwcaps-subdirs.c b/elf/dl-hwcaps-subdirs.c
> new file mode 100644
> index 0000000000..60c6d59731
> --- /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[] = "";
> +
> +uint32_t
> +_dl_hwcaps_subdirs_active (void)
> +{
> + return 0;
> +}
Ok.
> diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c
> index 44dbac099f..f611f3a1a6 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 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;
> +};
> +
Ok.
> +/* 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;
> + }
> +}
> +
Ok.
> +/* 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;
> + }
> +}
> +
Ok.
> /* 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)
Ok.
> @@ -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;
Ok.
> @@ -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
Ok.
> @@ -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;
> }
Ok.
> diff --git a/elf/dl-hwcaps.h b/elf/dl-hwcaps.h
> index b66da59b89..ab39d8a46d 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 +33,103 @@
> # 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;
> +}
Ok.
> +
> +/* 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;
> +}
> +
Ok.
> +/* 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;
I find it confusing that an null hwcap result true while an empty
relies on name. Do we need that NULL to be handled special here?
> +
> +/* 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)
> +{
Should it any assert to check if subdirs and/or active is within the
expected range?
> + /* 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 */
> 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;
> +}
> +
Ok.
> +_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;
> + }
> +}
> +
Ok.
> +_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;
> +}
Ok.
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index f3201e7c14..9020f1646f 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. */
Ok.
> diff --git a/elf/dl-main.h b/elf/dl-main.h
> index b51256d3b4..566713a0d1 100644
> --- a/elf/dl-main.h
> +++ b/elf/dl-main.h
> @@ -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. */
Ok.
> @@ -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. */
Ok.
> 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);
Ok.
> diff --git a/elf/dl-usage.c b/elf/dl-usage.c
> index 796ad38b43..e22a9c3942 100644
> --- a/elf/dl-usage.c
> +++ b/elf/dl-usage.c
> @@ -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 (¬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. */
> + uint32_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
> @@ -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);
> }
Do we really need to export the new options with the '--glibc' prefix?
The loader options are an implementation detail (same for the internal
variable names).
> diff --git a/elf/markermodMARKER-VALUE.c b/elf/markermodMARKER-VALUE.c
> new file mode 100644
> index 0000000000..99bdcf71a4
> --- /dev/null
> +++ b/elf/markermodMARKER-VALUE.c
> @@ -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
Maybe also add a check for the VALUE?
> +
> +int
> +MARKER (void)
> +{
> + return VALUE;
> +}
> diff --git a/elf/rtld.c b/elf/rtld.c
> index 5d117d0d2c..e3ec66c030 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -289,6 +289,8 @@ 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;
> @@ -1244,6 +1246,22 @@ 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;
Ok.
> 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);
Ok.
> +
> + {
> + 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));
> + }
> +
Ok.
> + {
> + 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));
> + }
> +
Ok.
> + /* 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));
> + }
Ok.
> + {
> + 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));
> + }
> +
Ok.
> + /* 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));
Maybe add some tests with multiple ':'.
> +
> + 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"
Ok.
> diff --git a/elf/tst-glibc-hwcaps-mask.c b/elf/tst-glibc-hwcaps-mask.c
> new file mode 100644
> index 0000000000..27b09b358c
> --- /dev/null
> +++ b/elf/tst-glibc-hwcaps-mask.c
> @@ -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>
Ok.
> diff --git a/elf/tst-glibc-hwcaps-prepend.c b/elf/tst-glibc-hwcaps-prepend.c
> new file mode 100644
> index 0000000000..57d7319f14
> --- /dev/null
> +++ b/elf/tst-glibc-hwcaps-prepend.c
> @@ -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>
Ok.
> diff --git a/elf/tst-glibc-hwcaps.c b/elf/tst-glibc-hwcaps.c
> new file mode 100644
> index 0000000000..28f47cf891
> --- /dev/null
> +++ b/elf/tst-glibc-hwcaps.c
> @@ -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>
Ok.
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 382eeb9be0..0b2babc70c 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -1047,8 +1047,13 @@ 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
Ok.
> @@ -1072,9 +1077,14 @@ 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;
>
>
Ok.
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