diff options
Diffstat (limited to 'elf/dl-hwcaps.c')
| -rw-r--r-- | elf/dl-hwcaps.c | 138 |
1 files changed, 120 insertions, 18 deletions
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; +}; + +/* 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; } |