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Fix bus error on Debian bullseye

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Problem reported by Lars Ingebrigtsen, and problem diagnosis
and most of this patch by Pip Cet (Bug#42832).
* src/pdumper.c (dump_bitsets_init): Rename from dump_bitset_init.
All callers changed.  Initialize two bitsets with a single malloc
call.
(struct pdumper_loaded_dump_private): New member last_mark_bits.
(pdumper_find_object_type_impl): Return PDUMPER_NO_OBJECT if
the last_mark_bits’ bit is clear.
(pdumper_set_marked_impl): Assert that the last_mark_bits’
bit is set.
(pdumper_clear_marks_impl): Save mark_bits into
last_mark_bits before clearing mark_bits.
Co-authored-by: Pip Cet <pipcet@gmail.com>
This commit is contained in:
Paul Eggert 2020-08-14 14:33:21 -07:00
parent ca6c3bec07
commit 4ecc2ba01d
1 changed files with 23 additions and 9 deletions
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32
src/pdumper.c
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@ -4802,14 +4802,19 @@ struct dump_bitset
};
static bool
dump_bitset_init (struct dump_bitset *bitset, size_t number_bits)
dump_bitsets_init (struct dump_bitset bitset[2], size_t number_bits)
{
int xword_size = sizeof (bitset->bits[0]);
int xword_size = sizeof (bitset[0].bits[0]);
int bits_per_word = xword_size * CHAR_BIT;
ptrdiff_t words_needed = divide_round_up (number_bits, bits_per_word);
bitset->number_words = words_needed;
bitset->bits = calloc (words_needed, xword_size);
return bitset->bits != NULL;
dump_bitset_word *bits = calloc (words_needed, 2 * xword_size);
if (!bits)
return false;
bitset[0].bits = bits;
bitset[0].number_words = bitset[1].number_words = words_needed;
bitset[1].bits = memset (bits + words_needed, UCHAR_MAX,
words_needed * xword_size);
return true;
}
static dump_bitset_word *
@ -4870,7 +4875,7 @@ struct pdumper_loaded_dump_private
/* Copy of the header we read from the dump. */
struct dump_header header;
/* Mark bits for objects in the dump; used during GC. */
struct dump_bitset mark_bits;
struct dump_bitset mark_bits, last_mark_bits;
/* Time taken to load the dump. */
double load_time;
/* Dump file name. */
@ -4993,6 +4998,10 @@ pdumper_find_object_type_impl (const void *obj)
dump_off offset = ptrdiff_t_to_dump_off ((uintptr_t) obj - dump_public.start);
if (offset % DUMP_ALIGNMENT != 0)
return PDUMPER_NO_OBJECT;
ptrdiff_t bitno = offset / DUMP_ALIGNMENT;
if (offset < dump_private.header.cold_start
&& !dump_bitset_bit_set_p (&dump_private.last_mark_bits, bitno))
return PDUMPER_NO_OBJECT;
const struct dump_reloc *reloc =
dump_find_relocation (&dump_private.header.object_starts, offset);
return (reloc != NULL && dump_reloc_get_offset (*reloc) == offset)
@ -5021,12 +5030,16 @@ pdumper_set_marked_impl (const void *obj)
eassert (offset < dump_private.header.cold_start);
eassert (offset < dump_private.header.discardable_start);
ptrdiff_t bitno = offset / DUMP_ALIGNMENT;
eassert (dump_bitset_bit_set_p (&dump_private.last_mark_bits, bitno));
dump_bitset_set_bit (&dump_private.mark_bits, bitno);
}
void
pdumper_clear_marks_impl (void)
{
dump_bitset_word *swap = dump_private.last_mark_bits.bits;
dump_private.last_mark_bits.bits = dump_private.mark_bits.bits;
dump_private.mark_bits.bits = swap;
dump_bitset_clear (&dump_private.mark_bits);
}
@ -5243,7 +5256,7 @@ pdumper_load (const char *dump_filename)
int dump_page_size;
dump_off adj_discardable_start;
struct dump_bitset mark_bits;
struct dump_bitset mark_bits[2];
size_t mark_bits_needed;
struct dump_header header_buf = { 0 };
@ -5357,7 +5370,7 @@ pdumper_load (const char *dump_filename)
err = PDUMPER_LOAD_ERROR;
mark_bits_needed =
divide_round_up (header->discardable_start, DUMP_ALIGNMENT);
if (!dump_bitset_init (&mark_bits, mark_bits_needed))
if (!dump_bitsets_init (mark_bits, mark_bits_needed))
goto out;
/* Point of no return. */
@ -5365,7 +5378,8 @@ pdumper_load (const char *dump_filename)
dump_base = (uintptr_t) sections[DS_HOT].mapping;
gflags.dumped_with_pdumper_ = true;
dump_private.header = *header;
dump_private.mark_bits = mark_bits;
dump_private.mark_bits = mark_bits[0];
dump_private.last_mark_bits = mark_bits[1];
dump_public.start = dump_base;
dump_public.end = dump_public.start + dump_size;