tekhex buffer management and symbol types
Alan Modra
amodra@gmail.com
Fri Nov 7 10:14:00 GMT 2014
On Fri, Nov 07, 2014 at 01:23:37PM +1030, Alan Modra wrote:
> In my opinion it is a complete waste of time rewriting
> tekhex.c to better deal with fuzzed input.
So I wasted some time..
Dramatically reduces memory consumption and processing time for large
all-zero data segments. Allows multiple symbol types attached to a
given segment to survive objcopy.
* tekhex.c (CHUNK_SPAN): Define.
(struct data_struct <chunk_init>): Use one byte per span, update
all code accessing this field.
(find_chunk): Add create param, don't create new entry unless set.
(insert_byte): Don't save zeros.
(first_phase): Set section SEC_CODE or SEC_DATA flag depending
on symbol type. Create an alternate section if both types of
symbol are given. Attach type '2' and '6' symbols to absolute
section.
(move_section_contents): Fix caching of chunk. Don't create chunk
when reading, or for writing zeros.
(tekhex_set_section_contents): Don't create initial chunks.
(tekhex_write_object_contents): Use CHUNK_SPAN.
diff --git a/bfd/tekhex.c b/bfd/tekhex.c
index 2220d50..aaebcee 100644
--- a/bfd/tekhex.c
+++ b/bfd/tekhex.c
@@ -246,11 +246,12 @@ struct tekhex_data_list_struct
typedef struct tekhex_data_list_struct tekhex_data_list_type;
#define CHUNK_MASK 0x1fff
+#define CHUNK_SPAN 32
struct data_struct
{
- char chunk_data[CHUNK_MASK + 1];
- char chunk_init[CHUNK_MASK + 1];
+ unsigned char chunk_data[CHUNK_MASK + 1];
+ unsigned char chunk_init[(CHUNK_MASK + 1 + CHUNK_SPAN - 1) / CHUNK_SPAN];
bfd_vma vma;
struct data_struct *next;
};
@@ -312,7 +313,7 @@ getsym (char *dstp, char **srcp, unsigned int *lenp)
}
static struct data_struct *
-find_chunk (bfd *abfd, bfd_vma vma)
+find_chunk (bfd *abfd, bfd_vma vma, bfd_boolean create)
{
struct data_struct *d = abfd->tdata.tekhex_data->data;
@@ -320,7 +321,7 @@ find_chunk (bfd *abfd, bfd_vma vma)
while (d && (d->vma) != vma)
d = d->next;
- if (!d)
+ if (!d && create)
{
/* No chunk for this address, so make one up. */
d = (struct data_struct *)
@@ -339,11 +340,14 @@ find_chunk (bfd *abfd, bfd_vma vma)
static void
insert_byte (bfd *abfd, int value, bfd_vma addr)
{
- /* Find the chunk that this byte needs and put it in. */
- struct data_struct *d = find_chunk (abfd, addr);
+ if (value != 0)
+ {
+ /* Find the chunk that this byte needs and put it in. */
+ struct data_struct *d = find_chunk (abfd, addr, TRUE);
- d->chunk_data[addr & CHUNK_MASK] = value;
- d->chunk_init[addr & CHUNK_MASK] = 1;
+ d->chunk_data[addr & CHUNK_MASK] = value;
+ d->chunk_init[(addr & CHUNK_MASK) / CHUNK_SPAN] = 1;
+ }
}
/* The first pass is to find the names of all the sections, and see
@@ -352,7 +356,7 @@ insert_byte (bfd *abfd, int value, bfd_vma addr)
static bfd_boolean
first_phase (bfd *abfd, int type, char *src)
{
- asection *section = bfd_abs_section_ptr;
+ asection *section, *alt_section;
unsigned int len;
bfd_vma val;
char sym[17]; /* A symbol can only be 16chars long. */
@@ -392,6 +396,7 @@ first_phase (bfd *abfd, int type, char *src)
if (section == NULL)
return FALSE;
}
+ alt_section = NULL;
while (*src)
{
switch (*src)
@@ -439,6 +444,42 @@ first_phase (bfd *abfd, int type, char *src)
new_symbol->symbol.flags = (BSF_GLOBAL | BSF_EXPORT);
else
new_symbol->symbol.flags = BSF_LOCAL;
+ if (stype == '2' || stype == '6')
+ new_symbol->symbol.section = bfd_abs_section_ptr;
+ else if (stype == '3' || stype == '7')
+ {
+ if ((section->flags & SEC_DATA) == 0)
+ section->flags |= SEC_CODE;
+ else
+ {
+ if (alt_section == NULL)
+ alt_section = bfd_get_next_section_by_name (section);
+ if (alt_section == NULL)
+ alt_section = bfd_make_section_anyway_with_flags
+ (abfd, section->name,
+ (section->flags & ~SEC_DATA) | SEC_CODE);
+ if (alt_section == NULL)
+ return FALSE;
+ new_symbol->symbol.section = alt_section;
+ }
+ }
+ else if (stype == '4' || stype == '8')
+ {
+ if ((section->flags & SEC_CODE) == 0)
+ section->flags |= SEC_DATA;
+ else
+ {
+ if (alt_section == NULL)
+ alt_section = bfd_get_next_section_by_name (section);
+ if (alt_section == NULL)
+ alt_section = bfd_make_section_anyway_with_flags
+ (abfd, section->name,
+ (section->flags & ~SEC_CODE) | SEC_DATA);
+ if (alt_section == NULL)
+ return FALSE;
+ new_symbol->symbol.section = alt_section;
+ }
+ }
if (!getvalue (&src, &val))
return FALSE;
new_symbol->symbol.value = val - section->vma;
@@ -589,22 +630,26 @@ move_section_contents (bfd *abfd,
/* Get high bits of address. */
bfd_vma chunk_number = addr & ~(bfd_vma) CHUNK_MASK;
bfd_vma low_bits = addr & CHUNK_MASK;
+ bfd_boolean must_write = !get && *location != 0;
- if (chunk_number != prev_number)
- /* Different chunk, so move pointer. */
- d = find_chunk (abfd, chunk_number);
+ if (chunk_number != prev_number || (!d && must_write))
+ {
+ /* Different chunk, so move pointer. */
+ d = find_chunk (abfd, chunk_number, must_write);
+ prev_number = chunk_number;
+ }
if (get)
{
- if (d->chunk_init[low_bits])
+ if (d)
*location = d->chunk_data[low_bits];
else
*location = 0;
}
- else
+ else if (must_write)
{
d->chunk_data[low_bits] = *location;
- d->chunk_init[low_bits] = (*location != 0);
+ d->chunk_init[low_bits / CHUNK_SPAN] = 1;
}
location++;
@@ -644,24 +689,6 @@ tekhex_set_section_contents (bfd *abfd,
file_ptr offset,
bfd_size_type bytes_to_do)
{
- if (! abfd->output_has_begun)
- {
- /* The first time around, allocate enough sections to hold all the chunks. */
- asection *s = abfd->sections;
- bfd_vma vma;
-
- for (s = abfd->sections; s; s = s->next)
- {
- if (s->flags & SEC_LOAD)
- {
- for (vma = s->vma & ~(bfd_vma) CHUNK_MASK;
- vma < s->vma + s->size;
- vma += CHUNK_MASK)
- find_chunk (abfd, vma);
- }
- }
- }
-
if (section->flags & (SEC_LOAD | SEC_ALLOC))
{
move_section_contents (abfd, section, locationp, offset, bytes_to_do,
@@ -772,26 +799,17 @@ tekhex_write_object_contents (bfd *abfd)
d = d->next)
{
int low;
-
- const int span = 32;
int addr;
/* Write it in blocks of 32 bytes. */
- for (addr = 0; addr < CHUNK_MASK + 1; addr += span)
+ for (addr = 0; addr < CHUNK_MASK + 1; addr += CHUNK_SPAN)
{
- int need = 0;
-
- /* Check to see if necessary. */
- for (low = 0; !need && low < span; low++)
- if (d->chunk_init[addr + low])
- need = 1;
-
- if (need)
+ if (d->chunk_init[addr / CHUNK_SPAN])
{
char *dst = buffer;
writevalue (&dst, addr + d->vma);
- for (low = 0; low < span; low++)
+ for (low = 0; low < CHUNK_SPAN; low++)
{
TOHEX (dst, d->chunk_data[addr + low]);
dst += 2;
--
Alan Modra
Australia Development Lab, IBM
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