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scratch: add stack frame support #523

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@@ -260,12 +260,10 @@ SECP256K1_API void secp256k1_context_set_error_callback(
*
* Returns: a newly created scratch space.
* Args: ctx: an existing context object (cannot be NULL)
* In: init_size: initial amount of memory to allocate
* max_size: maximum amount of memory to allocate
* In: max_size: maximum amount of memory to allocate
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT secp256k1_scratch_space* secp256k1_scratch_space_create(
const secp256k1_context* ctx,
size_t init_size,
size_t max_size
) SECP256K1_ARG_NONNULL(1);

@@ -154,7 +154,7 @@ int main(int argc, char **argv) {
/* Allocate stuff */
data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
scratch_size = secp256k1_strauss_scratch_size(POINTS) + STRAUSS_SCRATCH_OBJECTS*16;
data.scratch = secp256k1_scratch_space_create(data.ctx, scratch_size, scratch_size);
data.scratch = secp256k1_scratch_space_create(data.ctx, scratch_size);
data.scalars = malloc(sizeof(secp256k1_scalar) * POINTS);
data.seckeys = malloc(sizeof(secp256k1_scalar) * POINTS);
data.pubkeys = malloc(sizeof(secp256k1_ge) * POINTS);
@@ -525,10 +525,9 @@ static int secp256k1_ecmult_strauss_batch(const secp256k1_ecmult_context *ctx, s
return 1;
}

if (!secp256k1_scratch_resize(scratch, secp256k1_strauss_scratch_size(n_points), STRAUSS_SCRATCH_OBJECTS)) {
if (!secp256k1_scratch_allocate_frame(scratch, secp256k1_strauss_scratch_size(n_points), STRAUSS_SCRATCH_OBJECTS)) {
return 0;
}
secp256k1_scratch_reset(scratch);
points = (secp256k1_gej*)secp256k1_scratch_alloc(scratch, n_points * sizeof(secp256k1_gej));
scalars = (secp256k1_scalar*)secp256k1_scratch_alloc(scratch, n_points * sizeof(secp256k1_scalar));
state.prej = (secp256k1_gej*)secp256k1_scratch_alloc(scratch, n_points * ECMULT_TABLE_SIZE(WINDOW_A) * sizeof(secp256k1_gej));
@@ -543,10 +542,14 @@ static int secp256k1_ecmult_strauss_batch(const secp256k1_ecmult_context *ctx, s

for (i = 0; i < n_points; i++) {
secp256k1_ge point;
if (!cb(&scalars[i], &point, i+cb_offset, cbdata)) return 0;
if (!cb(&scalars[i], &point, i+cb_offset, cbdata)) {
secp256k1_scratch_deallocate_frame(scratch);
return 0;
}
secp256k1_gej_set_ge(&points[i], &point);
}
secp256k1_ecmult_strauss_wnaf(ctx, &state, r, n_points, points, scalars, inp_g_sc);
secp256k1_scratch_deallocate_frame(scratch);
return 1;
}

@@ -873,10 +876,9 @@ static int secp256k1_ecmult_pippenger_batch(const secp256k1_ecmult_context *ctx,
}

bucket_window = secp256k1_pippenger_bucket_window(n_points);
if (!secp256k1_scratch_resize(scratch, secp256k1_pippenger_scratch_size(n_points, bucket_window), PIPPENGER_SCRATCH_OBJECTS)) {
if (!secp256k1_scratch_allocate_frame(scratch, secp256k1_pippenger_scratch_size(n_points, bucket_window), PIPPENGER_SCRATCH_OBJECTS)) {
return 0;
}
secp256k1_scratch_reset(scratch);
points = (secp256k1_ge *) secp256k1_scratch_alloc(scratch, entries * sizeof(*points));
scalars = (secp256k1_scalar *) secp256k1_scratch_alloc(scratch, entries * sizeof(*scalars));
state_space = (struct secp256k1_pippenger_state *) secp256k1_scratch_alloc(scratch, sizeof(*state_space));
@@ -896,6 +898,7 @@ static int secp256k1_ecmult_pippenger_batch(const secp256k1_ecmult_context *ctx,

while (point_idx < n_points) {
if (!cb(&scalars[idx], &points[idx], point_idx + cb_offset, cbdata)) {
secp256k1_scratch_deallocate_frame(scratch);
return 0;
}
idx++;
@@ -919,6 +922,7 @@ static int secp256k1_ecmult_pippenger_batch(const secp256k1_ecmult_context *ctx,
for(i = 0; i < 1<<bucket_window; i++) {
secp256k1_gej_clear(&buckets[i]);
}
secp256k1_scratch_deallocate_frame(scratch);
return 1;
}

@@ -7,29 +7,33 @@
#ifndef _SECP256K1_SCRATCH_
#define _SECP256K1_SCRATCH_

#define SECP256K1_SCRATCH_MAX_FRAMES 5

/* The typedef is used internally; the struct name is used in the public API
* (where it is exposed as a different typedef) */
typedef struct secp256k1_scratch_space_struct {
void *data;
size_t offset;
size_t init_size;
void *data[SECP256K1_SCRATCH_MAX_FRAMES];
size_t offset[SECP256K1_SCRATCH_MAX_FRAMES];
size_t frame_size[SECP256K1_SCRATCH_MAX_FRAMES];
size_t frame;
size_t max_size;
const secp256k1_callback* error_callback;
} secp256k1_scratch;

static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t init_size, size_t max_size);
static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t max_size);

static void secp256k1_scratch_destroy(secp256k1_scratch* scratch);

/** Attempts to allocate a new stack frame with `n` available bytes. Returns 1 on success, 0 on failure */
static int secp256k1_scratch_allocate_frame(secp256k1_scratch* scratch, size_t n, size_t objects);

/** Deallocates a stack frame */
static void secp256k1_scratch_deallocate_frame(secp256k1_scratch* scratch);

/** Returns the maximum allocation the scratch space will allow */
static size_t secp256k1_scratch_max_allocation(const secp256k1_scratch* scratch, size_t n_objects);

/** Attempts to allocate so that there are `n` available bytes. Returns 1 on success, 0 on failure */
static int secp256k1_scratch_resize(secp256k1_scratch* scratch, size_t n, size_t n_objects);

/** Returns a pointer into the scratch space or NULL if there is insufficient available space */
/** Returns a pointer into the most recently allocated frame, or NULL if there is insufficient available space */
static void *secp256k1_scratch_alloc(secp256k1_scratch* scratch, size_t n);

/** Resets the returned pointer to the beginning of space */
static void secp256k1_scratch_reset(secp256k1_scratch* scratch);

#endif
@@ -15,16 +15,10 @@
* TODO: Determine this at configure time. */
#define ALIGNMENT 16

static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t init_size, size_t max_size) {
static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t max_size) {
secp256k1_scratch* ret = (secp256k1_scratch*)checked_malloc(error_callback, sizeof(*ret));
if (ret != NULL) {
ret->data = checked_malloc(error_callback, init_size);
if (ret->data == NULL) {
free (ret);
return NULL;
}
ret->offset = 0;
ret->init_size = init_size;
memset(ret, 0, sizeof(*ret));
ret->max_size = max_size;
ret->error_callback = error_callback;
}
@@ -33,45 +27,60 @@ static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* err

static void secp256k1_scratch_destroy(secp256k1_scratch* scratch) {
if (scratch != NULL) {
free(scratch->data);
VERIFY_CHECK(scratch->frame == 0);
free(scratch);
}
}

static size_t secp256k1_scratch_max_allocation(const secp256k1_scratch* scratch, size_t objects) {
if (scratch->max_size <= objects * ALIGNMENT) {
size_t i = 0;
size_t allocated = 0;
for (i = 0; i < scratch->frame; i++) {
allocated += scratch->frame_size[i];
}
if (scratch->max_size - allocated <= objects * ALIGNMENT) {
return 0;
}
return scratch->max_size - objects * ALIGNMENT;
return scratch->max_size - allocated - objects * ALIGNMENT;
}

static int secp256k1_scratch_resize(secp256k1_scratch* scratch, size_t n, size_t objects) {
n += objects * ALIGNMENT;
if (n > scratch->init_size && n <= scratch->max_size) {
void *tmp = checked_realloc(scratch->error_callback, scratch->data, n);
if (tmp == NULL) {
static int secp256k1_scratch_allocate_frame(secp256k1_scratch* scratch, size_t n, size_t objects) {
VERIFY_CHECK(scratch->frame < SECP256K1_SCRATCH_MAX_FRAMES);

if (n <= secp256k1_scratch_max_allocation(scratch, objects)) {
n += objects * ALIGNMENT;
scratch->data[scratch->frame] = checked_malloc(scratch->error_callback, n);
if (scratch->data[scratch->frame] == NULL) {
return 0;
}
scratch->init_size = n;
scratch->data = tmp;
scratch->frame_size[scratch->frame] = n;
scratch->offset[scratch->frame] = 0;
scratch->frame++;
return 1;
} else {
return 0;
}
return n <= scratch->max_size;
}

static void secp256k1_scratch_deallocate_frame(secp256k1_scratch* scratch) {
VERIFY_CHECK(scratch->frame > 0);
scratch->frame -= 1;
free(scratch->data[scratch->frame]);
}

static void *secp256k1_scratch_alloc(secp256k1_scratch* scratch, size_t size) {
void *ret;
size_t frame = scratch->frame - 1;
size = ((size + ALIGNMENT - 1) / ALIGNMENT) * ALIGNMENT;
if (size + scratch->offset > scratch->init_size) {

if (scratch->frame == 0 || size + scratch->offset[frame] > scratch->frame_size[frame]) {
return NULL;
}
ret = (void *) ((unsigned char *) scratch->data + scratch->offset);
ret = (void *) ((unsigned char *) scratch->data[frame] + scratch->offset[frame]);
memset(ret, 0, size);
scratch->offset += size;
return ret;
}
scratch->offset[frame] += size;

static void secp256k1_scratch_reset(secp256k1_scratch* scratch) {
scratch->offset = 0;
return ret;
}

#endif
@@ -115,11 +115,9 @@ void secp256k1_context_set_error_callback(secp256k1_context* ctx, void (*fun)(co
ctx->error_callback.data = data;
}

secp256k1_scratch_space* secp256k1_scratch_space_create(const secp256k1_context* ctx, size_t init_size, size_t max_size) {
secp256k1_scratch_space* secp256k1_scratch_space_create(const secp256k1_context* ctx, size_t max_size) {
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(max_size >= init_size);

return secp256k1_scratch_create(&ctx->error_callback, init_size, max_size);
return secp256k1_scratch_create(&ctx->error_callback, max_size);
}

void secp256k1_scratch_space_destroy(secp256k1_scratch_space* scratch) {
@@ -258,28 +258,31 @@ void run_scratch_tests(void) {

/* Test public API */
secp256k1_context_set_illegal_callback(none, counting_illegal_callback_fn, &ecount);
scratch = secp256k1_scratch_space_create(none, 100, 10);
CHECK(scratch == NULL);
CHECK(ecount == 1);

scratch = secp256k1_scratch_space_create(none, 100, 100);
CHECK(scratch != NULL);
CHECK(ecount == 1);
secp256k1_scratch_space_destroy(scratch);

scratch = secp256k1_scratch_space_create(none, 100, 1000);
scratch = secp256k1_scratch_space_create(none, 1000);
CHECK(scratch != NULL);
CHECK(ecount == 1);
CHECK(ecount == 0);

/* Test internal API */
CHECK(secp256k1_scratch_max_allocation(scratch, 0) == 1000);
CHECK(secp256k1_scratch_max_allocation(scratch, 1) < 1000);
CHECK(secp256k1_scratch_resize(scratch, 50, 1) == 1); /* no-op */
CHECK(secp256k1_scratch_resize(scratch, 200, 1) == 1);
CHECK(secp256k1_scratch_resize(scratch, 950, 1) == 1);
CHECK(secp256k1_scratch_resize(scratch, 1000, 1) == 0);
CHECK(secp256k1_scratch_resize(scratch, 2000, 1) == 0);

/* Allocating 500 bytes with no frame fails */
CHECK(secp256k1_scratch_alloc(scratch, 500) == NULL);
CHECK(secp256k1_scratch_max_allocation(scratch, 0) == 1000);

/* ...but pushing a new stack frame does affect the max allocation */
CHECK(secp256k1_scratch_allocate_frame(scratch, 500, 1 == 1));
CHECK(secp256k1_scratch_max_allocation(scratch, 1) < 500); /* 500 - ALIGNMENT */
CHECK(secp256k1_scratch_alloc(scratch, 500) != NULL);
CHECK(secp256k1_scratch_alloc(scratch, 500) == NULL);

CHECK(secp256k1_scratch_allocate_frame(scratch, 500, 1) == 0);

/* ...and this effect is undone by popping the frame */
secp256k1_scratch_deallocate_frame(scratch);
CHECK(secp256k1_scratch_max_allocation(scratch, 0) == 1000);
CHECK(secp256k1_scratch_alloc(scratch, 500) == NULL);

/* cleanup */
secp256k1_scratch_space_destroy(scratch);
@@ -2558,7 +2561,6 @@ void test_ecmult_multi(secp256k1_scratch *scratch, secp256k1_ecmult_multi_func e
data.sc = sc;
data.pt = pt;
secp256k1_scalar_set_int(&szero, 0);
secp256k1_scratch_reset(scratch);

/* No points to multiply */
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, NULL, ecmult_multi_callback, &data, 0));
@@ -2590,7 +2592,7 @@ void test_ecmult_multi(secp256k1_scratch *scratch, secp256k1_ecmult_multi_func e
CHECK(secp256k1_gej_is_infinity(&r));

/* Try to multiply 1 point, but scratch space is empty */
scratch_empty = secp256k1_scratch_create(&ctx->error_callback, 0, 0);
scratch_empty = secp256k1_scratch_create(&ctx->error_callback, 0);
CHECK(!ecmult_multi(&ctx->ecmult_ctx, scratch_empty, &r, &szero, ecmult_multi_callback, &data, 1));
secp256k1_scratch_destroy(scratch_empty);

@@ -2816,15 +2818,16 @@ void test_ecmult_multi_pippenger_max_points(void) {
int bucket_window = 0;

for(; scratch_size < max_size; scratch_size+=256) {
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, scratch_size);
scratch = secp256k1_scratch_create(&ctx->error_callback, scratch_size);
CHECK(scratch != NULL);
n_points_supported = secp256k1_pippenger_max_points(scratch);
if (n_points_supported == 0) {
secp256k1_scratch_destroy(scratch);
continue;
}
bucket_window = secp256k1_pippenger_bucket_window(n_points_supported);
CHECK(secp256k1_scratch_resize(scratch, secp256k1_pippenger_scratch_size(n_points_supported, bucket_window), PIPPENGER_SCRATCH_OBJECTS));
CHECK(secp256k1_scratch_allocate_frame(scratch, secp256k1_pippenger_scratch_size(n_points_supported, bucket_window), PIPPENGER_SCRATCH_OBJECTS));
secp256k1_scratch_deallocate_frame(scratch);
secp256k1_scratch_destroy(scratch);
}
CHECK(bucket_window == PIPPENGER_MAX_BUCKET_WINDOW);
@@ -2866,13 +2869,13 @@ void test_ecmult_multi_batching(void) {
data.pt = pt;

/* Test with empty scratch space */
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, 0);
scratch = secp256k1_scratch_create(&ctx->error_callback, 0);
CHECK(!secp256k1_ecmult_multi_var(&ctx->ecmult_ctx, scratch, &r, &scG, ecmult_multi_callback, &data, 1));
secp256k1_scratch_destroy(scratch);

/* Test with space for 1 point in pippenger. That's not enough because
* ecmult_multi selects strauss which requires more memory. */
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, secp256k1_pippenger_scratch_size(1, 1) + PIPPENGER_SCRATCH_OBJECTS*ALIGNMENT);
scratch = secp256k1_scratch_create(&ctx->error_callback, secp256k1_pippenger_scratch_size(1, 1) + PIPPENGER_SCRATCH_OBJECTS*ALIGNMENT);
CHECK(!secp256k1_ecmult_multi_var(&ctx->ecmult_ctx, scratch, &r, &scG, ecmult_multi_callback, &data, 1));
secp256k1_scratch_destroy(scratch);

@@ -2881,10 +2884,10 @@ void test_ecmult_multi_batching(void) {
if (i > ECMULT_PIPPENGER_THRESHOLD) {
int bucket_window = secp256k1_pippenger_bucket_window(i);
size_t scratch_size = secp256k1_pippenger_scratch_size(i, bucket_window);
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, scratch_size + PIPPENGER_SCRATCH_OBJECTS*ALIGNMENT);
scratch = secp256k1_scratch_create(&ctx->error_callback, scratch_size + PIPPENGER_SCRATCH_OBJECTS*ALIGNMENT);
} else {
size_t scratch_size = secp256k1_strauss_scratch_size(i);
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, scratch_size + STRAUSS_SCRATCH_OBJECTS*ALIGNMENT);
scratch = secp256k1_scratch_create(&ctx->error_callback, scratch_size + STRAUSS_SCRATCH_OBJECTS*ALIGNMENT);
}
CHECK(secp256k1_ecmult_multi_var(&ctx->ecmult_ctx, scratch, &r, &scG, ecmult_multi_callback, &data, n_points));
secp256k1_gej_add_var(&r, &r, &r2, NULL);
@@ -2900,14 +2903,14 @@ void run_ecmult_multi_tests(void) {

test_secp256k1_pippenger_bucket_window_inv();
test_ecmult_multi_pippenger_max_points();
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, 819200);
scratch = secp256k1_scratch_create(&ctx->error_callback, 819200);
test_ecmult_multi(scratch, secp256k1_ecmult_multi_var);
test_ecmult_multi(scratch, secp256k1_ecmult_pippenger_batch_single);
test_ecmult_multi(scratch, secp256k1_ecmult_strauss_batch_single);
secp256k1_scratch_destroy(scratch);

/* Run test_ecmult_multi with space for exactly one point */
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, secp256k1_strauss_scratch_size(1) + STRAUSS_SCRATCH_OBJECTS*ALIGNMENT);
scratch = secp256k1_scratch_create(&ctx->error_callback, secp256k1_strauss_scratch_size(1) + STRAUSS_SCRATCH_OBJECTS*ALIGNMENT);
test_ecmult_multi(scratch, secp256k1_ecmult_multi_var);
secp256k1_scratch_destroy(scratch);

@@ -196,7 +196,7 @@ static int ecmult_multi_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t

void test_exhaustive_ecmult_multi(const secp256k1_context *ctx, const secp256k1_ge *group, int order) {
int i, j, k, x, y;
secp256k1_scratch *scratch = secp256k1_scratch_create(&ctx->error_callback, 1024, 4096);
secp256k1_scratch *scratch = secp256k1_scratch_create(&ctx->error_callback, 4096);
for (i = 0; i < order; i++) {
for (j = 0; j < order; j++) {
for (k = 0; k < order; k++) {
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