/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 2009-2021 Ivan Maidanski
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#include "private/gc_priv.h"
#include <stdio.h>
/* Data structure for list of root sets. */
/* We keep a hash table, so that we can filter out duplicate additions. */
/* Under Win32, we need to do a better job of filtering overlaps, so */
/* we resort to sequential search, and pay the price. */
/* This is really declared in gc_priv.h:
struct roots {
ptr_t r_start;
ptr_t r_end;
# if !defined(MSWIN32) && !defined(MSWINCE) && !defined(CYGWIN32)
struct roots * r_next;
# endif
GC_bool r_tmp;
-- Delete before registering new dynamic libraries
};
struct roots GC_static_roots[MAX_ROOT_SETS];
*/
int GC_no_dls = 0; /* Register dynamic library data segments. */
#if !defined(NO_DEBUGGING) || defined(GC_ASSERTIONS)
/* Should return the same value as GC_root_size. */
GC_INNER word GC_compute_root_size(void)
{
int i;
word size = 0;
for (i = 0; i < n_root_sets; i++) {
size += GC_static_roots[i].r_end - GC_static_roots[i].r_start;
}
return size;
}
#endif /* !NO_DEBUGGING || GC_ASSERTIONS */
#if !defined(NO_DEBUGGING)
/* For debugging: */
void GC_print_static_roots(void)
{
int i;
word size;
for (i = 0; i < n_root_sets; i++) {
GC_printf("From %p to %p%s\n",
(void *)GC_static_roots[i].r_start,
(void *)GC_static_roots[i].r_end,
GC_static_roots[i].r_tmp ? " (temporary)" : "");
}
GC_printf("GC_root_size= %lu\n", (unsigned long)GC_root_size);
if ((size = GC_compute_root_size()) != GC_root_size)
GC_err_printf("GC_root_size incorrect!! Should be: %lu\n",
(unsigned long)size);
}
#endif /* !NO_DEBUGGING */
#ifndef THREADS
/* Primarily for debugging support: */
/* Is the address p in one of the registered static root sections? */
GC_INNER GC_bool GC_is_static_root(void *p)
{
static int last_root_set = MAX_ROOT_SETS;
int i;
if (last_root_set < n_root_sets
&& (word)p >= (word)GC_static_roots[last_root_set].r_start
&& (word)p < (word)GC_static_roots[last_root_set].r_end)
return(TRUE);
for (i = 0; i < n_root_sets; i++) {
if ((word)p >= (word)GC_static_roots[i].r_start
&& (word)p < (word)GC_static_roots[i].r_end) {
last_root_set = i;
return(TRUE);
}
}
return(FALSE);
}
#endif /* !THREADS */
#if !defined(MSWIN32) && !defined(MSWINCE) && !defined(CYGWIN32)
/*
# define LOG_RT_SIZE 6
# define RT_SIZE (1 << LOG_RT_SIZE) -- Power of 2, may be != MAX_ROOT_SETS
struct roots * GC_root_index[RT_SIZE];
-- Hash table header. Used only to check whether a range is
-- already present.
-- really defined in gc_priv.h
*/
GC_INLINE int rt_hash(ptr_t addr)
{
word result = (word) addr;
# if CPP_WORDSZ > 8*LOG_RT_SIZE
result ^= result >> 8*LOG_RT_SIZE;
# endif
# if CPP_WORDSZ > 4*LOG_RT_SIZE
result ^= result >> 4*LOG_RT_SIZE;
# endif
result ^= result >> 2*LOG_RT_SIZE;
result ^= result >> LOG_RT_SIZE;
result &= (RT_SIZE-1);
return(result);
}
/* Is a range starting at b already in the table? If so return a */
/* pointer to it, else NULL. */
GC_INNER void * GC_roots_present(ptr_t b)
{
int h = rt_hash(b);
struct roots *p = GC_root_index[h];
while (p != 0) {
if (p -> r_start == (ptr_t)b) return(p);
p = p -> r_next;
}
return NULL;
}
/* Add the given root structure to the index. */
GC_INLINE void add_roots_to_index(struct roots *p)
{
int h = rt_hash(p -> r_start);
if (!EXPECT(GC_is_initialized, TRUE)) GC_init();
LOCK();
GC_add_roots_inner((ptr_t)b, (ptr_t)e, FALSE);
UNLOCK();
}
/* Add [b,e) to the root set. Adding the same interval a second time */
/* is a moderately fast no-op, and hence benign. We do not handle */
/* different but overlapping intervals efficiently. (We do handle */
/* them correctly.) */
/* Tmp specifies that the interval may be deleted before */
/* re-registering dynamic libraries. */
void GC_add_roots_inner(ptr_t b, ptr_t e, GC_bool tmp)
{
GC_ASSERT((word)b <= (word)e);
b = (ptr_t)(((word)b + (sizeof(word) - 1)) & ~(word)(sizeof(word) - 1));
/* round b up to word boundary */
e = (ptr_t)((word)e & ~(word)(sizeof(word) - 1));
/* round e down to word boundary */
if ((word)b >= (word)e) return; /* nothing to do */
# if defined(MSWIN32) || defined(MSWINCE) || defined(CYGWIN32)
/* Spend the time to ensure that there are no overlapping */
/* or adjacent intervals. */
/* This could be done faster with e.g. a */
/* balanced tree. But the execution time here is */
/* virtually guaranteed to be dominated by the time it */
/* takes to scan the roots. */
{
int i;
struct roots * old = NULL; /* initialized to prevent warning. */
for (i = 0; i < n_root_sets; i++) {
old = GC_static_roots + i;
if ((word)b <= (word)old->r_end
&& (word)e >= (word)old->r_start) {
if ((word)b < (word)old->r_start) {
GC_root_size += old->r_start - b;
old -> r_start = b;
}
if ((word)e > (word)old->r_end) {
GC_root_size += e - old->r_end;
old -> r_end = e;
}
old -> r_tmp &= tmp;
break;
}
}
if (i < n_root_sets) {
/* merge other overlapping intervals */
struct roots *other;
for (i++; i < n_root_sets; i++) {
other = GC_static_roots + i;
b = other -> r_start;
e = other -> r_end;
if ((word)b <= (word)old->r_end
&& (word)e >= (word)old->r_start) {
if ((word)b < (word)old->r_start) {
GC_root_size += old->r_start - b;
old -> r_start = b;
}
if ((word)e > (word)old->r_end) {
GC_root_size += e - old->r_end;
old -> r_end = e;
}
old -> r_tmp &= other -> r_tmp;
/* Delete this entry. */
GC_root_size -= (other -> r_end - other -> r_start);
other -> r_start = GC_static_roots[n_root_sets-1].r_start;
other -> r_end = GC_static_roots[n_root_sets-1].r_end;
n_root_sets--;
}
}
return;
}
}
# else
{
struct roots * old = (struct roots *)GC_roots_present(b);
if (old != 0) {
if ((word)e <= (word)old->r_end) {
old -> r_tmp &= tmp;
return; /* already there */
}
if (old -> r_tmp == tmp || !tmp) {
/* Extend the existing root. */
GC_root_size += e - old -> r_end;
old -> r_end = e;
old -> r_tmp = tmp;
return;
}
b = old -> r_end;
}
}
# endif
if (n_root_sets == MAX_ROOT_SETS) {
ABORT("Too many root sets");
}
/* Should only be called when the lock is held */
STATIC void GC_remove_roots_inner(ptr_t b, ptr_t e)
{
int i;
# if !defined(MSWIN32) && !defined(MSWINCE) && !defined(CYGWIN32)
int old_n_roots = n_root_sets;
# endif
for (i = 0; i < n_root_sets; ) {
if ((word)GC_static_roots[i].r_start >= (word)b
&& (word)GC_static_roots[i].r_end <= (word)e) {
GC_remove_root_at_pos(i);
} else {
i++;
}
}
# if !defined(MSWIN32) && !defined(MSWINCE) && !defined(CYGWIN32)
if (n_root_sets < old_n_roots)
GC_rebuild_root_index();
# endif
}
#ifdef USE_PROC_FOR_LIBRARIES
/* Exchange the elements of the roots table. Requires rebuild of */
/* the roots index table after the swap. */
GC_INLINE void swap_static_roots(int i, int j)
{
ptr_t r_start = GC_static_roots[i].r_start;
ptr_t r_end = GC_static_roots[i].r_end;
GC_bool r_tmp = GC_static_roots[i].r_tmp;
GC_static_roots[i].r_start = GC_static_roots[j].r_start;
GC_static_roots[i].r_end = GC_static_roots[j].r_end;
GC_static_roots[i].r_tmp = GC_static_roots[j].r_tmp;
/* No need to swap r_next values. */
GC_static_roots[j].r_start = r_start;
GC_static_roots[j].r_end = r_end;
GC_static_roots[j].r_tmp = r_tmp;
}
/* Remove given range from every static root which intersects with */
/* the range. It is assumed GC_remove_tmp_roots is called before */
/* this function is called repeatedly by GC_register_map_entries. */
GC_INNER void GC_remove_roots_subregion(ptr_t b, ptr_t e)
{
int i;
GC_bool rebuild = FALSE;
GC_ASSERT(I_HOLD_LOCK());
GC_ASSERT((word)b % sizeof(word) == 0 && (word)e % sizeof(word) == 0);
for (i = 0; i < n_root_sets; i++) {
ptr_t r_start, r_end;
if (GC_static_roots[i].r_tmp) {
/* The remaining roots are skipped as they are all temporary. */
# ifdef GC_ASSERTIONS
int j;
for (j = i + 1; j < n_root_sets; j++) {
GC_ASSERT(GC_static_roots[j].r_tmp);
}
# endif
break;
}
r_start = GC_static_roots[i].r_start;
r_end = GC_static_roots[i].r_end;
if (!EXPECT((word)e <= (word)r_start || (word)r_end <= (word)b, TRUE)) {
# ifdef DEBUG_ADD_DEL_ROOTS
GC_log_printf("Removing %p .. %p from root section %d (%p .. %p)\n",
(void *)b, (void *)e,
i, (void *)r_start, (void *)r_end);
# endif
if ((word)r_start < (word)b) {
GC_root_size -= r_end - b;
GC_static_roots[i].r_end = b;
/* No need to rebuild as hash does not use r_end value. */
if ((word)e < (word)r_end) {
int j;
if (rebuild) {
GC_rebuild_root_index();
rebuild = FALSE;
}
GC_add_roots_inner(e, r_end, FALSE); /* updates n_root_sets */
for (j = i + 1; j < n_root_sets; j++)
if (GC_static_roots[j].r_tmp)
break;
if (j < n_root_sets-1 && !GC_static_roots[n_root_sets-1].r_tmp) {
/* Exchange the roots to have all temporary ones at the end. */
swap_static_roots(j, n_root_sets - 1);
rebuild = TRUE;
}
}
} else {
if ((word)e < (word)r_end) {
GC_root_size -= e - r_start;
GC_static_roots[i].r_start = e;
} else {
GC_remove_root_at_pos(i);
if (i < n_root_sets - 1 && GC_static_roots[i].r_tmp
&& !GC_static_roots[i + 1].r_tmp) {
int j;
for (j = i + 2; j < n_root_sets; j++)
if (GC_static_roots[j].r_tmp)
break;
/* Exchange the roots to have all temporary ones at the end. */
swap_static_roots(i, j - 1);
}
i--;
}
rebuild = TRUE;
}
}
}
if (rebuild)
GC_rebuild_root_index();
}
#endif /* USE_PROC_FOR_LIBRARIES */
#if !defined(NO_DEBUGGING)
/* For the debugging purpose only. */
/* Workaround for the OS mapping and unmapping behind our back: */
/* Is the address p in one of the temporary static root sections? */
GC_API int GC_CALL GC_is_tmp_root(void *p)
{
static int last_root_set = MAX_ROOT_SETS;
int i;
if (last_root_set < n_root_sets
&& (word)p >= (word)GC_static_roots[last_root_set].r_start
&& (word)p < (word)GC_static_roots[last_root_set].r_end)
return GC_static_roots[last_root_set].r_tmp;
for (i = 0; i < n_root_sets; i++) {
if ((word)p >= (word)GC_static_roots[i].r_start
&& (word)p < (word)GC_static_roots[i].r_end) {
last_root_set = i;
return GC_static_roots[i].r_tmp;
}
}
return(FALSE);
}
#endif /* !NO_DEBUGGING */
GC_INNER ptr_t GC_approx_sp(void)
{
volatile word sp;
# if ((defined(E2K) && defined(__clang__)) \
|| (defined(S390) && (__clang_major__ < 8))) && !defined(CPPCHECK)
/* Workaround some bugs in clang: */
/* "undefined reference to llvm.frameaddress" error (clang-9/e2k); */
/* a crash in SystemZTargetLowering of libLLVM-3.8 (S390). */
sp = (word)&sp;
# elif defined(CPPCHECK) || (__GNUC__ >= 4 /* GC_GNUC_PREREQ(4, 0) */ \
&& !defined(STACK_NOT_SCANNED))
/* TODO: Use GC_GNUC_PREREQ after fixing a bug in cppcheck. */
sp = (word)__builtin_frame_address(0);
# else
sp = (word)&sp;
# endif
/* Also force stack to grow if necessary. Otherwise the */
/* later accesses might cause the kernel to think we're */
/* doing something wrong. */
return((ptr_t)sp);
}
/*
* Data structure for excluded static roots.
* Real declaration is in gc_priv.h.
/* Return the first exclusion range that includes an address >= start_addr */
/* Assumes the exclusion table contains at least one entry (namely the */
/* GC data structures). */
STATIC struct exclusion * GC_next_exclusion(ptr_t start_addr)
{
size_t low = 0;
size_t high;
/* low <= mid < high */
if ((word) GC_excl_table[mid].e_end <= (word) start_addr) {
low = mid + 1;
} else {
high = mid;
}
}
if ((word) GC_excl_table[low].e_end <= (word) start_addr) return 0;
return GC_excl_table + low;
}
/* Should only be called when the lock is held. The range boundaries */
/* should be properly aligned and valid. */
GC_INNER void GC_exclude_static_roots_inner(void *start, void *finish)
{
struct exclusion * next;
size_t next_index;
/* Round boundaries (in direction reverse to that of GC_add_roots). */
b = (void *)((word)b & ~(word)(sizeof(word) - 1));
e = (void *)(((word)e + (sizeof(word) - 1)) & ~(word)(sizeof(word) - 1));
if (NULL == e)
e = (void *)(~(word)(sizeof(word) - 1)); /* handle overflow */
/* Similar to GC_push_all_eager, but only the */
/* part hotter than cold_gc_frame is scanned */
/* immediately. Needed to ensure that callee- */
/* save registers are not missed. */
/*
* A version of GC_push_all that treats all interior pointers as valid
* and scans part of the area immediately, to make sure that saved
* register values are not lost.
* Cold_gc_frame delimits the stack section that must be scanned
* eagerly. A zero value indicates that no eager scanning is needed.
* We don't need to worry about the manual VDB case here, since this
* is only called in the single-threaded case. We assume that we
* cannot collect between an assignment and the corresponding
* GC_dirty() call.
*/
STATIC void GC_push_all_stack_partially_eager(ptr_t bottom, ptr_t top,
ptr_t cold_gc_frame)
{
#ifndef NEED_FIXUP_POINTER
if (GC_all_interior_pointers) {
/* Push the hot end of the stack eagerly, so that register values */
/* saved inside GC frames are marked before they disappear. */
/* The rest of the marking can be deferred until later. */
if (0 == cold_gc_frame) {
GC_push_all_stack(bottom, top);
return;
}
GC_ASSERT((word)bottom <= (word)cold_gc_frame
&& (word)cold_gc_frame <= (word)top);
# ifdef STACK_GROWS_DOWN
GC_push_all(cold_gc_frame - sizeof(ptr_t), top);
GC_push_all_eager(bottom, cold_gc_frame);
# else /* STACK_GROWS_UP */
GC_push_all(bottom, cold_gc_frame + sizeof(ptr_t));
GC_push_all_eager(cold_gc_frame, top);
# endif /* STACK_GROWS_UP */
} else
#endif
/* else */ {
GC_push_all_eager(bottom, top);
}
# ifdef TRACE_BUF
GC_add_trace_entry("GC_push_all_stack", (word)bottom, (word)top);
# endif
}
/* Similar to GC_push_all_stack_sections() but also uses cold_gc_frame. */
STATIC void GC_push_all_stack_part_eager_sections(
ptr_t lo /* top */, ptr_t hi /* bottom */, ptr_t cold_gc_frame,
struct GC_traced_stack_sect_s *traced_stack_sect)
{
GC_ASSERT(traced_stack_sect == NULL || cold_gc_frame == NULL ||
(word)cold_gc_frame HOTTER_THAN (word)traced_stack_sect);
while (traced_stack_sect != NULL) {
GC_ASSERT((word)lo HOTTER_THAN (word)traced_stack_sect);
# ifdef STACK_GROWS_UP
GC_push_all_stack_partially_eager((ptr_t)traced_stack_sect, lo,
cold_gc_frame);
# else /* STACK_GROWS_DOWN */
GC_push_all_stack_partially_eager(lo, (ptr_t)traced_stack_sect,
cold_gc_frame);
# endif
lo = traced_stack_sect -> saved_stack_ptr;
GC_ASSERT(lo != NULL);
traced_stack_sect = traced_stack_sect -> prev;
cold_gc_frame = NULL; /* Use at most once. */
}
/* Push enough of the current stack eagerly to ensure that callee-save */
/* registers saved in GC frames are scanned. In the non-threads case, */
/* schedule entire stack for scanning. The 2nd argument is a pointer */
/* to the (possibly null) thread context, for (currently hypothetical) */
/* more precise stack scanning. In the presence of threads, push */
/* enough of the current stack to ensure that callee-save registers */
/* saved in collector frames have been seen. */
/* TODO: Merge it with per-thread stuff. */
STATIC void GC_push_current_stack(ptr_t cold_gc_frame,
void * context GC_ATTR_UNUSED)
{
# if defined(THREADS)
/* cold_gc_frame is non-NULL. */
# ifdef STACK_GROWS_DOWN
GC_push_all_eager(GC_approx_sp(), cold_gc_frame);
/* For IA64, the register stack backing store is handled */
/* in the thread-specific code. */
# else
GC_push_all_eager(cold_gc_frame, GC_approx_sp());
# endif
# else
GC_push_all_stack_part_eager_sections(GC_approx_sp(), GC_stackbottom,
cold_gc_frame, GC_traced_stack_sect);
# ifdef IA64
/* We also need to push the register stack backing store. */
/* This should really be done in the same way as the */
/* regular stack. For now we fudge it a bit. */
/* Note that the backing store grows up, so we can't use */
/* GC_push_all_stack_partially_eager. */
{
ptr_t bsp = GC_save_regs_ret_val;
ptr_t cold_gc_bs_pointer = bsp - 2048;
if (GC_all_interior_pointers
&& (word)cold_gc_bs_pointer > (word)BACKING_STORE_BASE) {
/* Adjust cold_gc_bs_pointer if below our innermost */
/* "traced stack section" in backing store. */
if (GC_traced_stack_sect != NULL
&& (word)cold_gc_bs_pointer
< (word)GC_traced_stack_sect->backing_store_end)
cold_gc_bs_pointer =
GC_traced_stack_sect->backing_store_end;
GC_push_all_register_sections(BACKING_STORE_BASE,
cold_gc_bs_pointer, FALSE, GC_traced_stack_sect);
GC_push_all_eager(cold_gc_bs_pointer, bsp);
} else {
GC_push_all_register_sections(BACKING_STORE_BASE, bsp,
TRUE /* eager */, GC_traced_stack_sect);
}
/* All values should be sufficiently aligned that we */
/* don't have to worry about the boundary. */
}
# elif defined(E2K)
/* We also need to push procedure stack store. */
/* Procedure stack grows up. */
{
ptr_t bs_lo;
size_t stack_size;
STATIC void GC_push_regs_and_stack(ptr_t cold_gc_frame)
{
# ifdef THREADS
if (NULL == cold_gc_frame)
return; /* GC_push_all_stacks should push registers and stack */
# endif
GC_with_callee_saves_pushed(GC_push_current_stack, cold_gc_frame);
}
/* Call the mark routines (GC_push_one for a single pointer, */
/* GC_push_conditional on groups of pointers) on every top level */
/* accessible pointer. If all is false, arrange to push only possibly */
/* altered values. Cold_gc_frame is an address inside a GC frame that */
/* remains valid until all marking is complete; a NULL value indicates */
/* that it is OK to miss some register values. Called with the */
/* allocation lock held. */
GC_INNER void GC_push_roots(GC_bool all, ptr_t cold_gc_frame GC_ATTR_UNUSED)
{
int i;
unsigned kind;
/* Next push static data. This must happen early on, since it is */
/* not robust against mark stack overflow. */
/* Re-register dynamic libraries, in case one got added. */
/* There is some argument for doing this as late as possible, */
/* especially on Win32, where it can change asynchronously. */
/* In those cases, we do it here. But on other platforms, it's */
/* not safe with the world stopped, so we do it earlier. */
# if !defined(REGISTER_LIBRARIES_EARLY)
GC_cond_register_dynamic_libraries();
# endif
/* Mark everything in static data areas. */
for (i = 0; i < n_root_sets; i++) {
GC_push_conditional_with_exclusions(
GC_static_roots[i].r_start,
GC_static_roots[i].r_end, all);
}
/* Mark all free list header blocks, if those were allocated from */
/* the garbage collected heap. This makes sure they don't */
/* disappear if we are not marking from static data. It also */
/* saves us the trouble of scanning them, and possibly that of */
/* marking the freelists. */
for (kind = 0; kind < GC_n_kinds; kind++) {
void *base = GC_base(GC_obj_kinds[kind].ok_freelist);
if (base != NULL) {
GC_set_mark_bit(base);
}
}
/* Mark from GC internal roots if those might otherwise have */
/* been excluded. */
# ifndef GC_NO_FINALIZATION
GC_push_finalizer_structures();
# endif
# ifdef THREADS
if (GC_no_dls || GC_roots_were_cleared)
GC_push_thread_structures();
# endif
if (GC_push_typed_structures)
GC_push_typed_structures();
/* Mark thread local free lists, even if their mark */
/* descriptor excludes the link field. */
/* If the world is not stopped, this is unsafe. It is */
/* also unnecessary, since we will do this again with the */
/* world stopped. */
# if defined(THREAD_LOCAL_ALLOC)
if (GC_world_stopped)
GC_mark_thread_local_free_lists();
# endif
/* Now traverse stacks, and mark from register contents. */
/* These must be done last, since they can legitimately */
/* overflow the mark stack. This is usually done by saving */
/* the current context on the stack, and then just tracing */
/* from the stack. */
# ifndef STACK_NOT_SCANNED
GC_push_regs_and_stack(cold_gc_frame);
# endif
if (GC_push_other_roots != 0) {
/* In the threads case, this also pushes thread stacks. */
/* Note that without interior pointer recognition lots */
/* of stuff may have been pushed already, and this */
/* should be careful about mark stack overflows. */
(*GC_push_other_roots)();
}
}
