server-skynet-source-3rd-je.../include/jemalloc/internal/ehooks.h

413 lines
14 KiB
C

#ifndef JEMALLOC_INTERNAL_EHOOKS_H
#define JEMALLOC_INTERNAL_EHOOKS_H
#include "jemalloc/internal/atomic.h"
#include "jemalloc/internal/extent_mmap.h"
/*
* This module is the internal interface to the extent hooks (both
* user-specified and external). Eventually, this will give us the flexibility
* to use multiple different versions of user-visible extent-hook APIs under a
* single user interface.
*
* Current API expansions (not available to anyone but the default hooks yet):
* - Head state tracking. Hooks can decide whether or not to merge two
* extents based on whether or not one of them is the head (i.e. was
* allocated on its own). The later extent loses its "head" status.
*/
extern const extent_hooks_t ehooks_default_extent_hooks;
typedef struct ehooks_s ehooks_t;
struct ehooks_s {
/*
* The user-visible id that goes with the ehooks (i.e. that of the base
* they're a part of, the associated arena's index within the arenas
* array).
*/
unsigned ind;
/* Logically an extent_hooks_t *. */
atomic_p_t ptr;
};
extern const extent_hooks_t ehooks_default_extent_hooks;
/*
* These are not really part of the public API. Each hook has a fast-path for
* the default-hooks case that can avoid various small inefficiencies:
* - Forgetting tsd and then calling tsd_get within the hook.
* - Getting more state than necessary out of the extent_t.
* - Doing arena_ind -> arena -> arena_ind lookups.
* By making the calls to these functions visible to the compiler, it can move
* those extra bits of computation down below the fast-paths where they get ignored.
*/
void *ehooks_default_alloc_impl(tsdn_t *tsdn, void *new_addr, size_t size,
size_t alignment, bool *zero, bool *commit, unsigned arena_ind);
bool ehooks_default_dalloc_impl(void *addr, size_t size);
void ehooks_default_destroy_impl(void *addr, size_t size);
bool ehooks_default_commit_impl(void *addr, size_t offset, size_t length);
bool ehooks_default_decommit_impl(void *addr, size_t offset, size_t length);
#ifdef PAGES_CAN_PURGE_LAZY
bool ehooks_default_purge_lazy_impl(void *addr, size_t offset, size_t length);
#endif
#ifdef PAGES_CAN_PURGE_FORCED
bool ehooks_default_purge_forced_impl(void *addr, size_t offset, size_t length);
#endif
bool ehooks_default_split_impl(void);
/*
* Merge is the only default extent hook we declare -- see the comment in
* ehooks_merge.
*/
bool ehooks_default_merge(extent_hooks_t *extent_hooks, void *addr_a,
size_t size_a, void *addr_b, size_t size_b, bool committed,
unsigned arena_ind);
bool ehooks_default_merge_impl(tsdn_t *tsdn, void *addr_a, void *addr_b);
void ehooks_default_zero_impl(void *addr, size_t size);
void ehooks_default_guard_impl(void *guard1, void *guard2);
void ehooks_default_unguard_impl(void *guard1, void *guard2);
/*
* We don't officially support reentrancy from wtihin the extent hooks. But
* various people who sit within throwing distance of the jemalloc team want
* that functionality in certain limited cases. The default reentrancy guards
* assert that we're not reentrant from a0 (since it's the bootstrap arena,
* where reentrant allocations would be redirected), which we would incorrectly
* trigger in cases where a0 has extent hooks (those hooks themselves can't be
* reentrant, then, but there are reasonable uses for such functionality, like
* putting internal metadata on hugepages). Therefore, we use the raw
* reentrancy guards.
*
* Eventually, we need to think more carefully about whether and where we
* support allocating from within extent hooks (and what that means for things
* like profiling, stats collection, etc.), and document what the guarantee is.
*/
static inline void
ehooks_pre_reentrancy(tsdn_t *tsdn) {
tsd_t *tsd = tsdn_null(tsdn) ? tsd_fetch() : tsdn_tsd(tsdn);
tsd_pre_reentrancy_raw(tsd);
}
static inline void
ehooks_post_reentrancy(tsdn_t *tsdn) {
tsd_t *tsd = tsdn_null(tsdn) ? tsd_fetch() : tsdn_tsd(tsdn);
tsd_post_reentrancy_raw(tsd);
}
/* Beginning of the public API. */
void ehooks_init(ehooks_t *ehooks, extent_hooks_t *extent_hooks, unsigned ind);
static inline unsigned
ehooks_ind_get(const ehooks_t *ehooks) {
return ehooks->ind;
}
static inline void
ehooks_set_extent_hooks_ptr(ehooks_t *ehooks, extent_hooks_t *extent_hooks) {
atomic_store_p(&ehooks->ptr, extent_hooks, ATOMIC_RELEASE);
}
static inline extent_hooks_t *
ehooks_get_extent_hooks_ptr(ehooks_t *ehooks) {
return (extent_hooks_t *)atomic_load_p(&ehooks->ptr, ATOMIC_ACQUIRE);
}
static inline bool
ehooks_are_default(ehooks_t *ehooks) {
return ehooks_get_extent_hooks_ptr(ehooks) ==
&ehooks_default_extent_hooks;
}
/*
* In some cases, a caller needs to allocate resources before attempting to call
* a hook. If that hook is doomed to fail, this is wasteful. We therefore
* include some checks for such cases.
*/
static inline bool
ehooks_dalloc_will_fail(ehooks_t *ehooks) {
if (ehooks_are_default(ehooks)) {
return opt_retain;
} else {
return ehooks_get_extent_hooks_ptr(ehooks)->dalloc == NULL;
}
}
static inline bool
ehooks_split_will_fail(ehooks_t *ehooks) {
return ehooks_get_extent_hooks_ptr(ehooks)->split == NULL;
}
static inline bool
ehooks_merge_will_fail(ehooks_t *ehooks) {
return ehooks_get_extent_hooks_ptr(ehooks)->merge == NULL;
}
static inline bool
ehooks_guard_will_fail(ehooks_t *ehooks) {
/*
* Before the guard hooks are officially introduced, limit the use to
* the default hooks only.
*/
return !ehooks_are_default(ehooks);
}
/*
* Some hooks are required to return zeroed memory in certain situations. In
* debug mode, we do some heuristic checks that they did what they were supposed
* to.
*
* This isn't really ehooks-specific (i.e. anyone can check for zeroed memory).
* But incorrect zero information indicates an ehook bug.
*/
static inline void
ehooks_debug_zero_check(void *addr, size_t size) {
assert(((uintptr_t)addr & PAGE_MASK) == 0);
assert((size & PAGE_MASK) == 0);
assert(size > 0);
if (config_debug) {
/* Check the whole first page. */
size_t *p = (size_t *)addr;
for (size_t i = 0; i < PAGE / sizeof(size_t); i++) {
assert(p[i] == 0);
}
/*
* And 4 spots within. There's a tradeoff here; the larger
* this number, the more likely it is that we'll catch a bug
* where ehooks return a sparsely non-zero range. But
* increasing the number of checks also increases the number of
* page faults in debug mode. FreeBSD does much of their
* day-to-day development work in debug mode, so we don't want
* even the debug builds to be too slow.
*/
const size_t nchecks = 4;
assert(PAGE >= sizeof(size_t) * nchecks);
for (size_t i = 0; i < nchecks; ++i) {
assert(p[i * (size / sizeof(size_t) / nchecks)] == 0);
}
}
}
static inline void *
ehooks_alloc(tsdn_t *tsdn, ehooks_t *ehooks, void *new_addr, size_t size,
size_t alignment, bool *zero, bool *commit) {
bool orig_zero = *zero;
void *ret;
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
ret = ehooks_default_alloc_impl(tsdn, new_addr, size,
alignment, zero, commit, ehooks_ind_get(ehooks));
} else {
ehooks_pre_reentrancy(tsdn);
ret = extent_hooks->alloc(extent_hooks, new_addr, size,
alignment, zero, commit, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
}
assert(new_addr == NULL || ret == NULL || new_addr == ret);
assert(!orig_zero || *zero);
if (*zero && ret != NULL) {
ehooks_debug_zero_check(ret, size);
}
return ret;
}
static inline bool
ehooks_dalloc(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
bool committed) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
return ehooks_default_dalloc_impl(addr, size);
} else if (extent_hooks->dalloc == NULL) {
return true;
} else {
ehooks_pre_reentrancy(tsdn);
bool err = extent_hooks->dalloc(extent_hooks, addr, size,
committed, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
return err;
}
}
static inline void
ehooks_destroy(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
bool committed) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
ehooks_default_destroy_impl(addr, size);
} else if (extent_hooks->destroy == NULL) {
/* Do nothing. */
} else {
ehooks_pre_reentrancy(tsdn);
extent_hooks->destroy(extent_hooks, addr, size, committed,
ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
}
}
static inline bool
ehooks_commit(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
size_t offset, size_t length) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
bool err;
if (extent_hooks == &ehooks_default_extent_hooks) {
err = ehooks_default_commit_impl(addr, offset, length);
} else if (extent_hooks->commit == NULL) {
err = true;
} else {
ehooks_pre_reentrancy(tsdn);
err = extent_hooks->commit(extent_hooks, addr, size,
offset, length, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
}
if (!err) {
ehooks_debug_zero_check(addr, size);
}
return err;
}
static inline bool
ehooks_decommit(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
size_t offset, size_t length) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
return ehooks_default_decommit_impl(addr, offset, length);
} else if (extent_hooks->decommit == NULL) {
return true;
} else {
ehooks_pre_reentrancy(tsdn);
bool err = extent_hooks->decommit(extent_hooks, addr, size,
offset, length, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
return err;
}
}
static inline bool
ehooks_purge_lazy(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
size_t offset, size_t length) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
#ifdef PAGES_CAN_PURGE_LAZY
if (extent_hooks == &ehooks_default_extent_hooks) {
return ehooks_default_purge_lazy_impl(addr, offset, length);
}
#endif
if (extent_hooks->purge_lazy == NULL) {
return true;
} else {
ehooks_pre_reentrancy(tsdn);
bool err = extent_hooks->purge_lazy(extent_hooks, addr, size,
offset, length, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
return err;
}
}
static inline bool
ehooks_purge_forced(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
size_t offset, size_t length) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
/*
* It would be correct to have a ehooks_debug_zero_check call at the end
* of this function; purge_forced is required to zero. But checking
* would touch the page in question, which may have performance
* consequences (imagine the hooks are using hugepages, with a global
* zero page off). Even in debug mode, it's usually a good idea to
* avoid cases that can dramatically increase memory consumption.
*/
#ifdef PAGES_CAN_PURGE_FORCED
if (extent_hooks == &ehooks_default_extent_hooks) {
return ehooks_default_purge_forced_impl(addr, offset, length);
}
#endif
if (extent_hooks->purge_forced == NULL) {
return true;
} else {
ehooks_pre_reentrancy(tsdn);
bool err = extent_hooks->purge_forced(extent_hooks, addr, size,
offset, length, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
return err;
}
}
static inline bool
ehooks_split(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
size_t size_a, size_t size_b, bool committed) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (ehooks_are_default(ehooks)) {
return ehooks_default_split_impl();
} else if (extent_hooks->split == NULL) {
return true;
} else {
ehooks_pre_reentrancy(tsdn);
bool err = extent_hooks->split(extent_hooks, addr, size, size_a,
size_b, committed, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
return err;
}
}
static inline bool
ehooks_merge(tsdn_t *tsdn, ehooks_t *ehooks, void *addr_a, size_t size_a,
void *addr_b, size_t size_b, bool committed) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
return ehooks_default_merge_impl(tsdn, addr_a, addr_b);
} else if (extent_hooks->merge == NULL) {
return true;
} else {
ehooks_pre_reentrancy(tsdn);
bool err = extent_hooks->merge(extent_hooks, addr_a, size_a,
addr_b, size_b, committed, ehooks_ind_get(ehooks));
ehooks_post_reentrancy(tsdn);
return err;
}
}
static inline void
ehooks_zero(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
ehooks_default_zero_impl(addr, size);
} else {
/*
* It would be correct to try using the user-provided purge
* hooks (since they are required to have zeroed the extent if
* they indicate success), but we don't necessarily know their
* cost. We'll be conservative and use memset.
*/
memset(addr, 0, size);
}
}
static inline bool
ehooks_guard(tsdn_t *tsdn, ehooks_t *ehooks, void *guard1, void *guard2) {
bool err;
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
ehooks_default_guard_impl(guard1, guard2);
err = false;
} else {
err = true;
}
return err;
}
static inline bool
ehooks_unguard(tsdn_t *tsdn, ehooks_t *ehooks, void *guard1, void *guard2) {
bool err;
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
ehooks_default_unguard_impl(guard1, guard2);
err = false;
} else {
err = true;
}
return err;
}
#endif /* JEMALLOC_INTERNAL_EHOOKS_H */