5ae6e7cbfa
The hook module allows a low-reader-overhead way of finding hooks to invoke and calling them. For now, none of the allocation pathways are tied into the hooks; this will come later.
126 lines
3.9 KiB
C
126 lines
3.9 KiB
C
#ifndef JEMALLOC_INTERNAL_HOOK_H
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#define JEMALLOC_INTERNAL_HOOK_H
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#include "jemalloc/internal/tsd.h"
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/*
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* This API is *extremely* experimental, and may get ripped out, changed in API-
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* and ABI-incompatible ways, be insufficiently or incorrectly documented, etc.
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*
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* It allows hooking the stateful parts of the API to see changes as they
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* happen.
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*
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* Allocation hooks are called after the allocation is done, free hooks are
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* called before the free is done, and expand hooks are called after the
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* allocation is expanded.
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*
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* For realloc and rallocx, if the expansion happens in place, the expansion
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* hook is called. If it is moved, then the alloc hook is called on the new
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* location, and then the free hook is called on the old location.
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*
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* (We omit no-ops, like free(NULL), etc.).
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*
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* Reentrancy:
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* Is not protected against. If your hooks allocate, then the hooks will be
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* called again. Note that you can guard against this with a thread-local
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* "in_hook" bool.
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* Threading:
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* The installation of a hook synchronizes with all its uses. If you can
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* prove the installation of a hook happens-before a jemalloc entry point,
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* then the hook will get invoked (unless there's a racing removal).
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*
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* Hook insertion appears to be atomic at a per-thread level (i.e. if a thread
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* allocates and has the alloc hook invoked, then a subsequent free on the
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* same thread will also have the free hook invoked).
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*
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* The *removal* of a hook does *not* block until all threads are done with
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* the hook. Hook authors have to be resilient to this, and need some
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* out-of-band mechanism for cleaning up any dynamically allocated memory
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* associated with their hook.
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* Ordering:
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* Order of hook execution is unspecified, and may be different than insertion
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* order.
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*/
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enum hook_alloc_e {
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hook_alloc_malloc,
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hook_alloc_posix_memalign,
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hook_alloc_aligned_alloc,
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hook_alloc_calloc,
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hook_alloc_memalign,
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hook_alloc_valloc,
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hook_alloc_mallocx,
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/* The reallocating functions have both alloc and dalloc variants */
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hook_alloc_realloc,
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hook_alloc_rallocx,
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};
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/*
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* We put the enum typedef after the enum, since this file may get included by
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* jemalloc_cpp.cpp, and C++ disallows enum forward declarations.
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*/
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typedef enum hook_alloc_e hook_alloc_t;
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enum hook_dalloc_e {
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hook_dalloc_free,
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hook_dalloc_dallocx,
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hook_dalloc_sdallocx,
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/*
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* The dalloc halves of reallocation (not called if in-place expansion
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* happens).
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*/
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hook_dalloc_realloc,
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hook_dalloc_rallocx,
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};
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typedef enum hook_dalloc_e hook_dalloc_t;
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enum hook_expand_e {
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hook_expand_realloc,
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hook_expand_rallocx,
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hook_expand_xallocx,
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};
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typedef enum hook_expand_e hook_expand_t;
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typedef void (*hook_alloc)(
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void *extra, hook_alloc_t type, void *result, uintptr_t result_raw,
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uintptr_t args_raw[3]);
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typedef void (*hook_dalloc)(
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void *extra, hook_dalloc_t type, void *address, uintptr_t args_raw[3]);
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typedef void (*hook_expand)(
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void *extra, hook_expand_t type, void *address, size_t old_usize,
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size_t new_usize, uintptr_t result_raw, uintptr_t args_raw[4]);
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typedef struct hooks_s hooks_t;
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struct hooks_s {
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hook_alloc alloc_hook;
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hook_dalloc dalloc_hook;
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hook_expand expand_hook;
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};
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/*
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* Returns an opaque handle to be used when removing the hook. NULL means that
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* we couldn't install the hook.
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*/
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bool hook_boot();
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void *hook_install(tsdn_t *tsdn, hooks_t *hooks, void *extra);
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/* Uninstalls the hook with the handle previously returned from hook_install. */
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void hook_remove(tsdn_t *tsdn, void *opaque);
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/* Hooks */
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void hook_invoke_alloc(hook_alloc_t type, void *result, uintptr_t result_raw,
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uintptr_t args_raw[3]);
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void hook_invoke_dalloc(hook_dalloc_t type, void *address,
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uintptr_t args_raw[3]);
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void hook_invoke_expand(hook_expand_t type, void *address, size_t old_usize,
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size_t new_usize, uintptr_t result_raw, uintptr_t args_raw[4]);
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#endif /* JEMALLOC_INTERNAL_HOOK_H */
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