mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-21 04:31:04 +08:00
5d28a8962d
It can be used to speed up the libgcc unwinder, and the internal _dl_find_dso_for_object function (which is used for caller identification in dlopen and related functions, and in dladdr). _dl_find_object is in the internal namespace due to bug 28503. If libgcc switches to _dl_find_object, this namespace issue will be fixed. It is located in libc for two reasons: it is necessary to forward the call to the static libc after static dlopen, and there is a link ordering issue with -static-libgcc and libgcc_eh.a because libc.so is not a linker script that includes ld.so in the glibc build tree (so that GCC's internal -lc after libgcc_eh.a does not pick up ld.so). It is necessary to do the i386 customization in the sysdeps/x86/bits/dl_find_object.h header shared with x86-64 because otherwise, multilib installations are broken. The implementation uses software transactional memory, as suggested by Torvald Riegel. Two copies of the supporting data structures are used, also achieving full async-signal-safety. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
295 lines
14 KiB
Plaintext
295 lines
14 KiB
Plaintext
@node Internal Probes
|
|
@c @node Internal Probes, Tunables, Dynamic Linker, Top
|
|
@c %MENU% Probes to monitor libc internal behavior
|
|
@chapter Internal probes
|
|
|
|
In order to aid in debugging and monitoring internal behavior,
|
|
@theglibc{} exposes nearly-zero-overhead SystemTap probes marked with
|
|
the @code{libc} provider.
|
|
|
|
These probes are not part of the @glibcadj{} stable ABI, and they are
|
|
subject to change or removal across releases. Our only promise with
|
|
regard to them is that, if we find a need to remove or modify the
|
|
arguments of a probe, the modified probe will have a different name, so
|
|
that program monitors relying on the old probe will not get unexpected
|
|
arguments.
|
|
|
|
@menu
|
|
* Memory Allocation Probes:: Probes in the memory allocation subsystem
|
|
* Non-local Goto Probes:: Probes in setjmp and longjmp
|
|
@end menu
|
|
|
|
@node Memory Allocation Probes
|
|
@section Memory Allocation Probes
|
|
|
|
These probes are designed to signal relatively unusual situations within
|
|
the virtual memory subsystem of @theglibc{}.
|
|
|
|
@deftp Probe memory_sbrk_more (void *@var{$arg1}, size_t @var{$arg2})
|
|
This probe is triggered after the main arena is extended by calling
|
|
@code{sbrk}. Argument @var{$arg1} is the additional size requested to
|
|
@code{sbrk}, and @var{$arg2} is the pointer that marks the end of the
|
|
@code{sbrk} area, returned in response to the request.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_sbrk_less (void *@var{$arg1}, size_t @var{$arg2})
|
|
This probe is triggered after the size of the main arena is decreased by
|
|
calling @code{sbrk}. Argument @var{$arg1} is the size released by
|
|
@code{sbrk} (the positive value, rather than the negative value passed
|
|
to @code{sbrk}), and @var{$arg2} is the pointer that marks the end of
|
|
the @code{sbrk} area, returned in response to the request.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_heap_new (void *@var{$arg1}, size_t @var{$arg2})
|
|
This probe is triggered after a new heap is @code{mmap}ed. Argument
|
|
@var{$arg1} is a pointer to the base of the memory area, where the
|
|
@code{heap_info} data structure is held, and @var{$arg2} is the size of
|
|
the heap.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_heap_free (void *@var{$arg1}, size_t @var{$arg2})
|
|
This probe is triggered @emph{before} (unlike the other sbrk and heap
|
|
probes) a heap is completely removed via @code{munmap}. Argument
|
|
@var{$arg1} is a pointer to the heap, and @var{$arg2} is the size of the
|
|
heap.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_heap_more (void *@var{$arg1}, size_t @var{$arg2})
|
|
This probe is triggered after a trailing portion of an @code{mmap}ed
|
|
heap is extended. Argument @var{$arg1} is a pointer to the heap, and
|
|
@var{$arg2} is the new size of the heap.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_heap_less (void *@var{$arg1}, size_t @var{$arg2})
|
|
This probe is triggered after a trailing portion of an @code{mmap}ed
|
|
heap is released. Argument @var{$arg1} is a pointer to the heap, and
|
|
@var{$arg2} is the new size of the heap.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_malloc_retry (size_t @var{$arg1})
|
|
@deftpx Probe memory_realloc_retry (size_t @var{$arg1}, void *@var{$arg2})
|
|
@deftpx Probe memory_memalign_retry (size_t @var{$arg1}, size_t @var{$arg2})
|
|
@deftpx Probe memory_calloc_retry (size_t @var{$arg1})
|
|
These probes are triggered when the corresponding functions fail to
|
|
obtain the requested amount of memory from the arena in use, before they
|
|
call @code{arena_get_retry} to select an alternate arena in which to
|
|
retry the allocation. Argument @var{$arg1} is the amount of memory
|
|
requested by the user; in the @code{calloc} case, that is the total size
|
|
computed from both function arguments. In the @code{realloc} case,
|
|
@var{$arg2} is the pointer to the memory area being resized. In the
|
|
@code{memalign} case, @var{$arg2} is the alignment to be used for the
|
|
request, which may be stricter than the value passed to the
|
|
@code{memalign} function. A @code{memalign} probe is also used by functions
|
|
@code{posix_memalign, valloc} and @code{pvalloc}.
|
|
|
|
Note that the argument order does @emph{not} match that of the
|
|
corresponding two-argument functions, so that in all of these probes the
|
|
user-requested allocation size is in @var{$arg1}.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_arena_retry (size_t @var{$arg1}, void *@var{$arg2})
|
|
This probe is triggered within @code{arena_get_retry} (the function
|
|
called to select the alternate arena in which to retry an allocation
|
|
that failed on the first attempt), before the selection of an alternate
|
|
arena. This probe is redundant, but much easier to use when it's not
|
|
important to determine which of the various memory allocation functions
|
|
is failing to allocate on the first try. Argument @var{$arg1} is the
|
|
same as in the function-specific probes, except for extra room for
|
|
padding introduced by functions that have to ensure stricter alignment.
|
|
Argument @var{$arg2} is the arena in which allocation failed.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_arena_new (void *@var{$arg1}, size_t @var{$arg2})
|
|
This probe is triggered when @code{malloc} allocates and initializes an
|
|
additional arena (not the main arena), but before the arena is assigned
|
|
to the running thread or inserted into the internal linked list of
|
|
arenas. The arena's @code{malloc_state} internal data structure is
|
|
located at @var{$arg1}, within a newly-allocated heap big enough to hold
|
|
at least @var{$arg2} bytes.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_arena_reuse (void *@var{$arg1}, void *@var{$arg2})
|
|
This probe is triggered when @code{malloc} has just selected an existing
|
|
arena to reuse, and (temporarily) reserved it for exclusive use.
|
|
Argument @var{$arg1} is a pointer to the newly-selected arena, and
|
|
@var{$arg2} is a pointer to the arena previously used by that thread.
|
|
|
|
This occurs within
|
|
@code{reused_arena}, right after the mutex mentioned in probe
|
|
@code{memory_arena_reuse_wait} is acquired; argument @var{$arg1} will
|
|
point to the same arena. In this configuration, this will usually only
|
|
occur once per thread. The exception is when a thread first selected
|
|
the main arena, but a subsequent allocation from it fails: then, and
|
|
only then, may we switch to another arena to retry that allocation, and
|
|
for further allocations within that thread.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_arena_reuse_wait (void *@var{$arg1}, void *@var{$arg2}, void *@var{$arg3})
|
|
This probe is triggered when @code{malloc} is about to wait for an arena
|
|
to become available for reuse. Argument @var{$arg1} holds a pointer to
|
|
the mutex the thread is going to wait on, @var{$arg2} is a pointer to a
|
|
newly-chosen arena to be reused, and @var{$arg3} is a pointer to the
|
|
arena previously used by that thread.
|
|
|
|
This occurs within
|
|
@code{reused_arena}, when a thread first tries to allocate memory or
|
|
needs a retry after a failure to allocate from the main arena, there
|
|
isn't any free arena, the maximum number of arenas has been reached, and
|
|
an existing arena was chosen for reuse, but its mutex could not be
|
|
immediately acquired. The mutex in @var{$arg1} is the mutex of the
|
|
selected arena.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_arena_reuse_free_list (void *@var{$arg1})
|
|
This probe is triggered when @code{malloc} has chosen an arena that is
|
|
in the free list for use by a thread, within the @code{get_free_list}
|
|
function. The argument @var{$arg1} holds a pointer to the selected arena.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered when function @code{mallopt} is called to change
|
|
@code{malloc} internal configuration parameters, before any change to
|
|
the parameters is made. The arguments @var{$arg1} and @var{$arg2} are
|
|
the ones passed to the @code{mallopt} function.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_mxfast (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_MXFAST}, and the requested
|
|
value is in an acceptable range. Argument @var{$arg1} is the requested
|
|
value, and @var{$arg2} is the previous value of this @code{malloc}
|
|
parameter.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_trim_threshold (int @var{$arg1}, int @var{$arg2}, int @var{$arg3})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_TRIM_THRESHOLD}. Argument
|
|
@var{$arg1} is the requested value, @var{$arg2} is the previous value of
|
|
this @code{malloc} parameter, and @var{$arg3} is nonzero if dynamic
|
|
threshold adjustment was already disabled.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_top_pad (int @var{$arg1}, int @var{$arg2}, int @var{$arg3})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_TOP_PAD}. Argument
|
|
@var{$arg1} is the requested value, @var{$arg2} is the previous value of
|
|
this @code{malloc} parameter, and @var{$arg3} is nonzero if dynamic
|
|
threshold adjustment was already disabled.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_mmap_threshold (int @var{$arg1}, int @var{$arg2}, int @var{$arg3})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_MMAP_THRESHOLD}, and the
|
|
requested value is in an acceptable range. Argument @var{$arg1} is the
|
|
requested value, @var{$arg2} is the previous value of this @code{malloc}
|
|
parameter, and @var{$arg3} is nonzero if dynamic threshold adjustment
|
|
was already disabled.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_mmap_max (int @var{$arg1}, int @var{$arg2}, int @var{$arg3})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_MMAP_MAX}. Argument
|
|
@var{$arg1} is the requested value, @var{$arg2} is the previous value of
|
|
this @code{malloc} parameter, and @var{$arg3} is nonzero if dynamic
|
|
threshold adjustment was already disabled.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_perturb (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_PERTURB}. Argument
|
|
@var{$arg1} is the requested value, and @var{$arg2} is the previous
|
|
value of this @code{malloc} parameter.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_arena_test (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_ARENA_TEST}, and the
|
|
requested value is in an acceptable range. Argument @var{$arg1} is the
|
|
requested value, and @var{$arg2} is the previous value of this
|
|
@code{malloc} parameter.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_arena_max (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered shortly after the @code{memory_mallopt} probe,
|
|
when the parameter to be changed is @code{M_ARENA_MAX}, and the
|
|
requested value is in an acceptable range. Argument @var{$arg1} is the
|
|
requested value, and @var{$arg2} is the previous value of this
|
|
@code{malloc} parameter.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_mallopt_free_dyn_thresholds (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered when function @code{free} decides to adjust the
|
|
dynamic brk/mmap thresholds. Argument @var{$arg1} and @var{$arg2} are
|
|
the adjusted mmap and trim thresholds, respectively.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_tunable_tcache_max_bytes (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered when the @code{glibc.malloc.tcache_max}
|
|
tunable is set. Argument @var{$arg1} is the requested value, and
|
|
@var{$arg2} is the previous value of this tunable.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_tunable_tcache_count (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered when the @code{glibc.malloc.tcache_count}
|
|
tunable is set. Argument @var{$arg1} is the requested value, and
|
|
@var{$arg2} is the previous value of this tunable.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_tunable_tcache_unsorted_limit (int @var{$arg1}, int @var{$arg2})
|
|
This probe is triggered when the
|
|
@code{glibc.malloc.tcache_unsorted_limit} tunable is set. Argument
|
|
@var{$arg1} is the requested value, and @var{$arg2} is the previous
|
|
value of this tunable.
|
|
@end deftp
|
|
|
|
@deftp Probe memory_tcache_double_free (void *@var{$arg1}, int @var{$arg2})
|
|
This probe is triggered when @code{free} determines that the memory
|
|
being freed has probably already been freed, and resides in the
|
|
per-thread cache. Note that there is an extremely unlikely chance
|
|
that this probe will trigger due to random payload data remaining in
|
|
the allocated memory matching the key used to detect double frees.
|
|
This probe actually indicates that an expensive linear search of the
|
|
tcache, looking for a double free, has happened. Argument @var{$arg1}
|
|
is the memory location as passed to @code{free}, Argument @var{$arg2}
|
|
is the tcache bin it resides in.
|
|
@end deftp
|
|
|
|
@node Non-local Goto Probes
|
|
@section Non-local Goto Probes
|
|
|
|
These probes are used to signal calls to @code{setjmp}, @code{sigsetjmp},
|
|
@code{longjmp} or @code{siglongjmp}.
|
|
|
|
@deftp Probe setjmp (void *@var{$arg1}, int @var{$arg2}, void *@var{$arg3})
|
|
This probe is triggered whenever @code{setjmp} or @code{sigsetjmp} is
|
|
called. Argument @var{$arg1} is a pointer to the @code{jmp_buf}
|
|
passed as the first argument of @code{setjmp} or @code{sigsetjmp},
|
|
@var{$arg2} is the second argument of @code{sigsetjmp} or zero if this
|
|
is a call to @code{setjmp} and @var{$arg3} is a pointer to the return
|
|
address that will be stored in the @code{jmp_buf}.
|
|
@end deftp
|
|
|
|
@deftp Probe longjmp (void *@var{$arg1}, int @var{$arg2}, void *@var{$arg3})
|
|
This probe is triggered whenever @code{longjmp} or @code{siglongjmp}
|
|
is called. Argument @var{$arg1} is a pointer to the @code{jmp_buf}
|
|
passed as the first argument of @code{longjmp} or @code{siglongjmp},
|
|
@var{$arg2} is the return value passed as the second argument of
|
|
@code{longjmp} or @code{siglongjmp} and @var{$arg3} is a pointer to
|
|
the return address @code{longjmp} or @code{siglongjmp} will return to.
|
|
|
|
The @code{longjmp} probe is triggered at a point where the registers
|
|
have not yet been restored to the values in the @code{jmp_buf} and
|
|
unwinding will show a call stack including the caller of
|
|
@code{longjmp} or @code{siglongjmp}.
|
|
@end deftp
|
|
|
|
@deftp Probe longjmp_target (void *@var{$arg1}, int @var{$arg2}, void *@var{$arg3})
|
|
This probe is triggered under the same conditions and with the same
|
|
arguments as the @code{longjmp} probe.
|
|
|
|
The @code{longjmp_target} probe is triggered at a point where the
|
|
registers have been restored to the values in the @code{jmp_buf} and
|
|
unwinding will show a call stack including the caller of @code{setjmp}
|
|
or @code{sigsetjmp}.
|
|
@end deftp
|