diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/dlfcn.h | 4 | ||||
| -rw-r--r-- | include/libc-symbols.h | 83 | ||||
| -rw-r--r-- | include/set-hooks.h | 3 |
3 files changed, 78 insertions, 12 deletions
diff --git a/include/dlfcn.h b/include/dlfcn.h index c231309083..0dc57dbe22 100644 --- a/include/dlfcn.h +++ b/include/dlfcn.h @@ -155,6 +155,8 @@ extern void __libc_register_dl_open_hook (struct link_map *map) extern void __libc_register_dlfcn_hook (struct link_map *map) attribute_hidden; #endif -#endif +extern void __dlerror_main_freeres (void) attribute_hidden; + +#endif #endif diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 6137304b0b..8b9273c13a 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -217,16 +217,6 @@ static const char __evoke_link_warning_##symbol[] \ __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \ = msg; -#define libc_freeres_ptr(decl) \ - __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \ - decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment))) -#define __libc_freeres_fn_section \ - __attribute__ ((section ("__libc_freeres_fn"))) - -#define libc_freeres_fn(name) \ - static void name (void) __attribute_used__ __libc_freeres_fn_section; \ - text_set_element (__libc_subfreeres, name); \ - static void name (void) /* A canned warning for sysdeps/stub functions. */ #define stub_warning(name) \ @@ -244,6 +234,79 @@ requires at runtime the shared libraries from the glibc version used \ for linking") #endif +/* Resource Freeing Hooks: + + Normally a process exits and the OS cleans up any allocated + memory. However, when tooling like mtrace or valgrind is monitoring + the process we need to free all resources that are part of the + process in order to provide the consistency required to track + memory leaks. + + A single public API exists and is __libc_freeres(), and this is used + by applications like valgrind to freee resouces. + + There are 3 cases: + + (a) __libc_freeres + + In this case all you need to do is define the freeing routine: + + foo.c: + libfoo_freeres_fn (foo_freeres) + { + complex_free (mem); + } + + This ensures the function is called at the right point to free + resources. + + (b) __libc_freeres_ptr + + The framework for (a) iterates over the list of pointers-to-free + in (b) and frees them. + + foo.c: + libc_freeres_ptr (static char *foo_buffer); + + Freeing these resources alaways happens last and is equivalent + to registering a function that does 'free (foo_buffer)'. + + (c) Explicit lists of free routines to call or objects to free. + + It is the intended goal to remove (a) and (b) which have some + non-determinism based on link order, and instead use explicit + lists of functions and frees to resolve cleanup ordering issues + and make it easy to debug and maintain. + + As of today the following subsystems use (c): + + Per-thread cleanup: + * malloc/thread-freeres.c + + libdl cleanup: + * dlfcn/dlfreeres.c + + libpthread cleanup: + * nptl/nptlfreeres.c + + So if you need any shutdown routines to run you should add them + directly to the appropriate subsystem's shutdown list. */ + +/* Resource pointers to free in libc.so. */ +#define libc_freeres_ptr(decl) \ + __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \ + decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment))) + +/* Resource freeing functions from libc.so go in this section. */ +#define __libc_freeres_fn_section \ + __attribute__ ((section ("__libc_freeres_fn"))) + +/* Resource freeing functions for libc.so. */ +#define libc_freeres_fn(name) \ + static void name (void) __attribute_used__ __libc_freeres_fn_section; \ + text_set_element (__libc_subfreeres, name); \ + static void name (void) + /* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes alias to ORIGINAL, when the assembler supports such declarations (such as in ELF). diff --git a/include/set-hooks.h b/include/set-hooks.h index 0207656bb9..b3bd8b4092 100644 --- a/include/set-hooks.h +++ b/include/set-hooks.h @@ -22,11 +22,12 @@ #define __need_size_t #include <stddef.h> #include <sys/cdefs.h> +#include <libc-symbols.h> #ifdef symbol_set_define /* Define a hook variable called NAME. Functions put on this hook take arguments described by PROTO. Use `text_set_element (NAME, FUNCTION)' - from gnu-stabs.h to add a function to the hook. */ + from include/libc-symbols.h to add a function to the hook. */ # define DEFINE_HOOK(NAME, PROTO) \ typedef void __##NAME##_hook_function_t PROTO; \ |