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Add a postinit debugger hook to rtld. This will be used by dtrace(1) to halt

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the victim process before its entry point is called, at which point probes
and DOF data are registered with the kernel. The r_debug_state hook cannot
be used for this purpose, as it is called before the program's init routines
are invoked and in particular before DOF data is registered (via drti.o).

Reviewed by:	kib
MFC after:	2 weeks
This commit is contained in:
Mark Johnston 2014-05-06 18:07:58 +00:00
parent 4aa74d8b65
commit a8509eb20e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=265456
2 changed files with 16 additions and 0 deletions
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1
libexec/rtld-elf/Symbol.map
View File

@ -30,4 +30,5 @@ FBSDprivate_1.0 {
_rtld_atfork_post;
_rtld_addr_phdr;
_rtld_get_stack_prot;
_rtld_debug_postinit;
};

15
libexec/rtld-elf/rtld.c
View File

@ -162,6 +162,7 @@ static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
const unsigned long);
void r_debug_state(struct r_debug *, struct link_map *) __noinline;
void _r_debug_postinit(struct link_map *) __noinline;
/*
* Data declarations.
@ -637,6 +638,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
if (obj_main->crt_no_init)
preinit_main();
objlist_call_init(&initlist, &lockstate);
_r_debug_postinit(&obj_main->linkmap);
objlist_clear(&initlist);
dbg("loading filtees");
for (obj = obj_list->next; obj != NULL; obj = obj->next) {
@ -3552,6 +3554,19 @@ r_debug_state(struct r_debug* rd, struct link_map *m)
__asm __volatile("" : : : "memory");
}
/*
* A function called after init routines have completed. This can be used to
* break before a program's entry routine is called, and can be used when
* main is not available in the symbol table.
*/
void
_r_debug_postinit(struct link_map *m)
{
/* See r_debug_state(). */
__asm __volatile("" : : : "memory");
}
/*
* Get address of the pointer variable in the main program.
* Prefer non-weak symbol over the weak one.