plt.c revision 2a61d19bd244dadcde5009f1632cf14b95623e3d 
1#include <gelf.h>
2#include "common.h"
3
4/* A bundle is 128 bits */
5#define BUNDLE_SIZE 16
6
7/*
8
9  The PLT has
10
11  ] 3 bundles as a header
12
13  ] The special reserved entry
14
15  ] Following that, each PLT entry has it's initial code that the GOT entry
16    points to.  Each PLT entry has one bundle allocated.
17
18  ] Following that, each PLT entry has two bundles of actual PLT code,
19    i.e. load up the address from the GOT and jump to it.  This is the
20    point we want to insert the breakpoint, as this will be captured
21    every time we jump to the PLT entry in the code.
22
23*/
24
25GElf_Addr
26arch_plt_sym_val(struct ltelf *lte, size_t ndx, GElf_Rela * rela) {
27	/* Find number of entires by removing header and special
28	 * entry, dividing total size by three, since each PLT entry
29	 * will have 3 bundles (1 for inital entry and two for the PLT
30	 * code). */
31	int entries = (lte->plt_size - 4 * BUNDLE_SIZE) / (3 * BUNDLE_SIZE);
32
33	/* Now the point we want to break on is the PLT entry after
34	 * all the header stuff */
35	unsigned long addr =
36	    lte->plt_addr + (4 * BUNDLE_SIZE) + (BUNDLE_SIZE * entries) +
37	    (2 * ndx * BUNDLE_SIZE);
38	debug(3, "Found PLT %d entry at %lx\n", ndx, addr);
39
40	return addr;
41}
42
43void *
44sym2addr(Process *proc, struct library_symbol *sym) {
45	return sym->enter_addr;
46}
47