mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-11-28 04:25:10 +08:00
93 lines
2.7 KiB
C
93 lines
2.7 KiB
C
/* Used by the elf ifunc tests. */
|
|
#ifndef ELF_IFUNC_SEL_H
|
|
#define ELF_IFUNC_SEL_H 1
|
|
|
|
extern int global;
|
|
|
|
static inline __attribute__ ((always_inline)) void *
|
|
ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
|
|
{
|
|
#ifdef __powerpc__
|
|
/* When generating PIC, powerpc gcc loads the address of "global"
|
|
from the GOT, but the GOT may not have been relocated.
|
|
Similarly, "f1", "f2" and "f3" may be loaded from non-relocated
|
|
GOT entries.
|
|
|
|
There is NO WAY to make this ill conceived IFUNC misfeature
|
|
reliably work on targets that use a GOT for function or variable
|
|
addresses, short of implementing two passes over relocations in
|
|
ld.so, with ifunc relocations being applied after all other
|
|
relocations, globally.
|
|
|
|
Cheat. Don't use the GOT. Rely on this function being inlined
|
|
and calculate all variable and function addresses relative to pc.
|
|
Using the 'X' constraint is risky, but that's the only way to
|
|
make the asm here see the function names for %4, %5 and %6.
|
|
Sadly, powerpc64 gcc doesn't accept use of %3 here with 'X' for
|
|
some reason, so we expand it ourselves. */
|
|
register void *ret __asm__ ("r3");
|
|
void *temp1, *temp2;
|
|
__asm__ ("mflr %1\n\t"
|
|
"bcl 20,31,1f\n"
|
|
"1:\tmflr %2\n\t"
|
|
"mtlr %1\n\t"
|
|
"addis %1,%2,global-1b@ha\n\t"
|
|
"lwz %1,global-1b@l(%1)\n\t"
|
|
"addis %0,%2,%4-1b@ha\n\t"
|
|
"addi %0,%0,%4-1b@l\n\t"
|
|
"cmpwi %1,1\n\t"
|
|
"beqlr\n\t"
|
|
"addis %0,%2,%5-1b@ha\n\t"
|
|
"addi %0,%0,%5-1b@l\n\t"
|
|
"cmpwi %1,-1\n\t"
|
|
"beqlr\n\t"
|
|
"addis %0,%2,%6-1b@ha\n\t"
|
|
"addi %0,%0,%6-1b@l"
|
|
: "=&b" (ret), "=&b" (temp1), "=&b" (temp2)
|
|
: "X" (&global), "X" (f1), "X" (f2), "X" (f3));
|
|
return ret;
|
|
#else
|
|
switch (global)
|
|
{
|
|
case 1:
|
|
return f1;
|
|
case -1:
|
|
return f2;
|
|
default:
|
|
return f3;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static inline __attribute__ ((always_inline)) void *
|
|
ifunc_one (int (*f1) (void))
|
|
{
|
|
#ifdef __powerpc__
|
|
/* As above, PIC may use an unrelocated GOT entry for f1.
|
|
|
|
Case study: ifuncmain6pie's shared library, ifuncmod6.so, wants
|
|
the address of "foo" in function get_foo(). So there is a GOT
|
|
entry for "foo" in ifuncmod6.so. ld.so relocates ifuncmod6.so
|
|
*before* ifuncmain6pie, and on finding "foo" to be STT_GNU_IFUNC,
|
|
calls this function with f1 set to "one". But the address of
|
|
"one" is loaded from ifuncmain6pie's GOT, which hasn't been
|
|
relocated yet.
|
|
|
|
Cheat as for ifunc-sel. */
|
|
register void *ret __asm__ ("r3");
|
|
void *temp;
|
|
__asm__ ("mflr %1\n\t"
|
|
"bcl 20,31,1f\n"
|
|
"1:\tmflr %0\n\t"
|
|
"mtlr %1\n\t"
|
|
"addis %0,%0,%2-1b@ha\n\t"
|
|
"addi %0,%0,%2-1b@l"
|
|
: "=&b" (ret), "=&r" (temp)
|
|
: "X" (f1));
|
|
return ret;
|
|
#else
|
|
return f1;
|
|
#endif
|
|
}
|
|
#endif
|