/*
* find all asm level function returns and forcibly set the highest bit of the return address
*/
static unsigned int execute_kernexec_retaddr(void)
{
rtx insn;
// 1. find function returns
for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) {
// rtl match: (jump_insn 41 40 42 2 (return) fptr.c:42 634 {return_internal} (nil))
// (jump_insn 12 9 11 2 (parallel [ (return) (unspec [ (0) ] UNSPEC_REP) ]) fptr.c:46 635 {return_internal_long} (nil))
// (jump_insn 97 96 98 6 (simple_return) fptr.c:50 -1 (nil) -> simple_return)
rtx body;
// is it a retn
if (!JUMP_P(insn))
continue;
body = PATTERN(insn);
if (GET_CODE(body) == PARALLEL)
body = XVECEXP(body, 0, 0);
if (!ANY_RETURN_P(body))
continue;
kernexec_instrument_retaddr(insn);
}
// print_simple_rtl(stderr, get_insns());
// print_rtl(stderr, get_insns());
return 0;
}
enum rtx_code
classify_insn (rtx x)
{
if (LABEL_P (x))
return CODE_LABEL;
if (GET_CODE (x) == CALL)
return CALL_INSN;
if (ANY_RETURN_P (x))
return JUMP_INSN;
if (GET_CODE (x) == SET)
{
if (GET_CODE (SET_DEST (x)) == PC)
return JUMP_INSN;
else if (GET_CODE (SET_SRC (x)) == CALL)
return CALL_INSN;
else
return INSN;
}
if (GET_CODE (x) == PARALLEL)
{
int j;
bool has_return_p = false;
for (j = XVECLEN (x, 0) - 1; j >= 0; j--)
if (GET_CODE (XVECEXP (x, 0, j)) == CALL)
return CALL_INSN;
else if (ANY_RETURN_P (XVECEXP (x, 0, j)))
has_return_p = true;
else if (GET_CODE (XVECEXP (x, 0, j)) == SET
&& GET_CODE (SET_DEST (XVECEXP (x, 0, j))) == PC)
return JUMP_INSN;
else if (GET_CODE (XVECEXP (x, 0, j)) == SET
&& GET_CODE (SET_SRC (XVECEXP (x, 0, j))) == CALL)
return CALL_INSN;
if (has_return_p)
return JUMP_INSN;
}
#ifdef GENERATOR_FILE
if (GET_CODE (x) == MATCH_OPERAND
|| GET_CODE (x) == MATCH_OPERATOR
|| GET_CODE (x) == MATCH_PARALLEL
|| GET_CODE (x) == MATCH_OP_DUP
|| GET_CODE (x) == MATCH_DUP
|| GET_CODE (x) == PARALLEL)
return UNKNOWN;
#endif
return INSN;
}
