} __attribute__ ((__aligned__ (8))) sigregs_;
sigregs_ *regs;
- int *signo = NULL;
+ int *signo;
/* svc $__NR_sigreturn or svc $__NR_rt_sigreturn */
if (pc[0] != 0x0a || (pc[1] != 119 && pc[1] != 173))
return _URC_END_OF_STACK;
+ /* Legacy frames:
+ old signal mask (8 bytes)
+ pointer to sigregs (8 bytes) - points always to next location
+ sigregs
+ retcode
+ This frame layout was used on kernels < 2.6.9 for non-RT frames,
+ and on kernels < 2.4.13 for RT frames as well. Note that we need
+ to look at RA to detect this layout -- this means that if you use
+ sa_restorer to install a different signal restorer on a legacy
+ kernel, unwinding from signal frames will not work. */
+ if (context->ra == context->cfa + 16 + sizeof (sigregs_))
+ {
+ regs = (sigregs_ *)(context->cfa + 16);
+ signo = NULL;
+ }
+
/* New-style RT frame:
retcode + alignment (8 bytes)
siginfo (128 bytes)
ucontext (contains sigregs) */
- if (context->ra == context->cfa)
+ else if (pc[1] == 173 /* __NR_rt_sigreturn */)
{
struct ucontext_
{
signo = context->cfa + sizeof(long);
}
- /* Old-style RT frame and all non-RT frames:
+ /* New-style non-RT frame:
old signal mask (8 bytes)
- pointer to sigregs */
+ pointer to sigregs (followed by signal number) */
else
{
regs = *(sigregs_ **)(context->cfa + 8);
-
- /* Recent kernels store the signal number immediately after
- the sigregs; old kernels have the return trampoline at
- this location. */
- if ((void *)(regs + 1) != context->ra)
- signo = (int *)(regs + 1);
+ signo = (int *)(regs + 1);
}
new_cfa = regs->gprs[15] + 16*sizeof(long) + 32;