Roland McGrath writes:
> For PPC32 signal handlers, while the frame itself was of properly aligned
> size, no alignment of the starting stack pointer was done at all, so that a
> signal handler can still get a misaligned stack pointer if the interrupted
> registers had one, though the kernel isn't gratuitously misaligning good
> ones like it is for PPC64. I added explicit alignment to fix that.
This part is unnecessary, because arch/ppc/kernel/signal.c:do_signal()
already aligns the stack pointer to a 16-byte boundary:
if ((ka.sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
&& !on_sig_stack(regs->gpr[1]))
newsp = current->sas_ss_sp + current->sas_ss_size;
else
newsp = regs->gpr[1];
newsp &= ~0xfUL;
/* Whee! Actually deliver the signal. */
if (ka.sa.sa_flags & SA_SIGINFO)
handle_rt_signal(signr, &ka, &info, oldset, regs, newsp);
else
handle_signal(signr, &ka, &info, oldset, regs, newsp);
The additions to arch/ppc64/kernel/signal32.c are likewise
unnecessary, because do_signal32() also does newsp &= ~0xfUL (in fact
the code there is very similar to the ppc32 code).
You are correct about the 64-bit case though. I thought we had fixed
that but evidently not. Your patch looks fine as far as
arch/ppc64/kernel/signal.c is concerned.
Regards,
Paul.
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