On Tue, 10 Dec 2013, Geert Uytterhoeven wrote:
> On '030, the relevant code is:
>
> if (mmusr & (MMU_I | MMU_WP)) {
> if (ssw & 4) {
> printk("Data %s fault at %#010lx in %s (pc=%#lx)\n",
> ssw & RW ? "read" : "write",
> fp->un.fmtb.daddr,
> space_names[ssw & DFC], fp->ptregs.pc);
> goto buserr;
> }
> /* Don't try to do anything further if an exception was
> handled. */
> if (do_page_fault (&fp->ptregs, addr, errorcode) < 0)
> return;
>
> But we never get to do_page_fault(), as ssw = 5 (SUPER_DATA).
>
> The "if (ssw & 4) { ... }" chunk was added in commit
> e48d483d581278fae02a5fffeba2b1fef47be4d4 (from full-history-linux):
The entire commit can be found here as well,
https://git.kernel.org/cgit/linux/kernel/git/tglx/history.git/commit/arch/m68k/kernel/traps.c?id=cf9c906f8eb31033b39f47b4313f7228dc5aa201
> Which originates from a CVS commit in 2003, based on v2 (v1 didn't have
> the chunk) of a patch in the thread "RMW instructions on MC68020/MC68851
> combo..." between Kars and Roman Z.
>
> I guess this case will work(TM) if you remove that chunk again? But what
> are the other implications of that?
So how shall we understand the intention of that patch? Here's the new
logic:
if (mmusr & (MMU_I | MMU_WP)) {
if (ssw & 4) {
...
}
...
} else if (!(mmusr & MMU_I)) {
/* propably a 020 cas fault */
...
} else if (mmusr & (MMU_B|MMU_L|MMU_S)) {
...
} else {
...
}
Seems to me that everything after the first else clause is dead code.
Finn
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