Re: [v3 4/7] powerpc/mce: Handle UE event for memcpy_mcsafe

On 7/6/19 3:23 PM, Nicholas Piggin wrote:

Santosh Sivaraj's on July 6, 2019 7:26 am:

quoted

If we take a UE on one of the instructions with a fixup entry, set nip
to continue exucution at the fixup entry. Stop processing the event
further or print it.

Minor nit, but can you instead a field in the mce data structure that
describes the property of the event, and then the code that intends to
ignore such events can test for it (with an appropriate comment).

So it would be has_fixup_handler or similar. Then queue_event can have
the logic

/*
 * Don't report this machine check because the caller has a fixup 
 * handler which will do the appropriate error handling and reporting.
 */

quoted

@@ -565,9 +567,18 @@ static int mce_handle_derror(struct pt_regs *regs,
 	return 0;
 }
 
-static long mce_handle_ue_error(struct pt_regs *regs)
+static long mce_handle_ue_error(struct pt_regs *regs,
+				struct mce_error_info *mce_err)
 {
 	long handled = 0;
+	const struct exception_table_entry *entry;
+
+	entry = search_exception_tables(regs->nip);

Uh oh, this searches module exception tables too... we can't do that
in real mode, can we?

Yeah, we can not do that in real mode.  Should we directly call
search_extable() for kernel exception table ?

Thanks,
Nick