On 03/30/2016 05:55 AM, Michael Ellerman wrote:

On Tue, 2016-29-03 at 18:34:37 UTC, Hari Bathini wrote:

quoted

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 7716ceb..e598580 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S

@@ -764,8 +764,8 @@ kvmppc_skip_Hinterrupt:
  #endif
  
  /*
- * Code from here down to __end_handlers is invoked from the
- * exception prologs above.  Because the prologs assemble the
+ * Code from here down to end of out of line handlers is invoked from
+ * the exception prologs above.  Because the prologs assemble the

I think it would be better to just replace __end_handlers with __end_interrupts,
that way it's entirely clear what location you're talking about.

quoted

@@ -953,11 +953,6 @@ hv_facility_unavailable_relon_trampoline:
  #endif
  	STD_RELON_EXCEPTION_PSERIES(0x5700, 0x1700, altivec_assist)
  
-	/* Other future vectors */
-	.align	7
-	.globl	__end_interrupts
-__end_interrupts:
-
  	.align	7
  system_call_entry:
  	b	system_call_common

@@ -1230,10 +1225,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
  	STD_EXCEPTION_COMMON(0xf60, facility_unavailable, facility_unavailable_exception)
  	STD_EXCEPTION_COMMON(0xf80, hv_facility_unavailable, facility_unavailable_exception)
  
-	.align	7
-	.globl	__end_handlers
-__end_handlers:
-

Sorry I wasn't clear in my last mail, please do this as a separate cleanup patch
after this patch.

ok..

quoted

@@ -1244,6 +1235,16 @@ __end_handlers:
  	STD_RELON_EXCEPTION_PSERIES_OOL(0xf60, facility_unavailable)
  	STD_RELON_EXCEPTION_HV_OOL(0xf80, hv_facility_unavailable)
  
+	/* FIXME: For now, let us move the __end_interrupts marker down past

Why is it FIXME?

In general I don't want to merge code that adds a FIXME unless there is some
very good reason.

AFAICS this is a permanent solution isn't it?

Except for a few short interrupt vectors like 0x4f00, 04f20, etc., all other
vectors defined till __end_interrupts marker ensure that LOAD_HANDLER() is
used for branching to labels like system_call_entry, data_access_common, 
etc.
that are currently not copied to real 0 in relocation case.

So, we are forced to move the __end_interrupts marker down only to handle
space constraint in the short vectors. So, I added the FIXME to remind the
scope for improvement in the code. But after thinking over again now, moving
the marker down makes us copy an additional 1~2 KB along with the 21~22 KB
that we are copying already. So, not much of an improvement to lose 
sleep over
or to add a FIXME, I guess. Your thoughts?

Also, FIXME is the reason, why I did not replace __end_handlers with
__end_interrupts in the comment earlier.

quoted

+	 * the out-of-line handlers, to make sure we also copy OOL handlers
+	 * to real adress 0x100 when running a relocatable kernel. This helps

It doesn't "help" it's 100% required.

Yep. Will change the wording.
Thanks for the review!

- Hari

quoted

+	 * in cases where interrupt vectors are not long enough (like 0x4f00,
+	 * 0x4f20, etc.) to branch out to OOL handlers with LOAD_HANDLER().
+	 */
+	.align	7
+	.globl	__end_interrupts
+__end_interrupts:
+
  #if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_POWERNV)
  /*
   * Data area reserved for FWNMI option.

cheers
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