linux-kernel - [ 010/103] powerpc: Remove unreachable relocation on exception handlers

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Message-Id: <20130723220419.707419827@linuxfoundation.org>
Date:	Tue, 23 Jul 2013 15:25:21 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Michael Ellerman <michael@...erman.id.au>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: [ 010/103] powerpc: Remove unreachable relocation on exception handlers

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Ellerman <michael@...erman.id.au>

commit 1d567cb4bd42d560a7621cac6f6aebe87343689e upstream.

We have relocation on exception handlers defined for h_data_storage and
h_instr_storage. However we will never take relocation on exceptions for
these because they can only come from a guest, and we never take
relocation on exceptions when we transition from guest to host.

We also have a handler for hmi_exception (Hypervisor Maintenance) which
is defined in the architecture to never be delivered with relocation on,
see see v2.07 Book III-S section 6.5.

So remove the handlers, leaving a branch to self just to be double extra
paranoid.

Signed-off-by: Michael Ellerman <michael@...erman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kernel/exceptions-64s.S |   18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -793,14 +793,10 @@ system_call_relon_pSeries:
 	STD_RELON_EXCEPTION_PSERIES(0x4d00, 0xd00, single_step)
 
 	. = 0x4e00
-	SET_SCRATCH0(r13)
-	EXCEPTION_PROLOG_0(PACA_EXGEN)
-	b	h_data_storage_relon_hv
+	b	.	/* Can't happen, see v2.07 Book III-S section 6.5 */
 
 	. = 0x4e20
-	SET_SCRATCH0(r13)
-	EXCEPTION_PROLOG_0(PACA_EXGEN)
-	b	h_instr_storage_relon_hv
+	b	.	/* Can't happen, see v2.07 Book III-S section 6.5 */
 
 	. = 0x4e40
 	SET_SCRATCH0(r13)
@@ -808,9 +804,7 @@ system_call_relon_pSeries:
 	b	emulation_assist_relon_hv
 
 	. = 0x4e60
-	SET_SCRATCH0(r13)
-	EXCEPTION_PROLOG_0(PACA_EXGEN)
-	b	hmi_exception_relon_hv
+	b	.	/* Can't happen, see v2.07 Book III-S section 6.5 */
 
 	. = 0x4e80
 	SET_SCRATCH0(r13)
@@ -1180,14 +1174,8 @@ tm_unavailable_common:
 __end_handlers:
 
 	/* Equivalents to the above handlers for relocation-on interrupt vectors */
-	STD_RELON_EXCEPTION_HV_OOL(0xe00, h_data_storage)
-	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe00)
-	STD_RELON_EXCEPTION_HV_OOL(0xe20, h_instr_storage)
-	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe20)
 	STD_RELON_EXCEPTION_HV_OOL(0xe40, emulation_assist)
 	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe40)
-	STD_RELON_EXCEPTION_HV_OOL(0xe60, hmi_exception)
-	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe60)
 	MASKABLE_RELON_EXCEPTION_HV_OOL(0xe80, h_doorbell)
 	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe80)
 


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