powerpc: Remove unreachable relocation on exception handlers

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@ellerman.id.au>
CC: <stable@vger.kernel.org> [v3.9+]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index e783453..dcadf03 100644 (file)
--- 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)