powerpc: Disable interrupts in 64-bit kernel FP and vector faults

If we get a floating point, altivec or vsx unavaible interrupt in
kernel, we trigger a kernel error. There is no point preserving
the interrupt state, in fact, that can even make debugging harder
as the processor state might change (we may even preempt) between
taking the exception and landing in a debugger.

So just make those 3 disable interrupts unconditionally.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

v2: On BookE only disable when hitting the kernel unavailable
    path, otherwise it will fail to restore softe as
    fast_exception_return doesn't do it.

3 files changed, 9 insertions, 7 deletions

diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 573613d747ac..3de9993c5c65 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -354,9 +354,9 @@ interrupt_end_book3e:
         /* we can probably do a shorter exception entry for that one... */
         EXCEPTION_COMMON(0x800, PACA_EXGEN, INTS_KEEP)
         bne     1f                      /* if from user, just load it up */
+        INTS_DISABLE_ALL
         bl      .save_nvgprs
         addi    r3,r1,STACK_FRAME_OVERHEAD
-        INTS_RESTORE_HARD
         bl      .kernel_fp_unavailable_exception
         BUG_OPCODE
 1:      ld      r12,_MSR(r1)
@@ -391,10 +391,9 @@ interrupt_end_book3e:
 /* Auxiliary Processor Unavailable Interrupt */
         START_EXCEPTION(ap_unavailable);
         NORMAL_EXCEPTION_PROLOG(0xf20, PROLOG_ADDITION_NONE)
-        EXCEPTION_COMMON(0xf20, PACA_EXGEN, INTS_KEEP)
-        addi    r3,r1,STACK_FRAME_OVERHEAD
+        EXCEPTION_COMMON(0xf20, PACA_EXGEN, INTS_DISABLE_ALL)
         bl      .save_nvgprs
-        INTS_RESTORE_HARD
+        addi    r3,r1,STACK_FRAME_OVERHEAD
         bl      .unknown_exception
         b       .ret_from_except
 
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index d8ff6d37fc4d..0fb42ae21694 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -762,8 +762,8 @@ fp_unavailable_common:
         EXCEPTION_PROLOG_COMMON(0x800, PACA_EXGEN)
         bne     1f                      /* if from user, just load it up */
         bl      .save_nvgprs
+        DISABLE_INTS
         addi    r3,r1,STACK_FRAME_OVERHEAD
-        ENABLE_INTS
         bl      .kernel_fp_unavailable_exception
         BUG_OPCODE
 1:      bl      .load_up_fpu
@@ -782,8 +782,8 @@ BEGIN_FTR_SECTION
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 #endif
         bl      .save_nvgprs
+        DISABLE_INTS
         addi    r3,r1,STACK_FRAME_OVERHEAD
-        ENABLE_INTS
         bl      .altivec_unavailable_exception
         b       .ret_from_except
 
@@ -798,8 +798,8 @@ BEGIN_FTR_SECTION
 END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 #endif
         bl      .save_nvgprs
+        DISABLE_INTS
         addi    r3,r1,STACK_FRAME_OVERHEAD
-        ENABLE_INTS
         bl      .vsx_unavailable_exception
         b       .ret_from_except
 
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 5d40e592ffcb..a750409ccc4e 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -247,6 +247,9 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
                                    addr, regs->nip, regs->link, code);
         }
 
+        if (!arch_irq_disabled_regs(regs))
+                local_irq_enable();
+
         memset(&info, 0, sizeof(info));
         info.si_signo = signr;
         info.si_code = code;