sparc64: Reschedule KGDB capture to a software interrupt.

Otherwise it might interrupt switch_to() midstream and use
half-cooked register window state.

Reported-by: Chris Torek <chris.torek@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 10 insertions, 24 deletions

diff --git a/arch/sparc/include/asm/pil.h b/arch/sparc/include/asm/pil.h
index 32a7efe76d00..266937030546 100644
--- a/arch/sparc/include/asm/pil.h
+++ b/arch/sparc/include/asm/pil.h
@@ -24,6 +24,7 @@
 #define PIL_DEVICE_IRQ          5
 #define PIL_SMP_CALL_FUNC_SNGL  6
 #define PIL_DEFERRED_PCR_WORK   7
+#define PIL_KGDB_CAPTURE        8
 #define PIL_NORMAL_MAX          14
 #define PIL_NMI                 15
 
diff --git a/arch/sparc/kernel/kgdb_64.c b/arch/sparc/kernel/kgdb_64.c
index fefbe6dc51be..f5a0fd490b59 100644
--- a/arch/sparc/kernel/kgdb_64.c
+++ b/arch/sparc/kernel/kgdb_64.c
@@ -108,7 +108,7 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 }
 
 #ifdef CONFIG_SMP
-void smp_kgdb_capture_client(struct pt_regs *regs)
+void smp_kgdb_capture_client(int irq, struct pt_regs *regs)
 {
         unsigned long flags;
 
diff --git a/arch/sparc/kernel/ttable.S b/arch/sparc/kernel/ttable.S
index d9bdfb9d5c18..76d837fc47d3 100644
--- a/arch/sparc/kernel/ttable.S
+++ b/arch/sparc/kernel/ttable.S
@@ -64,7 +64,12 @@ tl0_irq6:	TRAP_IRQ(smp_call_function_single_client, 6)
 tl0_irq6:       BTRAP(0x46)
 #endif
 tl0_irq7:       TRAP_IRQ(deferred_pcr_work_irq, 7)
-tl0_irq8:       BTRAP(0x48) BTRAP(0x49)
+#ifdef CONFIG_KGDB
+tl0_irq8:       TRAP_IRQ(smp_kgdb_capture_client, 8)
+#else
+tl0_irq8:       BTRAP(0x48)
+#endif
+tl0_irq9:       BTRAP(0x49)
 tl0_irq10:      BTRAP(0x4a) BTRAP(0x4b) BTRAP(0x4c) BTRAP(0x4d)
 tl0_irq14:      TRAP_IRQ(timer_interrupt, 14)
 tl0_irq15:      TRAP_NMI_IRQ(perfctr_irq, 15)
diff --git a/arch/sparc/mm/ultra.S b/arch/sparc/mm/ultra.S
index 80c788ec7c32..b57a5942ba64 100644
--- a/arch/sparc/mm/ultra.S
+++ b/arch/sparc/mm/ultra.S
@@ -679,28 +679,8 @@ xcall_new_mmu_context_version:
 #ifdef CONFIG_KGDB
         .globl          xcall_kgdb_capture
 xcall_kgdb_capture:
-661:    rdpr            %pstate, %g2
-        wrpr            %g2, PSTATE_IG | PSTATE_AG, %pstate
-        .section        .sun4v_2insn_patch, "ax"
-        .word           661b
-        nop
-        nop
-        .previous
-
-        rdpr            %pil, %g2
-        wrpr            %g0, PIL_NORMAL_MAX, %pil
-        sethi           %hi(109f), %g7
-        ba,pt           %xcc, etrap_irq
-109:     or             %g7, %lo(109b), %g7
-#ifdef CONFIG_TRACE_IRQFLAGS
-        call            trace_hardirqs_off
-         nop
-#endif
-        call            smp_kgdb_capture_client
-         add            %sp, PTREGS_OFF, %o0
-        /* Has to be a non-v9 branch due to the large distance. */
-        ba              rtrap_xcall
-         ldx            [%sp + PTREGS_OFF + PT_V9_TSTATE], %l1
+        wr              %g0, (1 << PIL_KGDB_CAPTURE), %set_softint
+        retry
 #endif
 
 #endif /* CONFIG_SMP */