sparc: Add kgdb support.

Current limitations:

1) On SMP single stepping has some fundamental issues,
   shared with other sw single-step architectures such
   as mips and arm.

2) On 32-bit sparc we don't support SMP kgdb yet.  That
   requires some reworking of the IPI mechanisms and
   infrastructure on that platform.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/sparc64/mm/ultra.S b/arch/sparc64/mm/ultra.S
index e686a67561af..796e005dad8b 100644
--- a/arch/sparc64/mm/ultra.S
+++ b/arch/sparc64/mm/ultra.S
@@ -676,6 +676,33 @@ xcall_new_mmu_context_version:
         wr              %g0, (1 << PIL_SMP_CTX_NEW_VERSION), %set_softint
         retry
 
+#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, 15, %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
+#endif
+
 #endif /* CONFIG_SMP */