sparc: Handle negative offsets in arch_jump_label_transform

Additionally, if the offset will overflow the immediate for a ba,pt
instruction, fall back on a standard ba to get an extra 3 bits.

Signed-off-by: James Clarke <jrtc27@jrtc27.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 6 deletions

diff --git a/arch/sparc/kernel/jump_label.c b/arch/sparc/kernel/jump_label.c
index 59bbeff55024..07933b9e9ce0 100644
--- a/arch/sparc/kernel/jump_label.c
+++ b/arch/sparc/kernel/jump_label.c
@@ -13,19 +13,30 @@
 void arch_jump_label_transform(struct jump_entry *entry,
                                enum jump_label_type type)
 {
-        u32 val;
         u32 *insn = (u32 *) (unsigned long) entry->code;
+        u32 val;
 
         if (type == JUMP_LABEL_JMP) {
                 s32 off = (s32)entry->target - (s32)entry->code;
+                bool use_v9_branch = false;
+
+                BUG_ON(off & 3);
 
 #ifdef CONFIG_SPARC64
-                /* ba,pt %xcc, . + (off << 2) */
-                val = 0x10680000 | ((u32) off >> 2);
-#else
-                /* ba . + (off << 2) */
-                val = 0x10800000 | ((u32) off >> 2);
+                if (off <= 0xfffff && off >= -0x100000)
+                        use_v9_branch = true;
 #endif
+                if (use_v9_branch) {
+                        /* WDISP19 - target is . + immed << 2 */
+                        /* ba,pt %xcc, . + off */
+                        val = 0x10680000 | (((u32) off >> 2) & 0x7ffff);
+                } else {
+                        /* WDISP22 - target is . + immed << 2 */
+                        BUG_ON(off > 0x7fffff);
+                        BUG_ON(off < -0x800000);
+                        /* ba . + off */
+                        val = 0x10800000 | (((u32) off >> 2) & 0x3fffff);
+                }
         } else {
                 val = 0x01000000;
         }