net: filter: Fix some minor issues in sparc JIT.

Correct conventions comments.  %o4 and %o5 were swapped,
%g3 was not documented.

Use r_TMP instead of r_SKB_DATA + r_OFF where possible in
assembler stubs.

Correct discussion of %o4 and %o5 in one of bpf_jit_compile()'s
comments.

Based upon feedback from Richard Mortimer.

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

3 files changed, 6 insertions, 5 deletions

diff --git a/arch/sparc/net/bpf_jit.h b/arch/sparc/net/bpf_jit.h
index 74f048be739c..05175be442fb 100644
--- a/arch/sparc/net/bpf_jit.h
+++ b/arch/sparc/net/bpf_jit.h
@@ -4,13 +4,14 @@
 /* Conventions:
  *  %g1 : temporary
  *  %g2 : Secondary temporary used by SKB data helper stubs.
+ *  %g3 : packet offset passed into SKB data helper stubs.
  *  %o0 : pointer to skb (first argument given to JIT function)
  *  %o1 : BPF A accumulator
  *  %o2 : BPF X accumulator
  *  %o3 : Holds saved %o7 so we can call helper functions without needing
  *        to allocate a register window.
- *  %o4 : skb->data
- *  %o5 : skb->len - skb->data_len
+ *  %o4 : skb->len - skb->data_len
+ *  %o5 : skb->data
  */
 
 #ifndef __ASSEMBLER__
diff --git a/arch/sparc/net/bpf_jit_asm.S b/arch/sparc/net/bpf_jit_asm.S
index fdc69324aabc..46d8f59f14c5 100644
--- a/arch/sparc/net/bpf_jit_asm.S
+++ b/arch/sparc/net/bpf_jit_asm.S
@@ -30,7 +30,7 @@ bpf_jit_load_word_positive_offset:
         bne     load_word_unaligned
          nop
         retl
-         ld     [r_SKB_DATA + r_OFF], r_A
+         ld     [r_TMP], r_A
 load_word_unaligned:
         ldub    [r_TMP + 0x0], r_OFF
         ldub    [r_TMP + 0x1], r_TMP2
@@ -59,7 +59,7 @@ bpf_jit_load_half_positive_offset:
         bne     load_half_unaligned
          nop
         retl
-         lduh   [r_SKB_DATA + r_OFF], r_A
+         lduh   [r_TMP], r_A
 load_half_unaligned:
         ldub    [r_TMP + 0x0], r_OFF
         ldub    [r_TMP + 0x1], r_TMP2
diff --git a/arch/sparc/net/bpf_jit_comp.c b/arch/sparc/net/bpf_jit_comp.c
index 86349cab60c5..ebc89809f585 100644
--- a/arch/sparc/net/bpf_jit_comp.c
+++ b/arch/sparc/net/bpf_jit_comp.c
@@ -378,7 +378,7 @@ void bpf_jit_compile(struct sk_filter *fp)
                                 emit_clear(r_X);
 
                         /* If this filter needs to access skb data,
-                         * load %o4 and %o4 with:
+                         * load %o4 and %o5 with:
                          *  %o4 = skb->len - skb->data_len
                          *  %o5 = skb->data
                          * And also back up %o7 into r_saved_O7 so we can