[PATCH bpf] sparc: Adjust bpf JIT prologue for PSEUDO calls.

[David Miller]

Move all arguments into output registers from input registers.

This path is exercised by test_verifier.c's "calls: two calls with
args" test.  Adjust BPF_TAILCALL_PROLOGUE_SKIP as needed.

Let's also make the prologue length a constant size regardless of
the combination of ->saw_frame_pointer and ->saw_tail_call
settings.

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

diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c
index 222785a..5fda4f7 100644
--- a/arch/sparc/net/bpf_jit_comp_64.c
+++ b/arch/sparc/net/bpf_jit_comp_64.c
@@ -791,7 +791,7 @@ static int emit_compare_and_branch(const u8 code, const u8 
dst, u8 src,
 }
 
 /* Just skip the save instruction and the ctx register move.  */
-#define BPF_TAILCALL_PROLOGUE_SKIP     16
+#define BPF_TAILCALL_PROLOGUE_SKIP     32
 #define BPF_TAILCALL_CNT_SP_OFF                (STACK_BIAS + 128)
 
 static void build_prologue(struct jit_ctx *ctx)
@@ -824,9 +824,15 @@ static void build_prologue(struct jit_ctx *ctx)
                const u8 vfp = bpf2sparc[BPF_REG_FP];
 
                emit(ADD | IMMED | RS1(FP) | S13(STACK_BIAS) | RD(vfp), ctx);
+       } else {
+               emit_nop(ctx);
        }
 
        emit_reg_move(I0, O0, ctx);
+       emit_reg_move(I1, O1, ctx);
+       emit_reg_move(I2, O2, ctx);
+       emit_reg_move(I3, O3, ctx);
+       emit_reg_move(I4, O4, ctx);
        /* If you add anything here, adjust BPF_TAILCALL_PROLOGUE_SKIP above. */
 }