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

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Date:   Mon, 26 Nov 2018 21:55:09 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     daniel@...earbox.net
CC:     ast@...nel.org, netdev@...r.kernel.org
Subject: [PATCH bpf] sparc: Adjust bpf JIT prologue for PSEUDO calls.

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 <davem@...emloft.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. */
 }