1 files changed, 54 insertions, 31 deletions

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 85113cab2046..c8a2620312c0 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -79,23 +79,66 @@ static inline void emit(const u32 insn, struct jit_ctx *ctx)
 	ctx->idx++;
 }
 
+static inline void emit_a64_mov_i(const int is64, const int reg,
+				  const s32 val, struct jit_ctx *ctx)
+{
+	u16 hi = val >> 16;
+	u16 lo = val & 0xffff;
+
+	if (hi & 0x8000) {
+		if (hi == 0xffff) {
+			emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx);
+		} else {
+			emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx);
+			if (lo != 0xffff)
+				emit(A64_MOVK(is64, reg, lo, 0), ctx);
+		}
+	} else {
+		emit(A64_MOVZ(is64, reg, lo, 0), ctx);
+		if (hi)
+			emit(A64_MOVK(is64, reg, hi, 16), ctx);
+	}
+}
+
+static int i64_i16_blocks(const u64 val, bool inverse)
+{
+	return (((val >>  0) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
+	       (((val >> 16) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
+	       (((val >> 32) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
+	       (((val >> 48) & 0xffff) != (inverse ? 0xffff : 0x0000));
+}
+
 static inline void emit_a64_mov_i64(const int reg, const u64 val,
 				    struct jit_ctx *ctx)
 {
-	u64 tmp = val;
-	int shift = 0;
-
-	emit(A64_MOVZ(1, reg, tmp & 0xffff, shift), ctx);
-	tmp >>= 16;
-	shift += 16;
-	while (tmp) {
-		if (tmp & 0xffff)
-			emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx);
-		tmp >>= 16;
-		shift += 16;
+	u64 nrm_tmp = val, rev_tmp = ~val;
+	bool inverse;
+	int shift;
+
+	if (!(nrm_tmp >> 32))
+		return emit_a64_mov_i(0, reg, (u32)val, ctx);
+
+	inverse = i64_i16_blocks(nrm_tmp, true) < i64_i16_blocks(nrm_tmp, false);
+	shift = max(round_down((inverse ? (fls64(rev_tmp) - 1) :
+					  (fls64(nrm_tmp) - 1)), 16), 0);
+	if (inverse)
+		emit(A64_MOVN(1, reg, (rev_tmp >> shift) & 0xffff, shift), ctx);
+	else
+		emit(A64_MOVZ(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx);
+	shift -= 16;
+	while (shift >= 0) {
+		if (((nrm_tmp >> shift) & 0xffff) != (inverse ? 0xffff : 0x0000))
+			emit(A64_MOVK(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx);
+		shift -= 16;
 	}
 }
 
+/*
+ * This is an unoptimized 64 immediate emission used for BPF to BPF call
+ * addresses. It will always do a full 64 bit decomposition as otherwise
+ * more complexity in the last extra pass is required since we previously
+ * reserved 4 instructions for the address.
+ */
 static inline void emit_addr_mov_i64(const int reg, const u64 val,
 				     struct jit_ctx *ctx)
 {
@@ -110,26 +153,6 @@ static inline void emit_addr_mov_i64(const int reg, const u64 val,
 	}
 }
 
-static inline void emit_a64_mov_i(const int is64, const int reg,
-				  const s32 val, struct jit_ctx *ctx)
-{
-	u16 hi = val >> 16;
-	u16 lo = val & 0xffff;
-
-	if (hi & 0x8000) {
-		if (hi == 0xffff) {
-			emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx);
-		} else {
-			emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx);
-			emit(A64_MOVK(is64, reg, lo, 0), ctx);
-		}
-	} else {
-		emit(A64_MOVZ(is64, reg, lo, 0), ctx);
-		if (hi)
-			emit(A64_MOVK(is64, reg, hi, 16), ctx);
-	}
-}
-
 static inline int bpf2a64_offset(int bpf_to, int bpf_from,
 				 const struct jit_ctx *ctx)
 {