ARM: net: bpf: provide accessor functions for BPF registers

Many of the code paths need to have knowledge about whether a register
is stacked or in a CPU register.  Move this decision making to a pair
of helper functions instead of having it scattered throughout the
code.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index e81401a..08fb4eb 100644 (file)
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -465,6 +465,31 @@ static bool is_stacked(s8 reg)
        return reg < 0;
 }
 
+/* If a BPF register is on the stack (stk is true), load it to the
+ * supplied temporary register and return the temporary register
+ * for subsequent operations, otherwise just use the CPU register.
+ */
+static s8 arm_bpf_get_reg32(s8 reg, s8 tmp, struct jit_ctx *ctx)
+{
+       if (is_stacked(reg)) {
+               emit(ARM_LDR_I(tmp, ARM_SP, STACK_VAR(reg)), ctx);
+               reg = tmp;
+       }
+       return reg;
+}
+
+/* If a BPF register is on the stack (stk is true), save the register
+ * back to the stack.  If the source register is not the same, then
+ * move it into the correct register.
+ */
+static void arm_bpf_put_reg32(s8 reg, s8 src, struct jit_ctx *ctx)
+{
+       if (is_stacked(reg))
+               emit(ARM_STR_I(src, ARM_SP, STACK_VAR(reg)), ctx);
+       else if (reg != src)
+               emit(ARM_MOV_R(reg, src), ctx);
+}
+
 static inline void emit_a32_mov_i(const s8 dst, const u32 val,
                                  struct jit_ctx *ctx)
 {
@@ -472,7 +497,7 @@ static inline void emit_a32_mov_i(const s8 dst, const u32 val,
 
        if (is_stacked(dst)) {
                emit_mov_i(tmp[1], val, ctx);
-               emit(ARM_STR_I(tmp[1], ARM_SP, STACK_VAR(dst)), ctx);
+               arm_bpf_put_reg32(dst, tmp[1], ctx);
        } else {
                emit_mov_i(dst, val, ctx);
        }
@@ -572,19 +597,13 @@ static inline void emit_a32_alu_r(const s8 dst, const s8 src,
                                  struct jit_ctx *ctx, const bool is64,
                                  const bool hi, const u8 op) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
-       s8 rn = is_stacked(src) ? tmp[1] : src;
-
-       if (is_stacked(src))
-               emit(ARM_LDR_I(rn, ARM_SP, STACK_VAR(src)), ctx);
+       s8 rn, rd;
 
+       rn = arm_bpf_get_reg32(src, tmp[1], ctx);
+       rd = arm_bpf_get_reg32(dst, tmp[0], ctx);
        /* ALU operation */
-       if (is_stacked(dst)) {
-               emit(ARM_LDR_I(tmp[0], ARM_SP, STACK_VAR(dst)), ctx);
-               emit_alu_r(tmp[0], rn, is64, hi, op, ctx);
-               emit(ARM_STR_I(tmp[0], ARM_SP, STACK_VAR(dst)), ctx);
-       } else {
-               emit_alu_r(dst, rn, is64, hi, op, ctx);
-       }
+       emit_alu_r(rd, rn, is64, hi, op, ctx);
+       arm_bpf_put_reg32(dst, rd, ctx);
 }
 
 /* ALU operation (64 bit) */
@@ -598,18 +617,14 @@ static inline void emit_a32_alu_r64(const bool is64, const s8 dst[],
                emit_a32_mov_i(dst_hi, 0, ctx);
 }
 
-/* dst = imm (4 bytes)*/
+/* dst = src (4 bytes)*/
 static inline void emit_a32_mov_r(const s8 dst, const s8 src,
                                  struct jit_ctx *ctx) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
-       s8 rt = is_stacked(src) ? tmp[0] : src;
+       s8 rt;
 
-       if (is_stacked(src))
-               emit(ARM_LDR_I(tmp[0], ARM_SP, STACK_VAR(src)), ctx);
-       if (is_stacked(dst))
-               emit(ARM_STR_I(rt, ARM_SP, STACK_VAR(dst)), ctx);
-       else
-               emit(ARM_MOV_R(dst, rt), ctx);
+       rt = arm_bpf_get_reg32(src, tmp[0], ctx);
+       arm_bpf_put_reg32(dst, rt, ctx);
 }
 
 /* dst = src */
@@ -630,10 +645,9 @@ static inline void emit_a32_mov_r64(const bool is64, const s8 dst[],
 static inline void emit_a32_alu_i(const s8 dst, const u32 val,
                                struct jit_ctx *ctx, const u8 op) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
-       s8 rd = is_stacked(dst) ? tmp[0] : dst;
+       s8 rd;
 
-       if (is_stacked(dst))
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst)), ctx);
+       rd = arm_bpf_get_reg32(dst, tmp[0], ctx);
 
        /* Do shift operation */
        switch (op) {
@@ -648,31 +662,25 @@ static inline void emit_a32_alu_i(const s8 dst, const u32 val,
                break;
        }
 
-       if (is_stacked(dst))
-               emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst)), ctx);
+       arm_bpf_put_reg32(dst, rd, ctx);
 }
 
 /* dst = ~dst (64 bit) */
 static inline void emit_a32_neg64(const s8 dst[],
                                struct jit_ctx *ctx){
        const s8 *tmp = bpf2a32[TMP_REG_1];
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst[1];
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst[0];
+       s8 rd, rm;
 
        /* Setup Operand */
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
        /* Do Negate Operation */
        emit(ARM_RSBS_I(rd, rd, 0), ctx);
        emit(ARM_RSC_I(rm, rm, 0), ctx);
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       arm_bpf_put_reg32(dst_lo, rd, ctx);
+       arm_bpf_put_reg32(dst_hi, rm, ctx);
 }
 
 /* dst = dst << src */
@@ -680,18 +688,12 @@ static inline void emit_a32_lsh_r64(const s8 dst[], const s8 src[],
                                    struct jit_ctx *ctx) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
        const s8 *tmp2 = bpf2a32[TMP_REG_2];
+       s8 rt, rd, rm;
 
        /* Setup Operands */
-       s8 rt = is_stacked(src_lo) ? tmp2[1] : src_lo;
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst_hi;
-
-       if (is_stacked(src_lo))
-               emit(ARM_LDR_I(rt, ARM_SP, STACK_VAR(src_lo)), ctx);
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       rt = arm_bpf_get_reg32(src_lo, tmp2[1], ctx);
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
        /* Do LSH operation */
        emit(ARM_SUB_I(ARM_IP, rt, 32), ctx);
@@ -701,13 +703,8 @@ static inline void emit_a32_lsh_r64(const s8 dst[], const s8 src[],
        emit(ARM_ORR_SR(ARM_IP, ARM_LR, rd, SRTYPE_LSR, tmp2[0]), ctx);
        emit(ARM_MOV_SR(ARM_LR, rd, SRTYPE_ASL, rt), ctx);
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(ARM_LR, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(ARM_IP, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       } else {
-               emit(ARM_MOV_R(rd, ARM_LR), ctx);
-               emit(ARM_MOV_R(rm, ARM_IP), ctx);
-       }
+       arm_bpf_put_reg32(dst_lo, ARM_LR, ctx);
+       arm_bpf_put_reg32(dst_hi, ARM_IP, ctx);
 }
 
 /* dst = dst >> src (signed)*/
@@ -715,17 +712,12 @@ static inline void emit_a32_arsh_r64(const s8 dst[], const s8 src[],
                                     struct jit_ctx *ctx) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
        const s8 *tmp2 = bpf2a32[TMP_REG_2];
+       s8 rt, rd, rm;
+
        /* Setup Operands */
-       s8 rt = is_stacked(src_lo) ? tmp2[1] : src_lo;
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst_hi;
-
-       if (is_stacked(src_lo))
-               emit(ARM_LDR_I(rt, ARM_SP, STACK_VAR(src_lo)), ctx);
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       rt = arm_bpf_get_reg32(src_lo, tmp2[1], ctx);
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
        /* Do the ARSH operation */
        emit(ARM_RSB_I(ARM_IP, rt, 32), ctx);
@@ -735,13 +727,9 @@ static inline void emit_a32_arsh_r64(const s8 dst[], const s8 src[],
        _emit(ARM_COND_MI, ARM_B(0), ctx);
        emit(ARM_ORR_SR(ARM_LR, ARM_LR, rm, SRTYPE_ASR, tmp2[0]), ctx);
        emit(ARM_MOV_SR(ARM_IP, rm, SRTYPE_ASR, rt), ctx);
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(ARM_LR, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(ARM_IP, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       } else {
-               emit(ARM_MOV_R(rd, ARM_LR), ctx);
-               emit(ARM_MOV_R(rm, ARM_IP), ctx);
-       }
+
+       arm_bpf_put_reg32(dst_lo, ARM_LR, ctx);
+       arm_bpf_put_reg32(dst_hi, ARM_IP, ctx);
 }
 
 /* dst = dst >> src */
@@ -749,17 +737,12 @@ static inline void emit_a32_rsh_r64(const s8 dst[], const s8 src[],
                                    struct jit_ctx *ctx) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
        const s8 *tmp2 = bpf2a32[TMP_REG_2];
+       s8 rt, rd, rm;
+
        /* Setup Operands */
-       s8 rt = is_stacked(src_lo) ? tmp2[1] : src_lo;
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst_hi;
-
-       if (is_stacked(src_lo))
-               emit(ARM_LDR_I(rt, ARM_SP, STACK_VAR(src_lo)), ctx);
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       rt = arm_bpf_get_reg32(src_lo, tmp2[1], ctx);
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
        /* Do RSH operation */
        emit(ARM_RSB_I(ARM_IP, rt, 32), ctx);
@@ -768,13 +751,9 @@ static inline void emit_a32_rsh_r64(const s8 dst[], const s8 src[],
        emit(ARM_ORR_SR(ARM_LR, ARM_LR, rm, SRTYPE_ASL, ARM_IP), ctx);
        emit(ARM_ORR_SR(ARM_LR, ARM_LR, rm, SRTYPE_LSR, tmp2[0]), ctx);
        emit(ARM_MOV_SR(ARM_IP, rm, SRTYPE_LSR, rt), ctx);
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(ARM_LR, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(ARM_IP, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       } else {
-               emit(ARM_MOV_R(rd, ARM_LR), ctx);
-               emit(ARM_MOV_R(rm, ARM_IP), ctx);
-       }
+
+       arm_bpf_put_reg32(dst_lo, ARM_LR, ctx);
+       arm_bpf_put_reg32(dst_hi, ARM_IP, ctx);
 }
 
 /* dst = dst << val */
@@ -782,14 +761,11 @@ static inline void emit_a32_lsh_i64(const s8 dst[],
                                    const u32 val, struct jit_ctx *ctx){
        const s8 *tmp = bpf2a32[TMP_REG_1];
        const s8 *tmp2 = bpf2a32[TMP_REG_2];
-       /* Setup operands */
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst_hi;
+       s8 rd, rm;
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       /* Setup operands */
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
        /* Do LSH operation */
        if (val < 32) {
@@ -804,10 +780,8 @@ static inline void emit_a32_lsh_i64(const s8 dst[],
                emit(ARM_EOR_R(rd, rd, rd), ctx);
        }
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       arm_bpf_put_reg32(dst_lo, rd, ctx);
+       arm_bpf_put_reg32(dst_hi, rm, ctx);
 }
 
 /* dst = dst >> val */
@@ -815,14 +789,11 @@ static inline void emit_a32_rsh_i64(const s8 dst[],
                                    const u32 val, struct jit_ctx *ctx) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
        const s8 *tmp2 = bpf2a32[TMP_REG_2];
-       /* Setup operands */
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst_hi;
+       s8 rd, rm;
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       /* Setup operands */
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
        /* Do LSR operation */
        if (val < 32) {
@@ -837,10 +808,8 @@ static inline void emit_a32_rsh_i64(const s8 dst[],
                emit(ARM_MOV_I(rm, 0), ctx);
        }
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       arm_bpf_put_reg32(dst_lo, rd, ctx);
+       arm_bpf_put_reg32(dst_hi, rm, ctx);
 }
 
 /* dst = dst >> val (signed) */
@@ -848,14 +817,11 @@ static inline void emit_a32_arsh_i64(const s8 dst[],
                                     const u32 val, struct jit_ctx *ctx){
        const s8 *tmp = bpf2a32[TMP_REG_1];
        const s8 *tmp2 = bpf2a32[TMP_REG_2];
-        /* Setup operands */
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst_hi;
+       s8 rd, rm;
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       /* Setup operands */
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
        /* Do ARSH operation */
        if (val < 32) {
@@ -870,30 +836,21 @@ static inline void emit_a32_arsh_i64(const s8 dst[],
                emit(ARM_MOV_SI(rm, rm, SRTYPE_ASR, 31), ctx);
        }
 
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
+       arm_bpf_put_reg32(dst_lo, rd, ctx);
+       arm_bpf_put_reg32(dst_hi, rm, ctx);
 }
 
 static inline void emit_a32_mul_r64(const s8 dst[], const s8 src[],
                                    struct jit_ctx *ctx) {
        const s8 *tmp = bpf2a32[TMP_REG_1];
        const s8 *tmp2 = bpf2a32[TMP_REG_2];
+       s8 rd, rm, rt, rn;
+
        /* Setup operands for multiplication */
-       s8 rd = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-       s8 rm = is_stacked(dst_lo) ? tmp[0] : dst_hi;
-       s8 rt = is_stacked(src_lo) ? tmp2[1] : src_lo;
-       s8 rn = is_stacked(src_lo) ? tmp2[0] : src_hi;
-
-       if (is_stacked(dst_lo)) {
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       }
-       if (is_stacked(src_lo)) {
-               emit(ARM_LDR_I(rt, ARM_SP, STACK_VAR(src_lo)), ctx);
-               emit(ARM_LDR_I(rn, ARM_SP, STACK_VAR(src_hi)), ctx);
-       }
+       rd = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+       rm = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
+       rt = arm_bpf_get_reg32(src_lo, tmp2[1], ctx);
+       rn = arm_bpf_get_reg32(src_hi, tmp2[0], ctx);
 
        /* Do Multiplication */
        emit(ARM_MUL(ARM_IP, rd, rn), ctx);
@@ -902,22 +859,18 @@ static inline void emit_a32_mul_r64(const s8 dst[], const s8 src[],
 
        emit(ARM_UMULL(ARM_IP, rm, rd, rt), ctx);
        emit(ARM_ADD_R(rm, ARM_LR, rm), ctx);
-       if (is_stacked(dst_lo)) {
-               emit(ARM_STR_I(ARM_IP, ARM_SP, STACK_VAR(dst_lo)), ctx);
-               emit(ARM_STR_I(rm, ARM_SP, STACK_VAR(dst_hi)), ctx);
-       } else {
-               emit(ARM_MOV_R(rd, ARM_IP), ctx);
-       }
+
+       arm_bpf_put_reg32(dst_lo, ARM_IP, ctx);
+       arm_bpf_put_reg32(dst_hi, rm, ctx);
 }
 
 /* *(size *)(dst + off) = src */
 static inline void emit_str_r(const s8 dst, const s8 src,
                              const s32 off, struct jit_ctx *ctx, const u8 sz){
        const s8 *tmp = bpf2a32[TMP_REG_1];
-       s8 rd = is_stacked(dst) ? tmp[1] : dst;
+       s8 rd;
 
-       if (is_stacked(dst))
-               emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst)), ctx);
+       rd = arm_bpf_get_reg32(dst, tmp[1], ctx);
        if (off) {
                emit_a32_mov_i(tmp[0], off, ctx);
                emit(ARM_ADD_R(tmp[0], rd, tmp[0]), ctx);
@@ -983,10 +936,9 @@ static inline void emit_ldx_r(const s8 dst[], const s8 src,
                emit(ARM_LDR_I(rd[0], rm, off + 4), ctx);
                break;
        }
-       if (is_stacked(dst_lo))
-               emit(ARM_STR_I(rd[1], ARM_SP, STACK_VAR(dst_lo)), ctx);
-       if (is_stacked(dst_lo) && sz == BPF_DW)
-               emit(ARM_STR_I(rd[0], ARM_SP, STACK_VAR(dst_hi)), ctx);
+       arm_bpf_put_reg32(dst[1], rd[1], ctx);
+       if (sz == BPF_DW)
+               arm_bpf_put_reg32(dst[0], rd[0], ctx);
 }
 
 /* Arithmatic Operation */
@@ -1034,6 +986,7 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
 #define cur_offset (ctx->idx - idx0)
 #define jmp_offset (out_offset - (cur_offset) - 2)
        u32 off, lo, hi;
+       s8 r_array, r_index, r_tc_lo, r_tc_hi;
 
        /* if (index >= array->map.max_entries)
         *      goto out;
@@ -1041,12 +994,12 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
        off = offsetof(struct bpf_array, map.max_entries);
        /* array->map.max_entries */
        emit_a32_mov_i(tmp[1], off, ctx);
-       emit(ARM_LDR_I(tmp2[1], ARM_SP, STACK_VAR(r2[1])), ctx);
-       emit(ARM_LDR_R(tmp[1], tmp2[1], tmp[1]), ctx);
+       r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx);
+       emit(ARM_LDR_R(tmp[1], r_array, tmp[1]), ctx);
        /* index is 32-bit for arrays */
-       emit(ARM_LDR_I(tmp2[1], ARM_SP, STACK_VAR(r3[1])), ctx);
+       r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx);
        /* index >= array->map.max_entries */
-       emit(ARM_CMP_R(tmp2[1], tmp[1]), ctx);
+       emit(ARM_CMP_R(r_index, tmp[1]), ctx);
        _emit(ARM_COND_CS, ARM_B(jmp_offset), ctx);
 
        /* if (tail_call_cnt > MAX_TAIL_CALL_CNT)
@@ -1055,15 +1008,15 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
         */
        lo = (u32)MAX_TAIL_CALL_CNT;
        hi = (u32)((u64)MAX_TAIL_CALL_CNT >> 32);
-       emit(ARM_LDR_I(tmp[1], ARM_SP, STACK_VAR(tcc[1])), ctx);
-       emit(ARM_LDR_I(tmp[0], ARM_SP, STACK_VAR(tcc[0])), ctx);
-       emit(ARM_CMP_I(tmp[0], hi), ctx);
-       _emit(ARM_COND_EQ, ARM_CMP_I(tmp[1], lo), ctx);
+       r_tc_lo = arm_bpf_get_reg32(tcc[1], tmp[1], ctx);
+       r_tc_hi = arm_bpf_get_reg32(tcc[0], tmp[0], ctx);
+       emit(ARM_CMP_I(r_tc_hi, hi), ctx);
+       _emit(ARM_COND_EQ, ARM_CMP_I(r_tc_lo, lo), ctx);
        _emit(ARM_COND_HI, ARM_B(jmp_offset), ctx);
-       emit(ARM_ADDS_I(tmp[1], tmp[1], 1), ctx);
-       emit(ARM_ADC_I(tmp[0], tmp[0], 0), ctx);
-       emit(ARM_STR_I(tmp[1], ARM_SP, STACK_VAR(tcc[1])), ctx);
-       emit(ARM_STR_I(tmp[0], ARM_SP, STACK_VAR(tcc[0])), ctx);
+       emit(ARM_ADDS_I(r_tc_lo, r_tc_lo, 1), ctx);
+       emit(ARM_ADC_I(r_tc_hi, r_tc_hi, 0), ctx);
+       arm_bpf_put_reg32(tcc[1], r_tc_lo, ctx);
+       arm_bpf_put_reg32(tcc[0], r_tc_hi, ctx);
 
        /* prog = array->ptrs[index]
         * if (prog == NULL)
@@ -1071,10 +1024,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
         */
        off = offsetof(struct bpf_array, ptrs);
        emit_a32_mov_i(tmp[1], off, ctx);
-       emit(ARM_LDR_I(tmp2[1], ARM_SP, STACK_VAR(r2[1])), ctx);
-       emit(ARM_ADD_R(tmp[1], tmp2[1], tmp[1]), ctx);
-       emit(ARM_LDR_I(tmp2[1], ARM_SP, STACK_VAR(r3[1])), ctx);
-       emit(ARM_MOV_SI(tmp[0], tmp2[1], SRTYPE_ASL, 2), ctx);
+       r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx);
+       emit(ARM_ADD_R(tmp[1], r_array, tmp[1]), ctx);
+       r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx);
+       emit(ARM_MOV_SI(tmp[0], r_index, SRTYPE_ASL, 2), ctx);
        emit(ARM_LDR_R(tmp[1], tmp[1], tmp[0]), ctx);
        emit(ARM_CMP_I(tmp[1], 0), ctx);
        _emit(ARM_COND_EQ, ARM_B(jmp_offset), ctx);
@@ -1317,15 +1270,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
        case BPF_ALU | BPF_DIV | BPF_X:
        case BPF_ALU | BPF_MOD | BPF_K:
        case BPF_ALU | BPF_MOD | BPF_X:
-               rd = is_stacked(dst_lo) ? tmp2[1] : dst_lo;
-               if (is_stacked(dst_lo))
-                       emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
+               rd = arm_bpf_get_reg32(dst_lo, tmp2[1], ctx);
                switch (BPF_SRC(code)) {
                case BPF_X:
-                       rt = is_stacked(rt) ? tmp2[0] : src_lo;
-                       if (is_stacked(src_lo))
-                               emit(ARM_LDR_I(rt, ARM_SP, STACK_VAR(src_lo)),
-                                    ctx);
+                       rt = arm_bpf_get_reg32(src_lo, tmp2[0], ctx);
                        break;
                case BPF_K:
                        rt = tmp2[0];
@@ -1336,8 +1284,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
                        break;
                }
                emit_udivmod(rd, rd, rt, ctx, BPF_OP(code));
-               if (is_stacked(dst_lo))
-                       emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst_lo)), ctx);
+               arm_bpf_put_reg32(dst_lo, rd, ctx);
                emit_a32_mov_i(dst_hi, 0, ctx);
                break;
        case BPF_ALU64 | BPF_DIV | BPF_K:
@@ -1417,12 +1364,8 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
        /* dst = htobe(dst) */
        case BPF_ALU | BPF_END | BPF_FROM_LE:
        case BPF_ALU | BPF_END | BPF_FROM_BE:
-               rd = is_stacked(dst_lo) ? tmp[0] : dst_hi;
-               rt = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-               if (is_stacked(dst_lo)) {
-                       emit(ARM_LDR_I(rt, ARM_SP, STACK_VAR(dst_lo)), ctx);
-                       emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_hi)), ctx);
-               }
+               rt = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+               rd = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
                if (BPF_SRC(code) == BPF_FROM_LE)
                        goto emit_bswap_uxt;
                switch (imm) {
@@ -1460,10 +1403,8 @@ emit_bswap_uxt:
                        break;
                }
 exit:
-               if (is_stacked(dst_lo)) {
-                       emit(ARM_STR_I(rt, ARM_SP, STACK_VAR(dst_lo)), ctx);
-                       emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst_hi)), ctx);
-               }
+               arm_bpf_put_reg32(dst_lo, rt, ctx);
+               arm_bpf_put_reg32(dst_hi, rd, ctx);
                break;
        /* dst = imm64 */
        case BPF_LD | BPF_IMM | BPF_DW:
@@ -1482,9 +1423,7 @@ exit:
        case BPF_LDX | BPF_MEM | BPF_H:
        case BPF_LDX | BPF_MEM | BPF_B:
        case BPF_LDX | BPF_MEM | BPF_DW:
-               rn = is_stacked(src_lo) ? tmp2[1] : src_lo;
-               if (is_stacked(src_lo))
-                       emit(ARM_LDR_I(rn, ARM_SP, STACK_VAR(src_lo)), ctx);
+               rn = arm_bpf_get_reg32(src_lo, tmp2[1], ctx);
                emit_ldx_r(dst, rn, off, ctx, BPF_SIZE(code));
                break;
        /* ST: *(size *)(dst + off) = imm */
@@ -1520,12 +1459,8 @@ exit:
        {
                u8 sz = BPF_SIZE(code);
 
-               rn = is_stacked(src_lo) ? tmp2[1] : src_lo;
-               rm = is_stacked(src_lo) ? tmp2[0] : src_hi;
-               if (is_stacked(src_lo)) {
-                       emit(ARM_LDR_I(rn, ARM_SP, STACK_VAR(src_lo)), ctx);
-                       emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(src_hi)), ctx);
-               }
+               rn = arm_bpf_get_reg32(src_lo, tmp2[1], ctx);
+               rm = arm_bpf_get_reg32(src_hi, tmp2[0], ctx);
 
                /* Store the value */
                if (BPF_SIZE(code) == BPF_DW) {
@@ -1559,12 +1494,8 @@ exit:
        case BPF_JMP | BPF_JSLT | BPF_X:
        case BPF_JMP | BPF_JSLE | BPF_X:
                /* Setup source registers */
-               rm = is_stacked(src_lo) ? tmp2[0] : src_hi;
-               rn = is_stacked(src_lo) ? tmp2[1] : src_lo;
-               if (is_stacked(src_lo)) {
-                       emit(ARM_LDR_I(rn, ARM_SP, STACK_VAR(src_lo)), ctx);
-                       emit(ARM_LDR_I(rm, ARM_SP, STACK_VAR(src_hi)), ctx);
-               }
+               rm = arm_bpf_get_reg32(src_hi, tmp2[0], ctx);
+               rn = arm_bpf_get_reg32(src_lo, tmp2[1], ctx);
                goto go_jmp;
        /* PC += off if dst == imm */
        /* PC += off if dst > imm */
@@ -1596,12 +1527,8 @@ exit:
                emit_a32_mov_i64(true, tmp2, imm, ctx);
 go_jmp:
                /* Setup destination register */
-               rd = is_stacked(dst_lo) ? tmp[0] : dst_hi;
-               rt = is_stacked(dst_lo) ? tmp[1] : dst_lo;
-               if (is_stacked(dst_lo)) {
-                       emit(ARM_LDR_I(rt, ARM_SP, STACK_VAR(dst_lo)), ctx);
-                       emit(ARM_LDR_I(rd, ARM_SP, STACK_VAR(dst_hi)), ctx);
-               }
+               rt = arm_bpf_get_reg32(dst_lo, tmp[1], ctx);
+               rd = arm_bpf_get_reg32(dst_hi, tmp[0], ctx);
 
                /* Check for the condition */
                emit_ar_r(rd, rt, rm, rn, ctx, BPF_OP(code));