riscv, bpf: Factor out emit_call for kernel and bpf context

[ Upstream commit 0fd1fd0104954380477353aea29c347e85dff16d ]

The current emit_call function is not suitable for kernel function call as
it store return value to bpf R0 register. We can separate it out for common
use. Meanwhile, simplify judgment logic, that is, fixed function address
can use jal or auipc+jalr, while the unfixed can use only auipc+jalr.

Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/bpf/20230215135205.1411105-3-pulehui@huaweicloud.com
Stable-dep-of: 2f1b0d3d7331 ("riscv, bpf: Sign-extend return values")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index f2417ac54edd6db01ab3cbdd2bd1d5be3fc942ab..69ebab81d9352d8a1f420a84d7ff191c0637af0d 100644 (file)
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -428,12 +428,12 @@ static void emit_sext_32_rd(u8 *rd, struct rv_jit_context *ctx)
        *rd = RV_REG_T2;
 }
 
-static int emit_jump_and_link(u8 rd, s64 rvoff, bool force_jalr,
+static int emit_jump_and_link(u8 rd, s64 rvoff, bool fixed_addr,
                              struct rv_jit_context *ctx)
 {
        s64 upper, lower;
 
-       if (rvoff && is_21b_int(rvoff) && !force_jalr) {
+       if (rvoff && fixed_addr && is_21b_int(rvoff)) {
                emit(rv_jal(rd, rvoff >> 1), ctx);
                return 0;
        } else if (in_auipc_jalr_range(rvoff)) {
@@ -454,24 +454,17 @@ static bool is_signed_bpf_cond(u8 cond)
                cond == BPF_JSGE || cond == BPF_JSLE;
 }
 
-static int emit_call(bool fixed, u64 addr, struct rv_jit_context *ctx)
+static int emit_call(u64 addr, bool fixed_addr, struct rv_jit_context *ctx)
 {
        s64 off = 0;
        u64 ip;
-       u8 rd;
-       int ret;
 
        if (addr && ctx->insns) {
                ip = (u64)(long)(ctx->insns + ctx->ninsns);
                off = addr - ip;
        }
 
-       ret = emit_jump_and_link(RV_REG_RA, off, !fixed, ctx);
-       if (ret)
-               return ret;
-       rd = bpf_to_rv_reg(BPF_REG_0, ctx);
-       emit_mv(rd, RV_REG_A0, ctx);
-       return 0;
+       return emit_jump_and_link(RV_REG_RA, off, fixed_addr, ctx);
 }
 
 static void emit_atomic(u8 rd, u8 rs, s16 off, s32 imm, bool is64,
@@ -913,7 +906,7 @@ out_be:
        /* JUMP off */
        case BPF_JMP | BPF_JA:
                rvoff = rv_offset(i, off, ctx);
-               ret = emit_jump_and_link(RV_REG_ZERO, rvoff, false, ctx);
+               ret = emit_jump_and_link(RV_REG_ZERO, rvoff, true, ctx);
                if (ret)
                        return ret;
                break;
@@ -1032,17 +1025,20 @@ out_be:
        /* function call */
        case BPF_JMP | BPF_CALL:
        {
-               bool fixed;
+               bool fixed_addr;
                u64 addr;
 
                mark_call(ctx);
-               ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass, &addr,
-                                           &fixed);
+               ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass,
+                                           &addr, &fixed_addr);
                if (ret < 0)
                        return ret;
-               ret = emit_call(fixed, addr, ctx);
+
+               ret = emit_call(addr, fixed_addr, ctx);
                if (ret)
                        return ret;
+
+               emit_mv(bpf_to_rv_reg(BPF_REG_0, ctx), RV_REG_A0, ctx);
                break;
        }
        /* tail call */
@@ -1057,7 +1053,7 @@ out_be:
                        break;
 
                rvoff = epilogue_offset(ctx);
-               ret = emit_jump_and_link(RV_REG_ZERO, rvoff, false, ctx);
+               ret = emit_jump_and_link(RV_REG_ZERO, rvoff, true, ctx);
                if (ret)
                        return ret;
                break;