LoongArch: BPF: Support sign-extension load instructions

Add support for sign-extension load instructions.

Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
index db9342b2d0e6605e8b13179acdc9e61bdb761dee..0c2bbca527efa800cea3b245ec2d400a72e020b7 100644 (file)
--- a/arch/loongarch/net/bpf_jit.c
+++ b/arch/loongarch/net/bpf_jit.c
@@ -411,7 +411,11 @@ static int add_exception_handler(const struct bpf_insn *insn,
        off_t offset;
        struct exception_table_entry *ex;
 
-       if (!ctx->image || !ctx->prog->aux->extable || BPF_MODE(insn->code) != BPF_PROBE_MEM)
+       if (!ctx->image || !ctx->prog->aux->extable)
+               return 0;
+
+       if (BPF_MODE(insn->code) != BPF_PROBE_MEM &&
+           BPF_MODE(insn->code) != BPF_PROBE_MEMSX)
                return 0;
 
        if (WARN_ON_ONCE(ctx->num_exentries >= ctx->prog->aux->num_exentries))
@@ -450,7 +454,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext
 {
        u8 tm = -1;
        u64 func_addr;
-       bool func_addr_fixed;
+       bool func_addr_fixed, sign_extend;
        int i = insn - ctx->prog->insnsi;
        int ret, jmp_offset;
        const u8 code = insn->code;
@@ -879,31 +883,56 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext
        case BPF_LDX | BPF_PROBE_MEM | BPF_W:
        case BPF_LDX | BPF_PROBE_MEM | BPF_H:
        case BPF_LDX | BPF_PROBE_MEM | BPF_B:
+       /* dst_reg = (s64)*(signed size *)(src_reg + off) */
+       case BPF_LDX | BPF_MEMSX | BPF_B:
+       case BPF_LDX | BPF_MEMSX | BPF_H:
+       case BPF_LDX | BPF_MEMSX | BPF_W:
+       case BPF_LDX | BPF_PROBE_MEMSX | BPF_B:
+       case BPF_LDX | BPF_PROBE_MEMSX | BPF_H:
+       case BPF_LDX | BPF_PROBE_MEMSX | BPF_W:
+               sign_extend = BPF_MODE(insn->code) == BPF_MEMSX ||
+                             BPF_MODE(insn->code) == BPF_PROBE_MEMSX;
                switch (BPF_SIZE(code)) {
                case BPF_B:
                        if (is_signed_imm12(off)) {
-                               emit_insn(ctx, ldbu, dst, src, off);
+                               if (sign_extend)
+                                       emit_insn(ctx, ldb, dst, src, off);
+                               else
+                                       emit_insn(ctx, ldbu, dst, src, off);
                        } else {
                                move_imm(ctx, t1, off, is32);
-                               emit_insn(ctx, ldxbu, dst, src, t1);
+                               if (sign_extend)
+                                       emit_insn(ctx, ldxb, dst, src, t1);
+                               else
+                                       emit_insn(ctx, ldxbu, dst, src, t1);
                        }
                        break;
                case BPF_H:
                        if (is_signed_imm12(off)) {
-                               emit_insn(ctx, ldhu, dst, src, off);
+                               if (sign_extend)
+                                       emit_insn(ctx, ldh, dst, src, off);
+                               else
+                                       emit_insn(ctx, ldhu, dst, src, off);
                        } else {
                                move_imm(ctx, t1, off, is32);
-                               emit_insn(ctx, ldxhu, dst, src, t1);
+                               if (sign_extend)
+                                       emit_insn(ctx, ldxh, dst, src, t1);
+                               else
+                                       emit_insn(ctx, ldxhu, dst, src, t1);
                        }
                        break;
                case BPF_W:
                        if (is_signed_imm12(off)) {
-                               emit_insn(ctx, ldwu, dst, src, off);
-                       } else if (is_signed_imm14(off)) {
-                               emit_insn(ctx, ldptrw, dst, src, off);
+                               if (sign_extend)
+                                       emit_insn(ctx, ldw, dst, src, off);
+                               else
+                                       emit_insn(ctx, ldwu, dst, src, off);
                        } else {
                                move_imm(ctx, t1, off, is32);
-                               emit_insn(ctx, ldxwu, dst, src, t1);
+                               if (sign_extend)
+                                       emit_insn(ctx, ldxw, dst, src, t1);
+                               else
+                                       emit_insn(ctx, ldxwu, dst, src, t1);
                        }
                        break;
                case BPF_DW: