bpf,s390: introduce emit_store_stack_imm64() for trampoline

Introduce a helper to store 64-bit immediate on the trampoline stack with
a help of a register.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20260224092208.1395085-2-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 211226748662337e3f43a4d2b056d50246e962b2..d72d682ad220422dee24484109f4e1e41436c3a7 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -2513,6 +2513,13 @@ static void load_imm64(struct bpf_jit *jit, int dst_reg, u64 val)
        EMIT6_IMM(0xc00d0000, dst_reg, val);
 }
 
+static void emit_store_stack_imm64(struct bpf_jit *jit, int tmp_reg, int stack_off, u64 imm)
+{
+       load_imm64(jit, tmp_reg, imm);
+       /* stg %tmp_reg,stack_off(%r15) */
+       EMIT6_DISP_LH(0xe3000000, 0x0024, tmp_reg, REG_0, REG_15, stack_off);
+}
+
 static int invoke_bpf_prog(struct bpf_tramp_jit *tjit,
                           const struct btf_func_model *m,
                           struct bpf_tramp_link *tlink, bool save_ret)
@@ -2527,10 +2534,7 @@ static int invoke_bpf_prog(struct bpf_tramp_jit *tjit,
         * run_ctx.cookie = tlink->cookie;
         */
 
-       /* %r0 = tlink->cookie */
-       load_imm64(jit, REG_W0, tlink->cookie);
-       /* stg %r0,cookie_off(%r15) */
-       EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W0, REG_0, REG_15, cookie_off);
+       emit_store_stack_imm64(jit, REG_W0, cookie_off, tlink->cookie);
 
        /*
         * if ((start = __bpf_prog_enter(p, &run_ctx)) == 0)
@@ -2750,13 +2754,8 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
         * arg_cnt = m->nr_args;
         */
 
-       if (flags & BPF_TRAMP_F_IP_ARG) {
-               /* %r0 = func_addr */
-               load_imm64(jit, REG_0, (u64)func_addr);
-               /* stg %r0,ip_off(%r15) */
-               EMIT6_DISP_LH(0xe3000000, 0x0024, REG_0, REG_0, REG_15,
-                             tjit->ip_off);
-       }
+       if (flags & BPF_TRAMP_F_IP_ARG)
+               emit_store_stack_imm64(jit, REG_0, tjit->ip_off, (u64)func_addr);
        /* lghi %r0,nr_bpf_args */
        EMIT4_IMM(0xa7090000, REG_0, nr_bpf_args);
        /* stg %r0,arg_cnt_off(%r15) */