LoongArch: BPF: Add struct ops support for trampoline

Use BPF_TRAMP_F_INDIRECT flag to detect struct ops and emit proper
prologue and epilogue for this case.

With this patch, all of the struct_ops related testcases (except
struct_ops_multi_pages) passed on LoongArch.

The testcase struct_ops_multi_pages failed is because the actual
image_pages_cnt is 40 which is bigger than MAX_TRAMP_IMAGE_PAGES.

Before:

  $ sudo ./test_progs -t struct_ops -d struct_ops_multi_pages
  ...
  WATCHDOG: test case struct_ops_module/struct_ops_load executes for 10 seconds...

After:

  $ sudo ./test_progs -t struct_ops -d struct_ops_multi_pages
  ...
  #15      bad_struct_ops:OK
  ...
  #399     struct_ops_autocreate:OK
  ...
  #400     struct_ops_kptr_return:OK
  ...
  #401     struct_ops_maybe_null:OK
  ...
  #402     struct_ops_module:OK
  ...
  #404     struct_ops_no_cfi:OK
  ...
  #405     struct_ops_private_stack:SKIP
  ...
  #406     struct_ops_refcounted:OK
  Summary: 8/25 PASSED, 3 SKIPPED, 0 FAILED

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
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 052136abb8ab864fa21cbeef23a57fcb48042648..0d11d90dc4c91616065e79dcb4f5d2b21c5b5910 100644 (file)
--- a/arch/loongarch/net/bpf_jit.c
+++ b/arch/loongarch/net/bpf_jit.c
@@ -1423,6 +1423,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
        int i, ret, save_ret;
        int stack_size = 0, nargs = 0;
        int retval_off, args_off, nargs_off, ip_off, run_ctx_off, sreg_off;
+       bool is_struct_ops = flags & BPF_TRAMP_F_INDIRECT;
        void *orig_call = func_addr;
        struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
        struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
@@ -1500,18 +1501,33 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
 
        stack_size = round_up(stack_size, 16);
 
-       /* For the trampoline called from function entry */
-       /* RA and FP for parent function */
-       emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, -16);
-       emit_insn(ctx, std, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, 8);
-       emit_insn(ctx, std, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, 0);
-       emit_insn(ctx, addid, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, 16);
-
-       /* RA and FP for traced function */
-       emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, -stack_size);
-       emit_insn(ctx, std, LOONGARCH_GPR_T0, LOONGARCH_GPR_SP, stack_size - 8);
-       emit_insn(ctx, std, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size - 16);
-       emit_insn(ctx, addid, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size);
+       if (is_struct_ops) {
+               /*
+                * For the trampoline called directly, just handle
+                * the frame of trampoline.
+                */
+               emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, -stack_size);
+               emit_insn(ctx, std, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, stack_size - 8);
+               emit_insn(ctx, std, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size - 16);
+               emit_insn(ctx, addid, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size);
+       } else {
+               /*
+                * For the trampoline called from function entry,
+                * the frame of traced function and the frame of
+                * trampoline need to be considered.
+                */
+               /* RA and FP for parent function */
+               emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, -16);
+               emit_insn(ctx, std, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, 8);
+               emit_insn(ctx, std, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, 0);
+               emit_insn(ctx, addid, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, 16);
+
+               /* RA and FP for traced function */
+               emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, -stack_size);
+               emit_insn(ctx, std, LOONGARCH_GPR_T0, LOONGARCH_GPR_SP, stack_size - 8);
+               emit_insn(ctx, std, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size - 16);
+               emit_insn(ctx, addid, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size);
+       }
 
        /* callee saved register S1 to pass start time */
        emit_insn(ctx, std, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
@@ -1599,21 +1615,30 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
 
        emit_insn(ctx, ldd, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
 
-       /* trampoline called from function entry */
-       emit_insn(ctx, ldd, LOONGARCH_GPR_T0, LOONGARCH_GPR_SP, stack_size - 8);
-       emit_insn(ctx, ldd, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size - 16);
-       emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, stack_size);
-
-       emit_insn(ctx, ldd, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, 8);
-       emit_insn(ctx, ldd, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, 0);
-       emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, 16);
+       if (is_struct_ops) {
+               /* trampoline called directly */
+               emit_insn(ctx, ldd, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, stack_size - 8);
+               emit_insn(ctx, ldd, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size - 16);
+               emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, stack_size);
 
-       if (flags & BPF_TRAMP_F_SKIP_FRAME)
-               /* return to parent function */
                emit_insn(ctx, jirl, LOONGARCH_GPR_ZERO, LOONGARCH_GPR_RA, 0);
-       else
-               /* return to traced function */
-               emit_insn(ctx, jirl, LOONGARCH_GPR_ZERO, LOONGARCH_GPR_T0, 0);
+       } else {
+               /* trampoline called from function entry */
+               emit_insn(ctx, ldd, LOONGARCH_GPR_T0, LOONGARCH_GPR_SP, stack_size - 8);
+               emit_insn(ctx, ldd, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_size - 16);
+               emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, stack_size);
+
+               emit_insn(ctx, ldd, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, 8);
+               emit_insn(ctx, ldd, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, 0);
+               emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, 16);
+
+               if (flags & BPF_TRAMP_F_SKIP_FRAME)
+                       /* return to parent function */
+                       emit_insn(ctx, jirl, LOONGARCH_GPR_ZERO, LOONGARCH_GPR_RA, 0);
+               else
+                       /* return to traced function */
+                       emit_insn(ctx, jirl, LOONGARCH_GPR_ZERO, LOONGARCH_GPR_T0, 0);
+       }
 
        ret = ctx->idx;
 out: