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Message-ID: <20250716043915.15034-1-yangtiezhu@loongson.cn>
Date: Wed, 16 Jul 2025 12:39:15 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>
Cc: Hengqi Chen <hengqi.chen@...il.com>,
bpf@...r.kernel.org,
loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH] 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@...ngson.cn>
---
This is a RFC patch, based on 6.16-rc6 and the following series:
[PATCH v3 0/5] Support trampoline for LoongArch
https://lore.kernel.org/loongarch/20250709055029.723243-1-duanchenghao@kylinos.cn/
arch/loongarch/net/bpf_jit.c | 71 ++++++++++++++++++++++++------------
1 file changed, 47 insertions(+), 24 deletions(-)
diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
index 6820558afce5..7663b84a4ff1 100644
--- a/arch/loongarch/net/bpf_jit.c
+++ b/arch/loongarch/net/bpf_jit.c
@@ -1599,6 +1599,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
+ bool is_struct_ops = flags & BPF_TRAMP_F_INDIRECT;
int ret, save_ret;
void *orig_call = func_addr;
u32 **branches = NULL;
@@ -1674,18 +1675,31 @@ 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 from function entry,
+ * the frame of traced function and the frame of
+ * trampoline need to be considered.
+ */
+ 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);
+
+ 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);
+ } else {
+ /*
+ * 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);
+ }
/* callee saved register S1 to pass start time */
emit_insn(ctx, std, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
@@ -1772,21 +1786,30 @@ 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);
+ if (!is_struct_ops) {
+ /* 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);
- 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);
+ } else {
+ /* 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);
+ }
ret = ctx->idx;
out:
--
2.42.0
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