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[PATCH v4 5/5] LoongArch: BPF: Add struct ops support for trampoline

Chenghao Duan posted 5 patches 2 months, 1 week ago
There is a newer version of this series
[PATCH v4 5/5] LoongArch: BPF: Add struct ops support for trampoline
Posted by Chenghao Duan 2 months, 1 week ago 
From: Tiezhu Yang <yangtiezhu@loongson.cn>

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>
---
 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 ac5ce3a28..6a84fb104 100644
--- a/arch/loongarch/net/bpf_jit.c
+++ b/arch/loongarch/net/bpf_jit.c
@@ -1603,6 +1603,7 @@ 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;
@@ -1678,18 +1679,31 @@ 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);
@@ -1779,21 +1793,30 @@ 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:
-- 
2.25.1
Re: [PATCH v4 5/5] LoongArch: BPF: Add struct ops support for trampoline
Posted by Hengqi Chen 2 months, 1 week ago 
On Thu, Jul 24, 2025 at 10:22 PM Chenghao Duan <duanchenghao@kylinos.cn> wrote:
>
> From: Tiezhu Yang <yangtiezhu@loongson.cn>
>
> 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>
> ---
>  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 ac5ce3a28..6a84fb104 100644
> --- a/arch/loongarch/net/bpf_jit.c
> +++ b/arch/loongarch/net/bpf_jit.c
> @@ -1603,6 +1603,7 @@ 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;
> @@ -1678,18 +1679,31 @@ 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);
> +       }
>

The diff removes code added in patch 4/5, this should be squashed to
the trampoline patch if possible.

>         /* callee saved register S1 to pass start time */
>         emit_insn(ctx, std, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
> @@ -1779,21 +1793,30 @@ 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:
> --
> 2.25.1
>
Re: [PATCH v4 5/5] LoongArch: BPF: Add struct ops support for trampoline
Posted by Chenghao Duan 2 months, 1 week ago 
On Mon, Jul 28, 2025 at 06:55:52PM +0800, Hengqi Chen wrote:
> On Thu, Jul 24, 2025 at 10:22 PM Chenghao Duan <duanchenghao@kylinos.cn> wrote:
> >
> > From: Tiezhu Yang <yangtiezhu@loongson.cn>
> >
> > 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>
> > ---
> >  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 ac5ce3a28..6a84fb104 100644
> > --- a/arch/loongarch/net/bpf_jit.c
> > +++ b/arch/loongarch/net/bpf_jit.c
> > @@ -1603,6 +1603,7 @@ 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;
> > @@ -1678,18 +1679,31 @@ 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);
> > +       }
> >
> 
> The diff removes code added in patch 4/5, this should be squashed to
> the trampoline patch if possible.

This patch was provided by Tiezhu Yang, and there was a discussion about
it at the time.
https://lore.kernel.org/all/cd190c8a-a7b9-53de-d363-c3d695fe3191@loongson.cn/

> 
> >         /* callee saved register S1 to pass start time */
> >         emit_insn(ctx, std, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
> > @@ -1779,21 +1793,30 @@ 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:
> > --
> > 2.25.1
> >
Re: [PATCH v4 5/5] LoongArch: BPF: Add struct ops support for trampoline
Posted by Huacai Chen 2 months, 1 week ago 
On Mon, Jul 28, 2025 at 9:34 PM Chenghao Duan <duanchenghao@kylinos.cn> wrote:
>
> On Mon, Jul 28, 2025 at 06:55:52PM +0800, Hengqi Chen wrote:
> > On Thu, Jul 24, 2025 at 10:22 PM Chenghao Duan <duanchenghao@kylinos.cn> wrote:
> > >
> > > From: Tiezhu Yang <yangtiezhu@loongson.cn>
> > >
> > > 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>
> > > ---
> > >  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 ac5ce3a28..6a84fb104 100644
> > > --- a/arch/loongarch/net/bpf_jit.c
> > > +++ b/arch/loongarch/net/bpf_jit.c
> > > @@ -1603,6 +1603,7 @@ 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;
> > > @@ -1678,18 +1679,31 @@ 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);
> > > +       }
> > >
> >
> > The diff removes code added in patch 4/5, this should be squashed to
> > the trampoline patch if possible.
>
> This patch was provided by Tiezhu Yang, and there was a discussion about
> it at the time.
> https://lore.kernel.org/all/cd190c8a-a7b9-53de-d363-c3d695fe3191@loongson.cn/
From my opinion I also prefer to squash.

Huacai

>
> >
> > >         /* callee saved register S1 to pass start time */
> > >         emit_insn(ctx, std, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
> > > @@ -1779,21 +1793,30 @@ 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:
> > > --
> > > 2.25.1
> > >

Patchew 2.1-devel-b67e4c2

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