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[PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION

Menglong Dong posted 7 patches 3 months, 2 weeks ago
There is a newer version of this series
[PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION
Posted by Menglong Dong 3 months, 2 weeks ago 
If TRACE_SESSION exists, we will use extra 8-bytes in the stack of the
trampoline to store the flags that we needed, and the 8-bytes lie after
the return value, which means ctx[nr_args + 1]. And we will store the
flag "is_exit" to the first bit of it.

Introduce the kfunc bpf_tracing_is_exit(), which is used to tell if it
is fexit currently. Meanwhile, inline it in the verifier.

Add the kfunc bpf_fsession_cookie(), which is similar to
bpf_session_cookie() and return the address of the session cookie. The
address of the session cookie is stored after session flags, which means
ctx[nr_args + 2]. Inline this kfunc in the verifier too.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Co-developed-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
v3:
- merge the bpf_tracing_is_exit and bpf_fsession_cookie into a single
  patch

v2:
- store the session flags after return value, instead of before nr_args
- inline the bpf_tracing_is_exit, as Jiri suggested
---
 include/linux/bpf.h      |  1 +
 kernel/bpf/verifier.c    | 33 ++++++++++++++++++++--
 kernel/trace/bpf_trace.c | 59 ++++++++++++++++++++++++++++++++++++++--
 3 files changed, 88 insertions(+), 5 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 6b5855c80fa6..ce55d3881c0d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1736,6 +1736,7 @@ struct bpf_prog {
 				enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */
 				call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */
 				call_get_func_ip:1, /* Do we call get_func_ip() */
+				call_session_cookie:1, /* Do we call bpf_fsession_cookie() */
 				tstamp_type_access:1, /* Accessed __sk_buff->tstamp_type */
 				sleepable:1;	/* BPF program is sleepable */
 	enum bpf_prog_type	type;		/* Type of BPF program */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 818deb6a06e4..6f8aa4718d6f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -12293,6 +12293,8 @@ enum special_kfunc_type {
 	KF___bpf_trap,
 	KF_bpf_task_work_schedule_signal,
 	KF_bpf_task_work_schedule_resume,
+	KF_bpf_tracing_is_exit,
+	KF_bpf_fsession_cookie,
 };
 
 BTF_ID_LIST(special_kfunc_list)
@@ -12365,6 +12367,8 @@ BTF_ID(func, bpf_res_spin_unlock_irqrestore)
 BTF_ID(func, __bpf_trap)
 BTF_ID(func, bpf_task_work_schedule_signal)
 BTF_ID(func, bpf_task_work_schedule_resume)
+BTF_ID(func, bpf_tracing_is_exit)
+BTF_ID(func, bpf_fsession_cookie)
 
 static bool is_task_work_add_kfunc(u32 func_id)
 {
@@ -12419,7 +12423,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
 	struct bpf_reg_state *reg = &regs[regno];
 	bool arg_mem_size = false;
 
-	if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
+	if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
+	    meta->func_id == special_kfunc_list[KF_bpf_tracing_is_exit] ||
+	    meta->func_id == special_kfunc_list[KF_bpf_fsession_cookie])
 		return KF_ARG_PTR_TO_CTX;
 
 	/* In this function, we verify the kfunc's BTF as per the argument type,
@@ -13912,7 +13918,8 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 		}
 	}
 
-	if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie]) {
+	if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie] ||
+	    meta.func_id == special_kfunc_list[KF_bpf_fsession_cookie]) {
 		meta.r0_size = sizeof(u64);
 		meta.r0_rdonly = false;
 	}
@@ -14193,6 +14200,9 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 			return err;
 	}
 
+	if (meta.func_id == special_kfunc_list[KF_bpf_fsession_cookie])
+		env->prog->call_session_cookie = true;
+
 	return 0;
 }
 
@@ -22012,6 +22022,25 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 		   desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
 		insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
 		*cnt = 1;
+	} else if (desc->func_id == special_kfunc_list[KF_bpf_tracing_is_exit]) {
+		/* Load nr_args from ctx - 8 */
+		insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
+		/* add rax, 1 */
+		insn_buf[1] = BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 1);
+		insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
+		insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
+		insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
+		insn_buf[5] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 1);
+		*cnt = 6;
+	} else if (desc->func_id == special_kfunc_list[KF_bpf_fsession_cookie]) {
+		/* Load nr_args from ctx - 8 */
+		insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
+		/* add rax, 2 */
+		insn_buf[1] = BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 2);
+		insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
+		insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
+		insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
+		*cnt = 5;
 	}
 
 	if (env->insn_aux_data[insn_idx].arg_prog) {
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 4f87c16d915a..4a8568bd654d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3356,12 +3356,65 @@ static const struct btf_kfunc_id_set bpf_kprobe_multi_kfunc_set = {
 	.filter = bpf_kprobe_multi_filter,
 };
 
-static int __init bpf_kprobe_multi_kfuncs_init(void)
+__bpf_kfunc_start_defs();
+
+__bpf_kfunc bool bpf_tracing_is_exit(void *ctx)
 {
-	return register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_kprobe_multi_kfunc_set);
+	/* This helper call is inlined by verifier. */
+	u64 nr_args = ((u64 *)ctx)[-1];
+
+	/*
+	 * ctx[nr_args + 1] is the session flags, and the last bit is
+	 * is_exit.
+	 */
+	return ((u64 *)ctx)[nr_args + 1] & 1;
+}
+
+__bpf_kfunc u64 *bpf_fsession_cookie(void *ctx)
+{
+	/* This helper call is inlined by verifier. */
+	u64 nr_args = ((u64 *)ctx)[-1];
+
+	/* ctx[nr_args + 2] is the session cookie address */
+	return (u64 *)((u64 *)ctx)[nr_args + 2];
+}
+
+__bpf_kfunc_end_defs();
+
+BTF_KFUNCS_START(tracing_kfunc_set_ids)
+BTF_ID_FLAGS(func, bpf_tracing_is_exit, KF_FASTCALL)
+BTF_ID_FLAGS(func, bpf_fsession_cookie, KF_FASTCALL)
+BTF_KFUNCS_END(tracing_kfunc_set_ids)
+
+static int bpf_tracing_filter(const struct bpf_prog *prog, u32 kfunc_id)
+{
+	if (!btf_id_set8_contains(&tracing_kfunc_set_ids, kfunc_id))
+		return 0;
+
+	if (prog->type != BPF_PROG_TYPE_TRACING ||
+	    prog->expected_attach_type != BPF_TRACE_SESSION)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct btf_kfunc_id_set bpf_tracing_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set = &tracing_kfunc_set_ids,
+	.filter = bpf_tracing_filter,
+};
+
+static int __init bpf_trace_kfuncs_init(void)
+{
+	int err = 0;
+
+	err = err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_kprobe_multi_kfunc_set);
+	err = err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_tracing_kfunc_set);
+
+	return err;
 }
 
-late_initcall(bpf_kprobe_multi_kfuncs_init);
+late_initcall(bpf_trace_kfuncs_init);
 
 typedef int (*copy_fn_t)(void *dst, const void *src, u32 size, struct task_struct *tsk);
 
-- 
2.51.1
Re: [PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION
Posted by Andrii Nakryiko 3 months ago 
On Sat, Oct 25, 2025 at 8:02 PM Menglong Dong <menglong8.dong@gmail.com> wrote:
>
> If TRACE_SESSION exists, we will use extra 8-bytes in the stack of the
> trampoline to store the flags that we needed, and the 8-bytes lie after
> the return value, which means ctx[nr_args + 1]. And we will store the
> flag "is_exit" to the first bit of it.
>
> Introduce the kfunc bpf_tracing_is_exit(), which is used to tell if it
> is fexit currently. Meanwhile, inline it in the verifier.
>
> Add the kfunc bpf_fsession_cookie(), which is similar to
> bpf_session_cookie() and return the address of the session cookie. The
> address of the session cookie is stored after session flags, which means
> ctx[nr_args + 2]. Inline this kfunc in the verifier too.
>
> Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
> Co-developed-by: Leon Hwang <leon.hwang@linux.dev>
> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
> ---
> v3:
> - merge the bpf_tracing_is_exit and bpf_fsession_cookie into a single
>   patch
>
> v2:
> - store the session flags after return value, instead of before nr_args
> - inline the bpf_tracing_is_exit, as Jiri suggested
> ---
>  include/linux/bpf.h      |  1 +
>  kernel/bpf/verifier.c    | 33 ++++++++++++++++++++--
>  kernel/trace/bpf_trace.c | 59 ++++++++++++++++++++++++++++++++++++++--
>  3 files changed, 88 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 6b5855c80fa6..ce55d3881c0d 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1736,6 +1736,7 @@ struct bpf_prog {
>                                 enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */
>                                 call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */
>                                 call_get_func_ip:1, /* Do we call get_func_ip() */
> +                               call_session_cookie:1, /* Do we call bpf_fsession_cookie() */
>                                 tstamp_type_access:1, /* Accessed __sk_buff->tstamp_type */
>                                 sleepable:1;    /* BPF program is sleepable */
>         enum bpf_prog_type      type;           /* Type of BPF program */
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 818deb6a06e4..6f8aa4718d6f 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -12293,6 +12293,8 @@ enum special_kfunc_type {
>         KF___bpf_trap,
>         KF_bpf_task_work_schedule_signal,
>         KF_bpf_task_work_schedule_resume,
> +       KF_bpf_tracing_is_exit,

we have bpf_session_is_return(), can't we just implement it for
fsession program type? Is that because we need ctx access? But we can
get bpf_run_ctx without that, can't we store this flag in run_ctx?

> +       KF_bpf_fsession_cookie,

same, we have bpf_session_cookie, can we support that? And again, we
can just make sure that session cookie is put into run_ctx.

And if not, let's at least use consistent naming then?
bpf_fsession_is_return() and bpf_fsession_cookie() as one more
consistent example?


>  };
>
>  BTF_ID_LIST(special_kfunc_list)
> @@ -12365,6 +12367,8 @@ BTF_ID(func, bpf_res_spin_unlock_irqrestore)
>  BTF_ID(func, __bpf_trap)
>  BTF_ID(func, bpf_task_work_schedule_signal)
>  BTF_ID(func, bpf_task_work_schedule_resume)
> +BTF_ID(func, bpf_tracing_is_exit)
> +BTF_ID(func, bpf_fsession_cookie)
>
>  static bool is_task_work_add_kfunc(u32 func_id)
>  {

[...]
Re: [PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION
Posted by Menglong Dong 3 months, 1 week ago 
On 2025/10/26 11:01, Menglong Dong wrote:
> If TRACE_SESSION exists, we will use extra 8-bytes in the stack of the
> trampoline to store the flags that we needed, and the 8-bytes lie after
> the return value, which means ctx[nr_args + 1]. And we will store the
> flag "is_exit" to the first bit of it.
> 
> Introduce the kfunc bpf_tracing_is_exit(), which is used to tell if it
> is fexit currently. Meanwhile, inline it in the verifier.
> 
> Add the kfunc bpf_fsession_cookie(), which is similar to
> bpf_session_cookie() and return the address of the session cookie. The
> address of the session cookie is stored after session flags, which means
> ctx[nr_args + 2]. Inline this kfunc in the verifier too.
> 
> Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
> Co-developed-by: Leon Hwang <leon.hwang@linux.dev>
> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
> ---
> v3:
> - merge the bpf_tracing_is_exit and bpf_fsession_cookie into a single
>   patch
> 
> v2:
> - store the session flags after return value, instead of before nr_args
> - inline the bpf_tracing_is_exit, as Jiri suggested
> ---
>  include/linux/bpf.h      |  1 +
>  kernel/bpf/verifier.c    | 33 ++++++++++++++++++++--
>  kernel/trace/bpf_trace.c | 59 ++++++++++++++++++++++++++++++++++++++--
>  3 files changed, 88 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 6b5855c80fa6..ce55d3881c0d 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1736,6 +1736,7 @@ struct bpf_prog {
>  				enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */
>  				call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */
>  				call_get_func_ip:1, /* Do we call get_func_ip() */
> +				call_session_cookie:1, /* Do we call bpf_fsession_cookie() */
>  				tstamp_type_access:1, /* Accessed __sk_buff->tstamp_type */
>  				sleepable:1;	/* BPF program is sleepable */
>  	enum bpf_prog_type	type;		/* Type of BPF program */
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 818deb6a06e4..6f8aa4718d6f 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -12293,6 +12293,8 @@ enum special_kfunc_type {
>  	KF___bpf_trap,
>  	KF_bpf_task_work_schedule_signal,
>  	KF_bpf_task_work_schedule_resume,
> +	KF_bpf_tracing_is_exit,
> +	KF_bpf_fsession_cookie,
>  };
>  
>  BTF_ID_LIST(special_kfunc_list)
> @@ -12365,6 +12367,8 @@ BTF_ID(func, bpf_res_spin_unlock_irqrestore)
>  BTF_ID(func, __bpf_trap)
>  BTF_ID(func, bpf_task_work_schedule_signal)
>  BTF_ID(func, bpf_task_work_schedule_resume)
> +BTF_ID(func, bpf_tracing_is_exit)
> +BTF_ID(func, bpf_fsession_cookie)
>  
>  static bool is_task_work_add_kfunc(u32 func_id)
>  {
> @@ -12419,7 +12423,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
>  	struct bpf_reg_state *reg = &regs[regno];
>  	bool arg_mem_size = false;
>  
> -	if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
> +	if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
> +	    meta->func_id == special_kfunc_list[KF_bpf_tracing_is_exit] ||
> +	    meta->func_id == special_kfunc_list[KF_bpf_fsession_cookie])
>  		return KF_ARG_PTR_TO_CTX;
>  
>  	/* In this function, we verify the kfunc's BTF as per the argument type,
> @@ -13912,7 +13918,8 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
>  		}
>  	}
>  
> -	if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie]) {
> +	if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie] ||
> +	    meta.func_id == special_kfunc_list[KF_bpf_fsession_cookie]) {
>  		meta.r0_size = sizeof(u64);
>  		meta.r0_rdonly = false;
>  	}
> @@ -14193,6 +14200,9 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
>  			return err;
>  	}
>  
> +	if (meta.func_id == special_kfunc_list[KF_bpf_fsession_cookie])
> +		env->prog->call_session_cookie = true;
> +
>  	return 0;
>  }
>  
> @@ -22012,6 +22022,25 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
>  		   desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
>  		insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
>  		*cnt = 1;
> +	} else if (desc->func_id == special_kfunc_list[KF_bpf_tracing_is_exit]) {
> +		/* Load nr_args from ctx - 8 */
> +		insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
> +		/* add rax, 1 */
> +		insn_buf[1] = BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 1);
> +		insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
> +		insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
> +		insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
> +		insn_buf[5] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 1);
> +		*cnt = 6;
> +	} else if (desc->func_id == special_kfunc_list[KF_bpf_fsession_cookie]) {
> +		/* Load nr_args from ctx - 8 */
> +		insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
> +		/* add rax, 2 */
> +		insn_buf[1] = BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 2);
> +		insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
> +		insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
> +		insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
> +		*cnt = 5;
>  	}
>  
>  	if (env->insn_aux_data[insn_idx].arg_prog) {
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 4f87c16d915a..4a8568bd654d 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -3356,12 +3356,65 @@ static const struct btf_kfunc_id_set bpf_kprobe_multi_kfunc_set = {
>  	.filter = bpf_kprobe_multi_filter,
>  };
>  
> -static int __init bpf_kprobe_multi_kfuncs_init(void)
> +__bpf_kfunc_start_defs();
> +
> +__bpf_kfunc bool bpf_tracing_is_exit(void *ctx)
>  {
> -	return register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_kprobe_multi_kfunc_set);
> +	/* This helper call is inlined by verifier. */
> +	u64 nr_args = ((u64 *)ctx)[-1];
> +
> +	/*
> +	 * ctx[nr_args + 1] is the session flags, and the last bit is
> +	 * is_exit.
> +	 */
> +	return ((u64 *)ctx)[nr_args + 1] & 1;
> +}
> +
> +__bpf_kfunc u64 *bpf_fsession_cookie(void *ctx)
> +{
> +	/* This helper call is inlined by verifier. */
> +	u64 nr_args = ((u64 *)ctx)[-1];
> +
> +	/* ctx[nr_args + 2] is the session cookie address */
> +	return (u64 *)((u64 *)ctx)[nr_args + 2];

This casting cause build warning in 32-bits arch. I'll make it
like this in the next version after more human comments
on this series:

    return (u64 *)(long)((u64 *)ctx)[nr_args + 2];

> +}
> +
> +__bpf_kfunc_end_defs();
> +
> +BTF_KFUNCS_START(tracing_kfunc_set_ids)
> +BTF_ID_FLAGS(func, bpf_tracing_is_exit, KF_FASTCALL)
> +BTF_ID_FLAGS(func, bpf_fsession_cookie, KF_FASTCALL)
> +BTF_KFUNCS_END(tracing_kfunc_set_ids)
> +
> +static int bpf_tracing_filter(const struct bpf_prog *prog, u32 kfunc_id)
> +{
> +	if (!btf_id_set8_contains(&tracing_kfunc_set_ids, kfunc_id))
> +		return 0;
> +
> +	if (prog->type != BPF_PROG_TYPE_TRACING ||
> +	    prog->expected_attach_type != BPF_TRACE_SESSION)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static const struct btf_kfunc_id_set bpf_tracing_kfunc_set = {
> +	.owner = THIS_MODULE,
> +	.set = &tracing_kfunc_set_ids,
> +	.filter = bpf_tracing_filter,
> +};
> +
> +static int __init bpf_trace_kfuncs_init(void)
> +{
> +	int err = 0;
> +
> +	err = err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_kprobe_multi_kfunc_set);
> +	err = err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_tracing_kfunc_set);
> +
> +	return err;
>  }
>  
> -late_initcall(bpf_kprobe_multi_kfuncs_init);
> +late_initcall(bpf_trace_kfuncs_init);
>  
>  typedef int (*copy_fn_t)(void *dst, const void *src, u32 size, struct task_struct *tsk);
>  
>
Re: [PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION
Posted by kernel test robot 3 months, 2 weeks ago 
Hi Menglong,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Menglong-Dong/bpf-add-tracing-session-support/20251026-110720
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20251026030143.23807-3-dongml2%40chinatelecom.cn
patch subject: [PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION
config: i386-randconfig-061-20251027 (https://download.01.org/0day-ci/archive/20251027/202510270955.mbxODFvZ-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251027/202510270955.mbxODFvZ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510270955.mbxODFvZ-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   kernel/trace/bpf_trace.c:833:41: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected void [noderef] __user *[addressable] [assigned] [usertype] sival_ptr @@     got void * @@
   kernel/trace/bpf_trace.c:833:41: sparse:     expected void [noderef] __user *[addressable] [assigned] [usertype] sival_ptr
   kernel/trace/bpf_trace.c:833:41: sparse:     got void *
   kernel/trace/bpf_trace.c:3573:52: sparse: sparse: cast removes address space '__user' of expression
   kernel/trace/bpf_trace.c:3587:56: sparse: sparse: cast removes address space '__user' of expression
   kernel/trace/bpf_trace.c:3601:52: sparse: sparse: cast removes address space '__user' of expression
   kernel/trace/bpf_trace.c:3608:56: sparse: sparse: cast removes address space '__user' of expression
   kernel/trace/bpf_trace.c:3616:52: sparse: sparse: cast removes address space '__user' of expression
   kernel/trace/bpf_trace.c:3624:56: sparse: sparse: cast removes address space '__user' of expression
   kernel/trace/bpf_trace.c: note: in included file (through include/linux/rbtree.h, include/linux/mm_types.h, include/linux/mmzone.h, ...):
   include/linux/rcupdate.h:895:9: sparse: sparse: context imbalance in 'uprobe_prog_run' - unexpected unlock
>> kernel/trace/bpf_trace.c:3379:35: sparse: sparse: non size-preserving integer to pointer cast

vim +3379 kernel/trace/bpf_trace.c

  3372	
  3373	__bpf_kfunc u64 *bpf_fsession_cookie(void *ctx)
  3374	{
  3375		/* This helper call is inlined by verifier. */
  3376		u64 nr_args = ((u64 *)ctx)[-1];
  3377	
  3378		/* ctx[nr_args + 2] is the session cookie address */
> 3379		return (u64 *)((u64 *)ctx)[nr_args + 2];
  3380	}
  3381	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Re: [PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION
Posted by kernel test robot 3 months, 2 weeks ago 
Hi Menglong,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Menglong-Dong/bpf-add-tracing-session-support/20251026-110720
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20251026030143.23807-3-dongml2%40chinatelecom.cn
patch subject: [PATCH bpf-next v3 2/7] bpf: add two kfunc for TRACE_SESSION
config: i386-buildonly-randconfig-003-20251026 (https://download.01.org/0day-ci/archive/20251026/202510261253.qRd57kJv-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251026/202510261253.qRd57kJv-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510261253.qRd57kJv-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/trace/bpf_trace.c: In function '____bpf_trace_printk':
   kernel/trace/bpf_trace.c:377:9: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
     377 |         ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
         |         ^~~
   kernel/trace/bpf_trace.c: In function '____bpf_trace_vprintk':
   kernel/trace/bpf_trace.c:433:9: warning: function '____bpf_trace_vprintk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
     433 |         ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
         |         ^~~
   kernel/trace/bpf_trace.c: In function '____bpf_seq_printf':
   kernel/trace/bpf_trace.c:475:9: warning: function '____bpf_seq_printf' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
     475 |         seq_bprintf(m, fmt, data.bin_args);
         |         ^~~~~~~~~~~
   kernel/trace/bpf_trace.c: In function 'bpf_fsession_cookie':
>> kernel/trace/bpf_trace.c:3379:16: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
    3379 |         return (u64 *)((u64 *)ctx)[nr_args + 2];
         |                ^

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for I2C_K1
   Depends on [n]: I2C [=y] && HAS_IOMEM [=y] && (ARCH_SPACEMIT || COMPILE_TEST [=y]) && OF [=n]
   Selected by [y]:
   - MFD_SPACEMIT_P1 [=y] && HAS_IOMEM [=y] && (ARCH_SPACEMIT || COMPILE_TEST [=y]) && I2C [=y]


vim +3379 kernel/trace/bpf_trace.c

  3372	
  3373	__bpf_kfunc u64 *bpf_fsession_cookie(void *ctx)
  3374	{
  3375		/* This helper call is inlined by verifier. */
  3376		u64 nr_args = ((u64 *)ctx)[-1];
  3377	
  3378		/* ctx[nr_args + 2] is the session cookie address */
> 3379		return (u64 *)((u64 *)ctx)[nr_args + 2];
  3380	}
  3381	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Patchew 2.1-devel-b67e4c2

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