2022-02-02 16:03:31

by Jiri Olsa

[permalink] [raw]
Subject: [PATCH 2/8] bpf: Add bpf_get_func_ip kprobe helper for fprobe link

Adding support to call get_func_ip_fprobe helper from kprobe
programs attached by fprobe link.

Also adding support to inline it, because it's single load
instruction.

Signed-off-by: Jiri Olsa <[email protected]>
---
kernel/bpf/verifier.c | 19 ++++++++++++++++++-
kernel/trace/bpf_trace.c | 16 +++++++++++++++-
2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1ae41d0cf96c..a745ded00635 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -13625,7 +13625,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
continue;
}

- /* Implement bpf_get_func_ip inline. */
+ /* Implement tracing bpf_get_func_ip inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_ip) {
/* Load IP address from ctx - 16 */
@@ -13640,6 +13640,23 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
continue;
}

+ /* Implement kprobe/fprobe bpf_get_func_ip inline. */
+ if (prog_type == BPF_PROG_TYPE_KPROBE &&
+ eatype == BPF_TRACE_FPROBE &&
+ insn->imm == BPF_FUNC_get_func_ip) {
+ /* Load IP address from ctx (struct pt_regs) ip */
+ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
+ offsetof(struct pt_regs, ip));
+
+ new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
+ if (!new_prog)
+ return -ENOMEM;
+
+ env->prog = prog = new_prog;
+ insn = new_prog->insnsi + i + delta;
+ continue;
+ }
+
patch_call_imm:
fn = env->ops->get_func_proto(insn->imm, env->prog);
/* all functions that have prototype and verifier allowed
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a2024ba32a20..28e59e31e3db 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1036,6 +1036,19 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
.arg1_type = ARG_PTR_TO_CTX,
};

+BPF_CALL_1(bpf_get_func_ip_fprobe, struct pt_regs *, regs)
+{
+ /* This helper call is inlined by verifier. */
+ return regs->ip;
+}
+
+static const struct bpf_func_proto bpf_get_func_ip_proto_fprobe = {
+ .func = bpf_get_func_ip_fprobe,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
{
struct bpf_trace_run_ctx *run_ctx;
@@ -1279,7 +1292,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_override_return_proto;
#endif
case BPF_FUNC_get_func_ip:
- return &bpf_get_func_ip_proto_kprobe;
+ return prog->expected_attach_type == BPF_TRACE_FPROBE ?
+ &bpf_get_func_ip_proto_fprobe : &bpf_get_func_ip_proto_kprobe;
case BPF_FUNC_get_attach_cookie:
return &bpf_get_attach_cookie_proto_trace;
default:
--
2.34.1


2022-02-08 07:52:42

by Alexei Starovoitov

[permalink] [raw]
Subject: Re: [PATCH 2/8] bpf: Add bpf_get_func_ip kprobe helper for fprobe link

On Mon, Feb 7, 2022 at 10:59 AM Andrii Nakryiko
<[email protected]> wrote:
>
> On Wed, Feb 2, 2022 at 5:53 AM Jiri Olsa <[email protected]> wrote:
> >
> > Adding support to call get_func_ip_fprobe helper from kprobe
> > programs attached by fprobe link.
> >
> > Also adding support to inline it, because it's single load
> > instruction.
> >
> > Signed-off-by: Jiri Olsa <[email protected]>
> > ---
> > kernel/bpf/verifier.c | 19 ++++++++++++++++++-
> > kernel/trace/bpf_trace.c | 16 +++++++++++++++-
> > 2 files changed, 33 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index 1ae41d0cf96c..a745ded00635 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -13625,7 +13625,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > continue;
> > }
> >
> > - /* Implement bpf_get_func_ip inline. */
> > + /* Implement tracing bpf_get_func_ip inline. */
> > if (prog_type == BPF_PROG_TYPE_TRACING &&
> > insn->imm == BPF_FUNC_get_func_ip) {
> > /* Load IP address from ctx - 16 */
> > @@ -13640,6 +13640,23 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > continue;
> > }
> >
> > + /* Implement kprobe/fprobe bpf_get_func_ip inline. */
> > + if (prog_type == BPF_PROG_TYPE_KPROBE &&
> > + eatype == BPF_TRACE_FPROBE &&
> > + insn->imm == BPF_FUNC_get_func_ip) {
> > + /* Load IP address from ctx (struct pt_regs) ip */
> > + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
> > + offsetof(struct pt_regs, ip));
>
> Isn't this architecture-specific? I'm starting to dislike this
> inlining whole more and more. It's just a complication in verifier
> without clear real-world benefits. We are clearly prematurely
> optimizing here. In practice you'll just call bpf_get_func_ip() once
> and that's it. Function call overhead will be negligible compare to
> other *userful* work you'll be doing in your BPF program.

We should be doing inlining when we can.
Every bit of performance matters.

2022-02-08 17:27:03

by Andrii Nakryiko

[permalink] [raw]
Subject: Re: [PATCH 2/8] bpf: Add bpf_get_func_ip kprobe helper for fprobe link

On Wed, Feb 2, 2022 at 5:53 AM Jiri Olsa <[email protected]> wrote:
>
> Adding support to call get_func_ip_fprobe helper from kprobe
> programs attached by fprobe link.
>
> Also adding support to inline it, because it's single load
> instruction.
>
> Signed-off-by: Jiri Olsa <[email protected]>
> ---
> kernel/bpf/verifier.c | 19 ++++++++++++++++++-
> kernel/trace/bpf_trace.c | 16 +++++++++++++++-
> 2 files changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 1ae41d0cf96c..a745ded00635 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -13625,7 +13625,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> continue;
> }
>
> - /* Implement bpf_get_func_ip inline. */
> + /* Implement tracing bpf_get_func_ip inline. */
> if (prog_type == BPF_PROG_TYPE_TRACING &&
> insn->imm == BPF_FUNC_get_func_ip) {
> /* Load IP address from ctx - 16 */
> @@ -13640,6 +13640,23 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> continue;
> }
>
> + /* Implement kprobe/fprobe bpf_get_func_ip inline. */
> + if (prog_type == BPF_PROG_TYPE_KPROBE &&
> + eatype == BPF_TRACE_FPROBE &&
> + insn->imm == BPF_FUNC_get_func_ip) {
> + /* Load IP address from ctx (struct pt_regs) ip */
> + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
> + offsetof(struct pt_regs, ip));

Isn't this architecture-specific? I'm starting to dislike this
inlining whole more and more. It's just a complication in verifier
without clear real-world benefits. We are clearly prematurely
optimizing here. In practice you'll just call bpf_get_func_ip() once
and that's it. Function call overhead will be negligible compare to
other *userful* work you'll be doing in your BPF program.


> +
> + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
> + if (!new_prog)
> + return -ENOMEM;
> +
> + env->prog = prog = new_prog;
> + insn = new_prog->insnsi + i + delta;
> + continue;
> + }
> +
> patch_call_imm:
> fn = env->ops->get_func_proto(insn->imm, env->prog);
> /* all functions that have prototype and verifier allowed
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index a2024ba32a20..28e59e31e3db 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1036,6 +1036,19 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
> .arg1_type = ARG_PTR_TO_CTX,
> };
>
> +BPF_CALL_1(bpf_get_func_ip_fprobe, struct pt_regs *, regs)
> +{
> + /* This helper call is inlined by verifier. */
> + return regs->ip;
> +}
> +
> +static const struct bpf_func_proto bpf_get_func_ip_proto_fprobe = {
> + .func = bpf_get_func_ip_fprobe,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> +};
> +
> BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
> {
> struct bpf_trace_run_ctx *run_ctx;
> @@ -1279,7 +1292,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> return &bpf_override_return_proto;
> #endif
> case BPF_FUNC_get_func_ip:
> - return &bpf_get_func_ip_proto_kprobe;
> + return prog->expected_attach_type == BPF_TRACE_FPROBE ?
> + &bpf_get_func_ip_proto_fprobe : &bpf_get_func_ip_proto_kprobe;
> case BPF_FUNC_get_attach_cookie:
> return &bpf_get_attach_cookie_proto_trace;
> default:
> --
> 2.34.1
>

2022-02-09 16:32:06

by Andrii Nakryiko

[permalink] [raw]
Subject: Re: [PATCH 2/8] bpf: Add bpf_get_func_ip kprobe helper for fprobe link

On Wed, Feb 9, 2022 at 7:01 AM Jiri Olsa <[email protected]> wrote:
>
> On Mon, Feb 07, 2022 at 10:59:18AM -0800, Andrii Nakryiko wrote:
> > On Wed, Feb 2, 2022 at 5:53 AM Jiri Olsa <[email protected]> wrote:
> > >
> > > Adding support to call get_func_ip_fprobe helper from kprobe
> > > programs attached by fprobe link.
> > >
> > > Also adding support to inline it, because it's single load
> > > instruction.
> > >
> > > Signed-off-by: Jiri Olsa <[email protected]>
> > > ---
> > > kernel/bpf/verifier.c | 19 ++++++++++++++++++-
> > > kernel/trace/bpf_trace.c | 16 +++++++++++++++-
> > > 2 files changed, 33 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > > index 1ae41d0cf96c..a745ded00635 100644
> > > --- a/kernel/bpf/verifier.c
> > > +++ b/kernel/bpf/verifier.c
> > > @@ -13625,7 +13625,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > > continue;
> > > }
> > >
> > > - /* Implement bpf_get_func_ip inline. */
> > > + /* Implement tracing bpf_get_func_ip inline. */
> > > if (prog_type == BPF_PROG_TYPE_TRACING &&
> > > insn->imm == BPF_FUNC_get_func_ip) {
> > > /* Load IP address from ctx - 16 */
> > > @@ -13640,6 +13640,23 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > > continue;
> > > }
> > >
> > > + /* Implement kprobe/fprobe bpf_get_func_ip inline. */
> > > + if (prog_type == BPF_PROG_TYPE_KPROBE &&
> > > + eatype == BPF_TRACE_FPROBE &&
> > > + insn->imm == BPF_FUNC_get_func_ip) {
> > > + /* Load IP address from ctx (struct pt_regs) ip */
> > > + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
> > > + offsetof(struct pt_regs, ip));
> >
> > Isn't this architecture-specific? I'm starting to dislike this
>
> ugh, it is.. I'm not sure we want #ifdef CONFIG_X86 in here,
> or some arch_* specific function?


So not inlining it isn't even considered? this function will be called
once or at most a few times per BPF program invocation. Anyone calling
it in a tight loop is going to use it very-very suboptimally (and even
then useful program logic will dominate). There is no point in
inlining it.

>
> jirka
>
> > inlining whole more and more. It's just a complication in verifier
> > without clear real-world benefits. We are clearly prematurely
> > optimizing here. In practice you'll just call bpf_get_func_ip() once
> > and that's it. Function call overhead will be negligible compare to
> > other *userful* work you'll be doing in your BPF program.
> >
> >
> > > +
> > > + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
> > > + if (!new_prog)
> > > + return -ENOMEM;
> > > +
> > > + env->prog = prog = new_prog;
> > > + insn = new_prog->insnsi + i + delta;
> > > + continue;
> > > + }
> > > +
> > > patch_call_imm:
> > > fn = env->ops->get_func_proto(insn->imm, env->prog);
> > > /* all functions that have prototype and verifier allowed
> > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > > index a2024ba32a20..28e59e31e3db 100644
> > > --- a/kernel/trace/bpf_trace.c
> > > +++ b/kernel/trace/bpf_trace.c
> > > @@ -1036,6 +1036,19 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
> > > .arg1_type = ARG_PTR_TO_CTX,
> > > };
> > >
> > > +BPF_CALL_1(bpf_get_func_ip_fprobe, struct pt_regs *, regs)
> > > +{
> > > + /* This helper call is inlined by verifier. */
> > > + return regs->ip;
> > > +}
> > > +
> > > +static const struct bpf_func_proto bpf_get_func_ip_proto_fprobe = {
> > > + .func = bpf_get_func_ip_fprobe,
> > > + .gpl_only = false,
> > > + .ret_type = RET_INTEGER,
> > > + .arg1_type = ARG_PTR_TO_CTX,
> > > +};
> > > +
> > > BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
> > > {
> > > struct bpf_trace_run_ctx *run_ctx;
> > > @@ -1279,7 +1292,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > > return &bpf_override_return_proto;
> > > #endif
> > > case BPF_FUNC_get_func_ip:
> > > - return &bpf_get_func_ip_proto_kprobe;
> > > + return prog->expected_attach_type == BPF_TRACE_FPROBE ?
> > > + &bpf_get_func_ip_proto_fprobe : &bpf_get_func_ip_proto_kprobe;
> > > case BPF_FUNC_get_attach_cookie:
> > > return &bpf_get_attach_cookie_proto_trace;
> > > default:
> > > --
> > > 2.34.1
> > >

2022-02-09 18:01:51

by Jiri Olsa

[permalink] [raw]
Subject: Re: [PATCH 2/8] bpf: Add bpf_get_func_ip kprobe helper for fprobe link

On Mon, Feb 07, 2022 at 10:59:18AM -0800, Andrii Nakryiko wrote:
> On Wed, Feb 2, 2022 at 5:53 AM Jiri Olsa <[email protected]> wrote:
> >
> > Adding support to call get_func_ip_fprobe helper from kprobe
> > programs attached by fprobe link.
> >
> > Also adding support to inline it, because it's single load
> > instruction.
> >
> > Signed-off-by: Jiri Olsa <[email protected]>
> > ---
> > kernel/bpf/verifier.c | 19 ++++++++++++++++++-
> > kernel/trace/bpf_trace.c | 16 +++++++++++++++-
> > 2 files changed, 33 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index 1ae41d0cf96c..a745ded00635 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -13625,7 +13625,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > continue;
> > }
> >
> > - /* Implement bpf_get_func_ip inline. */
> > + /* Implement tracing bpf_get_func_ip inline. */
> > if (prog_type == BPF_PROG_TYPE_TRACING &&
> > insn->imm == BPF_FUNC_get_func_ip) {
> > /* Load IP address from ctx - 16 */
> > @@ -13640,6 +13640,23 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > continue;
> > }
> >
> > + /* Implement kprobe/fprobe bpf_get_func_ip inline. */
> > + if (prog_type == BPF_PROG_TYPE_KPROBE &&
> > + eatype == BPF_TRACE_FPROBE &&
> > + insn->imm == BPF_FUNC_get_func_ip) {
> > + /* Load IP address from ctx (struct pt_regs) ip */
> > + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
> > + offsetof(struct pt_regs, ip));
>
> Isn't this architecture-specific? I'm starting to dislike this

ugh, it is.. I'm not sure we want #ifdef CONFIG_X86 in here,
or some arch_* specific function?

jirka

> inlining whole more and more. It's just a complication in verifier
> without clear real-world benefits. We are clearly prematurely
> optimizing here. In practice you'll just call bpf_get_func_ip() once
> and that's it. Function call overhead will be negligible compare to
> other *userful* work you'll be doing in your BPF program.
>
>
> > +
> > + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
> > + if (!new_prog)
> > + return -ENOMEM;
> > +
> > + env->prog = prog = new_prog;
> > + insn = new_prog->insnsi + i + delta;
> > + continue;
> > + }
> > +
> > patch_call_imm:
> > fn = env->ops->get_func_proto(insn->imm, env->prog);
> > /* all functions that have prototype and verifier allowed
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index a2024ba32a20..28e59e31e3db 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -1036,6 +1036,19 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
> > .arg1_type = ARG_PTR_TO_CTX,
> > };
> >
> > +BPF_CALL_1(bpf_get_func_ip_fprobe, struct pt_regs *, regs)
> > +{
> > + /* This helper call is inlined by verifier. */
> > + return regs->ip;
> > +}
> > +
> > +static const struct bpf_func_proto bpf_get_func_ip_proto_fprobe = {
> > + .func = bpf_get_func_ip_fprobe,
> > + .gpl_only = false,
> > + .ret_type = RET_INTEGER,
> > + .arg1_type = ARG_PTR_TO_CTX,
> > +};
> > +
> > BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
> > {
> > struct bpf_trace_run_ctx *run_ctx;
> > @@ -1279,7 +1292,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > return &bpf_override_return_proto;
> > #endif
> > case BPF_FUNC_get_func_ip:
> > - return &bpf_get_func_ip_proto_kprobe;
> > + return prog->expected_attach_type == BPF_TRACE_FPROBE ?
> > + &bpf_get_func_ip_proto_fprobe : &bpf_get_func_ip_proto_kprobe;
> > case BPF_FUNC_get_attach_cookie:
> > return &bpf_get_attach_cookie_proto_trace;
> > default:
> > --
> > 2.34.1
> >

2022-02-09 20:13:45

by Jiri Olsa

[permalink] [raw]
Subject: Re: [PATCH 2/8] bpf: Add bpf_get_func_ip kprobe helper for fprobe link

On Wed, Feb 09, 2022 at 08:05:05AM -0800, Andrii Nakryiko wrote:
> On Wed, Feb 9, 2022 at 7:01 AM Jiri Olsa <[email protected]> wrote:
> >
> > On Mon, Feb 07, 2022 at 10:59:18AM -0800, Andrii Nakryiko wrote:
> > > On Wed, Feb 2, 2022 at 5:53 AM Jiri Olsa <[email protected]> wrote:
> > > >
> > > > Adding support to call get_func_ip_fprobe helper from kprobe
> > > > programs attached by fprobe link.
> > > >
> > > > Also adding support to inline it, because it's single load
> > > > instruction.
> > > >
> > > > Signed-off-by: Jiri Olsa <[email protected]>
> > > > ---
> > > > kernel/bpf/verifier.c | 19 ++++++++++++++++++-
> > > > kernel/trace/bpf_trace.c | 16 +++++++++++++++-
> > > > 2 files changed, 33 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > > > index 1ae41d0cf96c..a745ded00635 100644
> > > > --- a/kernel/bpf/verifier.c
> > > > +++ b/kernel/bpf/verifier.c
> > > > @@ -13625,7 +13625,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > > > continue;
> > > > }
> > > >
> > > > - /* Implement bpf_get_func_ip inline. */
> > > > + /* Implement tracing bpf_get_func_ip inline. */
> > > > if (prog_type == BPF_PROG_TYPE_TRACING &&
> > > > insn->imm == BPF_FUNC_get_func_ip) {
> > > > /* Load IP address from ctx - 16 */
> > > > @@ -13640,6 +13640,23 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > > > continue;
> > > > }
> > > >
> > > > + /* Implement kprobe/fprobe bpf_get_func_ip inline. */
> > > > + if (prog_type == BPF_PROG_TYPE_KPROBE &&
> > > > + eatype == BPF_TRACE_FPROBE &&
> > > > + insn->imm == BPF_FUNC_get_func_ip) {
> > > > + /* Load IP address from ctx (struct pt_regs) ip */
> > > > + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
> > > > + offsetof(struct pt_regs, ip));
> > >
> > > Isn't this architecture-specific? I'm starting to dislike this
> >
> > ugh, it is.. I'm not sure we want #ifdef CONFIG_X86 in here,
> > or some arch_* specific function?
>
>
> So not inlining it isn't even considered? this function will be called
> once or at most a few times per BPF program invocation. Anyone calling
> it in a tight loop is going to use it very-very suboptimally (and even
> then useful program logic will dominate). There is no point in
> inlining it.

I agree that given its usage pattern there won't be too much gain,
on the other hand it's simple verifier code changing call/load/ret
into simple load, so I thought why not.. also there are just few
helpers we can inline so easily

but yea.. I can't think of any sane usage of this helper that inlining
would matter for.. which doesn't mean there isn't one ;-)

jirka

>
> >
> > jirka
> >
> > > inlining whole more and more. It's just a complication in verifier
> > > without clear real-world benefits. We are clearly prematurely
> > > optimizing here. In practice you'll just call bpf_get_func_ip() once
> > > and that's it. Function call overhead will be negligible compare to
> > > other *userful* work you'll be doing in your BPF program.
> > >
> > >
> > > > +
> > > > + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
> > > > + if (!new_prog)
> > > > + return -ENOMEM;
> > > > +
> > > > + env->prog = prog = new_prog;
> > > > + insn = new_prog->insnsi + i + delta;
> > > > + continue;
> > > > + }
> > > > +
> > > > patch_call_imm:
> > > > fn = env->ops->get_func_proto(insn->imm, env->prog);
> > > > /* all functions that have prototype and verifier allowed
> > > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > > > index a2024ba32a20..28e59e31e3db 100644
> > > > --- a/kernel/trace/bpf_trace.c
> > > > +++ b/kernel/trace/bpf_trace.c
> > > > @@ -1036,6 +1036,19 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
> > > > .arg1_type = ARG_PTR_TO_CTX,
> > > > };
> > > >
> > > > +BPF_CALL_1(bpf_get_func_ip_fprobe, struct pt_regs *, regs)
> > > > +{
> > > > + /* This helper call is inlined by verifier. */
> > > > + return regs->ip;
> > > > +}
> > > > +
> > > > +static const struct bpf_func_proto bpf_get_func_ip_proto_fprobe = {
> > > > + .func = bpf_get_func_ip_fprobe,
> > > > + .gpl_only = false,
> > > > + .ret_type = RET_INTEGER,
> > > > + .arg1_type = ARG_PTR_TO_CTX,
> > > > +};
> > > > +
> > > > BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
> > > > {
> > > > struct bpf_trace_run_ctx *run_ctx;
> > > > @@ -1279,7 +1292,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > > > return &bpf_override_return_proto;
> > > > #endif
> > > > case BPF_FUNC_get_func_ip:
> > > > - return &bpf_get_func_ip_proto_kprobe;
> > > > + return prog->expected_attach_type == BPF_TRACE_FPROBE ?
> > > > + &bpf_get_func_ip_proto_fprobe : &bpf_get_func_ip_proto_kprobe;
> > > > case BPF_FUNC_get_attach_cookie:
> > > > return &bpf_get_attach_cookie_proto_trace;
> > > > default:
> > > > --
> > > > 2.34.1
> > > >