[RFC PATCH bpf-next 00/17] bpf: Add tracing multi link

[RFC PATCH bpf-next 00/17] bpf: Add tracing multi link

[Jiri Olsa]

hi,
this is another attempt to add batch attachment support for
trampolines.

The patchset adds support to create 'multi' trampoline that is
attached to set of functions represented by BTF IDs.

Previous post [0] tried to implement multi trampolines overlapping,
but it turned out too complex, so I got back to simpler rules:
(we can discuss possible overlapping changes on top this change)

  - multi trampoline can attach on top of existing single trampolines,
    which creates 2 types of function IDs:

      1) single-IDs - functions that are attached within existing
         single trampolines
      2) multi-IDs  - functions that were 'not used' and are now
         taken by new 'multi' trampoline

  - we allow overlapping of 2 'multi' trampolines if they are attached
    to same IDs
  - we do now allow any other overlapping of 2 'multi' trampolines
  - any new 'single' trampoline cannot attach to existing multi-IDs IDs


Maybe better explained on following example:
    
  - you want to attach program P to functions A,B,C,D,E,F
    via bpf_trampoline_multi_attach

  - D,E,F already have standard trampoline attached

  - the bpf_trampoline_multi_attach will create new 'multi' trampoline
    which spans over A,B,C functions and attach program P to single
    trampolines D,E,F

 -  another program can be attached to A,B,C,D,E,F multi trampoline

  - A,B,C functions are now 'not attachable' by any trampoline
    until the above 'multi' trampoline is released

 -  D,E,F functions are still attachable by any new trampoline


Also now that we have trampoline helpers for function arguments,
we can just simply use function declaration with maximum arguments
for any multi trampoline or related single trampoline.

There are couple of things missing in this post (that I know of),
which I'll add when we agree that this is the way to go:

  - attaching by functions names
  - cookies support
  - find out better way of locking trampolines in bpf_trampoline_multi_attach
    and bpf_trampoline_multi_detach
  - bpf_tramp_update_set logic of calling multiple times register_ftrace_direct_multi
    function can be replaced by calling single update ftrace function that I have
    prototype for, but I will send it out separately to ftrace for review
  - arm trampoline code changes (won't compile now)
  - tests for error paths

thanks,
jirka


[0] - https://lore.kernel.org/bpf/20211118112455.475349-1-jolsa@kernel.org/
---
Jiri Olsa (17):
      bpf: Link shimlink directly in trampoline
      bpf: Replace bpf_tramp_links with bpf_tramp_progs
      bpf: Store trampoline progs in arrays
      bpf: Add multi tracing attach types
      bpf: Add bpf_tramp_id object
      bpf: Pass image struct to reg/unreg/modify fentry functions
      bpf: Add support to postpone trampoline update
      bpf: Factor bpf_trampoline_lookup function
      bpf: Factor bpf_trampoline_put function
      bpf: Add support to attach program to multiple trampolines
      bpf: Add support to create tracing multi link
      libbpf: Add btf__find_by_glob_kind function
      libbpf: Add support to create tracing multi link
      selftests/bpf: Add fentry tracing multi func test
      selftests/bpf: Add fexit tracing multi func test
      selftests/bpf: Add fentry/fexit tracing multi func test
      selftests/bpf: Add mixed tracing multi func test

 arch/x86/net/bpf_jit_comp.c                                    |  38 ++---
 include/linux/bpf.h                                            |  98 ++++++++----
 include/linux/trace_events.h                                   |   5 +
 include/uapi/linux/bpf.h                                       |   7 +
 kernel/bpf/bpf_struct_ops.c                                    |  30 ++--
 kernel/bpf/syscall.c                                           |  56 +++++--
 kernel/bpf/trampoline.c                                        | 723 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------
 kernel/bpf/verifier.c                                          |   8 +-
 kernel/trace/bpf_trace.c                                       | 240 +++++++++++++++++++++++++++++
 net/bpf/bpf_dummy_struct_ops.c                                 |  16 +-
 net/bpf/test_run.c                                             |   2 +
 tools/include/uapi/linux/bpf.h                                 |   7 +
 tools/lib/bpf/bpf.c                                            |   7 +
 tools/lib/bpf/bpf.h                                            |   4 +
 tools/lib/bpf/btf.c                                            |  41 +++++
 tools/lib/bpf/btf.h                                            |   3 +
 tools/lib/bpf/libbpf.c                                         |  91 ++++++++++-
 tools/lib/bpf/libbpf.h                                         |  14 ++
 tools/lib/bpf/libbpf.map                                       |   1 +
 tools/lib/bpf/libbpf_internal.h                                |   1 +
 tools/testing/selftests/bpf/Makefile                           |   9 +-
 tools/testing/selftests/bpf/prog_tests/tracing_multi.c         | 158 ++++++++++++++++++++
 tools/testing/selftests/bpf/progs/tracing_multi_check.c        | 158 ++++++++++++++++++++
 tools/testing/selftests/bpf/progs/tracing_multi_fentry.c       |  17 +++
 tools/testing/selftests/bpf/progs/tracing_multi_fentry_fexit.c |  28 ++++
 tools/testing/selftests/bpf/progs/tracing_multi_fexit.c        |  20 +++
 tools/testing/selftests/bpf/progs/tracing_multi_mixed.c        |  43 ++++++
 27 files changed, 1624 insertions(+), 201 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/tracing_multi.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_check.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_fentry.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_fentry_fexit.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_fexit.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_mixed.c

[RFC PATCH bpf-next 01/17] bpf: Link shimlink directly in trampoline

[Jiri Olsa]

We are going to get rid of struct bpf_tramp_link in following
changes and cgroup_shim_find logic does not fit to that.

We can store the link directly in the trampoline and omit the
cgroup_shim_find searching logic.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h     |  3 +++
 kernel/bpf/trampoline.c | 23 +++--------------------
 2 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 20c26aed7896..ed2a921094bc 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -841,6 +841,8 @@ struct bpf_tramp_image {
 	};
 };
 
+struct bpf_shim_tramp_link;
+
 struct bpf_trampoline {
 	/* hlist for trampoline_table */
 	struct hlist_node hlist;
@@ -868,6 +870,7 @@ struct bpf_trampoline {
 	struct bpf_tramp_image *cur_image;
 	u64 selector;
 	struct module *mod;
+	struct bpf_shim_tramp_link *shim_link;
 };
 
 struct bpf_attach_target_info {
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index ff87e38af8a7..7a65d33cda60 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -689,24 +689,6 @@ static struct bpf_shim_tramp_link *cgroup_shim_alloc(const struct bpf_prog *prog
 	return shim_link;
 }
 
-static struct bpf_shim_tramp_link *cgroup_shim_find(struct bpf_trampoline *tr,
-						    bpf_func_t bpf_func)
-{
-	struct bpf_tramp_link *link;
-	int kind;
-
-	for (kind = 0; kind < BPF_TRAMP_MAX; kind++) {
-		hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) {
-			struct bpf_prog *p = link->link.prog;
-
-			if (p->bpf_func == bpf_func)
-				return container_of(link, struct bpf_shim_tramp_link, link);
-		}
-	}
-
-	return NULL;
-}
-
 int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 				    int cgroup_atype)
 {
@@ -733,7 +715,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 
 	mutex_lock(&tr->mutex);
 
-	shim_link = cgroup_shim_find(tr, bpf_func);
+	shim_link = tr->shim_link;
 	if (shim_link) {
 		/* Reusing existing shim attached by the other program. */
 		bpf_link_inc(&shim_link->link.link);
@@ -756,6 +738,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 		goto err;
 
 	shim_link->trampoline = tr;
+	tr->shim_link = shim_link;
 	/* note, we're still holding tr refcnt from above */
 
 	mutex_unlock(&tr->mutex);
@@ -789,7 +772,7 @@ void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog)
 		return;
 
 	mutex_lock(&tr->mutex);
-	shim_link = cgroup_shim_find(tr, bpf_func);
+	shim_link = tr->shim_link;
 	mutex_unlock(&tr->mutex);
 
 	if (shim_link)
-- 
2.37.1

Re: [RFC PATCH bpf-next 01/17] bpf: Link shimlink directly in trampoline

[Song Liu]

On Mon, Aug 8, 2022 at 7:06 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> We are going to get rid of struct bpf_tramp_link in following
> changes and cgroup_shim_find logic does not fit to that.
>
> We can store the link directly in the trampoline and omit the
> cgroup_shim_find searching logic.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  include/linux/bpf.h     |  3 +++
>  kernel/bpf/trampoline.c | 23 +++--------------------
>  2 files changed, 6 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 20c26aed7896..ed2a921094bc 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -841,6 +841,8 @@ struct bpf_tramp_image {
>         };
>  };
>
> +struct bpf_shim_tramp_link;
> +
>  struct bpf_trampoline {
>         /* hlist for trampoline_table */
>         struct hlist_node hlist;
> @@ -868,6 +870,7 @@ struct bpf_trampoline {
>         struct bpf_tramp_image *cur_image;
>         u64 selector;
>         struct module *mod;
> +       struct bpf_shim_tramp_link *shim_link;
>  };

Hi Stanislav,

Is it possible to have multiple shim_link per bpf_trampoline? If so, I guess
this won't work.

Thanks,
Song

[...]

Re: [RFC PATCH bpf-next 01/17] bpf: Link shimlink directly in trampoline

[Stanislav Fomichev]

On Mon, Aug 8, 2022 at 10:40 AM Song Liu <song@kernel.org> wrote:
>
> On Mon, Aug 8, 2022 at 7:06 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > We are going to get rid of struct bpf_tramp_link in following
> > changes and cgroup_shim_find logic does not fit to that.
> >
> > We can store the link directly in the trampoline and omit the
> > cgroup_shim_find searching logic.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> >  include/linux/bpf.h     |  3 +++
> >  kernel/bpf/trampoline.c | 23 +++--------------------
> >  2 files changed, 6 insertions(+), 20 deletions(-)
> >
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index 20c26aed7896..ed2a921094bc 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -841,6 +841,8 @@ struct bpf_tramp_image {
> >         };
> >  };
> >
> > +struct bpf_shim_tramp_link;
> > +
> >  struct bpf_trampoline {
> >         /* hlist for trampoline_table */
> >         struct hlist_node hlist;
> > @@ -868,6 +870,7 @@ struct bpf_trampoline {
> >         struct bpf_tramp_image *cur_image;
> >         u64 selector;
> >         struct module *mod;
> > +       struct bpf_shim_tramp_link *shim_link;
> >  };
>
> Hi Stanislav,
>
> Is it possible to have multiple shim_link per bpf_trampoline? If so, I guess
> this won't work.

There is only one shim_link per bpf_trampoline. But I'm not sure
storing the pointer is enough. We have to do 'shim_link=NULL' when the
(final) shim is removed. (multiple lsm_cgroup progs can share the same
shim)

Re: [RFC PATCH bpf-next 01/17] bpf: Link shimlink directly in trampoline

[Jiri Olsa]

On Mon, Aug 08, 2022 at 10:58:36AM -0700, Stanislav Fomichev wrote:
> On Mon, Aug 8, 2022 at 10:40 AM Song Liu <song@kernel.org> wrote:
> >
> > On Mon, Aug 8, 2022 at 7:06 AM Jiri Olsa <jolsa@kernel.org> wrote:
> > >
> > > We are going to get rid of struct bpf_tramp_link in following
> > > changes and cgroup_shim_find logic does not fit to that.
> > >
> > > We can store the link directly in the trampoline and omit the
> > > cgroup_shim_find searching logic.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > > ---
> > >  include/linux/bpf.h     |  3 +++
> > >  kernel/bpf/trampoline.c | 23 +++--------------------
> > >  2 files changed, 6 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > > index 20c26aed7896..ed2a921094bc 100644
> > > --- a/include/linux/bpf.h
> > > +++ b/include/linux/bpf.h
> > > @@ -841,6 +841,8 @@ struct bpf_tramp_image {
> > >         };
> > >  };
> > >
> > > +struct bpf_shim_tramp_link;
> > > +
> > >  struct bpf_trampoline {
> > >         /* hlist for trampoline_table */
> > >         struct hlist_node hlist;
> > > @@ -868,6 +870,7 @@ struct bpf_trampoline {
> > >         struct bpf_tramp_image *cur_image;
> > >         u64 selector;
> > >         struct module *mod;
> > > +       struct bpf_shim_tramp_link *shim_link;
> > >  };
> >
> > Hi Stanislav,
> >
> > Is it possible to have multiple shim_link per bpf_trampoline? If so, I guess
> > this won't work.
> 
> There is only one shim_link per bpf_trampoline. But I'm not sure
> storing the pointer is enough. We have to do 'shim_link=NULL' when the
> (final) shim is removed. (multiple lsm_cgroup progs can share the same
> shim)

ok, will check on that

thanks,
jirka

[RFC PATCH bpf-next 02/17] bpf: Replace bpf_tramp_links with bpf_tramp_progs

[Jiri Olsa]

This is first part of replacing link based program storage
in trampoline with array of programs.

Changing bpf_trampoline_get_progs to return bpf_tramp_progs
instead of bpf_tramp_links and use this object all the way down
from bpf_trampoline_update to arch jit generation.

TODO now that we have ARM trampoline support we also need to
change that one the same way.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 arch/x86/net/bpf_jit_comp.c    | 38 +++++++++++++++---------------
 include/linux/bpf.h            | 16 +++++++++----
 kernel/bpf/bpf_struct_ops.c    | 18 +++++++--------
 kernel/bpf/trampoline.c        | 42 +++++++++++++++++++---------------
 net/bpf/bpf_dummy_struct_ops.c | 10 ++++----
 5 files changed, 67 insertions(+), 57 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index c1f6c1c51d99..05c01b007bae 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1782,7 +1782,7 @@ static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
 }
 
 static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
-			   struct bpf_tramp_link *l, int stack_size,
+			   struct bpf_tramp_prog *tp, int stack_size,
 			   int run_ctx_off, bool save_ret)
 {
 	void (*exit)(struct bpf_prog *prog, u64 start,
@@ -1792,8 +1792,8 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
 	u8 *prog = *pprog;
 	u8 *jmp_insn;
 	int ctx_cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
-	struct bpf_prog *p = l->link.prog;
-	u64 cookie = l->cookie;
+	struct bpf_prog *p = tp->prog;
+	u64 cookie = tp->cookie;
 
 	/* mov rdi, cookie */
 	emit_mov_imm64(&prog, BPF_REG_1, (long) cookie >> 32, (u32) (long) cookie);
@@ -1899,14 +1899,14 @@ static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)
 }
 
 static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
-		      struct bpf_tramp_links *tl, int stack_size,
+		      struct bpf_tramp_progs *tp, int stack_size,
 		      int run_ctx_off, bool save_ret)
 {
 	int i;
 	u8 *prog = *pprog;
 
-	for (i = 0; i < tl->nr_links; i++) {
-		if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size,
+	for (i = 0; i < tp->nr_progs; i++) {
+		if (invoke_bpf_prog(m, &prog, &tp->progs[i], stack_size,
 				    run_ctx_off, save_ret))
 			return -EINVAL;
 	}
@@ -1915,7 +1915,7 @@ static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
 }
 
 static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
-			      struct bpf_tramp_links *tl, int stack_size,
+			      struct bpf_tramp_progs *tp, int stack_size,
 			      int run_ctx_off, u8 **branches)
 {
 	u8 *prog = *pprog;
@@ -1926,8 +1926,8 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
 	 */
 	emit_mov_imm32(&prog, false, BPF_REG_0, 0);
 	emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
-	for (i = 0; i < tl->nr_links; i++) {
-		if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size, run_ctx_off, true))
+	for (i = 0; i < tp->nr_progs; i++) {
+		if (invoke_bpf_prog(m, &prog, &tp->progs[i], stack_size, run_ctx_off, true))
 			return -EINVAL;
 
 		/* mod_ret prog stored return value into [rbp - 8]. Emit:
@@ -2012,14 +2012,14 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
  */
 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
 				const struct btf_func_model *m, u32 flags,
-				struct bpf_tramp_links *tlinks,
+				struct bpf_tramp_progs *tprogs,
 				void *orig_call)
 {
 	int ret, i, nr_args = m->nr_args;
 	int regs_off, ip_off, args_off, stack_size = nr_args * 8, run_ctx_off;
-	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];
+	struct bpf_tramp_progs *fentry = &tprogs[BPF_TRAMP_FENTRY];
+	struct bpf_tramp_progs *fexit = &tprogs[BPF_TRAMP_FEXIT];
+	struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN];
 	u8 **branches = NULL;
 	u8 *prog;
 	bool save_ret;
@@ -2112,13 +2112,13 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 		}
 	}
 
-	if (fentry->nr_links)
+	if (fentry->nr_progs)
 		if (invoke_bpf(m, &prog, fentry, regs_off, run_ctx_off,
 			       flags & BPF_TRAMP_F_RET_FENTRY_RET))
 			return -EINVAL;
 
-	if (fmod_ret->nr_links) {
-		branches = kcalloc(fmod_ret->nr_links, sizeof(u8 *),
+	if (fmod_ret->nr_progs) {
+		branches = kcalloc(fmod_ret->nr_progs, sizeof(u8 *),
 				   GFP_KERNEL);
 		if (!branches)
 			return -ENOMEM;
@@ -2150,7 +2150,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 		prog += X86_PATCH_SIZE;
 	}
 
-	if (fmod_ret->nr_links) {
+	if (fmod_ret->nr_progs) {
 		/* From Intel 64 and IA-32 Architectures Optimization
 		 * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler
 		 * Coding Rule 11: All branch targets should be 16-byte
@@ -2160,12 +2160,12 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 		/* Update the branches saved in invoke_bpf_mod_ret with the
 		 * aligned address of do_fexit.
 		 */
-		for (i = 0; i < fmod_ret->nr_links; i++)
+		for (i = 0; i < fmod_ret->nr_progs; i++)
 			emit_cond_near_jump(&branches[i], prog, branches[i],
 					    X86_JNE);
 	}
 
-	if (fexit->nr_links)
+	if (fexit->nr_progs)
 		if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off, false)) {
 			ret = -EINVAL;
 			goto cleanup;
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index ed2a921094bc..80b2c17da64d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -767,9 +767,14 @@ struct btf_func_model {
  */
 #define BPF_MAX_TRAMP_LINKS 38
 
-struct bpf_tramp_links {
-	struct bpf_tramp_link *links[BPF_MAX_TRAMP_LINKS];
-	int nr_links;
+struct bpf_tramp_prog {
+	struct bpf_prog *prog;
+	u64 cookie;
+};
+
+struct bpf_tramp_progs {
+	struct bpf_tramp_prog progs[BPF_MAX_TRAMP_LINKS];
+	int nr_progs;
 };
 
 struct bpf_tramp_run_ctx;
@@ -797,7 +802,7 @@ struct bpf_tramp_run_ctx;
 struct bpf_tramp_image;
 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end,
 				const struct btf_func_model *m, u32 flags,
-				struct bpf_tramp_links *tlinks,
+				struct bpf_tramp_progs *tprogs,
 				void *orig_call);
 /* these two functions are called from generated trampoline */
 u64 notrace __bpf_prog_enter(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx);
@@ -907,6 +912,7 @@ static __always_inline __nocfi unsigned int bpf_dispatcher_nop_func(
 }
 
 #ifdef CONFIG_BPF_JIT
+struct bpf_tramp_link;
 int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
 int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
 struct bpf_trampoline *bpf_trampoline_get(u64 key,
@@ -1236,7 +1242,7 @@ bool bpf_struct_ops_get(const void *kdata);
 void bpf_struct_ops_put(const void *kdata);
 int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map, void *key,
 				       void *value);
-int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks,
+int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_progs *tprogs,
 				      struct bpf_tramp_link *link,
 				      const struct btf_func_model *model,
 				      void *image, void *image_end);
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 84b2d9dba79a..d51dced406eb 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -332,21 +332,21 @@ const struct bpf_link_ops bpf_struct_ops_link_lops = {
 	.dealloc = bpf_struct_ops_link_dealloc,
 };
 
-int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks,
+int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_progs *tprogs,
 				      struct bpf_tramp_link *link,
 				      const struct btf_func_model *model,
 				      void *image, void *image_end)
 {
 	u32 flags;
 
-	tlinks[BPF_TRAMP_FENTRY].links[0] = link;
-	tlinks[BPF_TRAMP_FENTRY].nr_links = 1;
+	tprogs[BPF_TRAMP_FENTRY].progs[0].prog = link->link.prog;
+	tprogs[BPF_TRAMP_FENTRY].nr_progs = 1;
 	/* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
 	 * and it must be used alone.
 	 */
 	flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0;
 	return arch_prepare_bpf_trampoline(NULL, image, image_end,
-					   model, flags, tlinks, NULL);
+					   model, flags, tprogs, NULL);
 }
 
 static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
@@ -357,7 +357,7 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
 	struct bpf_struct_ops_value *uvalue, *kvalue;
 	const struct btf_member *member;
 	const struct btf_type *t = st_ops->type;
-	struct bpf_tramp_links *tlinks = NULL;
+	struct bpf_tramp_progs *tprogs = NULL;
 	void *udata, *kdata;
 	int prog_fd, err = 0;
 	void *image, *image_end;
@@ -381,8 +381,8 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
 	if (uvalue->state || refcount_read(&uvalue->refcnt))
 		return -EINVAL;
 
-	tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
-	if (!tlinks)
+	tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL);
+	if (!tprogs)
 		return -ENOMEM;
 
 	uvalue = (struct bpf_struct_ops_value *)st_map->uvalue;
@@ -478,7 +478,7 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
 			      &bpf_struct_ops_link_lops, prog);
 		st_map->links[i] = &link->link;
 
-		err = bpf_struct_ops_prepare_trampoline(tlinks, link,
+		err = bpf_struct_ops_prepare_trampoline(tprogs, link,
 							&st_ops->func_models[i],
 							image, image_end);
 		if (err < 0)
@@ -520,7 +520,7 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
 	memset(uvalue, 0, map->value_size);
 	memset(kvalue, 0, map->value_size);
 unlock:
-	kfree(tlinks);
+	kfree(tprogs);
 	mutex_unlock(&st_map->lock);
 	return err;
 }
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 7a65d33cda60..f41fb1af9f0e 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -269,30 +269,34 @@ static int register_fentry(struct bpf_trampoline *tr, void *new_addr)
 	return ret;
 }
 
-static struct bpf_tramp_links *
+static struct bpf_tramp_progs *
 bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg)
 {
+	struct bpf_tramp_progs *tprogs;
 	struct bpf_tramp_link *link;
-	struct bpf_tramp_links *tlinks;
-	struct bpf_tramp_link **links;
+	struct bpf_tramp_prog *tp;
 	int kind;
 
 	*total = 0;
-	tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
-	if (!tlinks)
+	tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL);
+	if (!tprogs)
 		return ERR_PTR(-ENOMEM);
 
 	for (kind = 0; kind < BPF_TRAMP_MAX; kind++) {
-		tlinks[kind].nr_links = tr->progs_cnt[kind];
+		tprogs[kind].nr_progs = tr->progs_cnt[kind];
 		*total += tr->progs_cnt[kind];
-		links = tlinks[kind].links;
+		tp = &tprogs[kind].progs[0];
 
 		hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) {
-			*ip_arg |= link->link.prog->call_get_func_ip;
-			*links++ = link;
+			struct bpf_prog *prog = link->link.prog;
+
+			*ip_arg |= prog->call_get_func_ip;
+			tp->prog = prog;
+			tp->cookie = link->cookie;
+			tp++;
 		}
 	}
-	return tlinks;
+	return tprogs;
 }
 
 static void __bpf_tramp_image_put_deferred(struct work_struct *work)
@@ -431,14 +435,14 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx)
 static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex)
 {
 	struct bpf_tramp_image *im;
-	struct bpf_tramp_links *tlinks;
+	struct bpf_tramp_progs *tprogs;
 	u32 orig_flags = tr->flags;
 	bool ip_arg = false;
 	int err, total;
 
-	tlinks = bpf_trampoline_get_progs(tr, &total, &ip_arg);
-	if (IS_ERR(tlinks))
-		return PTR_ERR(tlinks);
+	tprogs = bpf_trampoline_get_progs(tr, &total, &ip_arg);
+	if (IS_ERR(tprogs))
+		return PTR_ERR(tprogs);
 
 	if (total == 0) {
 		err = unregister_fentry(tr, tr->cur_image->image);
@@ -457,8 +461,8 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 	/* clear all bits except SHARE_IPMODIFY */
 	tr->flags &= BPF_TRAMP_F_SHARE_IPMODIFY;
 
-	if (tlinks[BPF_TRAMP_FEXIT].nr_links ||
-	    tlinks[BPF_TRAMP_MODIFY_RETURN].nr_links) {
+	if (tprogs[BPF_TRAMP_FEXIT].nr_progs ||
+	    tprogs[BPF_TRAMP_MODIFY_RETURN].nr_progs) {
 		/* NOTE: BPF_TRAMP_F_RESTORE_REGS and BPF_TRAMP_F_SKIP_FRAME
 		 * should not be set together.
 		 */
@@ -478,7 +482,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 #endif
 
 	err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE,
-					  &tr->func.model, tr->flags, tlinks,
+					  &tr->func.model, tr->flags, tprogs,
 					  tr->func.addr);
 	if (err < 0)
 		goto out;
@@ -515,7 +519,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 	/* If any error happens, restore previous flags */
 	if (err)
 		tr->flags = orig_flags;
-	kfree(tlinks);
+	kfree(tprogs);
 	return err;
 }
 
@@ -983,7 +987,7 @@ void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr)
 int __weak
 arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end,
 			    const struct btf_func_model *m, u32 flags,
-			    struct bpf_tramp_links *tlinks,
+			    struct bpf_tramp_progs *tprogs,
 			    void *orig_call)
 {
 	return -ENOTSUPP;
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
index e78dadfc5829..17add0bdf323 100644
--- a/net/bpf/bpf_dummy_struct_ops.c
+++ b/net/bpf/bpf_dummy_struct_ops.c
@@ -80,7 +80,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 	const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
 	const struct btf_type *func_proto;
 	struct bpf_dummy_ops_test_args *args;
-	struct bpf_tramp_links *tlinks;
+	struct bpf_tramp_progs *tprogs;
 	struct bpf_tramp_link *link = NULL;
 	void *image = NULL;
 	unsigned int op_idx;
@@ -95,8 +95,8 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 	if (IS_ERR(args))
 		return PTR_ERR(args);
 
-	tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
-	if (!tlinks) {
+	tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL);
+	if (!tprogs) {
 		err = -ENOMEM;
 		goto out;
 	}
@@ -118,7 +118,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 	bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog);
 
 	op_idx = prog->expected_attach_type;
-	err = bpf_struct_ops_prepare_trampoline(tlinks, link,
+	err = bpf_struct_ops_prepare_trampoline(tprogs, link,
 						&st_ops->func_models[op_idx],
 						image, image + PAGE_SIZE);
 	if (err < 0)
@@ -138,7 +138,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 	bpf_jit_free_exec(image);
 	if (link)
 		bpf_link_put(&link->link);
-	kfree(tlinks);
+	kfree(tprogs);
 	return err;
 }
 
-- 
2.37.1

[RFC PATCH bpf-next 03/17] bpf: Store trampoline progs in arrays

[Jiri Olsa]

Storing programs for trampoline in array instead of in link
based list. This way we can have same program coming from
one link being shared across multiple trampolines.

Replacing list_head links array with bpf_prog_array objects
array that now stores all trampoline programs.

We already have bpf_trampoline_get_progs returning bpf_tramp_progs
object, so this patch does the rest:

  - storing trampoline programs of given type in bpf_prog_array
    objects

  - using bpf_tramp_prog object as program reference in link/unlink
    functions:

      int bpf_trampoline_link_prog(struct bpf_tramp_prog *tp,
                                   struct bpf_trampoline *tr);
      int bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp,
                                    struct bpf_trampoline *tr);

  - changing all the callers on above link/unlink to work with new
    interface

  - removing bpf_tramp_link struct, because it's no longer needed

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h            |  25 ++++----
 kernel/bpf/bpf_struct_ops.c    |  16 +++--
 kernel/bpf/syscall.c           |  19 +++---
 kernel/bpf/trampoline.c        | 105 ++++++++++++++++++++-------------
 net/bpf/bpf_dummy_struct_ops.c |   8 +--
 5 files changed, 96 insertions(+), 77 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 80b2c17da64d..0617982ca859 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -868,7 +868,7 @@ struct bpf_trampoline {
 	 */
 	struct bpf_prog *extension_prog;
 	/* list of BPF programs using this trampoline */
-	struct hlist_head progs_hlist[BPF_TRAMP_MAX];
+	struct bpf_prog_array *progs_array[BPF_TRAMP_MAX];
 	/* Number of attached programs. A counter per kind. */
 	int progs_cnt[BPF_TRAMP_MAX];
 	/* Executable image of trampoline */
@@ -912,9 +912,8 @@ static __always_inline __nocfi unsigned int bpf_dispatcher_nop_func(
 }
 
 #ifdef CONFIG_BPF_JIT
-struct bpf_tramp_link;
-int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
-int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
+int bpf_trampoline_link_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr);
+int bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr);
 struct bpf_trampoline *bpf_trampoline_get(u64 key,
 					  struct bpf_attach_target_info *tgt_info);
 void bpf_trampoline_put(struct bpf_trampoline *tr);
@@ -963,12 +962,12 @@ int bpf_jit_charge_modmem(u32 size);
 void bpf_jit_uncharge_modmem(u32 size);
 bool bpf_prog_has_trampoline(const struct bpf_prog *prog);
 #else
-static inline int bpf_trampoline_link_prog(struct bpf_tramp_link *link,
+static inline int bpf_trampoline_link_prog(struct bpf_tramp_prog *tp,
 					   struct bpf_trampoline *tr)
 {
 	return -ENOTSUPP;
 }
-static inline int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link,
+static inline int bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp,
 					     struct bpf_trampoline *tr)
 {
 	return -ENOTSUPP;
@@ -1187,19 +1186,15 @@ struct bpf_link_ops {
 			      struct bpf_link_info *info);
 };
 
-struct bpf_tramp_link {
-	struct bpf_link link;
-	struct hlist_node tramp_hlist;
-	u64 cookie;
-};
-
 struct bpf_shim_tramp_link {
-	struct bpf_tramp_link link;
+	struct bpf_link link;
+	struct bpf_tramp_prog tp;
 	struct bpf_trampoline *trampoline;
 };
 
 struct bpf_tracing_link {
-	struct bpf_tramp_link link;
+	struct bpf_link link;
+	struct bpf_tramp_prog tp;
 	enum bpf_attach_type attach_type;
 	struct bpf_trampoline *trampoline;
 	struct bpf_prog *tgt_prog;
@@ -1243,7 +1238,7 @@ void bpf_struct_ops_put(const void *kdata);
 int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map, void *key,
 				       void *value);
 int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_progs *tprogs,
-				      struct bpf_tramp_link *link,
+				      struct bpf_prog *prog,
 				      const struct btf_func_model *model,
 				      void *image, void *image_end);
 static inline bool bpf_try_module_get(const void *data, struct module *owner)
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index d51dced406eb..910f1b7deb8f 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -322,9 +322,7 @@ static void bpf_struct_ops_link_release(struct bpf_link *link)
 
 static void bpf_struct_ops_link_dealloc(struct bpf_link *link)
 {
-	struct bpf_tramp_link *tlink = container_of(link, struct bpf_tramp_link, link);
-
-	kfree(tlink);
+	kfree(link);
 }
 
 const struct bpf_link_ops bpf_struct_ops_link_lops = {
@@ -333,13 +331,13 @@ const struct bpf_link_ops bpf_struct_ops_link_lops = {
 };
 
 int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_progs *tprogs,
-				      struct bpf_tramp_link *link,
+				      struct bpf_prog *prog,
 				      const struct btf_func_model *model,
 				      void *image, void *image_end)
 {
 	u32 flags;
 
-	tprogs[BPF_TRAMP_FENTRY].progs[0].prog = link->link.prog;
+	tprogs[BPF_TRAMP_FENTRY].progs[0].prog = prog;
 	tprogs[BPF_TRAMP_FENTRY].nr_progs = 1;
 	/* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
 	 * and it must be used alone.
@@ -405,7 +403,7 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
 	for_each_member(i, t, member) {
 		const struct btf_type *mtype, *ptype;
 		struct bpf_prog *prog;
-		struct bpf_tramp_link *link;
+		struct bpf_link *link;
 		u32 moff;
 
 		moff = __btf_member_bit_offset(t, member) / 8;
@@ -474,11 +472,11 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
 			err = -ENOMEM;
 			goto reset_unlock;
 		}
-		bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS,
+		bpf_link_init(link, BPF_LINK_TYPE_STRUCT_OPS,
 			      &bpf_struct_ops_link_lops, prog);
-		st_map->links[i] = &link->link;
+		st_map->links[i] = link;
 
-		err = bpf_struct_ops_prepare_trampoline(tprogs, link,
+		err = bpf_struct_ops_prepare_trampoline(tprogs, prog,
 							&st_ops->func_models[i],
 							image, image_end);
 		if (err < 0)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 83c7136c5788..42272909ac08 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2887,9 +2887,9 @@ EXPORT_SYMBOL(bpf_link_get_from_fd);
 static void bpf_tracing_link_release(struct bpf_link *link)
 {
 	struct bpf_tracing_link *tr_link =
-		container_of(link, struct bpf_tracing_link, link.link);
+		container_of(link, struct bpf_tracing_link, link);
 
-	WARN_ON_ONCE(bpf_trampoline_unlink_prog(&tr_link->link,
+	WARN_ON_ONCE(bpf_trampoline_unlink_prog(&tr_link->tp,
 						tr_link->trampoline));
 
 	bpf_trampoline_put(tr_link->trampoline);
@@ -2902,7 +2902,7 @@ static void bpf_tracing_link_release(struct bpf_link *link)
 static void bpf_tracing_link_dealloc(struct bpf_link *link)
 {
 	struct bpf_tracing_link *tr_link =
-		container_of(link, struct bpf_tracing_link, link.link);
+		container_of(link, struct bpf_tracing_link, link);
 
 	kfree(tr_link);
 }
@@ -2911,7 +2911,7 @@ static void bpf_tracing_link_show_fdinfo(const struct bpf_link *link,
 					 struct seq_file *seq)
 {
 	struct bpf_tracing_link *tr_link =
-		container_of(link, struct bpf_tracing_link, link.link);
+		container_of(link, struct bpf_tracing_link, link);
 
 	seq_printf(seq,
 		   "attach_type:\t%d\n",
@@ -2922,7 +2922,7 @@ static int bpf_tracing_link_fill_link_info(const struct bpf_link *link,
 					   struct bpf_link_info *info)
 {
 	struct bpf_tracing_link *tr_link =
-		container_of(link, struct bpf_tracing_link, link.link);
+		container_of(link, struct bpf_tracing_link, link);
 
 	info->tracing.attach_type = tr_link->attach_type;
 	bpf_trampoline_unpack_key(tr_link->trampoline->key,
@@ -3004,10 +3004,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
 		err = -ENOMEM;
 		goto out_put_prog;
 	}
-	bpf_link_init(&link->link.link, BPF_LINK_TYPE_TRACING,
+	bpf_link_init(&link->link, BPF_LINK_TYPE_TRACING,
 		      &bpf_tracing_link_lops, prog);
 	link->attach_type = prog->expected_attach_type;
-	link->link.cookie = bpf_cookie;
+	link->tp.cookie = bpf_cookie;
+	link->tp.prog = prog;
 
 	mutex_lock(&prog->aux->dst_mutex);
 
@@ -3075,11 +3076,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
 		tgt_prog = prog->aux->dst_prog;
 	}
 
-	err = bpf_link_prime(&link->link.link, &link_primer);
+	err = bpf_link_prime(&link->link, &link_primer);
 	if (err)
 		goto out_unlock;
 
-	err = bpf_trampoline_link_prog(&link->link, tr);
+	err = bpf_trampoline_link_prog(&link->tp, tr);
 	if (err) {
 		bpf_link_cleanup(&link_primer);
 		link = NULL;
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index f41fb1af9f0e..854d0a3b9b31 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -152,7 +152,6 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 {
 	struct bpf_trampoline *tr;
 	struct hlist_head *head;
-	int i;
 
 	mutex_lock(&trampoline_mutex);
 	head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)];
@@ -181,8 +180,6 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 	hlist_add_head(&tr->hlist, head);
 	refcount_set(&tr->refcnt, 1);
 	mutex_init(&tr->mutex);
-	for (i = 0; i < BPF_TRAMP_MAX; i++)
-		INIT_HLIST_HEAD(&tr->progs_hlist[i]);
 out:
 	mutex_unlock(&trampoline_mutex);
 	return tr;
@@ -272,9 +269,11 @@ static int register_fentry(struct bpf_trampoline *tr, void *new_addr)
 static struct bpf_tramp_progs *
 bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg)
 {
+	const struct bpf_prog_array_item *item;
+	struct bpf_prog_array *prog_array;
 	struct bpf_tramp_progs *tprogs;
-	struct bpf_tramp_link *link;
 	struct bpf_tramp_prog *tp;
+	struct bpf_prog *prog;
 	int kind;
 
 	*total = 0;
@@ -287,13 +286,16 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_a
 		*total += tr->progs_cnt[kind];
 		tp = &tprogs[kind].progs[0];
 
-		hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) {
-			struct bpf_prog *prog = link->link.prog;
+		prog_array = tr->progs_array[kind];
+		if (!prog_array)
+			continue;
+		item = &prog_array->items[0];
 
+		while ((prog = READ_ONCE(item->prog))) {
 			*ip_arg |= prog->call_get_func_ip;
 			tp->prog = prog;
-			tp->cookie = link->cookie;
-			tp++;
+			tp->cookie = item->bpf_cookie;
+			tp++; item++;
 		}
 	}
 	return tprogs;
@@ -545,14 +547,16 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog)
 	}
 }
 
-static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
+static int __bpf_trampoline_link_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr)
 {
+	struct bpf_prog_array *old_array, *new_array;
+	const struct bpf_prog_array_item *item;
 	enum bpf_tramp_prog_type kind;
-	struct bpf_tramp_link *link_exiting;
+	struct bpf_prog *prog;
 	int err = 0;
 	int cnt = 0, i;
 
-	kind = bpf_attach_type_to_tramp(link->link.prog);
+	kind = bpf_attach_type_to_tramp(tp->prog);
 	if (tr->extension_prog)
 		/* cannot attach fentry/fexit if extension prog is attached.
 		 * cannot overwrite extension prog either.
@@ -566,48 +570,57 @@ static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_tr
 		/* Cannot attach extension if fentry/fexit are in use. */
 		if (cnt)
 			return -EBUSY;
-		tr->extension_prog = link->link.prog;
+		tr->extension_prog = tp->prog;
 		return bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL,
-					  link->link.prog->bpf_func);
+					  tp->prog->bpf_func);
 	}
 	if (cnt >= BPF_MAX_TRAMP_LINKS)
 		return -E2BIG;
-	if (!hlist_unhashed(&link->tramp_hlist))
-		/* prog already linked */
-		return -EBUSY;
-	hlist_for_each_entry(link_exiting, &tr->progs_hlist[kind], tramp_hlist) {
-		if (link_exiting->link.prog != link->link.prog)
-			continue;
-		/* prog already linked */
-		return -EBUSY;
+	old_array = tr->progs_array[kind];
+	if (old_array) {
+		item = &old_array->items[0];
+
+		while ((prog = READ_ONCE(item->prog))) {
+			/* prog already linked */
+			if (prog == tp->prog)
+				return -EBUSY;
+			item++;
+		}
 	}
 
-	hlist_add_head(&link->tramp_hlist, &tr->progs_hlist[kind]);
+	err = bpf_prog_array_copy(old_array, NULL, tp->prog, tp->cookie, &new_array);
+	if (err < 0)
+		return -ENOMEM;
+	tr->progs_array[kind] = new_array;
 	tr->progs_cnt[kind]++;
 	err = bpf_trampoline_update(tr, true /* lock_direct_mutex */);
 	if (err) {
-		hlist_del_init(&link->tramp_hlist);
+		tr->progs_array[kind] = old_array;
 		tr->progs_cnt[kind]--;
+		bpf_prog_array_free(new_array);
+	} else {
+		bpf_prog_array_free(old_array);
 	}
 	return err;
 }
 
-int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
+int bpf_trampoline_link_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr)
 {
 	int err;
 
 	mutex_lock(&tr->mutex);
-	err = __bpf_trampoline_link_prog(link, tr);
+	err = __bpf_trampoline_link_prog(tp, tr);
 	mutex_unlock(&tr->mutex);
 	return err;
 }
 
-static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
+static int __bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr)
 {
+	struct bpf_prog_array *old_array, *new_array;
 	enum bpf_tramp_prog_type kind;
 	int err;
 
-	kind = bpf_attach_type_to_tramp(link->link.prog);
+	kind = bpf_attach_type_to_tramp(tp->prog);
 	if (kind == BPF_TRAMP_REPLACE) {
 		WARN_ON_ONCE(!tr->extension_prog);
 		err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP,
@@ -615,18 +628,26 @@ static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_
 		tr->extension_prog = NULL;
 		return err;
 	}
-	hlist_del_init(&link->tramp_hlist);
+
+	old_array = tr->progs_array[kind];
+
+	err = bpf_prog_array_copy(old_array, tp->prog, NULL, 0, &new_array);
+	if (err < 0)
+		return err;
+
 	tr->progs_cnt[kind]--;
+	tr->progs_array[kind] = new_array;
+	bpf_prog_array_free(old_array);
 	return bpf_trampoline_update(tr, true /* lock_direct_mutex */);
 }
 
 /* bpf_trampoline_unlink_prog() should never fail. */
-int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
+int bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr)
 {
 	int err;
 
 	mutex_lock(&tr->mutex);
-	err = __bpf_trampoline_unlink_prog(link, tr);
+	err = __bpf_trampoline_unlink_prog(tp, tr);
 	mutex_unlock(&tr->mutex);
 	return err;
 }
@@ -635,20 +656,20 @@ int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampolin
 static void bpf_shim_tramp_link_release(struct bpf_link *link)
 {
 	struct bpf_shim_tramp_link *shim_link =
-		container_of(link, struct bpf_shim_tramp_link, link.link);
+		container_of(link, struct bpf_shim_tramp_link, link);
 
 	/* paired with 'shim_link->trampoline = tr' in bpf_trampoline_link_cgroup_shim */
 	if (!shim_link->trampoline)
 		return;
 
-	WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline));
+	WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->tp, shim_link->trampoline));
 	bpf_trampoline_put(shim_link->trampoline);
 }
 
 static void bpf_shim_tramp_link_dealloc(struct bpf_link *link)
 {
 	struct bpf_shim_tramp_link *shim_link =
-		container_of(link, struct bpf_shim_tramp_link, link.link);
+		container_of(link, struct bpf_shim_tramp_link, link);
 
 	kfree(shim_link);
 }
@@ -686,9 +707,10 @@ static struct bpf_shim_tramp_link *cgroup_shim_alloc(const struct bpf_prog *prog
 	p->type = BPF_PROG_TYPE_LSM;
 	p->expected_attach_type = BPF_LSM_MAC;
 	bpf_prog_inc(p);
-	bpf_link_init(&shim_link->link.link, BPF_LINK_TYPE_UNSPEC,
+	bpf_link_init(&shim_link->link, BPF_LINK_TYPE_UNSPEC,
 		      &bpf_shim_tramp_link_lops, p);
 	bpf_cgroup_atype_get(p->aux->attach_btf_id, cgroup_atype);
+	shim_link->tp.prog = p;
 
 	return shim_link;
 }
@@ -722,7 +744,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 	shim_link = tr->shim_link;
 	if (shim_link) {
 		/* Reusing existing shim attached by the other program. */
-		bpf_link_inc(&shim_link->link.link);
+		bpf_link_inc(&shim_link->link);
 
 		mutex_unlock(&tr->mutex);
 		bpf_trampoline_put(tr); /* bpf_trampoline_get above */
@@ -737,7 +759,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 		goto err;
 	}
 
-	err = __bpf_trampoline_link_prog(&shim_link->link, tr);
+	err = __bpf_trampoline_link_prog(&shim_link->tp, tr);
 	if (err)
 		goto err;
 
@@ -752,7 +774,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 	mutex_unlock(&tr->mutex);
 
 	if (shim_link)
-		bpf_link_put(&shim_link->link.link);
+		bpf_link_put(&shim_link->link);
 
 	/* have to release tr while _not_ holding its mutex */
 	bpf_trampoline_put(tr); /* bpf_trampoline_get above */
@@ -780,7 +802,7 @@ void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog)
 	mutex_unlock(&tr->mutex);
 
 	if (shim_link)
-		bpf_link_put(&shim_link->link.link);
+		bpf_link_put(&shim_link->link);
 
 	bpf_trampoline_put(tr); /* bpf_trampoline_lookup above */
 }
@@ -817,9 +839,12 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
 		goto out;
 	WARN_ON_ONCE(mutex_is_locked(&tr->mutex));
 
-	for (i = 0; i < BPF_TRAMP_MAX; i++)
-		if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[i])))
+	for (i = 0; i < BPF_TRAMP_MAX; i++) {
+		if (!tr->progs_array[i])
+			continue;
+		if (WARN_ON_ONCE(!bpf_prog_array_is_empty(tr->progs_array[i])))
 			goto out;
+	}
 
 	/* This code will be executed even when the last bpf_tramp_image
 	 * is alive. All progs are detached from the trampoline and the
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
index 17add0bdf323..5a771cc74edf 100644
--- a/net/bpf/bpf_dummy_struct_ops.c
+++ b/net/bpf/bpf_dummy_struct_ops.c
@@ -81,7 +81,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 	const struct btf_type *func_proto;
 	struct bpf_dummy_ops_test_args *args;
 	struct bpf_tramp_progs *tprogs;
-	struct bpf_tramp_link *link = NULL;
+	struct bpf_link *link = NULL;
 	void *image = NULL;
 	unsigned int op_idx;
 	int prog_ret;
@@ -115,10 +115,10 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 	}
 	/* prog doesn't take the ownership of the reference from caller */
 	bpf_prog_inc(prog);
-	bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog);
+	bpf_link_init(link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog);
 
 	op_idx = prog->expected_attach_type;
-	err = bpf_struct_ops_prepare_trampoline(tprogs, link,
+	err = bpf_struct_ops_prepare_trampoline(tprogs, prog,
 						&st_ops->func_models[op_idx],
 						image, image + PAGE_SIZE);
 	if (err < 0)
@@ -137,7 +137,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 	kfree(args);
 	bpf_jit_free_exec(image);
 	if (link)
-		bpf_link_put(&link->link);
+		bpf_link_put(link);
 	kfree(tprogs);
 	return err;
 }
-- 
2.37.1

[RFC PATCH bpf-next 04/17] bpf: Add multi tracing attach types

[Jiri Olsa]

Adding new attach type to identify multi tracing attachment:
  BPF_TRACE_FENTRY_MULTI
  BPF_TRACE_FEXIT_MULTI

Programs with such attach type will use specific link attachment
interface coming in following changes.

This was suggested by Andrii some (long) time ago and turned out
to be easier than having special program flag for that.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h            |  5 +++++
 include/uapi/linux/bpf.h       |  2 ++
 kernel/bpf/syscall.c           | 35 ++++++++++++++++++++++++++++++----
 kernel/bpf/trampoline.c        |  3 +++
 kernel/bpf/verifier.c          |  8 +++++++-
 net/bpf/test_run.c             |  2 ++
 tools/include/uapi/linux/bpf.h |  2 ++
 7 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0617982ca859..32168ea92551 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1256,6 +1256,11 @@ static inline void bpf_module_put(const void *data, struct module *owner)
 		module_put(owner);
 }
 
+static inline bool is_tracing_multi(enum bpf_attach_type type)
+{
+	return type == BPF_TRACE_FENTRY_MULTI || type == BPF_TRACE_FEXIT_MULTI;
+}
+
 #ifdef CONFIG_NET
 /* Define it here to avoid the use of forward declaration */
 struct bpf_dummy_ops_state {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7bf9ba1329be..fb6bc2c5e9e8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -999,6 +999,8 @@ enum bpf_attach_type {
 	BPF_PERF_EVENT,
 	BPF_TRACE_KPROBE_MULTI,
 	BPF_LSM_CGROUP,
+	BPF_TRACE_FENTRY_MULTI,
+	BPF_TRACE_FEXIT_MULTI,
 	__MAX_BPF_ATTACH_TYPE
 };
 
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 42272909ac08..2e4765c7e6d4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -35,6 +35,7 @@
 #include <linux/rcupdate_trace.h>
 #include <linux/memcontrol.h>
 #include <linux/trace_events.h>
+#include <linux/btf_ids.h>
 
 #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
 			  (map)->map_type == BPF_MAP_TYPE_CGROUP_ARRAY || \
@@ -2304,7 +2305,8 @@ static int
 bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
 			   enum bpf_attach_type expected_attach_type,
 			   struct btf *attach_btf, u32 btf_id,
-			   struct bpf_prog *dst_prog)
+			   struct bpf_prog *dst_prog,
+			   bool multi_func)
 {
 	if (btf_id) {
 		if (btf_id > BTF_MAX_TYPE)
@@ -2324,6 +2326,14 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
 		}
 	}
 
+	if (multi_func) {
+		if (prog_type != BPF_PROG_TYPE_TRACING)
+			return -EINVAL;
+		if (!attach_btf || btf_id)
+			return -EINVAL;
+		return 0;
+	}
+
 	if (attach_btf && (!btf_id || dst_prog))
 		return -EINVAL;
 
@@ -2447,6 +2457,16 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type)
 	}
 }
 
+#define DEFINE_BPF_MULTI_FUNC(args...)			\
+	extern int bpf_multi_func(args);		\
+	int __init bpf_multi_func(args) { return 0; }
+
+DEFINE_BPF_MULTI_FUNC(unsigned long a1, unsigned long a2,
+		      unsigned long a3, unsigned long a4,
+		      unsigned long a5, unsigned long a6)
+
+BTF_ID_LIST_SINGLE(bpf_multi_func_btf_id, func, bpf_multi_func)
+
 /* last field in 'union bpf_attr' used by this command */
 #define	BPF_PROG_LOAD_LAST_FIELD core_relo_rec_size
 
@@ -2457,6 +2477,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 	struct btf *attach_btf = NULL;
 	int err;
 	char license[128];
+	bool multi_func;
 	bool is_gpl;
 
 	if (CHECK_ATTR(BPF_PROG_LOAD))
@@ -2498,6 +2519,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 	if (is_perfmon_prog_type(type) && !perfmon_capable())
 		return -EPERM;
 
+	multi_func = is_tracing_multi(attr->expected_attach_type);
+
 	/* attach_prog_fd/attach_btf_obj_fd can specify fd of either bpf_prog
 	 * or btf, we need to check which one it is
 	 */
@@ -2516,7 +2539,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 				return -ENOTSUPP;
 			}
 		}
-	} else if (attr->attach_btf_id) {
+	} else if (attr->attach_btf_id || multi_func) {
 		/* fall back to vmlinux BTF, if BTF type ID is specified */
 		attach_btf = bpf_get_btf_vmlinux();
 		if (IS_ERR(attach_btf))
@@ -2529,7 +2552,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 	bpf_prog_load_fixup_attach_type(attr);
 	if (bpf_prog_load_check_attach(type, attr->expected_attach_type,
 				       attach_btf, attr->attach_btf_id,
-				       dst_prog)) {
+				       dst_prog, multi_func)) {
 		if (dst_prog)
 			bpf_prog_put(dst_prog);
 		if (attach_btf)
@@ -2549,7 +2572,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 
 	prog->expected_attach_type = attr->expected_attach_type;
 	prog->aux->attach_btf = attach_btf;
-	prog->aux->attach_btf_id = attr->attach_btf_id;
+	prog->aux->attach_btf_id = multi_func ? bpf_multi_func_btf_id[0] : attr->attach_btf_id;
 	prog->aux->dst_prog = dst_prog;
 	prog->aux->offload_requested = !!attr->prog_ifindex;
 	prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE;
@@ -2955,6 +2978,8 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
 	case BPF_PROG_TYPE_TRACING:
 		if (prog->expected_attach_type != BPF_TRACE_FENTRY &&
 		    prog->expected_attach_type != BPF_TRACE_FEXIT &&
+		    prog->expected_attach_type != BPF_TRACE_FENTRY_MULTI &&
+		    prog->expected_attach_type != BPF_TRACE_FEXIT_MULTI &&
 		    prog->expected_attach_type != BPF_MODIFY_RETURN) {
 			err = -EINVAL;
 			goto out_put_prog;
@@ -3429,6 +3454,8 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type)
 	case BPF_TRACE_RAW_TP:
 	case BPF_TRACE_FENTRY:
 	case BPF_TRACE_FEXIT:
+	case BPF_TRACE_FENTRY_MULTI:
+	case BPF_TRACE_FEXIT_MULTI:
 	case BPF_MODIFY_RETURN:
 		return BPF_PROG_TYPE_TRACING;
 	case BPF_LSM_MAC:
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 854d0a3b9b31..56899d63c08c 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -112,6 +112,7 @@ bool bpf_prog_has_trampoline(const struct bpf_prog *prog)
 
 	return (ptype == BPF_PROG_TYPE_TRACING &&
 		(eatype == BPF_TRACE_FENTRY || eatype == BPF_TRACE_FEXIT ||
+		 eatype == BPF_TRACE_FENTRY_MULTI || eatype == BPF_TRACE_FEXIT_MULTI ||
 		 eatype == BPF_MODIFY_RETURN)) ||
 		(ptype == BPF_PROG_TYPE_LSM && eatype == BPF_LSM_MAC);
 }
@@ -529,10 +530,12 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog)
 {
 	switch (prog->expected_attach_type) {
 	case BPF_TRACE_FENTRY:
+	case BPF_TRACE_FENTRY_MULTI:
 		return BPF_TRAMP_FENTRY;
 	case BPF_MODIFY_RETURN:
 		return BPF_TRAMP_MODIFY_RETURN;
 	case BPF_TRACE_FEXIT:
+	case BPF_TRACE_FEXIT_MULTI:
 		return BPF_TRAMP_FEXIT;
 	case BPF_LSM_MAC:
 		if (!prog->aux->attach_func_proto->type)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 096fdac70165..5bc2e4183b58 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10526,6 +10526,8 @@ static int check_return_code(struct bpf_verifier_env *env)
 		switch (env->prog->expected_attach_type) {
 		case BPF_TRACE_FENTRY:
 		case BPF_TRACE_FEXIT:
+		case BPF_TRACE_FENTRY_MULTI:
+		case BPF_TRACE_FEXIT_MULTI:
 			range = tnum_const(0);
 			break;
 		case BPF_TRACE_RAW_TP:
@@ -14289,6 +14291,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 		if (prog_type == BPF_PROG_TYPE_TRACING &&
 		    insn->imm == BPF_FUNC_get_func_ret) {
 			if (eatype == BPF_TRACE_FEXIT ||
+			    eatype == BPF_TRACE_FEXIT_MULTI ||
 			    eatype == BPF_MODIFY_RETURN) {
 				/* Load nr_args from ctx - 8 */
 				insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
@@ -14937,6 +14940,8 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 	case BPF_LSM_CGROUP:
 	case BPF_TRACE_FENTRY:
 	case BPF_TRACE_FEXIT:
+	case BPF_TRACE_FENTRY_MULTI:
+	case BPF_TRACE_FEXIT_MULTI:
 		if (!btf_type_is_func(t)) {
 			bpf_log(log, "attach_btf_id %u is not a function\n",
 				btf_id);
@@ -15093,7 +15098,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 		if (!bpf_iter_prog_supported(prog))
 			return -EINVAL;
 		return 0;
-	}
+	} else if (is_tracing_multi(prog->expected_attach_type))
+		return prog->type == BPF_PROG_TYPE_TRACING ? 0 : -EINVAL;
 
 	if (prog->type == BPF_PROG_TYPE_LSM) {
 		ret = bpf_lsm_verify_prog(&env->log, prog);
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index cbc9cd5058cb..2cb78d4b0d32 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -760,6 +760,8 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
 	switch (prog->expected_attach_type) {
 	case BPF_TRACE_FENTRY:
 	case BPF_TRACE_FEXIT:
+	case BPF_TRACE_FENTRY_MULTI:
+	case BPF_TRACE_FEXIT_MULTI:
 		if (bpf_fentry_test1(1) != 2 ||
 		    bpf_fentry_test2(2, 3) != 5 ||
 		    bpf_fentry_test3(4, 5, 6) != 15 ||
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 59a217ca2dfd..94d623affd5f 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -999,6 +999,8 @@ enum bpf_attach_type {
 	BPF_PERF_EVENT,
 	BPF_TRACE_KPROBE_MULTI,
 	BPF_LSM_CGROUP,
+	BPF_TRACE_FENTRY_MULTI,
+	BPF_TRACE_FEXIT_MULTI,
 	__MAX_BPF_ATTACH_TYPE
 };
 
-- 
2.37.1

[RFC PATCH bpf-next 05/17] bpf: Add bpf_tramp_id object

[Jiri Olsa]

Adding bpf_tramp_id object that allows to store multiple BTF
function ids together with their resolved addresses.

It will be used in following changes to identify and attach
multiple functions to trampolines.

The bpf_tramp_id object will be shared between trampoline and
link in following changes, so it keeps refcount for that.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h     | 12 ++++++++++++
 kernel/bpf/trampoline.c | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 32168ea92551..a5738d57f6bd 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -27,6 +27,7 @@
 #include <linux/bpfptr.h>
 #include <linux/btf.h>
 #include <linux/rcupdate_trace.h>
+#include <linux/refcount.h>
 
 struct bpf_verifier_env;
 struct bpf_verifier_log;
@@ -846,6 +847,15 @@ struct bpf_tramp_image {
 	};
 };
 
+struct bpf_tramp_id {
+	u32 max;
+	u32 cnt;
+	u32 obj_id;
+	u32 *id;
+	void **addr;
+	refcount_t refcnt;
+};
+
 struct bpf_shim_tramp_link;
 
 struct bpf_trampoline {
@@ -917,6 +927,8 @@ int bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline
 struct bpf_trampoline *bpf_trampoline_get(u64 key,
 					  struct bpf_attach_target_info *tgt_info);
 void bpf_trampoline_put(struct bpf_trampoline *tr);
+struct bpf_tramp_id *bpf_tramp_id_alloc(u32 cnt);
+void bpf_tramp_id_put(struct bpf_tramp_id *id);
 int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs);
 #define BPF_DISPATCHER_INIT(_name) {				\
 	.mutex = __MUTEX_INITIALIZER(_name.mutex),		\
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 56899d63c08c..c0983ff5aa3a 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -149,6 +149,44 @@ void bpf_image_ksym_del(struct bpf_ksym *ksym)
 			   PAGE_SIZE, true, ksym->name);
 }
 
+struct bpf_tramp_id *bpf_tramp_id_alloc(u32 max)
+{
+	struct bpf_tramp_id *id;
+
+	id = kzalloc(sizeof(*id), GFP_KERNEL);
+	if (id) {
+		id->id = kcalloc(max, sizeof(u32), GFP_KERNEL);
+		id->addr = kcalloc(max, sizeof(*id->addr), GFP_KERNEL);
+		if (!id->id || !id->addr) {
+			kfree(id->id);
+			kfree(id->addr);
+			kfree(id);
+			return NULL;
+		}
+		id->max = max;
+		refcount_set(&id->refcnt, 1);
+	}
+	return id;
+}
+
+__maybe_unused
+static struct bpf_tramp_id *bpf_tramp_id_get(struct bpf_tramp_id *id)
+{
+	refcount_inc(&id->refcnt);
+	return id;
+}
+
+void bpf_tramp_id_put(struct bpf_tramp_id *id)
+{
+	if (!id)
+		return;
+	if (!refcount_dec_and_test(&id->refcnt))
+		return;
+	kfree(id->addr);
+	kfree(id->id);
+	kfree(id);
+}
+
 static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 {
 	struct bpf_trampoline *tr;
-- 
2.37.1

[RFC PATCH bpf-next 06/17] bpf: Pass image struct to reg/unreg/modify fentry functions

[Jiri Olsa]

Passing image struct to reg/unreg/modify fentry functions
as a preparation for following change, where we need to
use the whole image in the update logic.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/trampoline.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index c0983ff5aa3a..d28070247fa3 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -244,8 +244,9 @@ static void bpf_trampoline_module_put(struct bpf_trampoline *tr)
 	tr->mod = NULL;
 }
 
-static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr)
+static int unregister_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im)
 {
+	void *old_addr = im->image;
 	void *ip = tr->func.addr;
 	int ret;
 
@@ -259,9 +260,11 @@ static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr)
 	return ret;
 }
 
-static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr,
+static int modify_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im,
 			 bool lock_direct_mutex)
 {
+	void *old_addr = tr->cur_image->image;
+	void *new_addr = im->image;
 	void *ip = tr->func.addr;
 	int ret;
 
@@ -277,8 +280,9 @@ static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_ad
 }
 
 /* first time registering */
-static int register_fentry(struct bpf_trampoline *tr, void *new_addr)
+static int register_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im)
 {
+	void *new_addr = im->image;
 	void *ip = tr->func.addr;
 	unsigned long faddr;
 	int ret;
@@ -486,7 +490,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 		return PTR_ERR(tprogs);
 
 	if (total == 0) {
-		err = unregister_fentry(tr, tr->cur_image->image);
+		err = unregister_fentry(tr, tr->cur_image);
 		bpf_tramp_image_put(tr->cur_image);
 		tr->cur_image = NULL;
 		tr->selector = 0;
@@ -532,10 +536,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 	WARN_ON(!tr->cur_image && tr->selector);
 	if (tr->cur_image)
 		/* progs already running at this address */
-		err = modify_fentry(tr, tr->cur_image->image, im->image, lock_direct_mutex);
+		err = modify_fentry(tr, im, lock_direct_mutex);
 	else
 		/* first time registering */
-		err = register_fentry(tr, im->image);
+		err = register_fentry(tr, im);
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	if (err == -EAGAIN) {
-- 
2.37.1

[RFC PATCH bpf-next 07/17] bpf: Add support to postpone trampoline update

[Jiri Olsa]

Adding support to postpone the trampoline update and record
it to the update list. If the update list is provided, all
the reg/unreg/modify functions only add trampoline to the
update list and stores the requested update information/data
to the trampoline.

It will bed used in following changes where we need to do the
actual trampoline update at the end of the attachment.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h     | 31 ++++++++++++-----
 kernel/bpf/trampoline.c | 76 +++++++++++++++++++++++++++++------------
 2 files changed, 78 insertions(+), 29 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a5738d57f6bd..a23ff5b8d14c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -768,6 +768,28 @@ struct btf_func_model {
  */
 #define BPF_MAX_TRAMP_LINKS 38
 
+enum bpf_tramp_update_action {
+	BPF_TRAMP_UPDATE_REG,
+	BPF_TRAMP_UPDATE_UNREG,
+	BPF_TRAMP_UPDATE_MODIFY,
+};
+
+enum bpf_tramp_prog_type {
+	BPF_TRAMP_FENTRY,
+	BPF_TRAMP_FEXIT,
+	BPF_TRAMP_MODIFY_RETURN,
+	BPF_TRAMP_MAX,
+	BPF_TRAMP_REPLACE, /* more than MAX */
+};
+
+struct bpf_tramp_update {
+	enum bpf_tramp_update_action action;
+	struct bpf_tramp_image *im;
+	enum bpf_tramp_prog_type kind;
+	struct bpf_prog_array *old_array;
+	struct list_head list;
+};
+
 struct bpf_tramp_prog {
 	struct bpf_prog *prog;
 	u64 cookie;
@@ -827,14 +849,6 @@ struct bpf_ksym {
 	bool			 prog;
 };
 
-enum bpf_tramp_prog_type {
-	BPF_TRAMP_FENTRY,
-	BPF_TRAMP_FEXIT,
-	BPF_TRAMP_MODIFY_RETURN,
-	BPF_TRAMP_MAX,
-	BPF_TRAMP_REPLACE, /* more than MAX */
-};
-
 struct bpf_tramp_image {
 	void *image;
 	struct bpf_ksym ksym;
@@ -886,6 +900,7 @@ struct bpf_trampoline {
 	u64 selector;
 	struct module *mod;
 	struct bpf_shim_tramp_link *shim_link;
+	struct bpf_tramp_update update;
 };
 
 struct bpf_attach_target_info {
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index d28070247fa3..e926692ded85 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -31,7 +31,8 @@ static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE];
 static DEFINE_MUTEX(trampoline_mutex);
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
-static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex);
+static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex,
+				 struct list_head *upd);
 
 static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, enum ftrace_ops_cmd cmd)
 {
@@ -87,13 +88,13 @@ static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, enum ftrace_ops_cmd
 
 		if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) &&
 		    !(tr->flags & BPF_TRAMP_F_ORIG_STACK))
-			ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */);
+			ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */, NULL);
 		break;
 	case FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER:
 		tr->flags &= ~BPF_TRAMP_F_SHARE_IPMODIFY;
 
 		if (tr->flags & BPF_TRAMP_F_ORIG_STACK)
-			ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */);
+			ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */, NULL);
 		break;
 	default:
 		ret = -EINVAL;
@@ -244,12 +245,20 @@ static void bpf_trampoline_module_put(struct bpf_trampoline *tr)
 	tr->mod = NULL;
 }
 
-static int unregister_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im)
+static int unregister_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im,
+			     struct list_head *upd)
 {
 	void *old_addr = im->image;
 	void *ip = tr->func.addr;
 	int ret;
 
+	if (upd) {
+		tr->update.action = BPF_TRAMP_UPDATE_UNREG;
+		tr->update.im = NULL;
+		list_add_tail(&tr->update.list, upd);
+		return 0;
+	}
+
 	if (tr->func.ftrace_managed)
 		ret = unregister_ftrace_direct_multi(tr->fops, (long)old_addr);
 	else
@@ -257,17 +266,24 @@ static int unregister_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *
 
 	if (!ret)
 		bpf_trampoline_module_put(tr);
+
 	return ret;
 }
 
 static int modify_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im,
-			 bool lock_direct_mutex)
+			 bool lock_direct_mutex, struct list_head *upd)
 {
 	void *old_addr = tr->cur_image->image;
 	void *new_addr = im->image;
 	void *ip = tr->func.addr;
 	int ret;
 
+	if (upd) {
+		tr->update.action = BPF_TRAMP_UPDATE_MODIFY;
+		tr->update.im = im;
+		list_add_tail(&tr->update.list, upd);
+		return 0;
+	}
 	if (tr->func.ftrace_managed) {
 		if (lock_direct_mutex)
 			ret = modify_ftrace_direct_multi(tr->fops, (long)new_addr);
@@ -280,7 +296,8 @@ static int modify_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im,
 }
 
 /* first time registering */
-static int register_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im)
+static int register_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im,
+			   struct list_head *upd)
 {
 	void *new_addr = im->image;
 	void *ip = tr->func.addr;
@@ -294,6 +311,15 @@ static int register_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im
 		tr->func.ftrace_managed = true;
 	}
 
+	if (upd) {
+		if (ip && !tr->func.ftrace_managed)
+			return -ENOTSUPP;
+		tr->update.action = BPF_TRAMP_UPDATE_REG;
+		tr->update.im = im;
+		list_add_tail(&tr->update.list, upd);
+		return 0;
+	}
+
 	if (bpf_trampoline_module_get(tr))
 		return -ENOENT;
 
@@ -477,7 +503,8 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx)
 	return ERR_PTR(err);
 }
 
-static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex)
+static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex,
+				 struct list_head *upd)
 {
 	struct bpf_tramp_image *im;
 	struct bpf_tramp_progs *tprogs;
@@ -490,10 +517,12 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 		return PTR_ERR(tprogs);
 
 	if (total == 0) {
-		err = unregister_fentry(tr, tr->cur_image);
-		bpf_tramp_image_put(tr->cur_image);
-		tr->cur_image = NULL;
-		tr->selector = 0;
+		err = unregister_fentry(tr, tr->cur_image, upd);
+		if (!upd) {
+			bpf_tramp_image_put(tr->cur_image);
+			tr->cur_image = NULL;
+			tr->selector = 0;
+		}
 		goto out;
 	}
 
@@ -536,10 +565,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 	WARN_ON(!tr->cur_image && tr->selector);
 	if (tr->cur_image)
 		/* progs already running at this address */
-		err = modify_fentry(tr, im, lock_direct_mutex);
+		err = modify_fentry(tr, im, lock_direct_mutex, upd);
 	else
 		/* first time registering */
-		err = register_fentry(tr, im);
+		err = register_fentry(tr, im, upd);
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	if (err == -EAGAIN) {
@@ -553,7 +582,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 		goto again;
 	}
 #endif
-	if (err)
+	if (err || upd)
 		goto out;
 
 	if (tr->cur_image)
@@ -592,7 +621,8 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog)
 	}
 }
 
-static int __bpf_trampoline_link_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr)
+static int __bpf_trampoline_link_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr,
+				      struct list_head *upd)
 {
 	struct bpf_prog_array *old_array, *new_array;
 	const struct bpf_prog_array_item *item;
@@ -638,11 +668,14 @@ static int __bpf_trampoline_link_prog(struct bpf_tramp_prog *tp, struct bpf_tram
 		return -ENOMEM;
 	tr->progs_array[kind] = new_array;
 	tr->progs_cnt[kind]++;
-	err = bpf_trampoline_update(tr, true /* lock_direct_mutex */);
+	err = bpf_trampoline_update(tr, true /* lock_direct_mutex */, upd);
 	if (err) {
 		tr->progs_array[kind] = old_array;
 		tr->progs_cnt[kind]--;
 		bpf_prog_array_free(new_array);
+	} else if (upd) {
+		tr->update.kind = kind;
+		tr->update.old_array = old_array;
 	} else {
 		bpf_prog_array_free(old_array);
 	}
@@ -654,12 +687,13 @@ int bpf_trampoline_link_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *t
 	int err;
 
 	mutex_lock(&tr->mutex);
-	err = __bpf_trampoline_link_prog(tp, tr);
+	err = __bpf_trampoline_link_prog(tp, tr, NULL);
 	mutex_unlock(&tr->mutex);
 	return err;
 }
 
-static int __bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr)
+static int __bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline *tr,
+					struct list_head *upd)
 {
 	struct bpf_prog_array *old_array, *new_array;
 	enum bpf_tramp_prog_type kind;
@@ -683,7 +717,7 @@ static int __bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_tr
 	tr->progs_cnt[kind]--;
 	tr->progs_array[kind] = new_array;
 	bpf_prog_array_free(old_array);
-	return bpf_trampoline_update(tr, true /* lock_direct_mutex */);
+	return bpf_trampoline_update(tr, true /* lock_direct_mutex */, upd);
 }
 
 /* bpf_trampoline_unlink_prog() should never fail. */
@@ -692,7 +726,7 @@ int bpf_trampoline_unlink_prog(struct bpf_tramp_prog *tp, struct bpf_trampoline
 	int err;
 
 	mutex_lock(&tr->mutex);
-	err = __bpf_trampoline_unlink_prog(tp, tr);
+	err = __bpf_trampoline_unlink_prog(tp, tr, NULL);
 	mutex_unlock(&tr->mutex);
 	return err;
 }
@@ -804,7 +838,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
 		goto err;
 	}
 
-	err = __bpf_trampoline_link_prog(&shim_link->tp, tr);
+	err = __bpf_trampoline_link_prog(&shim_link->tp, tr, NULL);
 	if (err)
 		goto err;
 
-- 
2.37.1

[RFC PATCH bpf-next 08/17] bpf: Factor bpf_trampoline_lookup function

[Jiri Olsa]

Factoring bpf_trampoline_lookup function and adding to new
functions which will be needed in following changes:

  struct bpf_trampoline *__bpf_trampoline_lookup(u64 key)
  - returns trampoline without locking trampoline_mutex

  static struct bpf_trampoline *bpf_trampoline_alloc(void)
  - alocates trampoline object

The bpf_trampoline_lookup logic stays the same.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/trampoline.c | 45 ++++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index e926692ded85..15801f6c5071 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -188,38 +188,59 @@ void bpf_tramp_id_put(struct bpf_tramp_id *id)
 	kfree(id);
 }
 
-static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
+static struct bpf_trampoline *__bpf_trampoline_lookup(u64 key)
 {
 	struct bpf_trampoline *tr;
 	struct hlist_head *head;
 
-	mutex_lock(&trampoline_mutex);
 	head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)];
 	hlist_for_each_entry(tr, head, hlist) {
-		if (tr->key == key) {
-			refcount_inc(&tr->refcnt);
-			goto out;
-		}
+		if (tr->key == key)
+			return tr;
 	}
+	return NULL;
+}
+
+static struct bpf_trampoline *bpf_trampoline_alloc(void)
+{
+	struct bpf_trampoline *tr;
+
 	tr = kzalloc(sizeof(*tr), GFP_KERNEL);
 	if (!tr)
-		goto out;
+		return NULL;
+
+	INIT_HLIST_NODE(&tr->hlist);
+	refcount_set(&tr->refcnt, 1);
+	mutex_init(&tr->mutex);
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	tr->fops = kzalloc(sizeof(struct ftrace_ops), GFP_KERNEL);
 	if (!tr->fops) {
 		kfree(tr);
-		tr = NULL;
-		goto out;
+		return NULL;
 	}
 	tr->fops->private = tr;
 	tr->fops->ops_func = bpf_tramp_ftrace_ops_func;
 #endif
+	return tr;
+}
+
+static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
+{
+	struct bpf_trampoline *tr;
+	struct hlist_head *head;
 
+	mutex_lock(&trampoline_mutex);
+	tr = __bpf_trampoline_lookup(key);
+	if (tr) {
+		refcount_inc(&tr->refcnt);
+		goto out;
+	}
+	tr = bpf_trampoline_alloc();
+	if (!tr)
+		goto out;
 	tr->key = key;
-	INIT_HLIST_NODE(&tr->hlist);
+	head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)];
 	hlist_add_head(&tr->hlist, head);
-	refcount_set(&tr->refcnt, 1);
-	mutex_init(&tr->mutex);
 out:
 	mutex_unlock(&trampoline_mutex);
 	return tr;
-- 
2.37.1

[RFC PATCH bpf-next 09/17] bpf: Factor bpf_trampoline_put function

[Jiri Olsa]

Factoring bpf_trampoline_put function and adding new
__bpf_trampoline_put function without locking trampoline_mutex.

It will be needed in following changes.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/trampoline.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 15801f6c5071..b6b57aa09364 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -928,22 +928,19 @@ struct bpf_trampoline *bpf_trampoline_get(u64 key,
 	return tr;
 }
 
-void bpf_trampoline_put(struct bpf_trampoline *tr)
+static void __bpf_trampoline_put(struct bpf_trampoline *tr)
 {
 	int i;
 
-	if (!tr)
-		return;
-	mutex_lock(&trampoline_mutex);
 	if (!refcount_dec_and_test(&tr->refcnt))
-		goto out;
+		return;
 	WARN_ON_ONCE(mutex_is_locked(&tr->mutex));
 
 	for (i = 0; i < BPF_TRAMP_MAX; i++) {
 		if (!tr->progs_array[i])
 			continue;
 		if (WARN_ON_ONCE(!bpf_prog_array_is_empty(tr->progs_array[i])))
-			goto out;
+			return;
 	}
 
 	/* This code will be executed even when the last bpf_tramp_image
@@ -958,7 +955,14 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
 		kfree(tr->fops);
 	}
 	kfree(tr);
-out:
+}
+
+void bpf_trampoline_put(struct bpf_trampoline *tr)
+{
+	if (!tr)
+		return;
+	mutex_lock(&trampoline_mutex);
+	__bpf_trampoline_put(tr);
 	mutex_unlock(&trampoline_mutex);
 }
 
-- 
2.37.1

[RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Jiri Olsa]

Adding support to attach program to multiple trampolines
with new attach/detach interface:

  int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
                                  struct bpf_tramp_id *id)
  int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
                                  struct bpf_tramp_id *id)

The program is passed as bpf_tramp_prog object and trampolines to
attach it to are passed as bpf_tramp_id object.

The interface creates new bpf_trampoline object which is initialized
as 'multi' trampoline and stored separtely from standard trampolines.

There are following rules how the standard and multi trampolines
go along:
  - multi trampoline can attach on top of existing single trampolines,
    which creates 2 types of function IDs:

      1) single-IDs - functions that are attached within existing single
         trampolines
      2) multi-IDs  - functions that were 'free' and are now taken by new
         'multi' trampoline

  - we allow overlapping of 2 'multi' trampolines if they are attached
    to same IDs
  - we do now allow any other overlapping of 2 'multi' trampolines
  - any new 'single' trampoline cannot attach to existing multi-IDs IDs.

Maybe better explained on following example:

   - you want to attach program P to functions A,B,C,D,E,F
     via bpf_trampoline_multi_attach

   - D,E,F already have standard trampoline attached

   - the bpf_trampoline_multi_attach will create new 'multi' trampoline
     which spans over A,B,C functions and attach program P to single
     trampolines D,E,F

   - A,B,C functions are now 'not attachable' by any trampoline
     until the above 'multi' trampoline is released

  -  D,E,F functions are still attachable by any new trampoline

If the bpf_tramp_id object contains ID that exists as the standard
trampoline the interface will add the program

These limitations are there to avoid extra complexity of splitting
existing trampolines, which turned out to be nightmare. However the
current code does not prevent any such feature improvement in the
future.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h     |   8 +
 kernel/bpf/trampoline.c | 393 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 394 insertions(+), 7 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a23ff5b8d14c..9842554e4fa4 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -901,6 +901,12 @@ struct bpf_trampoline {
 	struct module *mod;
 	struct bpf_shim_tramp_link *shim_link;
 	struct bpf_tramp_update update;
+	struct {
+		struct list_head list;
+		struct bpf_tramp_id *id;
+		struct bpf_tramp_id *id_multi;
+		struct bpf_tramp_id *id_singles;
+	} multi;
 };
 
 struct bpf_attach_target_info {
@@ -945,6 +951,8 @@ void bpf_trampoline_put(struct bpf_trampoline *tr);
 struct bpf_tramp_id *bpf_tramp_id_alloc(u32 cnt);
 void bpf_tramp_id_put(struct bpf_tramp_id *id);
 int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs);
+int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp, struct bpf_tramp_id *id);
+int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp, struct bpf_tramp_id *id);
 #define BPF_DISPATCHER_INIT(_name) {				\
 	.mutex = __MUTEX_INITIALIZER(_name.mutex),		\
 	.func = &_name##_func,					\
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index b6b57aa09364..9be6e5737eba 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -14,6 +14,7 @@
 #include <linux/bpf_verifier.h>
 #include <linux/bpf_lsm.h>
 #include <linux/delay.h>
+#include <linux/bsearch.h>
 
 /* dummy _ops. The verifier will operate on target program's ops. */
 const struct bpf_verifier_ops bpf_extension_verifier_ops = {
@@ -33,6 +34,7 @@ static DEFINE_MUTEX(trampoline_mutex);
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex,
 				 struct list_head *upd);
+static bool key_in_multi_trampoline(u64 key);
 
 static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, enum ftrace_ops_cmd cmd)
 {
@@ -170,7 +172,6 @@ struct bpf_tramp_id *bpf_tramp_id_alloc(u32 max)
 	return id;
 }
 
-__maybe_unused
 static struct bpf_tramp_id *bpf_tramp_id_get(struct bpf_tramp_id *id)
 {
 	refcount_inc(&id->refcnt);
@@ -226,10 +227,12 @@ static struct bpf_trampoline *bpf_trampoline_alloc(void)
 
 static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 {
-	struct bpf_trampoline *tr;
+	struct bpf_trampoline *tr = NULL;
 	struct hlist_head *head;
 
 	mutex_lock(&trampoline_mutex);
+	if (key_in_multi_trampoline(key))
+		goto out;
 	tr = __bpf_trampoline_lookup(key);
 	if (tr) {
 		refcount_inc(&tr->refcnt);
@@ -357,7 +360,7 @@ static int register_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im
 }
 
 static struct bpf_tramp_progs *
-bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg)
+bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg, bool *multi)
 {
 	const struct bpf_prog_array_item *item;
 	struct bpf_prog_array *prog_array;
@@ -383,6 +386,7 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_a
 
 		while ((prog = READ_ONCE(item->prog))) {
 			*ip_arg |= prog->call_get_func_ip;
+			*multi |= is_tracing_multi(prog->expected_attach_type);
 			tp->prog = prog;
 			tp->cookie = item->bpf_cookie;
 			tp++; item++;
@@ -524,16 +528,23 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx)
 	return ERR_PTR(err);
 }
 
+static struct btf_func_model btf_multi_func_model = {
+	.ret_size = 0,
+	.nr_args = 6,
+	.arg_size = { 8, 8, 8, 8, 8, 8, },
+};
+
 static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex,
 				 struct list_head *upd)
 {
+	struct btf_func_model *model = &tr->func.model;
 	struct bpf_tramp_image *im;
 	struct bpf_tramp_progs *tprogs;
 	u32 orig_flags = tr->flags;
-	bool ip_arg = false;
+	bool ip_arg = false, multi = false;
 	int err, total;
 
-	tprogs = bpf_trampoline_get_progs(tr, &total, &ip_arg);
+	tprogs = bpf_trampoline_get_progs(tr, &total, &ip_arg, &multi);
 	if (IS_ERR(tprogs))
 		return PTR_ERR(tprogs);
 
@@ -568,6 +579,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 
 	if (ip_arg)
 		tr->flags |= BPF_TRAMP_F_IP_ARG;
+	if (multi) {
+		tr->flags |= BPF_TRAMP_F_ORIG_STACK;
+		model = &btf_multi_func_model;
+	}
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 again:
@@ -577,7 +592,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
 #endif
 
 	err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE,
-					  &tr->func.model, tr->flags, tprogs,
+					  model, tr->flags, tprogs,
 					  tr->func.addr);
 	if (err < 0)
 		goto out;
@@ -949,11 +964,18 @@ static void __bpf_trampoline_put(struct bpf_trampoline *tr)
 	 * fexit progs. The fentry-only trampoline will be freed via
 	 * multiple rcu callbacks.
 	 */
-	hlist_del(&tr->hlist);
 	if (tr->fops) {
 		ftrace_free_filter(tr->fops);
 		kfree(tr->fops);
 	}
+	if (tr->multi.id) {
+		bpf_tramp_id_put(tr->multi.id);
+		bpf_tramp_id_put(tr->multi.id_multi);
+		bpf_tramp_id_put(tr->multi.id_singles);
+		list_del(&tr->multi.list);
+	} else {
+		hlist_del(&tr->hlist);
+	}
 	kfree(tr);
 }
 
@@ -966,6 +988,363 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
 	mutex_unlock(&trampoline_mutex);
 }
 
+static LIST_HEAD(multi_trampolines);
+
+static int btf_id_cmp(const void *a, const void *b)
+{
+	const u32 *x = a;
+	const u32 *y = b;
+
+	if (*x == *y)
+		return 0;
+	return *x < *y ? -1 : 1;
+}
+
+static bool id_match(struct bpf_tramp_id *a, struct bpf_tramp_id *b)
+{
+	if (a->obj_id != b->obj_id)
+		return false;
+	if (a->cnt != b->cnt)
+		return false;
+	return memcmp(a->id, b->id, sizeof(u32) * a->cnt) == 0;
+}
+
+static bool id_cross(struct bpf_tramp_id *a, struct bpf_tramp_id *b)
+{
+	u32 i, id;
+
+	for (i = 0; i < a->cnt; i++) {
+		id = a->id[i];
+		if (bsearch(&id, b->id, b->cnt, sizeof(u32), btf_id_cmp))
+			return true;
+	}
+	return false;
+}
+
+static void id_add(struct bpf_tramp_id *id, int btf_id, void *addr)
+{
+	if (WARN_ON_ONCE(id->cnt >= id->max))
+		return;
+	id->id[id->cnt] = btf_id;
+	id->addr[id->cnt] = addr;
+	id->cnt++;
+}
+
+static bool key_in_multi_trampoline(u64 key)
+{
+	struct bpf_trampoline *tr;
+	struct bpf_tramp_id *id;
+	u32 obj_id, btf_id;
+
+	bpf_trampoline_unpack_key(key, &obj_id, &btf_id);
+
+	list_for_each_entry(tr, &multi_trampolines, multi.list) {
+		id = tr->multi.id_multi;
+
+		if (obj_id != id->obj_id)
+			continue;
+		if (bsearch(&btf_id, id->id, id->cnt, sizeof(u32), btf_id_cmp))
+			return true;
+	}
+	return false;
+}
+
+static void bpf_trampoline_rollback(struct bpf_trampoline *tr)
+{
+	struct bpf_tramp_update *upd = &tr->update;
+
+	tr->progs_array[upd->kind] = upd->old_array;
+	tr->progs_cnt[upd->kind]--;
+	if (tr->update.im)
+		bpf_tramp_image_put(tr->update.im);
+}
+
+static void bpf_trampoline_commit(struct bpf_trampoline *tr)
+{
+	if (tr->cur_image)
+		bpf_tramp_image_put(tr->cur_image);
+	tr->cur_image = tr->update.im;
+	if (tr->update.action == BPF_TRAMP_UPDATE_UNREG)
+		tr->selector = 0;
+	else
+		tr->selector++;
+}
+
+static int bpf_tramp_update_set(struct list_head *upd)
+{
+	struct bpf_trampoline *tr, *trm = NULL;
+	int i, rollback_cnt = 0, err = -EINVAL;
+	unsigned long ip, image_new, image_old;
+
+	list_for_each_entry(tr, upd, update.list) {
+		if (tr->multi.id_multi) {
+			trm = tr;
+			continue;
+		}
+
+		ip = (unsigned long) tr->func.addr;
+		image_new = tr->update.im ? (unsigned long) tr->update.im->image : 0;
+		image_old = tr->cur_image ? (unsigned long) tr->cur_image->image : 0;
+
+		switch (tr->update.action) {
+		case BPF_TRAMP_UPDATE_REG:
+			err = register_ftrace_direct_multi(tr->fops, image_new);
+			break;
+		case BPF_TRAMP_UPDATE_MODIFY:
+			err = modify_ftrace_direct_multi(tr->fops, image_new);
+			break;
+		case BPF_TRAMP_UPDATE_UNREG:
+			err = unregister_ftrace_direct_multi(tr->fops, image_old);
+			break;
+		}
+		if (err)
+			goto out_rollback;
+		rollback_cnt++;
+	}
+
+	if (!trm)
+		return 0;
+
+	if (trm->update.action == BPF_TRAMP_UPDATE_REG) {
+		for (i = 0; i < trm->multi.id_multi->cnt; i++) {
+			ip = (unsigned long) trm->multi.id_multi->addr[i];
+			err = ftrace_set_filter_ip(trm->fops, ip, 0, 0);
+			if (err)
+				goto out_rollback;
+		}
+	}
+
+	image_new = trm->update.im ? (unsigned long) trm->update.im->image : 0;
+	image_old = trm->cur_image ? (unsigned long) trm->cur_image->image : 0;
+
+	switch (trm->update.action) {
+	case BPF_TRAMP_UPDATE_REG:
+		err = register_ftrace_direct_multi(trm->fops, image_new);
+		break;
+	case BPF_TRAMP_UPDATE_MODIFY:
+		err = modify_ftrace_direct_multi(trm->fops, image_new);
+		break;
+	case BPF_TRAMP_UPDATE_UNREG:
+		err = unregister_ftrace_direct_multi(trm->fops, image_old);
+		break;
+	default:
+		break;
+	}
+
+	if (!err)
+		return 0;
+
+out_rollback:
+	i = 0;
+	list_for_each_entry(tr, upd, update.list) {
+		if (tr->multi.id_multi)
+			continue;
+
+		ip = (unsigned long) tr->func.addr;
+		image_new = tr->update.im ? (unsigned long) tr->update.im->image : 0;
+		image_old = tr->cur_image ? (unsigned long) tr->cur_image->image : 0;
+
+		switch (tr->update.action) {
+		case BPF_TRAMP_UPDATE_REG:
+			err = unregister_ftrace_direct_multi(tr->fops, image_new);
+			break;
+		case BPF_TRAMP_UPDATE_MODIFY:
+			err = modify_ftrace_direct_multi(tr->fops, image_old);
+			break;
+		case BPF_TRAMP_UPDATE_UNREG:
+			err = register_ftrace_direct_multi(tr->fops, image_old);
+			break;
+		}
+		if (rollback_cnt == ++i)
+			break;
+	}
+
+	return err;
+}
+
+static struct bpf_trampoline*
+multi_trampoline_alloc(struct bpf_tramp_id *id, struct bpf_tramp_prog *tp)
+{
+	struct bpf_tramp_id *id_multi = NULL, *id_singles = NULL;
+	struct bpf_trampoline *tr, *trm;
+	u64 key;
+	int i;
+
+	trm = bpf_trampoline_alloc();
+	if (!trm)
+		return NULL;
+
+	id_multi = bpf_tramp_id_alloc(id->cnt);
+	id_singles = bpf_tramp_id_alloc(id->cnt);
+	if (!id_multi || !id_singles)
+		goto error;
+
+	for (i = 0; i < id->cnt; i++) {
+		key = bpf_trampoline_compute_key(NULL, tp->prog->aux->attach_btf,
+						 id->id[i]);
+		tr = __bpf_trampoline_lookup(key);
+		if (!tr) {
+			id_add(id_multi, id->id[i], id->addr[i]);
+			continue;
+		}
+		id_add(id_singles, id->id[i], id->addr[i]);
+	}
+
+	trm->multi.id = bpf_tramp_id_get(id);
+	trm->multi.id_multi = id_multi;
+	trm->multi.id_singles = id_singles;
+
+	list_add_tail(&trm->multi.list, &multi_trampolines);
+	return trm;
+error:
+	bpf_tramp_id_put(id_multi);
+	bpf_tramp_id_put(id_singles);
+	kfree(trm);
+	return NULL;
+}
+
+int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp, struct bpf_tramp_id *id)
+{
+	struct bpf_trampoline *tr, *trm = NULL, *n;
+	struct bpf_tramp_id *id_singles = NULL;
+	int i, err = -EBUSY;
+	LIST_HEAD(upd);
+	u64 key;
+
+	mutex_lock(&trampoline_mutex);
+
+	list_for_each_entry(tr, &multi_trampolines, multi.list) {
+		if (id_match(id, tr->multi.id)) {
+			trm = tr;
+			break;
+		}
+		if (id_cross(id, tr->multi.id))
+			goto out_unlock;
+	}
+
+	if (trm) {
+		id_singles = tr->multi.id_singles;
+		refcount_inc(&tr->refcnt);
+	} else {
+		trm = multi_trampoline_alloc(id, tp);
+		if (!trm)
+			goto out_rollback;
+		id_singles = trm->multi.id_singles;
+	}
+
+	mutex_lock(&trm->mutex);
+	err = __bpf_trampoline_link_prog(tp, trm, &upd);
+	if (err) {
+		mutex_unlock(&trm->mutex);
+		__bpf_trampoline_put(trm);
+		goto out_unlock;
+	}
+
+	for (i = 0; i < id_singles->cnt; i++) {
+		key = bpf_trampoline_compute_key(NULL, tp->prog->aux->attach_btf,
+						 id_singles->id[i]);
+		tr = __bpf_trampoline_lookup(key);
+		if (!tr)
+			continue;
+		mutex_lock(&tr->mutex);
+		err = __bpf_trampoline_link_prog(tp, tr, &upd);
+		if (err) {
+			mutex_unlock(&tr->mutex);
+			goto out_rollback;
+		}
+		refcount_inc(&tr->refcnt);
+	}
+
+	err = bpf_tramp_update_set(&upd);
+	if (err)
+		goto out_rollback;
+
+	list_for_each_entry_safe(tr, n, &upd, update.list) {
+		bpf_trampoline_commit(tr);
+		list_del_init(&tr->update.list);
+		mutex_unlock(&tr->mutex);
+	}
+
+out_unlock:
+	mutex_unlock(&trampoline_mutex);
+	return err;
+
+out_rollback:
+	list_for_each_entry_safe(tr, n, &upd, update.list) {
+		bpf_trampoline_rollback(tr);
+		list_del_init(&tr->update.list);
+		mutex_unlock(&tr->mutex);
+		__bpf_trampoline_put(tr);
+	}
+	mutex_unlock(&trampoline_mutex);
+	return err;
+}
+
+int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp, struct bpf_tramp_id *id)
+{
+	struct bpf_trampoline *tr, *trm = NULL, *n;
+	LIST_HEAD(upd);
+	int i, err;
+	u64 key;
+
+	mutex_lock(&trampoline_mutex);
+	list_for_each_entry(tr, &multi_trampolines, multi.list) {
+		if (id_match(tr->multi.id, id)) {
+			trm = tr;
+			break;
+		}
+	}
+	if (!trm) {
+		err = -EINVAL;
+		goto fail_unlock;
+	}
+
+	mutex_lock(&trm->mutex);
+	err = __bpf_trampoline_unlink_prog(tp, trm, &upd);
+	if (err) {
+		mutex_unlock(&trm->mutex);
+		goto fail_unlock;
+	}
+
+	for (i = 0; i < trm->multi.id_singles->cnt; i++) {
+		key = bpf_trampoline_compute_key(NULL, tp->prog->aux->attach_btf,
+						 trm->multi.id_singles->id[i]);
+		tr = __bpf_trampoline_lookup(key);
+		if (!tr) {
+			err = -EINVAL;
+			goto fail_unlock;
+		}
+		mutex_lock(&tr->mutex);
+		err = __bpf_trampoline_unlink_prog(tp, tr, &upd);
+		if (err) {
+			mutex_unlock(&tr->mutex);
+			goto fail_unlock;
+		}
+	}
+
+	err = bpf_tramp_update_set(&upd);
+	if (err)
+		goto fail_unlock;
+
+	list_for_each_entry_safe(tr, n, &upd, update.list) {
+		bpf_trampoline_commit(tr);
+		list_del_init(&tr->update.list);
+		mutex_unlock(&tr->mutex);
+		__bpf_trampoline_put(tr);
+	}
+
+	mutex_unlock(&trampoline_mutex);
+	return 0;
+fail_unlock:
+	list_for_each_entry_safe(tr, n, &upd, update.list) {
+		bpf_trampoline_rollback(tr);
+		list_del_init(&tr->update.list);
+		mutex_unlock(&tr->mutex);
+	}
+	mutex_unlock(&trampoline_mutex);
+	return err;
+}
+
 #define NO_START_TIME 1
 static __always_inline u64 notrace bpf_prog_start_time(void)
 {
-- 
2.37.1

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Alexei Starovoitov]

On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> Adding support to attach program to multiple trampolines
> with new attach/detach interface:
> 
>   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
>                                   struct bpf_tramp_id *id)
>   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
>                                   struct bpf_tramp_id *id)
> 
> The program is passed as bpf_tramp_prog object and trampolines to
> attach it to are passed as bpf_tramp_id object.
> 
> The interface creates new bpf_trampoline object which is initialized
> as 'multi' trampoline and stored separtely from standard trampolines.
> 
> There are following rules how the standard and multi trampolines
> go along:
>   - multi trampoline can attach on top of existing single trampolines,
>     which creates 2 types of function IDs:
> 
>       1) single-IDs - functions that are attached within existing single
>          trampolines
>       2) multi-IDs  - functions that were 'free' and are now taken by new
>          'multi' trampoline
> 
>   - we allow overlapping of 2 'multi' trampolines if they are attached
>     to same IDs
>   - we do now allow any other overlapping of 2 'multi' trampolines
>   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> 
> Maybe better explained on following example:
> 
>    - you want to attach program P to functions A,B,C,D,E,F
>      via bpf_trampoline_multi_attach
> 
>    - D,E,F already have standard trampoline attached
> 
>    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
>      which spans over A,B,C functions and attach program P to single
>      trampolines D,E,F
> 
>    - A,B,C functions are now 'not attachable' by any trampoline
>      until the above 'multi' trampoline is released

This restriction is probably too severe.
Song added support for trampoline and KLPs to co-exist on the same function.
This multi trampoline restriction will resurface the same issue.
afiak this restriction is only because multi trampoline image
is the same for A,B,C. This memory optimization is probably going too far.
How about we keep existing logic of one tramp image per function.
Pretend that multi-prog P matches BTF of the target function,
create normal tramp for it and attach prog P there.
The prototype of P allows six u64. The args are potentially rearding
garbage, but there are no safety issues, since multi progs don't know BTF types.

We still need sinle bpf_link_multi to contain btf_ids of all functions,
but it can point to many bpf tramps. One for each attach function.

iirc we discussed something like this long ago, but I don't remember
why we didn't go that route.
arch_prepare_bpf_trampoline is fast.
bpf_tramp_image_alloc is fast too.
So attaching one multi-prog to thousands of btf_id-s should be fast too.
The destroy part is interesting.
There we will be doing thousands of bpf_tramp_image_put,
but it's all async now. We used to have synchronize_rcu() which could
be the reason why this approach was slow.
Or is this unregister_fentry that slows it down?
But register_ftrace_direct_multi() interface should have solved it
for both register and unregister?

Hopefully the bpf_tramp_id concept won't be needed.
It's bpf_link that will keep a link list or array of btf_ids and tramps.
bpf_tracing_link_multi ?
link destroy is simply going over all tramps and removing prog from them.

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Jiri Olsa]

On Tue, Aug 23, 2022 at 06:22:37PM -0700, Alexei Starovoitov wrote:
> On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> > Adding support to attach program to multiple trampolines
> > with new attach/detach interface:
> > 
> >   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
> >                                   struct bpf_tramp_id *id)
> >   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
> >                                   struct bpf_tramp_id *id)
> > 
> > The program is passed as bpf_tramp_prog object and trampolines to
> > attach it to are passed as bpf_tramp_id object.
> > 
> > The interface creates new bpf_trampoline object which is initialized
> > as 'multi' trampoline and stored separtely from standard trampolines.
> > 
> > There are following rules how the standard and multi trampolines
> > go along:
> >   - multi trampoline can attach on top of existing single trampolines,
> >     which creates 2 types of function IDs:
> > 
> >       1) single-IDs - functions that are attached within existing single
> >          trampolines
> >       2) multi-IDs  - functions that were 'free' and are now taken by new
> >          'multi' trampoline
> > 
> >   - we allow overlapping of 2 'multi' trampolines if they are attached
> >     to same IDs
> >   - we do now allow any other overlapping of 2 'multi' trampolines
> >   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> > 
> > Maybe better explained on following example:
> > 
> >    - you want to attach program P to functions A,B,C,D,E,F
> >      via bpf_trampoline_multi_attach
> > 
> >    - D,E,F already have standard trampoline attached
> > 
> >    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> >      which spans over A,B,C functions and attach program P to single
> >      trampolines D,E,F
> > 
> >    - A,B,C functions are now 'not attachable' by any trampoline
> >      until the above 'multi' trampoline is released
> 
> This restriction is probably too severe.
> Song added support for trampoline and KLPs to co-exist on the same function.
> This multi trampoline restriction will resurface the same issue.
> afiak this restriction is only because multi trampoline image
> is the same for A,B,C. This memory optimization is probably going too far.
> How about we keep existing logic of one tramp image per function.
> Pretend that multi-prog P matches BTF of the target function,
> create normal tramp for it and attach prog P there.
> The prototype of P allows six u64. The args are potentially rearding
> garbage, but there are no safety issues, since multi progs don't know BTF types.
> 
> We still need sinle bpf_link_multi to contain btf_ids of all functions,
> but it can point to many bpf tramps. One for each attach function.
> 
> iirc we discussed something like this long ago, but I don't remember
> why we didn't go that route.
> arch_prepare_bpf_trampoline is fast.
> bpf_tramp_image_alloc is fast too.
> So attaching one multi-prog to thousands of btf_id-s should be fast too.
> The destroy part is interesting.
> There we will be doing thousands of bpf_tramp_image_put,
> but it's all async now. We used to have synchronize_rcu() which could
> be the reason why this approach was slow.
> Or is this unregister_fentry that slows it down?
> But register_ftrace_direct_multi() interface should have solved it
> for both register and unregister?

I think it's the synchronize_rcu_tasks at the end of each ftrace update,
that's why we added un/register_ftrace_direct_multi that makes the changes
for multiple ips and syncs once at the end

un/register_ftrace_direct_multi will attach/detach multiple multiple ips
to single address (trampoline), so for this approach we would need to add new
ftrace direct api that would allow to set multiple ips to multiple trampolines
within one call.. I was already checking on that and looks doable

another problem might be that this update function will need to be called with
all related trampoline locks, which in this case would be thousands

jirka

> 
> Hopefully the bpf_tramp_id concept won't be needed.
> It's bpf_link that will keep a link list or array of btf_ids and tramps.
> bpf_tracing_link_multi ?
> link destroy is simply going over all tramps and removing prog from them.

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Alexei Starovoitov]

On Thu, Aug 25, 2022 at 9:08 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> On Tue, Aug 23, 2022 at 06:22:37PM -0700, Alexei Starovoitov wrote:
> > On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> > > Adding support to attach program to multiple trampolines
> > > with new attach/detach interface:
> > >
> > >   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
> > >                                   struct bpf_tramp_id *id)
> > >   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
> > >                                   struct bpf_tramp_id *id)
> > >
> > > The program is passed as bpf_tramp_prog object and trampolines to
> > > attach it to are passed as bpf_tramp_id object.
> > >
> > > The interface creates new bpf_trampoline object which is initialized
> > > as 'multi' trampoline and stored separtely from standard trampolines.
> > >
> > > There are following rules how the standard and multi trampolines
> > > go along:
> > >   - multi trampoline can attach on top of existing single trampolines,
> > >     which creates 2 types of function IDs:
> > >
> > >       1) single-IDs - functions that are attached within existing single
> > >          trampolines
> > >       2) multi-IDs  - functions that were 'free' and are now taken by new
> > >          'multi' trampoline
> > >
> > >   - we allow overlapping of 2 'multi' trampolines if they are attached
> > >     to same IDs
> > >   - we do now allow any other overlapping of 2 'multi' trampolines
> > >   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> > >
> > > Maybe better explained on following example:
> > >
> > >    - you want to attach program P to functions A,B,C,D,E,F
> > >      via bpf_trampoline_multi_attach
> > >
> > >    - D,E,F already have standard trampoline attached
> > >
> > >    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> > >      which spans over A,B,C functions and attach program P to single
> > >      trampolines D,E,F
> > >
> > >    - A,B,C functions are now 'not attachable' by any trampoline
> > >      until the above 'multi' trampoline is released
> >
> > This restriction is probably too severe.
> > Song added support for trampoline and KLPs to co-exist on the same function.
> > This multi trampoline restriction will resurface the same issue.
> > afiak this restriction is only because multi trampoline image
> > is the same for A,B,C. This memory optimization is probably going too far.
> > How about we keep existing logic of one tramp image per function.
> > Pretend that multi-prog P matches BTF of the target function,
> > create normal tramp for it and attach prog P there.
> > The prototype of P allows six u64. The args are potentially rearding
> > garbage, but there are no safety issues, since multi progs don't know BTF types.
> >
> > We still need sinle bpf_link_multi to contain btf_ids of all functions,
> > but it can point to many bpf tramps. One for each attach function.
> >
> > iirc we discussed something like this long ago, but I don't remember
> > why we didn't go that route.
> > arch_prepare_bpf_trampoline is fast.
> > bpf_tramp_image_alloc is fast too.
> > So attaching one multi-prog to thousands of btf_id-s should be fast too.
> > The destroy part is interesting.
> > There we will be doing thousands of bpf_tramp_image_put,
> > but it's all async now. We used to have synchronize_rcu() which could
> > be the reason why this approach was slow.
> > Or is this unregister_fentry that slows it down?
> > But register_ftrace_direct_multi() interface should have solved it
> > for both register and unregister?
>
> I think it's the synchronize_rcu_tasks at the end of each ftrace update,
> that's why we added un/register_ftrace_direct_multi that makes the changes
> for multiple ips and syncs once at the end

hmm. Can synchronize_rcu_tasks be made optional?
For ftrace_direct that points to bpf tramps is it really needed?

> un/register_ftrace_direct_multi will attach/detach multiple multiple ips
> to single address (trampoline), so for this approach we would need to add new
> ftrace direct api that would allow to set multiple ips to multiple trampolines
> within one call..

right

> I was already checking on that and looks doable

awesome.

> another problem might be that this update function will need to be called with
> all related trampoline locks, which in this case would be thousands

sure. but these will be newly allocated trampolines and
brand new mutexes, so no contention.
But thousands of cmpxchg-s will take time. Would be good to measure
though. It might not be that bad.

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Andrii Nakryiko]

On Thu, Aug 25, 2022 at 10:44 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Thu, Aug 25, 2022 at 9:08 AM Jiri Olsa <olsajiri@gmail.com> wrote:
> >
> > On Tue, Aug 23, 2022 at 06:22:37PM -0700, Alexei Starovoitov wrote:
> > > On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> > > > Adding support to attach program to multiple trampolines
> > > > with new attach/detach interface:
> > > >
> > > >   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
> > > >                                   struct bpf_tramp_id *id)
> > > >   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
> > > >                                   struct bpf_tramp_id *id)
> > > >
> > > > The program is passed as bpf_tramp_prog object and trampolines to
> > > > attach it to are passed as bpf_tramp_id object.
> > > >
> > > > The interface creates new bpf_trampoline object which is initialized
> > > > as 'multi' trampoline and stored separtely from standard trampolines.
> > > >
> > > > There are following rules how the standard and multi trampolines
> > > > go along:
> > > >   - multi trampoline can attach on top of existing single trampolines,
> > > >     which creates 2 types of function IDs:
> > > >
> > > >       1) single-IDs - functions that are attached within existing single
> > > >          trampolines
> > > >       2) multi-IDs  - functions that were 'free' and are now taken by new
> > > >          'multi' trampoline
> > > >
> > > >   - we allow overlapping of 2 'multi' trampolines if they are attached
> > > >     to same IDs
> > > >   - we do now allow any other overlapping of 2 'multi' trampolines
> > > >   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> > > >
> > > > Maybe better explained on following example:
> > > >
> > > >    - you want to attach program P to functions A,B,C,D,E,F
> > > >      via bpf_trampoline_multi_attach
> > > >
> > > >    - D,E,F already have standard trampoline attached
> > > >
> > > >    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> > > >      which spans over A,B,C functions and attach program P to single
> > > >      trampolines D,E,F
> > > >
> > > >    - A,B,C functions are now 'not attachable' by any trampoline
> > > >      until the above 'multi' trampoline is released
> > >
> > > This restriction is probably too severe.
> > > Song added support for trampoline and KLPs to co-exist on the same function.
> > > This multi trampoline restriction will resurface the same issue.
> > > afiak this restriction is only because multi trampoline image
> > > is the same for A,B,C. This memory optimization is probably going too far.
> > > How about we keep existing logic of one tramp image per function.
> > > Pretend that multi-prog P matches BTF of the target function,
> > > create normal tramp for it and attach prog P there.
> > > The prototype of P allows six u64. The args are potentially rearding
> > > garbage, but there are no safety issues, since multi progs don't know BTF types.
> > >
> > > We still need sinle bpf_link_multi to contain btf_ids of all functions,
> > > but it can point to many bpf tramps. One for each attach function.
> > >
> > > iirc we discussed something like this long ago, but I don't remember
> > > why we didn't go that route.
> > > arch_prepare_bpf_trampoline is fast.
> > > bpf_tramp_image_alloc is fast too.
> > > So attaching one multi-prog to thousands of btf_id-s should be fast too.
> > > The destroy part is interesting.
> > > There we will be doing thousands of bpf_tramp_image_put,
> > > but it's all async now. We used to have synchronize_rcu() which could
> > > be the reason why this approach was slow.
> > > Or is this unregister_fentry that slows it down?
> > > But register_ftrace_direct_multi() interface should have solved it
> > > for both register and unregister?
> >
> > I think it's the synchronize_rcu_tasks at the end of each ftrace update,
> > that's why we added un/register_ftrace_direct_multi that makes the changes
> > for multiple ips and syncs once at the end
>
> hmm. Can synchronize_rcu_tasks be made optional?
> For ftrace_direct that points to bpf tramps is it really needed?
>
> > un/register_ftrace_direct_multi will attach/detach multiple multiple ips
> > to single address (trampoline), so for this approach we would need to add new
> > ftrace direct api that would allow to set multiple ips to multiple trampolines
> > within one call..
>
> right
>
> > I was already checking on that and looks doable
>
> awesome.
>
> > another problem might be that this update function will need to be called with
> > all related trampoline locks, which in this case would be thousands
>
> sure. but these will be newly allocated trampolines and
> brand new mutexes, so no contention.
> But thousands of cmpxchg-s will take time. Would be good to measure
> though. It might not be that bad.

What about the memory overhead of thousands of trampolines and
trampoline images? Seems very wasteful to create one per each attach,
when each attachment in general will be identical.


If I remember correctly, last time we were also discussing creating a
generic BPF trampoline that would save all 6 input registers,
regardless of function's BTF signature. Such BPF trampoline should
support calling both generic fentry/fexit programs and typed ones,
because all the necessary data is stored on the stack correctly.

For the case when typed (non-generic) BPF trampoline is already
attached to a function and now we are attaching generic fentry, why
can't we "upgrade" existing BPF trampoline to become generic, and then
just add generic multi-fentry program to its trampoline image? Once
that multi-fentry is detached, we might choose to convert trampoline
back to typed BPF trampoline (i.e., save only necessary registers, not
all 6 of them), but that's more like an optimization, it doesn't have
to happen.

Or is there something that would make such generic trampoline impossible?

If we go with this approach, then each multi-fentry attachment will be
creating minimum amount of trampolines, determined by all the
combinations of attached programs at that point. If after we attach
multi-fentry to some set of functions we need to attach another
multi-fentry or typed fentry, we'd potentially need to split
trampolines and create a bit more of them. But while that sounds a bit
complicated, we do all that under locks so there isn't much problem in
doing that, no?

But in general, I agree with Alexei that this restriction on not being
able to attach to a function once multi-attach trampoline is attached
to it is a really-really bad restriction in production, where we can't
control exactly what BPF apps run and in which order.

P.S. I think this generic typeless BPF trampoline is a useful thing in
itself and we are half-way there already with bpf_get_func_ip() and
bpf_get_func_arg_cnt() helpers and storing such "parameters" on the
stack, so tbh, we can probably split the problem into two and try to
address a somewhat simpler and more straightforward generic BPF
trampoline first. Such generic type-less BPF trampoline will make
fentry a better and more generic alternative to kprobe, by being less
demanding about specifying BTF ID (even if we don't care about input
argument types) yet faster to trigger than kprobe.

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Jiri Olsa]

On Thu, Aug 25, 2022 at 07:35:44PM -0700, Andrii Nakryiko wrote:
> On Thu, Aug 25, 2022 at 10:44 AM Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
> >
> > On Thu, Aug 25, 2022 at 9:08 AM Jiri Olsa <olsajiri@gmail.com> wrote:
> > >
> > > On Tue, Aug 23, 2022 at 06:22:37PM -0700, Alexei Starovoitov wrote:
> > > > On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> > > > > Adding support to attach program to multiple trampolines
> > > > > with new attach/detach interface:
> > > > >
> > > > >   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
> > > > >                                   struct bpf_tramp_id *id)
> > > > >   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
> > > > >                                   struct bpf_tramp_id *id)
> > > > >
> > > > > The program is passed as bpf_tramp_prog object and trampolines to
> > > > > attach it to are passed as bpf_tramp_id object.
> > > > >
> > > > > The interface creates new bpf_trampoline object which is initialized
> > > > > as 'multi' trampoline and stored separtely from standard trampolines.
> > > > >
> > > > > There are following rules how the standard and multi trampolines
> > > > > go along:
> > > > >   - multi trampoline can attach on top of existing single trampolines,
> > > > >     which creates 2 types of function IDs:
> > > > >
> > > > >       1) single-IDs - functions that are attached within existing single
> > > > >          trampolines
> > > > >       2) multi-IDs  - functions that were 'free' and are now taken by new
> > > > >          'multi' trampoline
> > > > >
> > > > >   - we allow overlapping of 2 'multi' trampolines if they are attached
> > > > >     to same IDs
> > > > >   - we do now allow any other overlapping of 2 'multi' trampolines
> > > > >   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> > > > >
> > > > > Maybe better explained on following example:
> > > > >
> > > > >    - you want to attach program P to functions A,B,C,D,E,F
> > > > >      via bpf_trampoline_multi_attach
> > > > >
> > > > >    - D,E,F already have standard trampoline attached
> > > > >
> > > > >    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> > > > >      which spans over A,B,C functions and attach program P to single
> > > > >      trampolines D,E,F
> > > > >
> > > > >    - A,B,C functions are now 'not attachable' by any trampoline
> > > > >      until the above 'multi' trampoline is released
> > > >
> > > > This restriction is probably too severe.
> > > > Song added support for trampoline and KLPs to co-exist on the same function.
> > > > This multi trampoline restriction will resurface the same issue.
> > > > afiak this restriction is only because multi trampoline image
> > > > is the same for A,B,C. This memory optimization is probably going too far.
> > > > How about we keep existing logic of one tramp image per function.
> > > > Pretend that multi-prog P matches BTF of the target function,
> > > > create normal tramp for it and attach prog P there.
> > > > The prototype of P allows six u64. The args are potentially rearding
> > > > garbage, but there are no safety issues, since multi progs don't know BTF types.
> > > >
> > > > We still need sinle bpf_link_multi to contain btf_ids of all functions,
> > > > but it can point to many bpf tramps. One for each attach function.
> > > >
> > > > iirc we discussed something like this long ago, but I don't remember
> > > > why we didn't go that route.
> > > > arch_prepare_bpf_trampoline is fast.
> > > > bpf_tramp_image_alloc is fast too.
> > > > So attaching one multi-prog to thousands of btf_id-s should be fast too.
> > > > The destroy part is interesting.
> > > > There we will be doing thousands of bpf_tramp_image_put,
> > > > but it's all async now. We used to have synchronize_rcu() which could
> > > > be the reason why this approach was slow.
> > > > Or is this unregister_fentry that slows it down?
> > > > But register_ftrace_direct_multi() interface should have solved it
> > > > for both register and unregister?
> > >
> > > I think it's the synchronize_rcu_tasks at the end of each ftrace update,
> > > that's why we added un/register_ftrace_direct_multi that makes the changes
> > > for multiple ips and syncs once at the end
> >
> > hmm. Can synchronize_rcu_tasks be made optional?
> > For ftrace_direct that points to bpf tramps is it really needed?
> >
> > > un/register_ftrace_direct_multi will attach/detach multiple multiple ips
> > > to single address (trampoline), so for this approach we would need to add new
> > > ftrace direct api that would allow to set multiple ips to multiple trampolines
> > > within one call..
> >
> > right
> >
> > > I was already checking on that and looks doable
> >
> > awesome.
> >
> > > another problem might be that this update function will need to be called with
> > > all related trampoline locks, which in this case would be thousands
> >
> > sure. but these will be newly allocated trampolines and
> > brand new mutexes, so no contention.
> > But thousands of cmpxchg-s will take time. Would be good to measure
> > though. It might not be that bad.
> 
> What about the memory overhead of thousands of trampolines and
> trampoline images? Seems very wasteful to create one per each attach,
> when each attachment in general will be identical.
> 
> 
> If I remember correctly, last time we were also discussing creating a
> generic BPF trampoline that would save all 6 input registers,
> regardless of function's BTF signature. Such BPF trampoline should
> support calling both generic fentry/fexit programs and typed ones,
> because all the necessary data is stored on the stack correctly.
> 
> For the case when typed (non-generic) BPF trampoline is already
> attached to a function and now we are attaching generic fentry, why
> can't we "upgrade" existing BPF trampoline to become generic, and then
> just add generic multi-fentry program to its trampoline image? Once
> that multi-fentry is detached, we might choose to convert trampoline
> back to typed BPF trampoline (i.e., save only necessary registers, not
> all 6 of them), but that's more like an optimization, it doesn't have
> to happen.
> 
> Or is there something that would make such generic trampoline impossible?
> 
> If we go with this approach, then each multi-fentry attachment will be
> creating minimum amount of trampolines, determined by all the
> combinations of attached programs at that point. If after we attach
> multi-fentry to some set of functions we need to attach another
> multi-fentry or typed fentry, we'd potentially need to split
> trampolines and create a bit more of them. But while that sounds a bit
> complicated, we do all that under locks so there isn't much problem in
> doing that, no?
> 
> But in general, I agree with Alexei that this restriction on not being
> able to attach to a function once multi-attach trampoline is attached
> to it is a really-really bad restriction in production, where we can't
> control exactly what BPF apps run and in which order.

ah ok.. attaching single trampoline on top of attached multi trampoline
should be possible to add.. as long as one side of the problem is single
trampoline it should be doable, I'll check

leaving the restriction only to attaching one multi trampoline over
another (not equal) attached multi trampoline

would that be acceptable?

> 
> P.S. I think this generic typeless BPF trampoline is a useful thing in
> itself and we are half-way there already with bpf_get_func_ip() and
> bpf_get_func_arg_cnt() helpers and storing such "parameters" on the
> stack, so tbh, we can probably split the problem into two and try to
> address a somewhat simpler and more straightforward generic BPF
> trampoline first. Such generic type-less BPF trampoline will make
> fentry a better and more generic alternative to kprobe, by being less
> demanding about specifying BTF ID (even if we don't care about input
> argument types) yet faster to trigger than kprobe.

yes, with the help of those helpers the only 'generic' thing for
trampoline is its BTF type

jirka

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Andrii Nakryiko]

On Fri, Aug 26, 2022 at 7:20 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> On Thu, Aug 25, 2022 at 07:35:44PM -0700, Andrii Nakryiko wrote:
> > On Thu, Aug 25, 2022 at 10:44 AM Alexei Starovoitov
> > <alexei.starovoitov@gmail.com> wrote:
> > >
> > > On Thu, Aug 25, 2022 at 9:08 AM Jiri Olsa <olsajiri@gmail.com> wrote:
> > > >
> > > > On Tue, Aug 23, 2022 at 06:22:37PM -0700, Alexei Starovoitov wrote:
> > > > > On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> > > > > > Adding support to attach program to multiple trampolines
> > > > > > with new attach/detach interface:
> > > > > >
> > > > > >   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
> > > > > >                                   struct bpf_tramp_id *id)
> > > > > >   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
> > > > > >                                   struct bpf_tramp_id *id)
> > > > > >
> > > > > > The program is passed as bpf_tramp_prog object and trampolines to
> > > > > > attach it to are passed as bpf_tramp_id object.
> > > > > >
> > > > > > The interface creates new bpf_trampoline object which is initialized
> > > > > > as 'multi' trampoline and stored separtely from standard trampolines.
> > > > > >
> > > > > > There are following rules how the standard and multi trampolines
> > > > > > go along:
> > > > > >   - multi trampoline can attach on top of existing single trampolines,
> > > > > >     which creates 2 types of function IDs:
> > > > > >
> > > > > >       1) single-IDs - functions that are attached within existing single
> > > > > >          trampolines
> > > > > >       2) multi-IDs  - functions that were 'free' and are now taken by new
> > > > > >          'multi' trampoline
> > > > > >
> > > > > >   - we allow overlapping of 2 'multi' trampolines if they are attached
> > > > > >     to same IDs
> > > > > >   - we do now allow any other overlapping of 2 'multi' trampolines
> > > > > >   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> > > > > >
> > > > > > Maybe better explained on following example:
> > > > > >
> > > > > >    - you want to attach program P to functions A,B,C,D,E,F
> > > > > >      via bpf_trampoline_multi_attach
> > > > > >
> > > > > >    - D,E,F already have standard trampoline attached
> > > > > >
> > > > > >    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> > > > > >      which spans over A,B,C functions and attach program P to single
> > > > > >      trampolines D,E,F
> > > > > >
> > > > > >    - A,B,C functions are now 'not attachable' by any trampoline
> > > > > >      until the above 'multi' trampoline is released
> > > > >
> > > > > This restriction is probably too severe.
> > > > > Song added support for trampoline and KLPs to co-exist on the same function.
> > > > > This multi trampoline restriction will resurface the same issue.
> > > > > afiak this restriction is only because multi trampoline image
> > > > > is the same for A,B,C. This memory optimization is probably going too far.
> > > > > How about we keep existing logic of one tramp image per function.
> > > > > Pretend that multi-prog P matches BTF of the target function,
> > > > > create normal tramp for it and attach prog P there.
> > > > > The prototype of P allows six u64. The args are potentially rearding
> > > > > garbage, but there are no safety issues, since multi progs don't know BTF types.
> > > > >
> > > > > We still need sinle bpf_link_multi to contain btf_ids of all functions,
> > > > > but it can point to many bpf tramps. One for each attach function.
> > > > >
> > > > > iirc we discussed something like this long ago, but I don't remember
> > > > > why we didn't go that route.
> > > > > arch_prepare_bpf_trampoline is fast.
> > > > > bpf_tramp_image_alloc is fast too.
> > > > > So attaching one multi-prog to thousands of btf_id-s should be fast too.
> > > > > The destroy part is interesting.
> > > > > There we will be doing thousands of bpf_tramp_image_put,
> > > > > but it's all async now. We used to have synchronize_rcu() which could
> > > > > be the reason why this approach was slow.
> > > > > Or is this unregister_fentry that slows it down?
> > > > > But register_ftrace_direct_multi() interface should have solved it
> > > > > for both register and unregister?
> > > >
> > > > I think it's the synchronize_rcu_tasks at the end of each ftrace update,
> > > > that's why we added un/register_ftrace_direct_multi that makes the changes
> > > > for multiple ips and syncs once at the end
> > >
> > > hmm. Can synchronize_rcu_tasks be made optional?
> > > For ftrace_direct that points to bpf tramps is it really needed?
> > >
> > > > un/register_ftrace_direct_multi will attach/detach multiple multiple ips
> > > > to single address (trampoline), so for this approach we would need to add new
> > > > ftrace direct api that would allow to set multiple ips to multiple trampolines
> > > > within one call..
> > >
> > > right
> > >
> > > > I was already checking on that and looks doable
> > >
> > > awesome.
> > >
> > > > another problem might be that this update function will need to be called with
> > > > all related trampoline locks, which in this case would be thousands
> > >
> > > sure. but these will be newly allocated trampolines and
> > > brand new mutexes, so no contention.
> > > But thousands of cmpxchg-s will take time. Would be good to measure
> > > though. It might not be that bad.
> >
> > What about the memory overhead of thousands of trampolines and
> > trampoline images? Seems very wasteful to create one per each attach,
> > when each attachment in general will be identical.
> >
> >
> > If I remember correctly, last time we were also discussing creating a
> > generic BPF trampoline that would save all 6 input registers,
> > regardless of function's BTF signature. Such BPF trampoline should
> > support calling both generic fentry/fexit programs and typed ones,
> > because all the necessary data is stored on the stack correctly.
> >
> > For the case when typed (non-generic) BPF trampoline is already
> > attached to a function and now we are attaching generic fentry, why
> > can't we "upgrade" existing BPF trampoline to become generic, and then
> > just add generic multi-fentry program to its trampoline image? Once
> > that multi-fentry is detached, we might choose to convert trampoline
> > back to typed BPF trampoline (i.e., save only necessary registers, not
> > all 6 of them), but that's more like an optimization, it doesn't have
> > to happen.
> >
> > Or is there something that would make such generic trampoline impossible?
> >
> > If we go with this approach, then each multi-fentry attachment will be
> > creating minimum amount of trampolines, determined by all the
> > combinations of attached programs at that point. If after we attach
> > multi-fentry to some set of functions we need to attach another
> > multi-fentry or typed fentry, we'd potentially need to split
> > trampolines and create a bit more of them. But while that sounds a bit
> > complicated, we do all that under locks so there isn't much problem in
> > doing that, no?
> >
> > But in general, I agree with Alexei that this restriction on not being
> > able to attach to a function once multi-attach trampoline is attached
> > to it is a really-really bad restriction in production, where we can't
> > control exactly what BPF apps run and in which order.
>
> ah ok.. attaching single trampoline on top of attached multi trampoline
> should be possible to add.. as long as one side of the problem is single
> trampoline it should be doable, I'll check
>
> leaving the restriction only to attaching one multi trampoline over
> another (not equal) attached multi trampoline
>
> would that be acceptable?

I guess I'm missing what's fundamentally different between
multi-trampoline + single trampoline vs multi-tramp + multi-tramp?
Multi-tramp is already saving all registers, so can "host" other
generic fentry/fexit. So why this multi + multi restriction?

>
> >
> > P.S. I think this generic typeless BPF trampoline is a useful thing in
> > itself and we are half-way there already with bpf_get_func_ip() and
> > bpf_get_func_arg_cnt() helpers and storing such "parameters" on the
> > stack, so tbh, we can probably split the problem into two and try to
> > address a somewhat simpler and more straightforward generic BPF
> > trampoline first. Such generic type-less BPF trampoline will make
> > fentry a better and more generic alternative to kprobe, by being less
> > demanding about specifying BTF ID (even if we don't care about input
> > argument types) yet faster to trigger than kprobe.
>
> yes, with the help of those helpers the only 'generic' thing for
> trampoline is its BTF type
>
> jirka

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Jiri Olsa]

On Fri, Aug 26, 2022 at 10:15:40PM -0700, Andrii Nakryiko wrote:
> On Fri, Aug 26, 2022 at 7:20 AM Jiri Olsa <olsajiri@gmail.com> wrote:
> >
> > On Thu, Aug 25, 2022 at 07:35:44PM -0700, Andrii Nakryiko wrote:
> > > On Thu, Aug 25, 2022 at 10:44 AM Alexei Starovoitov
> > > <alexei.starovoitov@gmail.com> wrote:
> > > >
> > > > On Thu, Aug 25, 2022 at 9:08 AM Jiri Olsa <olsajiri@gmail.com> wrote:
> > > > >
> > > > > On Tue, Aug 23, 2022 at 06:22:37PM -0700, Alexei Starovoitov wrote:
> > > > > > On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> > > > > > > Adding support to attach program to multiple trampolines
> > > > > > > with new attach/detach interface:
> > > > > > >
> > > > > > >   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
> > > > > > >                                   struct bpf_tramp_id *id)
> > > > > > >   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
> > > > > > >                                   struct bpf_tramp_id *id)
> > > > > > >
> > > > > > > The program is passed as bpf_tramp_prog object and trampolines to
> > > > > > > attach it to are passed as bpf_tramp_id object.
> > > > > > >
> > > > > > > The interface creates new bpf_trampoline object which is initialized
> > > > > > > as 'multi' trampoline and stored separtely from standard trampolines.
> > > > > > >
> > > > > > > There are following rules how the standard and multi trampolines
> > > > > > > go along:
> > > > > > >   - multi trampoline can attach on top of existing single trampolines,
> > > > > > >     which creates 2 types of function IDs:
> > > > > > >
> > > > > > >       1) single-IDs - functions that are attached within existing single
> > > > > > >          trampolines
> > > > > > >       2) multi-IDs  - functions that were 'free' and are now taken by new
> > > > > > >          'multi' trampoline
> > > > > > >
> > > > > > >   - we allow overlapping of 2 'multi' trampolines if they are attached
> > > > > > >     to same IDs
> > > > > > >   - we do now allow any other overlapping of 2 'multi' trampolines
> > > > > > >   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> > > > > > >
> > > > > > > Maybe better explained on following example:
> > > > > > >
> > > > > > >    - you want to attach program P to functions A,B,C,D,E,F
> > > > > > >      via bpf_trampoline_multi_attach
> > > > > > >
> > > > > > >    - D,E,F already have standard trampoline attached
> > > > > > >
> > > > > > >    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> > > > > > >      which spans over A,B,C functions and attach program P to single
> > > > > > >      trampolines D,E,F
> > > > > > >
> > > > > > >    - A,B,C functions are now 'not attachable' by any trampoline
> > > > > > >      until the above 'multi' trampoline is released
> > > > > >
> > > > > > This restriction is probably too severe.
> > > > > > Song added support for trampoline and KLPs to co-exist on the same function.
> > > > > > This multi trampoline restriction will resurface the same issue.
> > > > > > afiak this restriction is only because multi trampoline image
> > > > > > is the same for A,B,C. This memory optimization is probably going too far.
> > > > > > How about we keep existing logic of one tramp image per function.
> > > > > > Pretend that multi-prog P matches BTF of the target function,
> > > > > > create normal tramp for it and attach prog P there.
> > > > > > The prototype of P allows six u64. The args are potentially rearding
> > > > > > garbage, but there are no safety issues, since multi progs don't know BTF types.
> > > > > >
> > > > > > We still need sinle bpf_link_multi to contain btf_ids of all functions,
> > > > > > but it can point to many bpf tramps. One for each attach function.
> > > > > >
> > > > > > iirc we discussed something like this long ago, but I don't remember
> > > > > > why we didn't go that route.
> > > > > > arch_prepare_bpf_trampoline is fast.
> > > > > > bpf_tramp_image_alloc is fast too.
> > > > > > So attaching one multi-prog to thousands of btf_id-s should be fast too.
> > > > > > The destroy part is interesting.
> > > > > > There we will be doing thousands of bpf_tramp_image_put,
> > > > > > but it's all async now. We used to have synchronize_rcu() which could
> > > > > > be the reason why this approach was slow.
> > > > > > Or is this unregister_fentry that slows it down?
> > > > > > But register_ftrace_direct_multi() interface should have solved it
> > > > > > for both register and unregister?
> > > > >
> > > > > I think it's the synchronize_rcu_tasks at the end of each ftrace update,
> > > > > that's why we added un/register_ftrace_direct_multi that makes the changes
> > > > > for multiple ips and syncs once at the end
> > > >
> > > > hmm. Can synchronize_rcu_tasks be made optional?
> > > > For ftrace_direct that points to bpf tramps is it really needed?
> > > >
> > > > > un/register_ftrace_direct_multi will attach/detach multiple multiple ips
> > > > > to single address (trampoline), so for this approach we would need to add new
> > > > > ftrace direct api that would allow to set multiple ips to multiple trampolines
> > > > > within one call..
> > > >
> > > > right
> > > >
> > > > > I was already checking on that and looks doable
> > > >
> > > > awesome.
> > > >
> > > > > another problem might be that this update function will need to be called with
> > > > > all related trampoline locks, which in this case would be thousands
> > > >
> > > > sure. but these will be newly allocated trampolines and
> > > > brand new mutexes, so no contention.
> > > > But thousands of cmpxchg-s will take time. Would be good to measure
> > > > though. It might not be that bad.
> > >
> > > What about the memory overhead of thousands of trampolines and
> > > trampoline images? Seems very wasteful to create one per each attach,
> > > when each attachment in general will be identical.
> > >
> > >
> > > If I remember correctly, last time we were also discussing creating a
> > > generic BPF trampoline that would save all 6 input registers,
> > > regardless of function's BTF signature. Such BPF trampoline should
> > > support calling both generic fentry/fexit programs and typed ones,
> > > because all the necessary data is stored on the stack correctly.
> > >
> > > For the case when typed (non-generic) BPF trampoline is already
> > > attached to a function and now we are attaching generic fentry, why
> > > can't we "upgrade" existing BPF trampoline to become generic, and then
> > > just add generic multi-fentry program to its trampoline image? Once
> > > that multi-fentry is detached, we might choose to convert trampoline
> > > back to typed BPF trampoline (i.e., save only necessary registers, not
> > > all 6 of them), but that's more like an optimization, it doesn't have
> > > to happen.
> > >
> > > Or is there something that would make such generic trampoline impossible?
> > >
> > > If we go with this approach, then each multi-fentry attachment will be
> > > creating minimum amount of trampolines, determined by all the
> > > combinations of attached programs at that point. If after we attach
> > > multi-fentry to some set of functions we need to attach another
> > > multi-fentry or typed fentry, we'd potentially need to split
> > > trampolines and create a bit more of them. But while that sounds a bit
> > > complicated, we do all that under locks so there isn't much problem in
> > > doing that, no?
> > >
> > > But in general, I agree with Alexei that this restriction on not being
> > > able to attach to a function once multi-attach trampoline is attached
> > > to it is a really-really bad restriction in production, where we can't
> > > control exactly what BPF apps run and in which order.
> >
> > ah ok.. attaching single trampoline on top of attached multi trampoline
> > should be possible to add.. as long as one side of the problem is single
> > trampoline it should be doable, I'll check
> >
> > leaving the restriction only to attaching one multi trampoline over
> > another (not equal) attached multi trampoline
> >
> > would that be acceptable?
> 
> I guess I'm missing what's fundamentally different between
> multi-trampoline + single trampoline vs multi-tramp + multi-tramp?
> Multi-tramp is already saving all registers, so can "host" other
> generic fentry/fexit. So why this multi + multi restriction?

so I did not find good generic solution for multi trampoline being attached
on top of already attached multi trampolines

say we have following multi trampolines:

  multi_a [1,2,3] P1 
  multi_b [4,5,6] P2

and want to add another multi trampoline:

  multi_c [1,4,7] P3

you end up with 5 new trampolines: 

  multi_1 [1]   P1,P3
  multi_2 [2,3] P1
  multi_3 [4]   P2,P3
  multi_4 [5,6] P2
  multi_5 [7]   P3

pain points were:
  - lookup for intersection on top of BTF ids, doable but tricky
    https://lore.kernel.org/bpf/20211118112455.475349-20-jolsa@kernel.org/

  - splitting existing trampolines and rollback in case of error,
    because the image update and ip are 2 separate things but we
    do them together
    https://lore.kernel.org/bpf/20211118112455.475349-20-jolsa@kernel.org/

  - trampoline can't be stored and managed in link, because it can
    be split into multiple new trampolines, so I added new layer
    to keep them
    https://lore.kernel.org/bpf/20211118112455.475349-14-jolsa@kernel.org/

  - all this must be locked.. all involved trampolines or one big lock

  - any new attachment of single trampoline is possibly splitting existing
    multi trampoline

  - when multi_c trampoline is detached we don't roll back to get original
    multi_a and multi_b - we keep the split trampolines, so each new attachment
    is making more trampolines and makes the new attachment possibly slower


the RFC for this is here:
  https://lore.kernel.org/bpf/20211118112455.475349-1-jolsa@kernel.org/

it did not bring too much attention so I simplified it down to the current
version ;-)

so far I could not think of better way than start with basic functionality
and add/rethink the complex multi/multi stuff later if needed, hopefully
with some better idea how to do that


note this was no problem for kprobe_multi which uses fprobe/ftrace_ops code
that takes care of this - we just say this function should be called from
set of ips and ftrace machinery does all the merging with existing attachments

but bpf trampolines use ftrace direct interface, which only attaches
trampoline to given function without any other logic 

jirka

Re: [RFC PATCH bpf-next 10/17] bpf: Add support to attach program to multiple trampolines

[Song Liu]

On Thu, Aug 25, 2022 at 10:44 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Thu, Aug 25, 2022 at 9:08 AM Jiri Olsa <olsajiri@gmail.com> wrote:
> >
> > On Tue, Aug 23, 2022 at 06:22:37PM -0700, Alexei Starovoitov wrote:
> > > On Mon, Aug 08, 2022 at 04:06:19PM +0200, Jiri Olsa wrote:
> > > > Adding support to attach program to multiple trampolines
> > > > with new attach/detach interface:
> > > >
> > > >   int bpf_trampoline_multi_attach(struct bpf_tramp_prog *tp,
> > > >                                   struct bpf_tramp_id *id)
> > > >   int bpf_trampoline_multi_detach(struct bpf_tramp_prog *tp,
> > > >                                   struct bpf_tramp_id *id)
> > > >
> > > > The program is passed as bpf_tramp_prog object and trampolines to
> > > > attach it to are passed as bpf_tramp_id object.
> > > >
> > > > The interface creates new bpf_trampoline object which is initialized
> > > > as 'multi' trampoline and stored separtely from standard trampolines.
> > > >
> > > > There are following rules how the standard and multi trampolines
> > > > go along:
> > > >   - multi trampoline can attach on top of existing single trampolines,
> > > >     which creates 2 types of function IDs:
> > > >
> > > >       1) single-IDs - functions that are attached within existing single
> > > >          trampolines
> > > >       2) multi-IDs  - functions that were 'free' and are now taken by new
> > > >          'multi' trampoline
> > > >
> > > >   - we allow overlapping of 2 'multi' trampolines if they are attached
> > > >     to same IDs
> > > >   - we do now allow any other overlapping of 2 'multi' trampolines
> > > >   - any new 'single' trampoline cannot attach to existing multi-IDs IDs.
> > > >
> > > > Maybe better explained on following example:
> > > >
> > > >    - you want to attach program P to functions A,B,C,D,E,F
> > > >      via bpf_trampoline_multi_attach
> > > >
> > > >    - D,E,F already have standard trampoline attached
> > > >
> > > >    - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> > > >      which spans over A,B,C functions and attach program P to single
> > > >      trampolines D,E,F
> > > >
> > > >    - A,B,C functions are now 'not attachable' by any trampoline
> > > >      until the above 'multi' trampoline is released
> > >
> > > This restriction is probably too severe.
> > > Song added support for trampoline and KLPs to co-exist on the same function.
> > > This multi trampoline restriction will resurface the same issue.
> > > afiak this restriction is only because multi trampoline image
> > > is the same for A,B,C. This memory optimization is probably going too far.
> > > How about we keep existing logic of one tramp image per function.
> > > Pretend that multi-prog P matches BTF of the target function,
> > > create normal tramp for it and attach prog P there.
> > > The prototype of P allows six u64. The args are potentially rearding
> > > garbage, but there are no safety issues, since multi progs don't know BTF types.
> > >
> > > We still need sinle bpf_link_multi to contain btf_ids of all functions,
> > > but it can point to many bpf tramps. One for each attach function.
> > >
> > > iirc we discussed something like this long ago, but I don't remember
> > > why we didn't go that route.
> > > arch_prepare_bpf_trampoline is fast.
> > > bpf_tramp_image_alloc is fast too.
> > > So attaching one multi-prog to thousands of btf_id-s should be fast too.
> > > The destroy part is interesting.
> > > There we will be doing thousands of bpf_tramp_image_put,
> > > but it's all async now. We used to have synchronize_rcu() which could
> > > be the reason why this approach was slow.
> > > Or is this unregister_fentry that slows it down?
> > > But register_ftrace_direct_multi() interface should have solved it
> > > for both register and unregister?
> >
> > I think it's the synchronize_rcu_tasks at the end of each ftrace update,
> > that's why we added un/register_ftrace_direct_multi that makes the changes
> > for multiple ips and syncs once at the end
>
> hmm. Can synchronize_rcu_tasks be made optional?
> For ftrace_direct that points to bpf tramps is it really needed?
>
> > un/register_ftrace_direct_multi will attach/detach multiple multiple ips
> > to single address (trampoline), so for this approach we would need to add new
> > ftrace direct api that would allow to set multiple ips to multiple trampolines
> > within one call..
>
> right
>
> > I was already checking on that and looks doable
>
> awesome.
>
> > another problem might be that this update function will need to be called with
> > all related trampoline locks, which in this case would be thousands
>
> sure. but these will be newly allocated trampolines and
> brand new mutexes, so no contention.

I guess we still need to lock existing tr->mutex in some cases? Say, we
have 3 functions, A, B, C, and A already have tr_A. If we want to attach
tr_multi for all three, we still need to lock tr_A->mutex, no?

Thanks,
Song

> But thousands of cmpxchg-s will take time. Would be good to measure
> though. It might not be that bad.

[RFC PATCH bpf-next 11/17] bpf: Add support to create tracing multi link

[Jiri Olsa]

Adding new link to allow to attach program to multiple
function BTF IDs.

New fields are added to bpf_attr::link_create to pass
array of BTF IDs:

  struct {
    __aligned_u64   btf_ids;        /* addresses to attach */
    __u32           btf_ids_cnt;    /* addresses count */
  } multi;

The new link code will load these IDs into bpf_tramp_id
object and resolve their ips.

The resolve itself is done as per Andrii's suggestion:

  - lookup all names for given IDs
  - store and sort them by name
  - go through all kallsyms symbols and use bsearch
    to find it in provided names
  - if name is found, store the address for the name
  - resort the names array based on ID

If there are multi symbols of the same name the first one
will be used to resolve the address.

The link is using bpf_trampoline_multi_attach interface
to attach this IDs to the program.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/trace_events.h   |   5 +
 include/uapi/linux/bpf.h       |   5 +
 kernel/bpf/syscall.c           |   2 +
 kernel/trace/bpf_trace.c       | 240 +++++++++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |   5 +
 5 files changed, 257 insertions(+)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index e6e95a9f07a5..7825f9b0d9c3 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -747,6 +747,7 @@ int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
 			    u32 *fd_type, const char **buf,
 			    u64 *probe_offset, u64 *probe_addr);
 int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
+int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr);
 #else
 static inline unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
 {
@@ -793,6 +794,10 @@ bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 {
 	return -EOPNOTSUPP;
 }
+int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 enum {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index fb6bc2c5e9e8..b4b3a47d5324 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1017,6 +1017,7 @@ enum bpf_link_type {
 	BPF_LINK_TYPE_PERF_EVENT = 7,
 	BPF_LINK_TYPE_KPROBE_MULTI = 8,
 	BPF_LINK_TYPE_STRUCT_OPS = 9,
+	BPF_LINK_TYPE_TRACING_MULTI = 10,
 
 	MAX_BPF_LINK_TYPE,
 };
@@ -1503,6 +1504,10 @@ union bpf_attr {
 				 */
 				__u64		cookie;
 			} tracing;
+			struct {
+				__aligned_u64	btf_ids;	/* addresses to attach */
+				__u32		btf_ids_cnt;	/* addresses count */
+			} tracing_multi;
 		};
 	} link_create;
 
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2e4765c7e6d4..2b51787e8899 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4604,6 +4604,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
 			ret = bpf_iter_link_attach(attr, uattr, prog);
 		else if (prog->expected_attach_type == BPF_LSM_CGROUP)
 			ret = cgroup_bpf_link_attach(attr, prog);
+		else if (is_tracing_multi(prog->expected_attach_type))
+			ret = bpf_tracing_multi_attach(prog, attr);
 		else
 			ret = bpf_tracing_prog_attach(prog,
 						      attr->link_create.target_fd,
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68e5cdd24cef..07a91a32e566 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2593,3 +2593,243 @@ static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx)
 	return 0;
 }
 #endif
+
+struct bpf_tracing_multi_link {
+	struct bpf_link link;
+	enum bpf_attach_type attach_type;
+	struct bpf_tramp_prog tp;
+	struct bpf_tramp_id *id;
+};
+
+static void bpf_tracing_multi_link_release(struct bpf_link *link)
+{
+	struct bpf_tracing_multi_link *tr_link =
+		container_of(link, struct bpf_tracing_multi_link, link);
+
+	WARN_ON_ONCE(bpf_trampoline_multi_detach(&tr_link->tp, tr_link->id));
+}
+
+static void bpf_tracing_multi_link_dealloc(struct bpf_link *link)
+{
+	struct bpf_tracing_multi_link *tr_link =
+		container_of(link, struct bpf_tracing_multi_link, link);
+
+	bpf_tramp_id_put(tr_link->id);
+	kfree(tr_link);
+}
+
+static void bpf_tracing_multi_link_show_fdinfo(const struct bpf_link *link,
+					       struct seq_file *seq)
+{
+	struct bpf_tracing_multi_link *tr_link =
+		container_of(link, struct bpf_tracing_multi_link, link);
+
+	seq_printf(seq, "attach_type:\t%d\n", tr_link->attach_type);
+}
+
+static int bpf_tracing_multi_link_fill_link_info(const struct bpf_link *link,
+						 struct bpf_link_info *info)
+{
+	struct bpf_tracing_multi_link *tr_link =
+		container_of(link, struct bpf_tracing_multi_link, link);
+
+	info->tracing.attach_type = tr_link->attach_type;
+	return 0;
+}
+
+static const struct bpf_link_ops bpf_tracing_multi_link_lops = {
+	.release = bpf_tracing_multi_link_release,
+	.dealloc = bpf_tracing_multi_link_dealloc,
+	.show_fdinfo = bpf_tracing_multi_link_show_fdinfo,
+	.fill_link_info = bpf_tracing_multi_link_fill_link_info,
+};
+
+static int check_multi_prog_type(struct bpf_prog *prog)
+{
+	if (prog->expected_attach_type != BPF_TRACE_FENTRY_MULTI &&
+	    prog->expected_attach_type != BPF_TRACE_FEXIT_MULTI)
+		return -EINVAL;
+	return 0;
+}
+
+static int btf_ids_cmp(const void *a, const void *b)
+{
+	const u32 *x = a;
+	const u32 *y = b;
+
+	if (*x == *y)
+		return 0;
+	return *x < *y ? -1 : 1;
+}
+
+struct resolve_id {
+	const char *name;
+	void *addr;
+	u32 id;
+};
+
+static int rid_name_cmp(const void *a, const void *b)
+{
+	const struct resolve_id *x = a;
+	const struct resolve_id *y = b;
+
+	return strcmp(x->name, y->name);
+}
+
+static int rid_id_cmp(const void *a, const void *b)
+{
+	const struct resolve_id *x = a;
+	const struct resolve_id *y = b;
+
+	if (x->id == y->id)
+		return 0;
+	return x->id < y->id ? -1 : 1;
+}
+
+struct kallsyms_data {
+	struct resolve_id *rid;
+	u32 cnt;
+	u32 found;
+};
+
+static int kallsyms_callback(void *data, const char *name,
+			     struct module *mod, unsigned long addr)
+{
+	struct kallsyms_data *args = data;
+	struct resolve_id *rid, id = {
+		.name = name,
+	};
+
+	rid = bsearch(&id, args->rid, args->cnt, sizeof(*rid), rid_name_cmp);
+	if (rid && !rid->addr) {
+		rid->addr = (void *) addr;
+		args->found++;
+	}
+	return args->found == args->cnt ? 1 : 0;
+}
+
+static int bpf_tramp_id_resolve(struct bpf_tramp_id *id, struct bpf_prog *prog)
+{
+	struct kallsyms_data args;
+	const struct btf_type *t;
+	struct resolve_id *rid;
+	const char *name;
+	struct btf *btf;
+	int err = 0;
+	u32 i;
+
+	btf = prog->aux->attach_btf;
+	if (!btf)
+		return -EINVAL;
+
+	rid = kcalloc(id->cnt, sizeof(*rid), GFP_KERNEL);
+	if (!rid)
+		return -ENOMEM;
+
+	err = -EINVAL;
+	for (i = 0; i < id->cnt; i++) {
+		t = btf_type_by_id(btf, id->id[i]);
+		if (!t)
+			goto out_free;
+
+		name = btf_name_by_offset(btf, t->name_off);
+		if (!name)
+			goto out_free;
+
+		rid[i].name = name;
+		rid[i].id = id->id[i];
+	}
+
+	sort(rid, id->cnt, sizeof(*rid), rid_name_cmp, NULL);
+
+	args.rid = rid;
+	args.cnt = id->cnt;
+	args.found = 0;
+	kallsyms_on_each_symbol(kallsyms_callback, &args);
+
+	sort(rid, id->cnt, sizeof(*rid), rid_id_cmp, NULL);
+
+	for (i = 0; i < id->cnt; i++) {
+		if (!rid[i].addr) {
+			err = -EINVAL;
+			goto out_free;
+		}
+		/* all the addresses must be ftrace managed */
+		if (!ftrace_location((unsigned long) rid[i].addr)) {
+			err = -EINVAL;
+			goto out_free;
+		}
+		id->addr[i] = rid[i].addr;
+	}
+	err = 0;
+out_free:
+	kfree(rid);
+	return err;
+}
+
+int bpf_tracing_multi_attach(struct bpf_prog *prog,
+			     const union bpf_attr *attr)
+{
+	void __user *uids = u64_to_user_ptr(attr->link_create.tracing_multi.btf_ids);
+	u32 cnt_size, cnt = attr->link_create.tracing_multi.btf_ids_cnt;
+	struct bpf_tracing_multi_link *link = NULL;
+	struct bpf_link_primer link_primer;
+	struct bpf_tramp_id *id = NULL;
+	int err = -EINVAL;
+
+	if (check_multi_prog_type(prog))
+		return -EINVAL;
+	if (!cnt || !uids)
+		return -EINVAL;
+
+	id = bpf_tramp_id_alloc(cnt);
+	if (!id)
+		return -ENOMEM;
+
+	err = -EFAULT;
+	cnt_size = cnt * sizeof(id->id[0]);
+	if (copy_from_user(id->id, uids, cnt_size))
+		goto out_free_id;
+
+	id->cnt = cnt;
+	id->obj_id = btf_obj_id(prog->aux->attach_btf);
+
+	/* Sort user provided BTF ids, so we can use memcmp
+	 * and bsearch on top of it later.
+	 */
+	sort(id->id, cnt, sizeof(u32), btf_ids_cmp, NULL);
+
+	err = bpf_tramp_id_resolve(id, prog);
+	if (err)
+		goto out_free_id;
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link) {
+		err = -ENOMEM;
+		goto out_free_id;
+	}
+
+	bpf_link_init(&link->link, BPF_LINK_TYPE_TRACING_MULTI,
+		      &bpf_tracing_multi_link_lops, prog);
+	link->attach_type = prog->expected_attach_type;
+
+	err = bpf_link_prime(&link->link, &link_primer);
+	if (err) {
+		kfree(link);
+		goto out_free_id;
+	}
+
+	link->id = id;
+	link->tp.cookie = 0;
+	link->tp.prog = prog;
+
+	err = bpf_trampoline_multi_attach(&link->tp, id);
+	if (err) {
+		bpf_link_cleanup(&link_primer);
+		return err;
+	}
+	return bpf_link_settle(&link_primer);
+out_free_id:
+	bpf_tramp_id_put(id);
+	return err;
+}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 94d623affd5f..4969f31471d5 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1017,6 +1017,7 @@ enum bpf_link_type {
 	BPF_LINK_TYPE_PERF_EVENT = 7,
 	BPF_LINK_TYPE_KPROBE_MULTI = 8,
 	BPF_LINK_TYPE_STRUCT_OPS = 9,
+	BPF_LINK_TYPE_TRACING_MULTI = 10,
 
 	MAX_BPF_LINK_TYPE,
 };
@@ -1503,6 +1504,10 @@ union bpf_attr {
 				 */
 				__u64		cookie;
 			} tracing;
+			struct {
+				__aligned_u64	btf_ids;	/* addresses to attach */
+				__u32		btf_ids_cnt;	/* addresses count */
+			} tracing_multi;
 		};
 	} link_create;
 
-- 
2.37.1

[RFC PATCH bpf-next 12/17] libbpf: Add btf__find_by_glob_kind function

[Jiri Olsa]

Adding btf__find_by_glob_kind function that returns array of
BTF ids that match given kind and allow/deny patterns.

int btf__find_by_glob_kind(const struct btf *btf, __u32 kind,
                           const char *allow_pattern,
                           const char *deny_pattern,
                           __u32 **__ids);

The __ids array is allocated and needs to be manually freed.

The pattern check is done by glob_match function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/lib/bpf/btf.c             | 41 +++++++++++++++++++++++++++++++++
 tools/lib/bpf/btf.h             |  3 +++
 tools/lib/bpf/libbpf.c          |  2 +-
 tools/lib/bpf/libbpf_internal.h |  1 +
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 2d14f1a52d7a..ffe08acb2f9b 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -770,6 +770,47 @@ __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
 	return btf_find_by_name_kind(btf, 1, type_name, kind);
 }
 
+int btf__find_by_glob_kind(const struct btf *btf, __u32 kind,
+			   const char *allow_pattern, const char *deny_pattern,
+			   __u32 **__ids)
+{
+	__u32 i, nr_types = btf__type_cnt(btf);
+	int cnt = 0, alloc = 0;
+	__u32 *ids = NULL;
+
+	for (i = 1; i < nr_types; i++) {
+		const struct btf_type *t = btf__type_by_id(btf, i);
+		const char *name;
+		__u32 *p;
+
+		if (btf_kind(t) != kind)
+			continue;
+		name = btf__name_by_offset(btf, t->name_off);
+		if (!name)
+			continue;
+
+		if (deny_pattern && glob_match(name, deny_pattern))
+			continue;
+		if (allow_pattern && !glob_match(name, allow_pattern))
+			continue;
+
+		if (cnt == alloc) {
+			alloc = max(16, alloc * 3 / 2);
+			p = libbpf_reallocarray(ids, alloc, sizeof(__u32));
+			if (!p) {
+				free(ids);
+				return -ENOMEM;
+			}
+			ids = p;
+		}
+		ids[cnt] = i;
+		cnt++;
+	}
+
+	*__ids = ids;
+	return cnt;
+}
+
 static bool btf_is_modifiable(const struct btf *btf)
 {
 	return (void *)btf->hdr != btf->raw_data;
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 583760df83b4..4c05d2e77771 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -546,6 +546,9 @@ static inline struct btf_decl_tag *btf_decl_tag(const struct btf_type *t)
 	return (struct btf_decl_tag *)(t + 1);
 }
 
+int btf__find_by_glob_kind(const struct btf *btf, __u32 kind,
+			   const char *allow_pattern, const char *deny_pattern,
+			   __u32 **__ids);
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 77e3797cf75a..0952eac92eab 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10153,7 +10153,7 @@ struct bpf_link *bpf_program__attach_ksyscall(const struct bpf_program *prog,
 }
 
 /* Adapted from perf/util/string.c */
-static bool glob_match(const char *str, const char *pat)
+bool glob_match(const char *str, const char *pat)
 {
 	while (*str && *pat && *pat != '*') {
 		if (*pat == '?') {      /* Matches any single character */
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 4135ae0a2bc3..9dfc11f26364 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -573,4 +573,5 @@ static inline bool is_pow_of_2(size_t x)
 	return x && (x & (x - 1)) == 0;
 }
 
+bool glob_match(const char *str, const char *pat);
 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */
-- 
2.37.1

[RFC PATCH bpf-next 13/17] libbpf: Add support to create tracing multi link

[Jiri Olsa]

Adding new interface tion to attach programs with
tracing multi link:

  bpf_program__attach_tracing_multi(const struct bpf_program *prog,
                             const char *pattern,
                             const struct bpf_tracing_multi_opts *opts);

The program is attach to functions specified by patter
or by btf IDs specified in bpf_tracing_multi_opts object.

Adding support for new sections to attach programs
with above functions:

   fentry.multi/pattern
   fexit.multi/pattern

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/lib/bpf/bpf.c      |  7 ++++
 tools/lib/bpf/bpf.h      |  4 ++
 tools/lib/bpf/libbpf.c   | 89 ++++++++++++++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.h   | 14 +++++++
 tools/lib/bpf/libbpf.map |  1 +
 5 files changed, 115 insertions(+)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index efcc06dafbd9..06e6666ee90e 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -713,6 +713,13 @@ int bpf_link_create(int prog_fd, int target_fd,
 		if (!OPTS_ZEROED(opts, kprobe_multi))
 			return libbpf_err(-EINVAL);
 		break;
+	case BPF_TRACE_FENTRY_MULTI:
+	case BPF_TRACE_FEXIT_MULTI:
+		attr.link_create.tracing_multi.btf_ids = (__u64) OPTS_GET(opts, tracing_multi.btf_ids, 0);
+		attr.link_create.tracing_multi.btf_ids_cnt = OPTS_GET(opts, tracing_multi.btf_ids_cnt, 0);
+		if (!OPTS_ZEROED(opts, tracing_multi))
+			return libbpf_err(-EINVAL);
+		break;
 	case BPF_TRACE_FENTRY:
 	case BPF_TRACE_FEXIT:
 	case BPF_MODIFY_RETURN:
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 9c50beabdd14..71676228f032 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -321,6 +321,10 @@ struct bpf_link_create_opts {
 		struct {
 			__u64 cookie;
 		} tracing;
+		struct {
+			__u32 *btf_ids;
+			__u32  btf_ids_cnt;
+		} tracing_multi;
 	};
 	size_t :0;
 };
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0952eac92eab..209a42bed165 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -116,6 +116,8 @@ static const char * const attach_type_name[] = {
 	[BPF_SK_REUSEPORT_SELECT_OR_MIGRATE]	= "sk_reuseport_select_or_migrate",
 	[BPF_PERF_EVENT]		= "perf_event",
 	[BPF_TRACE_KPROBE_MULTI]	= "trace_kprobe_multi",
+	[BPF_TRACE_FENTRY_MULTI]	= "trace_fentry_multi",
+	[BPF_TRACE_FEXIT_MULTI]		= "trace_fexit_multi",
 };
 
 static const char * const link_type_name[] = {
@@ -129,6 +131,7 @@ static const char * const link_type_name[] = {
 	[BPF_LINK_TYPE_PERF_EVENT]		= "perf_event",
 	[BPF_LINK_TYPE_KPROBE_MULTI]		= "kprobe_multi",
 	[BPF_LINK_TYPE_STRUCT_OPS]		= "struct_ops",
+	[BPF_LINK_TYPE_TRACING_MULTI]		= "tracing_multi",
 };
 
 static const char * const map_type_name[] = {
@@ -8445,6 +8448,7 @@ static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_
 static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_tracing_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 
 static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("socket",		SOCKET_FILTER, 0, SEC_NONE),
@@ -8477,6 +8481,8 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("fentry.s+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
 	SEC_DEF("fmod_ret.s+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
 	SEC_DEF("fexit.s+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("fentry.multi/",	TRACING, BPF_TRACE_FENTRY_MULTI, 0, attach_tracing_multi),
+	SEC_DEF("fexit.multi/",		TRACING, BPF_TRACE_FEXIT_MULTI, 0, attach_tracing_multi),
 	SEC_DEF("freplace+",		EXT, 0, SEC_ATTACH_BTF, attach_trace),
 	SEC_DEF("lsm+",			LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
 	SEC_DEF("lsm.s+",		LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
@@ -10374,6 +10380,89 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru
 	return libbpf_get_error(*link);
 }
 
+struct bpf_link *
+bpf_program__attach_tracing_multi(const struct bpf_program *prog, const char *pattern,
+				  const struct bpf_tracing_multi_opts *opts)
+{
+	LIBBPF_OPTS(bpf_link_create_opts, lopts);
+	__u32 *btf_ids, cnt, *free_ids = NULL;
+	char errmsg[STRERR_BUFSIZE];
+	int prog_fd, link_fd, err;
+	struct bpf_link *link;
+
+	btf_ids = OPTS_GET(opts, btf_ids, false);
+	cnt = OPTS_GET(opts, cnt, false);
+
+	if (!pattern && !btf_ids && !cnt)
+		return libbpf_err_ptr(-EINVAL);
+	if (pattern && (btf_ids || cnt))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (pattern) {
+		err = bpf_object__load_vmlinux_btf(prog->obj, true);
+		if (err)
+			return libbpf_err_ptr(err);
+
+		cnt = btf__find_by_glob_kind(prog->obj->btf_vmlinux, BTF_KIND_FUNC,
+					     pattern, NULL, &btf_ids);
+		if (cnt <= 0)
+			return libbpf_err_ptr(-EINVAL);
+		free_ids = btf_ids;
+	}
+
+	lopts.tracing_multi.btf_ids = btf_ids;
+	lopts.tracing_multi.btf_ids_cnt = cnt;
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	prog_fd = bpf_program__fd(prog);
+	link_fd = bpf_link_create(prog_fd, 0, prog->expected_attach_type, &lopts);
+	if (link_fd < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to attach: %s\n",
+			prog->name, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto error;
+	}
+	link->fd = link_fd;
+	free(free_ids);
+	return link;
+error:
+	free(link);
+	free(free_ids);
+	return libbpf_err_ptr(err);
+}
+
+static int attach_tracing_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	const char *spec;
+	char *pattern;
+	bool is_fexit;
+	int n;
+
+	/* no auto-attach for SEC("fentry.multi") and SEC("fexit.multi") */
+	if (strcmp(prog->sec_name, "fentry.multi") == 0 ||
+	    strcmp(prog->sec_name, "fexit.multi") == 0)
+		return 0;
+
+	is_fexit = str_has_pfx(prog->sec_name, "fexit.multi/");
+	if (is_fexit)
+		spec = prog->sec_name + sizeof("fexit.multi/") - 1;
+	else
+		spec = prog->sec_name + sizeof("fentry.multi/") - 1;
+
+	n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
+	if (n < 1) {
+		pr_warn("tracing multi pattern is invalid: %s\n", pattern);
+		return -EINVAL;
+	}
+
+	*link = bpf_program__attach_tracing_multi(prog, pattern, NULL);
+	return libbpf_get_error(*link);
+}
+
 static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
 					 const char *binary_path, uint64_t offset)
 {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 61493c4cddac..07992d8ee06c 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -503,6 +503,20 @@ bpf_program__attach_ksyscall(const struct bpf_program *prog,
 			     const char *syscall_name,
 			     const struct bpf_ksyscall_opts *opts);
 
+struct bpf_tracing_multi_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	__u32 *btf_ids;
+	size_t cnt;
+	size_t :0;
+};
+
+#define bpf_kprobe_multi_opts__last_field retprobe
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tracing_multi(const struct bpf_program *prog, const char *pattern,
+				  const struct bpf_tracing_multi_opts *opts);
+
 struct bpf_uprobe_opts {
 	/* size of this struct, for forward/backward compatiblity */
 	size_t sz;
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 119e6e1ea7f1..2168516a75a5 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -358,6 +358,7 @@ LIBBPF_1.0.0 {
 		bpf_obj_get_opts;
 		bpf_prog_query_opts;
 		bpf_program__attach_ksyscall;
+		bpf_program__attach_tracing_multi;
 		btf__add_enum64;
 		btf__add_enum64_value;
 		libbpf_bpf_attach_type_str;
-- 
2.37.1

[RFC PATCH bpf-next 14/17] selftests/bpf: Add fentry tracing multi func test

[Jiri Olsa]

Adding selftest for fentry multi func test that attaches
to bpf_fentry_test* functions and checks argument values
based on the processed function.

We need to cast to real arguments types in multi_arg_check,
because the checked value can be shorter than u64.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/testing/selftests/bpf/Makefile          |   3 +-
 .../selftests/bpf/prog_tests/tracing_multi.c  |  34 +++++
 .../selftests/bpf/progs/tracing_multi_check.c | 132 ++++++++++++++++++
 .../bpf/progs/tracing_multi_fentry.c          |  17 +++
 4 files changed, 185 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/tracing_multi.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_check.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_fentry.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 8d59ec7f4c2d..24f0ace18af2 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -348,7 +348,7 @@ SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c
 LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
 		linked_vars.skel.h linked_maps.skel.h 			\
 		test_subskeleton.skel.h test_subskeleton_lib.skel.h	\
-		test_usdt.skel.h
+		test_usdt.skel.h tracing_multi_fentry_test.skel.h
 
 LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
 	test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \
@@ -366,6 +366,7 @@ linked_maps.skel.h-deps := linked_maps1.o linked_maps2.o
 test_subskeleton.skel.h-deps := test_subskeleton_lib2.o test_subskeleton_lib.o test_subskeleton.o
 test_subskeleton_lib.skel.h-deps := test_subskeleton_lib2.o test_subskeleton_lib.o
 test_usdt.skel.h-deps := test_usdt.o test_usdt_multispec.o
+tracing_multi_fentry_test.skel.h-deps := tracing_multi_fentry.o tracing_multi_check.o
 
 LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 
diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
new file mode 100644
index 000000000000..fbf2108ebb8a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include "tracing_multi_fentry_test.skel.h"
+#include "trace_helpers.h"
+
+static void multi_fentry_test(void)
+{
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+	struct tracing_multi_fentry_test *skel = NULL;
+	int err, prog_fd;
+
+	skel = tracing_multi_fentry_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fentry_multi_skel_load"))
+		goto cleanup;
+
+	err = tracing_multi_fentry_test__attach(skel);
+	if (!ASSERT_OK(err, "fentry_attach"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.test);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+
+	ASSERT_EQ(skel->bss->test_result, 8, "test_result");
+
+cleanup:
+	tracing_multi_fentry_test__destroy(skel);
+}
+
+void test_tracing_multi_test(void)
+{
+	if (test__start_subtest("fentry"))
+		multi_fentry_test();
+}
diff --git a/tools/testing/selftests/bpf/progs/tracing_multi_check.c b/tools/testing/selftests/bpf/progs/tracing_multi_check.c
new file mode 100644
index 000000000000..945dc4d070e1
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tracing_multi_check.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern const void bpf_fentry_test1 __ksym;
+extern const void bpf_fentry_test2 __ksym;
+extern const void bpf_fentry_test3 __ksym;
+extern const void bpf_fentry_test4 __ksym;
+extern const void bpf_fentry_test5 __ksym;
+extern const void bpf_fentry_test6 __ksym;
+extern const void bpf_fentry_test7 __ksym;
+extern const void bpf_fentry_test8 __ksym;
+
+void multi_arg_check(__u64 *ctx, __u64 *test_result)
+{
+	void *ip = (void *) bpf_get_func_ip(ctx);
+	__u64 value = 0;
+
+	if (ip == &bpf_fentry_test1) {
+		int a;
+
+		if (bpf_get_func_arg(ctx, 0, &value))
+			return;
+		a = (int) value;
+
+		*test_result += a == 1;
+	} else if (ip == &bpf_fentry_test2) {
+		__u64 b;
+		int a;
+
+		if (bpf_get_func_arg(ctx, 0, &value))
+			return;
+		a = (int) value;
+		if (bpf_get_func_arg(ctx, 1, &value))
+			return;
+		b = value;
+
+		*test_result += a == 2 && b == 3;
+	} else if (ip == &bpf_fentry_test3) {
+		char a, b;
+		__u64 c;
+
+		if (bpf_get_func_arg(ctx, 0, &value))
+			return;
+		a = (int) value;
+		if (bpf_get_func_arg(ctx, 1, &value))
+			return;
+		b = (int) value;
+		if (bpf_get_func_arg(ctx, 2, &value))
+			return;
+		c = value;
+
+		*test_result += a == 4 && b == 5 && c == 6;
+	} else if (ip == &bpf_fentry_test4) {
+		void *a;
+		char b;
+		int c;
+		__u64 d;
+
+		if (bpf_get_func_arg(ctx, 0, &value))
+			return;
+		a = (void *) value;
+		if (bpf_get_func_arg(ctx, 1, &value))
+			return;
+		b = (char) value;
+		if (bpf_get_func_arg(ctx, 2, &value))
+			return;
+		c = (int) value;
+		if (bpf_get_func_arg(ctx, 3, &value))
+			return;
+		d = value;
+
+		*test_result += a == (void *) 7 && b == 8 && c == 9 && d == 10;
+	} else if (ip == &bpf_fentry_test5) {
+		__u64 a;
+		void *b;
+		short c;
+		int d;
+		__u64 e;
+
+		if (bpf_get_func_arg(ctx, 0, &value))
+			return;
+		a = value;
+		if (bpf_get_func_arg(ctx, 1, &value))
+			return;
+		b = (void *) value;
+		if (bpf_get_func_arg(ctx, 2, &value))
+			return;
+		c = (short) value;
+		if (bpf_get_func_arg(ctx, 3, &value))
+			return;
+		d = (int) value;
+		if (bpf_get_func_arg(ctx, 4, &value))
+			return;
+		e = value;
+
+		*test_result += a == 11 && b == (void *) 12 && c == 13 && d == 14 && e == 15;
+	} else if (ip == &bpf_fentry_test6) {
+		__u64 a;
+		void *b;
+		short c;
+		int d;
+		void *e;
+		__u64 f;
+
+		if (bpf_get_func_arg(ctx, 0, &value))
+			return;
+		a = value;
+		if (bpf_get_func_arg(ctx, 1, &value))
+			return;
+		b = (void *) value;
+		if (bpf_get_func_arg(ctx, 2, &value))
+			return;
+		c = (short) value;
+		if (bpf_get_func_arg(ctx, 3, &value))
+			return;
+		d = (int) value;
+		if (bpf_get_func_arg(ctx, 4, &value))
+			return;
+		e = (void *) value;
+		if (bpf_get_func_arg(ctx, 5, &value))
+			return;
+		f = value;
+
+		*test_result += a == 16 && b == (void *) 17 && c == 18 && d == 19 && e == (void *) 20 && f == 21;
+	} else if (ip == &bpf_fentry_test7) {
+		*test_result += 1;
+	} else if (ip == &bpf_fentry_test8) {
+		*test_result += 1;
+	}
+}
diff --git a/tools/testing/selftests/bpf/progs/tracing_multi_fentry.c b/tools/testing/selftests/bpf/progs/tracing_multi_fentry.c
new file mode 100644
index 000000000000..b78d36772aa6
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tracing_multi_fentry.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u64 test_result = 0;
+
+__hidden extern void multi_arg_check(__u64 *ctx, __u64 *test_result);
+
+SEC("fentry.multi/bpf_fentry_test*")
+int BPF_PROG(test, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f)
+{
+	multi_arg_check(ctx, &test_result);
+	return 0;
+}
-- 
2.37.1

[RFC PATCH bpf-next 15/17] selftests/bpf: Add fexit tracing multi func test

[Jiri Olsa]

Adding selftest for fexit multi func test that attaches
to bpf_fentry_test* functions and checks argument values
based on the processed function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/testing/selftests/bpf/Makefile          |  4 ++-
 .../selftests/bpf/prog_tests/tracing_multi.c  | 28 +++++++++++++++++++
 .../selftests/bpf/progs/tracing_multi_check.c | 26 +++++++++++++++++
 .../selftests/bpf/progs/tracing_multi_fexit.c | 20 +++++++++++++
 4 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_fexit.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 24f0ace18af2..9c0b26e6e645 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -348,7 +348,8 @@ SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c
 LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
 		linked_vars.skel.h linked_maps.skel.h 			\
 		test_subskeleton.skel.h test_subskeleton_lib.skel.h	\
-		test_usdt.skel.h tracing_multi_fentry_test.skel.h
+		test_usdt.skel.h tracing_multi_fentry_test.skel.h	\
+		tracing_multi_fexit_test.skel.h
 
 LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
 	test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \
@@ -367,6 +368,7 @@ test_subskeleton.skel.h-deps := test_subskeleton_lib2.o test_subskeleton_lib.o t
 test_subskeleton_lib.skel.h-deps := test_subskeleton_lib2.o test_subskeleton_lib.o
 test_usdt.skel.h-deps := test_usdt.o test_usdt_multispec.o
 tracing_multi_fentry_test.skel.h-deps := tracing_multi_fentry.o tracing_multi_check.o
+tracing_multi_fexit_test.skel.h-deps := tracing_multi_fexit.o tracing_multi_check.o
 
 LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 
diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
index fbf2108ebb8a..b7b1e42754da 100644
--- a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
 #include "tracing_multi_fentry_test.skel.h"
+#include "tracing_multi_fexit_test.skel.h"
 #include "trace_helpers.h"
 
 static void multi_fentry_test(void)
@@ -27,8 +28,35 @@ static void multi_fentry_test(void)
 	tracing_multi_fentry_test__destroy(skel);
 }
 
+static void multi_fexit_test(void)
+{
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+	struct tracing_multi_fexit_test *skel = NULL;
+	int err, prog_fd;
+
+	skel = tracing_multi_fexit_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "tracing_multi_fentry_test__open_and_load"))
+		goto cleanup;
+
+	err = tracing_multi_fexit_test__attach(skel);
+	if (!ASSERT_OK(err, "tracing_multi_fentry_test__attach"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.test);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+
+	ASSERT_EQ(skel->bss->test_arg_result, 8, "test_arg_result");
+	ASSERT_EQ(skel->bss->test_ret_result, 8, "test_ret_result");
+
+cleanup:
+	tracing_multi_fexit_test__destroy(skel);
+}
+
 void test_tracing_multi_test(void)
 {
 	if (test__start_subtest("fentry"))
 		multi_fentry_test();
+	if (test__start_subtest("fexit"))
+		multi_fexit_test();
 }
diff --git a/tools/testing/selftests/bpf/progs/tracing_multi_check.c b/tools/testing/selftests/bpf/progs/tracing_multi_check.c
index 945dc4d070e1..7144df65607e 100644
--- a/tools/testing/selftests/bpf/progs/tracing_multi_check.c
+++ b/tools/testing/selftests/bpf/progs/tracing_multi_check.c
@@ -130,3 +130,29 @@ void multi_arg_check(__u64 *ctx, __u64 *test_result)
 		*test_result += 1;
 	}
 }
+
+void multi_ret_check(void *ctx, __u64 *test_result)
+{
+	void *ip = (void *) bpf_get_func_ip(ctx);
+	__u64 ret = 0;
+	int err;
+
+	if (bpf_get_func_ret(ctx, &ret))
+		return;
+	if (ip == &bpf_fentry_test1)
+		*test_result += ret == 2;
+	else if (ip == &bpf_fentry_test2)
+		*test_result += ret == 5;
+	else if (ip == &bpf_fentry_test3)
+		*test_result += ret == 15;
+	else if (ip == &bpf_fentry_test4)
+		*test_result += ret == 34;
+	else if (ip == &bpf_fentry_test5)
+		*test_result += ret == 65;
+	else if (ip == &bpf_fentry_test6)
+		*test_result += ret == 111;
+	else if (ip == &bpf_fentry_test7)
+		*test_result += ret == 0;
+	else if (ip == &bpf_fentry_test8)
+		*test_result += ret == 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/tracing_multi_fexit.c b/tools/testing/selftests/bpf/progs/tracing_multi_fexit.c
new file mode 100644
index 000000000000..54624acc7071
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tracing_multi_fexit.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+__hidden extern void multi_arg_check(__u64 *ctx, __u64 *test_result);
+__hidden extern void multi_ret_check(void *ctx, __u64 *test_result);
+
+__u64 test_arg_result = 0;
+__u64 test_ret_result = 0;
+
+SEC("fexit.multi/bpf_fentry_test*")
+int BPF_PROG(test)
+{
+	multi_arg_check(ctx, &test_arg_result);
+	multi_ret_check(ctx, &test_ret_result);
+	return 0;
+}
-- 
2.37.1

[RFC PATCH bpf-next 16/17] selftests/bpf: Add fentry/fexit tracing multi func test

[Jiri Olsa]

Adding selftest for fentry/fexit multi func tests that attaches
to bpf_fentry_test* functions and checks argument values based
on the processed function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/testing/selftests/bpf/Makefile          |  4 ++-
 .../selftests/bpf/prog_tests/tracing_multi.c  | 29 +++++++++++++++++++
 .../bpf/progs/tracing_multi_fentry_fexit.c    | 28 ++++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_fentry_fexit.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 9c0b26e6e645..a231cca9882f 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -349,7 +349,8 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
 		linked_vars.skel.h linked_maps.skel.h 			\
 		test_subskeleton.skel.h test_subskeleton_lib.skel.h	\
 		test_usdt.skel.h tracing_multi_fentry_test.skel.h	\
-		tracing_multi_fexit_test.skel.h
+		tracing_multi_fexit_test.skel.h				\
+		tracing_multi_fentry_fexit_test.skel.h
 
 LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
 	test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \
@@ -369,6 +370,7 @@ test_subskeleton_lib.skel.h-deps := test_subskeleton_lib2.o test_subskeleton_lib
 test_usdt.skel.h-deps := test_usdt.o test_usdt_multispec.o
 tracing_multi_fentry_test.skel.h-deps := tracing_multi_fentry.o tracing_multi_check.o
 tracing_multi_fexit_test.skel.h-deps := tracing_multi_fexit.o tracing_multi_check.o
+tracing_multi_fentry_fexit_test.skel.h-deps := tracing_multi_fentry_fexit.o tracing_multi_check.o
 
 LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 
diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
index b7b1e42754da..409bcf1e3653 100644
--- a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
@@ -2,6 +2,7 @@
 #include <test_progs.h>
 #include "tracing_multi_fentry_test.skel.h"
 #include "tracing_multi_fexit_test.skel.h"
+#include "tracing_multi_fentry_fexit_test.skel.h"
 #include "trace_helpers.h"
 
 static void multi_fentry_test(void)
@@ -53,10 +54,38 @@ static void multi_fexit_test(void)
 	tracing_multi_fexit_test__destroy(skel);
 }
 
+static void multi_fentry_fexit_test(void)
+{
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+	struct tracing_multi_fentry_fexit_test *skel = NULL;
+	int err, prog_fd;
+
+	skel = tracing_multi_fentry_fexit_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "tracing_multi_fentry_fexit_test__open_and_load"))
+		goto cleanup;
+
+	err = tracing_multi_fentry_fexit_test__attach(skel);
+	if (!ASSERT_OK(err, "tracing_multi_fentry_fexit_test__attach"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.test2);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+
+	ASSERT_EQ(skel->bss->test1_arg_result, 8, "test1_arg_result");
+	ASSERT_EQ(skel->bss->test2_arg_result, 8, "test2_arg_result");
+	ASSERT_EQ(skel->bss->test2_ret_result, 8, "test2_ret_result");
+
+cleanup:
+	tracing_multi_fentry_fexit_test__destroy(skel);
+}
+
 void test_tracing_multi_test(void)
 {
 	if (test__start_subtest("fentry"))
 		multi_fentry_test();
 	if (test__start_subtest("fexit"))
 		multi_fexit_test();
+	if (test__start_subtest("fentry_fexit"))
+		multi_fentry_fexit_test();
 }
diff --git a/tools/testing/selftests/bpf/progs/tracing_multi_fentry_fexit.c b/tools/testing/selftests/bpf/progs/tracing_multi_fentry_fexit.c
new file mode 100644
index 000000000000..54ee94d060b2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tracing_multi_fentry_fexit.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u64 test1_arg_result = 0;
+__u64 test2_arg_result = 0;
+__u64 test2_ret_result = 0;
+
+__hidden extern void multi_arg_check(__u64 *ctx, __u64 *test_result);
+__hidden extern void multi_ret_check(void *ctx, __u64 *test_result);
+
+SEC("fentry.multi/bpf_fentry_test*")
+int BPF_PROG(test1, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f)
+{
+	multi_arg_check(ctx, &test1_arg_result);
+	return 0;
+}
+
+SEC("fexit.multi/bpf_fentry_test*")
+int BPF_PROG(test2, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f, int ret)
+{
+	multi_arg_check(ctx, &test2_arg_result);
+	multi_ret_check(ctx, &test2_ret_result);
+	return 0;
+}
-- 
2.37.1

[RFC PATCH bpf-next 17/17] selftests/bpf: Add mixed tracing multi func test

[Jiri Olsa]

Adding selftest for fentry/fexit multi func tests that attaches
to bpf_fentry_test* functions, where some of them have already
attached single trampoline.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/testing/selftests/bpf/Makefile          |  4 +-
 .../selftests/bpf/prog_tests/tracing_multi.c  | 67 +++++++++++++++++++
 .../selftests/bpf/progs/tracing_multi_mixed.c | 43 ++++++++++++
 3 files changed, 113 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_mixed.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index a231cca9882f..9d507615383b 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -350,7 +350,8 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
 		test_subskeleton.skel.h test_subskeleton_lib.skel.h	\
 		test_usdt.skel.h tracing_multi_fentry_test.skel.h	\
 		tracing_multi_fexit_test.skel.h				\
-		tracing_multi_fentry_fexit_test.skel.h
+		tracing_multi_fentry_fexit_test.skel.h			\
+		tracing_multi_mixed_test.skel.h
 
 LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
 	test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \
@@ -371,6 +372,7 @@ test_usdt.skel.h-deps := test_usdt.o test_usdt_multispec.o
 tracing_multi_fentry_test.skel.h-deps := tracing_multi_fentry.o tracing_multi_check.o
 tracing_multi_fexit_test.skel.h-deps := tracing_multi_fexit.o tracing_multi_check.o
 tracing_multi_fentry_fexit_test.skel.h-deps := tracing_multi_fentry_fexit.o tracing_multi_check.o
+tracing_multi_mixed_test.skel.h-deps := tracing_multi_mixed.o tracing_multi_check.o
 
 LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 
diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
index 409bcf1e3653..416940dcde48 100644
--- a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
@@ -3,6 +3,7 @@
 #include "tracing_multi_fentry_test.skel.h"
 #include "tracing_multi_fexit_test.skel.h"
 #include "tracing_multi_fentry_fexit_test.skel.h"
+#include "tracing_multi_mixed_test.skel.h"
 #include "trace_helpers.h"
 
 static void multi_fentry_test(void)
@@ -80,6 +81,70 @@ static void multi_fentry_fexit_test(void)
 	tracing_multi_fentry_fexit_test__destroy(skel);
 }
 
+static void multi_mixed_test(void)
+{
+	struct bpf_link *linkm1 = NULL, *linkm2 = NULL;
+	struct bpf_link *link1 = NULL, *link2 = NULL;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+	struct tracing_multi_mixed_test *skel = NULL;
+	int err, prog_fd;
+
+	skel = tracing_multi_mixed_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "tracing_multi_mixed_test__open_and_load"))
+		goto cleanup;
+
+	link1 = bpf_program__attach_trace(skel->progs.test1);
+	if (!ASSERT_OK_PTR(link1, "attach_trace"))
+		goto cleanup;
+
+	link2 = bpf_program__attach_trace(skel->progs.test2);
+	if (!ASSERT_OK_PTR(link2, "attach_trace"))
+		goto cleanup;
+
+	linkm1 = bpf_program__attach_tracing_multi(skel->progs.test3,
+						  "bpf_fentry_test*", NULL);
+	if (!ASSERT_OK_PTR(linkm1, "attach_tracing_multi"))
+		goto cleanup;
+
+	linkm2 = bpf_program__attach_tracing_multi(skel->progs.test4,
+						  "bpf_fentry_test*", NULL);
+	if (!ASSERT_OK_PTR(linkm2, "attach_tracing_multi"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.test1);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+
+	ASSERT_EQ(skel->bss->test1_result, 1, "test1_result");
+	ASSERT_EQ(skel->bss->test2_result, 1, "test2_result");
+	ASSERT_EQ(skel->bss->test3_arg_result, 8, "test3_arg_result");
+	ASSERT_EQ(skel->bss->test4_arg_result, 8, "test4_arg_result");
+	ASSERT_EQ(skel->bss->test4_ret_result, 8, "test4_ret_result");
+
+	bpf_link__destroy(link1);
+	bpf_link__destroy(link2);
+	bpf_link__destroy(linkm1);
+	bpf_link__destroy(linkm2);
+
+	linkm2 = link1 = link2 = NULL;
+
+	linkm1 = bpf_program__attach_tracing_multi(skel->progs.test3,
+						  "bpf_fentry_test*", NULL);
+	if (!ASSERT_OK_PTR(linkm1, "attach_tracing_multi"))
+		goto cleanup;
+
+	link1 = bpf_program__attach_trace(skel->progs.test1);
+	if (!ASSERT_ERR_PTR(link1, "attach_trace"))
+		goto cleanup;
+
+cleanup:
+	bpf_link__destroy(link1);
+	bpf_link__destroy(link2);
+	bpf_link__destroy(linkm1);
+	bpf_link__destroy(linkm2);
+	tracing_multi_mixed_test__destroy(skel);
+}
+
 void test_tracing_multi_test(void)
 {
 	if (test__start_subtest("fentry"))
@@ -88,4 +153,6 @@ void test_tracing_multi_test(void)
 		multi_fexit_test();
 	if (test__start_subtest("fentry_fexit"))
 		multi_fentry_fexit_test();
+	if (test__start_subtest("mixed"))
+		multi_mixed_test();
 }
diff --git a/tools/testing/selftests/bpf/progs/tracing_multi_mixed.c b/tools/testing/selftests/bpf/progs/tracing_multi_mixed.c
new file mode 100644
index 000000000000..468a044753e9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tracing_multi_mixed.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+__hidden extern void multi_arg_check(__u64 *ctx, __u64 *test_result);
+__hidden extern void multi_ret_check(void *ctx, __u64 *test_result);
+
+__u64 test1_result = 0;
+SEC("fentry/bpf_fentry_test1")
+int BPF_PROG(test1, int a)
+{
+	test1_result += a == 1;
+	return 0;
+}
+
+__u64 test2_result = 0;
+SEC("fexit/bpf_fentry_test2")
+int BPF_PROG(test2, int a, __u64 b, int ret)
+{
+	test2_result += a == 2 && b == 3;
+	return 0;
+}
+
+__u64 test3_arg_result = 0;
+SEC("fentry.multi/bpf_fentry_test*")
+int BPF_PROG(test3, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f)
+{
+	multi_arg_check(ctx, &test3_arg_result);
+	return 0;
+}
+
+__u64 test4_arg_result = 0;
+__u64 test4_ret_result = 0;
+SEC("fexit.multi/bpf_fentry_test*")
+int BPF_PROG(test4, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f, int ret)
+{
+	multi_arg_check(ctx, &test4_arg_result);
+	multi_ret_check(ctx, &test4_ret_result);
+	return 0;
+}
-- 
2.37.1

Re: [RFC PATCH bpf-next 00/17] bpf: Add tracing multi link

[Song Liu]

On Mon, Aug 8, 2022 at 7:06 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
[...]
>
> Maybe better explained on following example:
>
>   - you want to attach program P to functions A,B,C,D,E,F
>     via bpf_trampoline_multi_attach
>
>   - D,E,F already have standard trampoline attached
>
>   - the bpf_trampoline_multi_attach will create new 'multi' trampoline
>     which spans over A,B,C functions and attach program P to single
>     trampolines D,E,F

IIUC, we have 4 trampolines (1 multi, 3 singles) at this moment?

>
>  -  another program can be attached to A,B,C,D,E,F multi trampoline
>
>   - A,B,C functions are now 'not attachable' by any trampoline
>     until the above 'multi' trampoline is released

I guess the limitation here is, multi trampolines cannot be splitted after
attached. While multi trampoline is motivated by short term use cases
like retsnoop, it is allowed to run them for extended periods of time.
Then, this limitation might be a real issue in production.

Thanks,
Song

>
>  -  D,E,F functions are still attachable by any new trampoline
>

Re: [RFC PATCH bpf-next 00/17] bpf: Add tracing multi link

[Jiri Olsa]

On Mon, Aug 08, 2022 at 10:50:28AM -0700, Song Liu wrote:
> On Mon, Aug 8, 2022 at 7:06 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> [...]
> >
> > Maybe better explained on following example:
> >
> >   - you want to attach program P to functions A,B,C,D,E,F
> >     via bpf_trampoline_multi_attach
> >
> >   - D,E,F already have standard trampoline attached
> >
> >   - the bpf_trampoline_multi_attach will create new 'multi' trampoline
> >     which spans over A,B,C functions and attach program P to single
> >     trampolines D,E,F
> 
> IIUC, we have 4 trampolines (1 multi, 3 singles) at this moment?

yes

> 
> >
> >  -  another program can be attached to A,B,C,D,E,F multi trampoline
> >
> >   - A,B,C functions are now 'not attachable' by any trampoline
> >     until the above 'multi' trampoline is released
> 
> I guess the limitation here is, multi trampolines cannot be splitted after
> attached. While multi trampoline is motivated by short term use cases
> like retsnoop, it is allowed to run them for extended periods of time.
> Then, this limitation might be a real issue in production.

I think it'd be possible to allow adding single trampoline on top of
multi trampoline by removing that single id from it and creating single
trampoline for that

I also thought of possibility to convert intersection IDs of two
multi trampolines into single trampolines.. but that might get slow 
if the common set is too big

the difficulty for the common solution was that if you allow to
split trampolines then bpf link can't carry pointers to trampolines
because they can be split into multiple new trampolines, so link
would need to store just array of IDs and use it to attach a program

then un/linking program and doing intersections with stored trampolines
and handling all the split cases turned out to be nightmare

but perhaps there's another solution

jirka