| Message ID | 20210223012014.2087583-1-songliubraving@fb.com |
|---|---|
| Headers | show |
| Series | bpf: enable task local storage for tracing programs | expand |
On Mon, Feb 22, 2021 at 5:24 PM Song Liu <songliubraving@fb.com> wrote: > > Update the Makefile to prefer using $(O)/mvlinux, $(KBUILD_OUTPUT)/vmlinux > (for selftests) or ../../../vmlinux. These two files should have latest > definitions for vmlinux.h. > > Signed-off-by: Song Liu <songliubraving@fb.com> > --- Acked-by: Andrii Nakryiko <andrii@kernel.org> > tools/bpf/runqslower/Makefile | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile > index 9d9fb6209be1b..c96ba90c6f018 100644 > --- a/tools/bpf/runqslower/Makefile > +++ b/tools/bpf/runqslower/Makefile > @@ -16,7 +16,10 @@ CFLAGS := -g -Wall > > # Try to detect best kernel BTF source > KERNEL_REL := $(shell uname -r) > -VMLINUX_BTF_PATHS := /sys/kernel/btf/vmlinux /boot/vmlinux-$(KERNEL_REL) > +VMLINUX_BTF_PATHS := $(if $(O),$(O)/vmlinux) \ > + $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux) \ > + ../../../vmlinux /sys/kernel/btf/vmlinux \ > + /boot/vmlinux-$(KERNEL_REL) > VMLINUX_BTF_PATH := $(or $(VMLINUX_BTF),$(firstword \ > $(wildcard $(VMLINUX_BTF_PATHS)))) > > -- > 2.24.1 >
On Mon, Feb 22, 2021 at 05:20:09PM -0800, Song Liu wrote: [ ... ] > diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c > index e0da0258b732d..2034019966d44 100644 > --- a/kernel/bpf/bpf_task_storage.c > +++ b/kernel/bpf/bpf_task_storage.c > @@ -15,7 +15,6 @@ > #include <linux/bpf_local_storage.h> > #include <linux/filter.h> > #include <uapi/linux/btf.h> > -#include <linux/bpf_lsm.h> > #include <linux/btf_ids.h> > #include <linux/fdtable.h> > > @@ -24,12 +23,8 @@ DEFINE_BPF_STORAGE_CACHE(task_cache); > static struct bpf_local_storage __rcu **task_storage_ptr(void *owner) > { > struct task_struct *task = owner; > - struct bpf_storage_blob *bsb; > > - bsb = bpf_task(task); > - if (!bsb) > - return NULL; task_storage_ptr() no longer returns NULL. All "!task_storage_ptr(task)" checks should be removed also. e.g. In bpf_task_storage_get and bpf_pid_task_storage_update_elem. > - return &bsb->storage; > + return &task->bpf_storage; > } >
> On Feb 23, 2021, at 11:23 AM, Martin Lau <kafai@fb.com> wrote: > > On Mon, Feb 22, 2021 at 05:20:09PM -0800, Song Liu wrote: > [ ... ] > >> diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c >> index e0da0258b732d..2034019966d44 100644 >> --- a/kernel/bpf/bpf_task_storage.c >> +++ b/kernel/bpf/bpf_task_storage.c >> @@ -15,7 +15,6 @@ >> #include <linux/bpf_local_storage.h> >> #include <linux/filter.h> >> #include <uapi/linux/btf.h> >> -#include <linux/bpf_lsm.h> >> #include <linux/btf_ids.h> >> #include <linux/fdtable.h> >> >> @@ -24,12 +23,8 @@ DEFINE_BPF_STORAGE_CACHE(task_cache); >> static struct bpf_local_storage __rcu **task_storage_ptr(void *owner) >> { >> struct task_struct *task = owner; >> - struct bpf_storage_blob *bsb; >> >> - bsb = bpf_task(task); >> - if (!bsb) >> - return NULL; > task_storage_ptr() no longer returns NULL. All "!task_storage_ptr(task)" > checks should be removed also. e.g. In bpf_task_storage_get > and bpf_pid_task_storage_update_elem. Good catch! Fixed it in v5. Thanks, Song > >> - return &bsb->storage; >> + return &task->bpf_storage; >> } >>
On Mon, Feb 22, 2021 at 05:20:13PM -0800, Song Liu wrote:
> Update the Makefile to prefer using $(O)/mvlinux, $(KBUILD_OUTPUT)/vmlinux
s/mvlinux/vmlinux/
This set enables task local storage for non-BPF_LSM programs. It is common for tracing BPF program to access per-task data. Currently, these data are stored in hash tables with pid as the key. In bcc/libbpftools [1], 9 out of 23 tools use such hash tables. However, hash table is not ideal for many use case. Task local storage provides better usability and performance for BPF programs. Please refer to 4/4 for some performance comparison of task local storage vs. hash table. Changes v3 => v4: 1. Prevent deadlock from recursive calls of bpf_task_storage_[get|delete]. (2/6 checks potential deadlock and fails over, 4/6 adds a selftest). Changes v2 => v3: 1. Make the selftest more robust. (Andrii) 2. Small changes with runqslower. (Andrii) 3. Shortern CC list to make it easy for vger. Changes v1 => v2: 1. Do not allocate task local storage when the task is being freed. 2. Revise the selftest and added a new test for a task being freed. 3. Minor changes in runqslower. Song Liu (6): bpf: enable task local storage for tracing programs bpf: prevent deadlock from recursive bpf_task_storage_[get|delete] selftests/bpf: add non-BPF_LSM test for task local storage selftests/bpf: test deadlock from recursive bpf_task_storage_[get|delete] bpf: runqslower: prefer using local vmlimux to generate vmlinux.h bpf: runqslower: use task local storage include/linux/bpf.h | 7 ++ include/linux/bpf_lsm.h | 22 ----- include/linux/bpf_types.h | 2 +- include/linux/sched.h | 5 + kernel/bpf/Makefile | 3 +- kernel/bpf/bpf_local_storage.c | 28 +++--- kernel/bpf/bpf_lsm.c | 4 - kernel/bpf/bpf_task_storage.c | 89 +++++++++++------- kernel/fork.c | 5 + kernel/trace/bpf_trace.c | 4 + tools/bpf/runqslower/Makefile | 5 +- tools/bpf/runqslower/runqslower.bpf.c | 33 ++++--- .../bpf/prog_tests/task_local_storage.c | 92 +++++++++++++++++++ .../selftests/bpf/progs/task_local_storage.c | 64 +++++++++++++ .../bpf/progs/task_local_storage_exit_creds.c | 32 +++++++ .../selftests/bpf/progs/task_ls_recursion.c | 70 ++++++++++++++ 16 files changed, 381 insertions(+), 84 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/task_local_storage.c create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage.c create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage_exit_creds.c create mode 100644 tools/testing/selftests/bpf/progs/task_ls_recursion.c -- 2.24.1