| Message ID | 20211025083315.4752-11-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | extend task comm from 16 to 24 | expand |
On Mon, Oct 25, 2021 at 08:33:13AM +0000, Yafang Shao wrote: > The hard-coded 16 is used in various bpf progs. These progs get task > comm either via bpf_get_current_comm() or prctl() or > bpf_core_read_str(), all of which can work well even if the task comm size > is changed. > > In these BPF programs, one thing to be improved is the > sched:sched_switch tracepoint args. As the tracepoint args are derived > from the kernel, we'd better make it same with the kernel. So the macro > TASK_COMM_LEN is converted to type enum, then all the BPF programs can > get it through BTF. > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> > Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Al Viro <viro@zeniv.linux.org.uk> > Cc: Kees Cook <keescook@chromium.org> > Cc: Petr Mladek <pmladek@suse.com> > --- > include/linux/sched.h | 9 +++++++-- > tools/testing/selftests/bpf/progs/test_stacktrace_map.c | 6 +++--- > tools/testing/selftests/bpf/progs/test_tracepoint.c | 6 +++--- > 3 files changed, 13 insertions(+), 8 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index c1a927ddec64..124538db792c 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -274,8 +274,13 @@ struct task_group; > > #define get_current_state() READ_ONCE(current->__state) > > -/* Task command name length: */ > -#define TASK_COMM_LEN 16 > +/* > + * Define the task command name length as enum, then it can be visible to > + * BPF programs. > + */ > +enum { > + TASK_COMM_LEN = 16, > +}; > > extern void scheduler_tick(void); > > diff --git a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > index 00ed48672620..e9b602a6dc1b 100644 > --- a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > +++ b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > @@ -1,7 +1,7 @@ > // SPDX-License-Identifier: GPL-2.0 > // Copyright (c) 2018 Facebook > > -#include <linux/bpf.h> > +#include <vmlinux.h> Why is this change needed here and below? > #include <bpf/bpf_helpers.h> > > #ifndef PERF_MAX_STACK_DEPTH > @@ -41,11 +41,11 @@ struct { > /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ > struct sched_switch_args { > unsigned long long pad; > - char prev_comm[16]; > + char prev_comm[TASK_COMM_LEN]; > int prev_pid; > int prev_prio; > long long prev_state; > - char next_comm[16]; > + char next_comm[TASK_COMM_LEN]; > int next_pid; > int next_prio; > }; > diff --git a/tools/testing/selftests/bpf/progs/test_tracepoint.c b/tools/testing/selftests/bpf/progs/test_tracepoint.c > index 4b825ee122cf..f21982681e28 100644 > --- a/tools/testing/selftests/bpf/progs/test_tracepoint.c > +++ b/tools/testing/selftests/bpf/progs/test_tracepoint.c > @@ -1,17 +1,17 @@ > // SPDX-License-Identifier: GPL-2.0 > // Copyright (c) 2017 Facebook > > -#include <linux/bpf.h> > +#include <vmlinux.h> > #include <bpf/bpf_helpers.h> > > /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ > struct sched_switch_args { > unsigned long long pad; > - char prev_comm[16]; > + char prev_comm[TASK_COMM_LEN]; > int prev_pid; > int prev_prio; > long long prev_state; > - char next_comm[16]; > + char next_comm[TASK_COMM_LEN]; > int next_pid; > int next_prio; > }; > -- > 2.17.1 >
On Tue, Oct 26, 2021 at 5:29 AM Kees Cook <keescook@chromium.org> wrote: > > On Mon, Oct 25, 2021 at 08:33:13AM +0000, Yafang Shao wrote: > > The hard-coded 16 is used in various bpf progs. These progs get task > > comm either via bpf_get_current_comm() or prctl() or > > bpf_core_read_str(), all of which can work well even if the task comm size > > is changed. > > > > In these BPF programs, one thing to be improved is the > > sched:sched_switch tracepoint args. As the tracepoint args are derived > > from the kernel, we'd better make it same with the kernel. So the macro > > TASK_COMM_LEN is converted to type enum, then all the BPF programs can > > get it through BTF. > > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > > Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> > > Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Steven Rostedt <rostedt@goodmis.org> > > Cc: Al Viro <viro@zeniv.linux.org.uk> > > Cc: Kees Cook <keescook@chromium.org> > > Cc: Petr Mladek <pmladek@suse.com> > > --- > > include/linux/sched.h | 9 +++++++-- > > tools/testing/selftests/bpf/progs/test_stacktrace_map.c | 6 +++--- > > tools/testing/selftests/bpf/progs/test_tracepoint.c | 6 +++--- > > 3 files changed, 13 insertions(+), 8 deletions(-) > > > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index c1a927ddec64..124538db792c 100644 > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -274,8 +274,13 @@ struct task_group; > > > > #define get_current_state() READ_ONCE(current->__state) > > > > -/* Task command name length: */ > > -#define TASK_COMM_LEN 16 > > +/* > > + * Define the task command name length as enum, then it can be visible to > > + * BPF programs. > > + */ > > +enum { > > + TASK_COMM_LEN = 16, > > +}; > > > > extern void scheduler_tick(void); > > > > diff --git a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > > index 00ed48672620..e9b602a6dc1b 100644 > > --- a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > > +++ b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > > @@ -1,7 +1,7 @@ > > // SPDX-License-Identifier: GPL-2.0 > > // Copyright (c) 2018 Facebook > > > > -#include <linux/bpf.h> > > +#include <vmlinux.h> > > Why is this change needed here and below? > If the BPF programs want to use the type defined in the kernel, for example the enum we used here, we must include the vmlinux.h generated by BTF. > > #include <bpf/bpf_helpers.h> > > > > #ifndef PERF_MAX_STACK_DEPTH > > @@ -41,11 +41,11 @@ struct { > > /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ > > struct sched_switch_args { > > unsigned long long pad; > > - char prev_comm[16]; > > + char prev_comm[TASK_COMM_LEN]; > > int prev_pid; > > int prev_prio; > > long long prev_state; > > - char next_comm[16]; > > + char next_comm[TASK_COMM_LEN]; > > int next_pid; > > int next_prio; > > }; > > diff --git a/tools/testing/selftests/bpf/progs/test_tracepoint.c b/tools/testing/selftests/bpf/progs/test_tracepoint.c > > index 4b825ee122cf..f21982681e28 100644 > > --- a/tools/testing/selftests/bpf/progs/test_tracepoint.c > > +++ b/tools/testing/selftests/bpf/progs/test_tracepoint.c > > @@ -1,17 +1,17 @@ > > // SPDX-License-Identifier: GPL-2.0 > > // Copyright (c) 2017 Facebook > > > > -#include <linux/bpf.h> > > +#include <vmlinux.h> > > #include <bpf/bpf_helpers.h> > > > > /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ > > struct sched_switch_args { > > unsigned long long pad; > > - char prev_comm[16]; > > + char prev_comm[TASK_COMM_LEN]; > > int prev_pid; > > int prev_prio; > > long long prev_state; > > - char next_comm[16]; > > + char next_comm[TASK_COMM_LEN]; > > int next_pid; > > int next_prio; > > }; > > -- > > 2.17.1 > > > > -- > Kees Cook
diff --git a/include/linux/sched.h b/include/linux/sched.h index c1a927ddec64..124538db792c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -274,8 +274,13 @@ struct task_group; #define get_current_state() READ_ONCE(current->__state) -/* Task command name length: */ -#define TASK_COMM_LEN 16 +/* + * Define the task command name length as enum, then it can be visible to + * BPF programs. + */ +enum { + TASK_COMM_LEN = 16, +}; extern void scheduler_tick(void); diff --git a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c index 00ed48672620..e9b602a6dc1b 100644 --- a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c +++ b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 // Copyright (c) 2018 Facebook -#include <linux/bpf.h> +#include <vmlinux.h> #include <bpf/bpf_helpers.h> #ifndef PERF_MAX_STACK_DEPTH @@ -41,11 +41,11 @@ struct { /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ struct sched_switch_args { unsigned long long pad; - char prev_comm[16]; + char prev_comm[TASK_COMM_LEN]; int prev_pid; int prev_prio; long long prev_state; - char next_comm[16]; + char next_comm[TASK_COMM_LEN]; int next_pid; int next_prio; }; diff --git a/tools/testing/selftests/bpf/progs/test_tracepoint.c b/tools/testing/selftests/bpf/progs/test_tracepoint.c index 4b825ee122cf..f21982681e28 100644 --- a/tools/testing/selftests/bpf/progs/test_tracepoint.c +++ b/tools/testing/selftests/bpf/progs/test_tracepoint.c @@ -1,17 +1,17 @@ // SPDX-License-Identifier: GPL-2.0 // Copyright (c) 2017 Facebook -#include <linux/bpf.h> +#include <vmlinux.h> #include <bpf/bpf_helpers.h> /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ struct sched_switch_args { unsigned long long pad; - char prev_comm[16]; + char prev_comm[TASK_COMM_LEN]; int prev_pid; int prev_prio; long long prev_state; - char next_comm[16]; + char next_comm[TASK_COMM_LEN]; int next_pid; int next_prio; };
The hard-coded 16 is used in various bpf progs. These progs get task comm either via bpf_get_current_comm() or prctl() or bpf_core_read_str(), all of which can work well even if the task comm size is changed. In these BPF programs, one thing to be improved is the sched:sched_switch tracepoint args. As the tracepoint args are derived from the kernel, we'd better make it same with the kernel. So the macro TASK_COMM_LEN is converted to type enum, then all the BPF programs can get it through BTF. Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: Petr Mladek <pmladek@suse.com> --- include/linux/sched.h | 9 +++++++-- tools/testing/selftests/bpf/progs/test_stacktrace_map.c | 6 +++--- tools/testing/selftests/bpf/progs/test_tracepoint.c | 6 +++--- 3 files changed, 13 insertions(+), 8 deletions(-)