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samples/bpf/test_overhead_kprobe_kern: replace bpf_probe_read_kernel with bpf_probe_read_kernel_str to get task comm 

bpf_probe_read_kernel_str() will add a nul terminator to the dst, then
we don't care about if the dst size is big enough.  This patch also
replaces the hard-coded 16 with TASK_COMM_LEN to make it grepable.

Link: https://lkml.kernel.org/r/20211120112738.45980-6-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Yafang Shao 2022-01-19 18:08:33 -08:00 committed by Linus Torvalds
parent 95af469c4f
commit d068144d3b
3 changed files with 11 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
samples/bpf/offwaketime_kern.c
View File

@ -113,11 +113,11 @@ static inline int update_counts(void *ctx, u32 pid, u64 delta)
/* 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;
};

11
samples/bpf/test_overhead_kprobe_kern.c
View File

@ -6,6 +6,7 @@
*/
#include <linux/version.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <uapi/linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
@ -22,17 +23,17 @@ int prog(struct pt_regs *ctx)
{
struct signal_struct *signal;
struct task_struct *tsk;
char oldcomm[16] = {};
char newcomm[16] = {};
char oldcomm[TASK_COMM_LEN] = {};
char newcomm[TASK_COMM_LEN] = {};
u16 oom_score_adj;
u32 pid;
tsk = (void *)PT_REGS_PARM1(ctx);
pid = _(tsk->pid);
bpf_probe_read_kernel(oldcomm, sizeof(oldcomm), &tsk->comm);
bpf_probe_read_kernel(newcomm, sizeof(newcomm),
(void *)PT_REGS_PARM2(ctx));
bpf_probe_read_kernel_str(oldcomm, sizeof(oldcomm), &tsk->comm);
bpf_probe_read_kernel_str(newcomm, sizeof(newcomm),
(void *)PT_REGS_PARM2(ctx));
signal = _(tsk->signal);
oom_score_adj = _(signal->oom_score_adj);
return 0;

5
samples/bpf/test_overhead_tp_kern.c
View File

@ -4,6 +4,7 @@
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <linux/sched.h>
#include <uapi/linux/bpf.h>
#include <bpf/bpf_helpers.h>
@ -11,8 +12,8 @@
struct task_rename {
__u64 pad;
__u32 pid;
char oldcomm[16];
char newcomm[16];
char oldcomm[TASK_COMM_LEN];
char newcomm[TASK_COMM_LEN];
__u16 oom_score_adj;
};
SEC("tracepoint/task/task_rename")