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authorSong Liu <songliubraving@fb.com>2020-06-30 09:28:44 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-07-01 18:23:19 +0300
commitfa28dcb82a38f8e3993b0fae9106b1a80b59e4f0 (patch)
treedf5f451d9328757debc8dd7b81a5e34149577f90 /kernel/bpf/verifier.c
parentd141b8bc5773cbbaf5b8530f08f94fc10fff9e8c (diff)
downloadlinux-fa28dcb82a38f8e3993b0fae9106b1a80b59e4f0.tar.xz
bpf: Introduce helper bpf_get_task_stack()
Introduce helper bpf_get_task_stack(), which dumps stack trace of given task. This is different to bpf_get_stack(), which gets stack track of current task. One potential use case of bpf_get_task_stack() is to call it from bpf_iter__task and dump all /proc/<pid>/stack to a seq_file. bpf_get_task_stack() uses stack_trace_save_tsk() instead of get_perf_callchain() for kernel stack. The benefit of this choice is that stack_trace_save_tsk() doesn't require changes in arch/. The downside of using stack_trace_save_tsk() is that stack_trace_save_tsk() dumps the stack trace to unsigned long array. For 32-bit systems, we need to translate it to u64 array. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200630062846.664389-3-songliubraving@fb.com
Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r--kernel/bpf/verifier.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7de98906ddf4..b608185e1ffd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4864,7 +4864,9 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
if (err)
return err;
- if (func_id == BPF_FUNC_get_stack && !env->prog->has_callchain_buf) {
+ if ((func_id == BPF_FUNC_get_stack ||
+ func_id == BPF_FUNC_get_task_stack) &&
+ !env->prog->has_callchain_buf) {
const char *err_str;
#ifdef CONFIG_PERF_EVENTS