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64f0013c07
Song Liu says:
====================
This set introduces a new helper bpf_get_task_stack(). The primary use case
is to dump all /proc/*/stack to seq_file via bpf_iter__task.
A few different approaches have been explored and compared:
1. A simple wrapper around stack_trace_save_tsk(), as v1 [1].
This approach introduces new syntax, which is different to existing
helper bpf_get_stack(). Therefore, this is not ideal.
2. Extend get_perf_callchain() to support "task" as argument.
This approach reuses most of bpf_get_stack(). However, extending
get_perf_callchain() requires non-trivial changes to architecture
specific code. Which is error prone.
3. Current (v2) approach, leverages most of existing bpf_get_stack(), and
uses stack_trace_save_tsk() to handle architecture specific logic.
[1] https://lore.kernel.org/netdev/20200623070802.2310018-1-songliubraving@fb.com/
Changes v4 => v5:
1. Rebase and work around git-am issue. (Alexei)
2. Update commit log for 4/4. (Yonghong)
Changes v3 => v4:
1. Simplify the selftests with bpf_iter.h. (Yonghong)
2. Add example output to commit log of 4/4. (Yonghong)
Changes v2 => v3:
1. Rebase on top of bpf-next. (Yonghong)
2. Sanitize get_callchain_entry(). (Peter)
3. Use has_callchain_buf for bpf_get_task_stack. (Andrii)
4. Other small clean up. (Yonghong, Andrii).
Changes v1 => v2:
1. Reuse most of bpf_get_stack() logic. (Andrii)
2. Fix unsigned long vs. u64 mismatch for 32-bit systems. (Yonghong)
3. Add %pB support in bpf_trace_printk(). (Daniel)
4. Fix buffer size to bytes.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.