23ec6fc52c
[ Upstream commit 979e9c9fc9c2a761303585e07fe2699bdd88182f ]
In 616b14b47a86d880 ("perf build: Conditionally define NDEBUG") we
started using NDEBUG=1 when DEBUG=1 isn't present, so code that is
enclosed with assert() is not called.
In dd317df072071903 ("perf build: Make binutil libraries opt in") we
stopped linking against binutils-devel, for licensing reasons.
Recently people asked me why annotation of BPF programs wasn't working,
i.e. this:
$ perf annotate bpf_prog_5280546344e3f45c_kfree_skb
was returning:
case SYMBOL_ANNOTATE_ERRNO__NO_LIBOPCODES_FOR_BPF:
scnprintf(buf, buflen, "Please link with binutils's libopcode to enable BPF annotation");
This was on a fedora rpm, so its new enough that I had to try to test by
rebuilding using BUILD_NONDISTRO=1, only to get it segfaulting on me.
This combination made this libopcode function not to be called:
assert(bfd_check_format(bfdf, bfd_object));
Changing it to:
if (!bfd_check_format(bfdf, bfd_object))
abort();
Made it work, looking at this "check" function made me realize it
changes the 'bfdf' internal state, i.e. we better call it.
So stop using assert() on it, just call it and abort if it fails.
Probably it is better to propagate the error, etc, but it seems it is
unlikely to fail from the usage done so far and we really need to stop
using libopcodes, so do the quick fix above and move on.
With it we have BPF annotation back working when built with
BUILD_NONDISTRO=1:
⬢[acme@toolbox perf-tools-next]$ perf annotate --stdio2 bpf_prog_5280546344e3f45c_kfree_skb | head
No kallsyms or vmlinux with build-id 939bc71a1a51cdc434e60af93c7e734f7d5c0e7e was found
Samples: 12 of event 'cpu-clock:ppp', 4000 Hz, Event count (approx.): 3000000, [percent: local period]
bpf_prog_5280546344e3f45c_kfree_skb() bpf_prog_5280546344e3f45c_kfree_skb
Percent int kfree_skb(struct trace_event_raw_kfree_skb *args) {
nop
33.33 xchg %ax,%ax
push %rbp
mov %rsp,%rbp
sub $0x180,%rsp
push %rbx
push %r13
⬢[acme@toolbox perf-tools-next]$
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.