linux/tools
Jordan Rome b8e3a87a62 bpf: Add crosstask check to __bpf_get_stack
Currently get_perf_callchain only supports user stack walking for
the current task. Passing the correct *crosstask* param will return
0 frames if the task passed to __bpf_get_stack isn't the current
one instead of a single incorrect frame/address. This change
passes the correct *crosstask* param but also does a preemptive
check in __bpf_get_stack if the task is current and returns
-EOPNOTSUPP if it is not.

This issue was found using bpf_get_task_stack inside a BPF
iterator ("iter/task"), which iterates over all tasks.
bpf_get_task_stack works fine for fetching kernel stacks
but because get_perf_callchain relies on the caller to know
if the requested *task* is the current one (via *crosstask*)
it was failing in a confusing way.

It might be possible to get user stacks for all tasks utilizing
something like access_process_vm but that requires the bpf
program calling bpf_get_task_stack to be sleepable and would
therefore be a breaking change.

Fixes: fa28dcb82a ("bpf: Introduce helper bpf_get_task_stack()")
Signed-off-by: Jordan Rome <jordalgo@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231108112334.3433136-1-jordalgo@meta.com
2023-11-10 11:06:10 -08:00
..
accounting
arch ARM: 2023-11-02 15:45:15 -10:00
bootconfig
bpf bpftool: Fix prog object type in manpage 2023-11-09 19:07:38 -08:00
build perf tools fixes for v6.6: 2nd batch 2023-10-30 13:46:27 -07:00
certs
cgroup
counter
crypto/ccp crypto: ccp - Fix some unfused tests 2023-09-15 18:29:45 +08:00
debugging
edid
firewire
firmware
gpio
hv hv/hv_kvp_daemon:Support for keyfile based connection profile 2023-10-10 03:42:29 +00:00
iio tools: iio: iio_generic_buffer ensure alignment 2023-10-05 16:16:20 +01:00
include bpf: Add crosstask check to __bpf_get_stack 2023-11-10 11:06:10 -08:00
kvm/kvm_stat
laptop
leds
lib libbpf: Fix potential uninitialized tail padding with LIBBPF_OPTS_RESET 2023-11-09 19:07:51 -08:00
memory-model
mm tools/mm: update the usage output to be more organized 2023-10-18 14:34:19 -07:00
net/ynl nfsd: regenerate user space parsers after ynl-gen changes 2023-11-06 09:03:46 +00:00
objtool * Refactor and clean up TDX hypercall/module call infrastructure 2023-11-01 10:28:32 -10:00
pci
pcmcia
perf perf tools changes for v6.7 2023-11-03 08:17:38 -10:00
power Merge branch 'pm-tools' 2023-11-07 20:46:13 +01:00
rcu
scripts tools/build: Fix -s detection code in tools/scripts/Makefile.include 2023-10-18 15:29:47 -07:00
spi
testing selftests/bpf: Test bpf_refcount_acquire of node obtained via direct ld 2023-11-09 19:07:51 -08:00
thermal tools/thermal: Remove unused 'mds' and 'nrhandler' variables 2023-10-15 23:40:10 +02:00
time
tracing rtla: Fix uninitialized variable found 2023-10-30 19:00:12 +01:00
usb
verification verification/dot2k: Delete duplicate imports 2023-10-30 16:59:12 +01:00
virtio tools/virtio: Add dma sync api for virtio test 2023-10-16 05:32:23 -04:00
wmi
workqueue
Makefile