kernel_optimize_test/kernel
Namhyung Kim 90805175a2 bpf: Adjust BPF stack helper functions to accommodate skip > 0
commit ee2a098851bfbe8bcdd964c0121f4246f00ff41e upstream.

Let's say that the caller has storage for num_elem stack frames.  Then,
the BPF stack helper functions walk the stack for only num_elem frames.
This means that if skip > 0, one keeps only 'num_elem - skip' frames.

This is because it sets init_nr in the perf_callchain_entry to the end
of the buffer to save num_elem entries only.  I believe it was because
the perf callchain code unwound the stack frames until it reached the
global max size (sysctl_perf_event_max_stack).

However it now has perf_callchain_entry_ctx.max_stack to limit the
iteration locally.  This simplifies the code to handle init_nr in the
BPF callstack entries and removes the confusion with the perf_event's
__PERF_SAMPLE_CALLCHAIN_EARLY which sets init_nr to 0.

Also change the comment on bpf_get_stack() in the header file to be
more explicit what the return value means.

Fixes: c195651e56 ("bpf: add bpf_get_stack helper")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/30a7b5d5-6726-1cc2-eaee-8da2828a9a9c@oracle.com
Link: https://lore.kernel.org/bpf/20220314182042.71025-1-namhyung@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Based-on-patch-by: Eugene Loh <eugene.loh@oracle.com>
2022-04-08 14:40:43 +02:00
..
bpf bpf: Adjust BPF stack helper functions to accommodate skip > 0 2022-04-08 14:40:43 +02:00
cgroup cgroup-v1: Correct privileges check in release_agent writes 2022-03-28 09:57:08 +02:00
configs
debug kdb: Fix the putarea helper function 2022-04-08 14:40:29 +02:00
dma dma-debug: fix return value of __setup handlers 2022-04-08 14:40:25 +02:00
entry KVM: rseq: Update rseq when processing NOTIFY_RESUME on xfer to KVM guest 2021-10-06 15:55:49 +02:00
events perf/core: Fix address filter parser for multiple filters 2022-04-08 14:40:03 +02:00
gcov
irq genirq/timings: Fix error return code in irq_timings_test_irqs() 2021-09-15 09:50:29 +02:00
kcsan kcsan: Fix debugfs initcall return type 2021-05-26 12:06:54 +02:00
livepatch livepatch: Fix build failure on 32 bits processors 2022-04-08 14:40:15 +02:00
locking locking/lockdep: Iterate lock_classes directly when reading lockdep files 2022-04-08 14:40:32 +02:00
power PM: suspend: fix return value of __setup handler 2022-04-08 14:40:01 +02:00
printk printk: fix return value of printk.devkmsg __setup handler 2022-04-08 14:40:08 +02:00
rcu rcu: Don't deboost before reporting expedited quiescent state 2022-03-28 09:57:10 +02:00
sched sched/core: Export pelt_thermal_tp 2022-04-08 14:40:03 +02:00
time clocksource: Avoid accidental unstable marking of clocksources 2022-01-27 10:54:06 +01:00
trace tracing: Ensure trace buffer is at least 4096 bytes large 2022-03-16 14:16:00 +01:00
.gitignore kbuild: update config_data.gz only when the content of .config is changed 2021-05-11 14:47:37 +02:00
acct.c
async.c Revert "module, async: async_synchronize_full() on module init iff async is used" 2022-02-23 12:01:00 +01:00
audit_fsnotify.c
audit_tree.c audit: move put_tree() to avoid trim_trees refcount underflow and UAF 2021-09-03 10:09:31 +02:00
audit_watch.c
audit.c audit: improve audit queue handling when "audit=1" on cmdline 2022-02-08 18:30:34 +01:00
audit.h audit: log AUDIT_TIME_* records only from rules 2022-04-08 14:40:00 +02:00
auditfilter.c
auditsc.c audit: log AUDIT_TIME_* records only from rules 2022-04-08 14:40:00 +02:00
backtracetest.c
bounds.c
capability.c
compat.c
configs.c
context_tracking.c
cpu_pm.c PM: cpu: Make notifier chain use a raw_spinlock_t 2021-09-15 09:50:40 +02:00
cpu.c sched/scs: Reset task stack state in bringup_cpu() 2021-12-01 09:19:08 +01:00
crash_core.c crash_core, vmcoreinfo: append 'SECTION_SIZE_BITS' to vmcoreinfo 2021-06-23 14:42:52 +02:00
crash_dump.c
cred.c Revert "Add a reference to ucounts for each cred" 2021-09-08 08:49:00 +02:00
delayacct.c
dma.c
exec_domain.c
exit.c
extable.c
fail_function.c
fork.c copy_process(): Move fd_install() out of sighand->siglock critical section 2022-02-23 12:01:08 +01:00
freezer.c
futex.c mm, futex: fix shared futex pgoff on shmem huge page 2021-06-30 08:47:29 -04:00
gen_kheaders.sh
groups.c
hung_task.c
iomem.c
irq_work.c
jump_label.c jump_label: Fix jump_label_text_reserved() vs __init 2021-07-20 16:05:58 +02:00
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c
kexec_core.c
kexec_elf.c
kexec_file.c kernel: kexec_file: fix error return code of kexec_calculate_store_digests() 2021-05-19 10:13:09 +02:00
kexec_internal.h
kexec.c
kheaders.c
kmod.c
kprobes.c kprobes: Limit max data_size of the kretprobe instances 2021-12-08 09:03:20 +01:00
ksysfs.c
kthread.c kthread: Fix PF_KTHREAD vs to_kthread() race 2021-09-03 10:09:31 +02:00
latencytop.c
Makefile kbuild: update config_data.gz only when the content of .config is changed 2021-05-11 14:47:37 +02:00
module_signature.c
module_signing.c
module-internal.h
module.c Revert "module, async: async_synchronize_full() on module init iff async is used" 2022-02-23 12:01:00 +01:00
notifier.c
nsproxy.c
padata.c
panic.c
params.c
pid_namespace.c memcg: enable accounting for pids in nested pid namespaces 2021-09-18 13:40:36 +02:00
pid.c
profile.c profiling: fix shift-out-of-bounds bugs 2021-09-26 14:08:58 +02:00
ptrace.c ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE 2022-04-08 14:39:50 +02:00
range.c
reboot.c
regset.c
relay.c
resource.c kernel/resource: make walk_mem_res() find all busy IORESOURCE_MEM resources 2021-05-19 10:13:09 +02:00
rseq.c rseq: Remove broken uapi field layout on 32-bit little endian 2022-04-08 14:40:03 +02:00
scftorture.c
scs.c
seccomp.c seccomp: Fix setting loaded filter count during TSYNC 2021-08-18 08:59:06 +02:00
signal.c signal: Remove the bogus sigkill_pending in ptrace_stop 2021-11-18 14:03:47 +01:00
smp.c smp: Fix smp_call_function_single_async prototype 2021-05-14 09:50:46 +02:00
smpboot.c sched/core: Initialize the idle task with preemption disabled 2021-07-14 16:55:50 +02:00
smpboot.h
softirq.c
stackleak.c gcc-plugins/stackleak: Use noinstr in favor of notrace 2022-02-23 12:01:00 +01:00
stacktrace.c
static_call.c static_call: Fix unused variable warn w/o MODULE 2021-09-08 08:49:00 +02:00
stop_machine.c
sys_ni.c
sys.c prctl: allow to setup brk for et_dyn executables 2021-09-26 14:08:57 +02:00
sysctl-test.c
sysctl.c x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting 2022-03-11 12:11:49 +01:00
task_work.c
taskstats.c
test_kprobes.c
torture.c
tracepoint.c tracepoint: Use rcu get state and cond sync for static call updates 2021-09-03 10:09:30 +02:00
tsacct.c taskstats: Cleanup the use of task->exit_code 2022-01-27 10:54:33 +01:00
ucount.c Revert "Add a reference to ucounts for each cred" 2021-09-08 08:49:00 +02:00
uid16.c
uid16.h
umh.c
up.c smp: Fix smp_call_function_single_async prototype 2021-05-14 09:50:46 +02:00
user_namespace.c Revert "Add a reference to ucounts for each cred" 2021-09-08 08:49:00 +02:00
user-return-notifier.c
user.c
usermode_driver.c
utsname_sysctl.c
utsname.c
watch_queue.c watch_queue: Free the page array when watch_queue is dismantled 2022-04-08 14:40:41 +02:00
watchdog_hld.c
watchdog.c watchdog: fix barriers when printing backtraces from all CPUs 2021-05-19 10:13:00 +02:00
workqueue_internal.h
workqueue.c workqueue: Fix unbind_workers() VS wq_worker_running() race 2022-01-16 09:14:22 +01:00