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492e639f0c
linux/kernel
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Yonghong Song 492e639f0c bpf: Add bpf_seq_printf and bpf_seq_write helpers 
Two helpers bpf_seq_printf and bpf_seq_write, are added for
writing data to the seq_file buffer.

bpf_seq_printf supports common format string flag/width/type
fields so at least I can get identical results for
netlink and ipv6_route targets.

For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW
specifically indicates a write failure due to overflow, which
means the object will be repeated in the next bpf invocation
if object collection stays the same. Note that if the object
collection is changed, depending how collection traversal is
done, even if the object still in the collection, it may not
be visited.

For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to
read kernel memory. Reading kernel memory may fail in
the following two cases:
  - invalid kernel address, or
  - valid kernel address but requiring a major fault
If reading kernel memory failed, the %s string will be
an empty string and %p{i,I}{4,6} will be all 0.
Not returning error to bpf program is consistent with
what bpf_trace_printk() does for now.

bpf_seq_printf may return -EBUSY meaning that internal percpu
buffer for memory copy of strings or other pointees is
not available. Bpf program can return 1 to indicate it
wants the same object to be repeated. Right now, this should not
happen on no-RT kernels since migrate_disable(), which guards
bpf prog call, calls preempt_disable().

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 17:05:26 -07:00
..
bpf bpf: Add PTR_TO_BTF_ID_OR_NULL support 2020-05-09 17:05:26 -07:00
cgroup bpf: Refactor bpf_link update handling 2020-04-28 17:27:07 -07:00
configs compiler: remove CONFIG_OPTIMIZE_INLINING entirely 2020-04-07 10:43:42 -07:00
debug SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
dma dma-debug: fix displaying of dma allocation type 2020-04-08 21:46:57 +02:00
events Merge branch 'work.sysctl' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-04-28 21:23:38 +02:00
gcov kernel/gcov/fs.c: gcov_seq_next() should increase position index 2020-04-10 15:36:22 -07:00
irq genirq: Remove setup_irq() and remove_irq() 2020-04-14 10:08:50 +02:00
livepatch New tracing features: 2019-11-27 11:42:01 -08:00
locking locking/lockdep: Improve 'invalid wait context' splat 2020-04-08 12:05:07 +02:00
power PM / sleep: handle the compat case in snapshot_set_swap_area() 2020-04-06 21:42:36 +02:00
printk sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
rcu Merge branch 'urgent-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent 2020-04-14 08:36:41 +02:00
sched Merge branch 'work.sysctl' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-04-28 21:23:38 +02:00
time Merge branch 'work.sysctl' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-04-28 21:23:38 +02:00
trace bpf: Add bpf_seq_printf and bpf_seq_write helpers 2020-05-09 17:05:26 -07:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
acct.c acct: stop using get_seconds() 2019-12-18 18:07:31 +01:00
async.c
audit_fsnotify.c fsnotify: use helpers to access data by data_type 2020-03-23 18:19:06 +01:00
audit_tree.c
audit_watch.c \n 2020-04-06 08:58:42 -07:00
audit.c audit: check the length of userspace generated audit records 2020-04-20 17:10:58 -04:00
audit.h audit: trigger accompanying records when no rules present 2020-03-12 10:42:51 -04:00
auditfilter.c audit: fix error handling in audit_data_to_entry() 2020-02-22 20:36:47 -05:00
auditsc.c audit: trigger accompanying records when no rules present 2020-03-12 10:42:51 -04:00
backtracetest.c
bounds.c
capability.c
compat.c y2038: remove unused time32 interfaces 2020-02-21 11:22:15 -08:00
configs.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
context_tracking.c context-tracking: Introduce CONFIG_HAVE_TIF_NOHZ 2020-02-14 16:05:04 +01:00
cpu_pm.c
cpu.c CPU (hotplug) updates: 2020-03-30 18:06:39 -07:00
crash_core.c
crash_dump.c
cred.c kernel: doc: remove outdated comment cred.c 2020-03-25 10:04:01 -05:00
delayacct.c
dma.c
elfcore.c kernel/elfcore.c: include proper prototypes 2019-09-25 17:51:39 -07:00
exec_domain.c
exit.c proc: Put thread_pid in release_task not proc_flush_pid 2020-04-24 15:49:00 -05:00
extable.c kernel/extable.c: use address-of operator on section symbols 2020-04-07 10:43:42 -07:00
fail_function.c
fork.c clone3: add build-time CLONE_ARGS_SIZE_VER* validity checks 2020-04-15 09:56:32 +02:00
freezer.c Revert "libata, freezer: avoid block device removal while system is frozen" 2019-10-06 09:11:37 -06:00
futex.c Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2020-03-30 16:17:15 -07:00
gen_kheaders.sh kheaders: explain why include/config/autoconf.h is excluded from md5sum 2019-11-11 20:10:01 +09:00
groups.c
hung_task.c
iomem.c
irq_work.c lockdep: Annotate irq_work 2020-03-21 16:00:24 +01:00
jump_label.c jump_label: Don't warn on __exit jump entries 2019-08-29 15:10:10 +01:00
kallsyms.c kallsyms: unexport kallsyms_lookup_name() and kallsyms_on_each_symbol() 2020-04-07 10:43:44 -07:00
kcmp.c kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve 2020-03-25 10:04:01 -05:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks sched/rt, locking: Use CONFIG_PREEMPTION 2019-12-08 14:37:36 +01:00
Kconfig.preempt sched/Kconfig: Fix spelling mistake in user-visible help text 2019-11-12 11:35:32 +01:00
kcov.c kcov: remote coverage support 2019-12-04 19:44:14 -08:00
kexec_core.c kexec: add machine_kexec_post_load() 2020-01-08 16:32:55 +00:00
kexec_elf.c kexec_elf: support 32 bit ELF files 2019-09-06 23:58:44 +02:00
kexec_file.c kexec: add machine_kexec_post_load() 2020-01-08 16:32:55 +00:00
kexec_internal.h kexec: add machine_kexec_post_load() 2020-01-08 16:32:55 +00:00
kexec.c kexec: add machine_kexec_post_load() 2020-01-08 16:32:55 +00:00
kheaders.c
kmod.c kmod: make request_module() return an error when autoloading is disabled 2020-04-10 15:36:22 -07:00
kprobes.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
ksysfs.c
kthread.c kthread: Do not preempt current task if it is going to call schedule() 2020-03-20 13:06:20 +01:00
latencytop.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
Makefile kcov: ignore fault-inject and stacktrace 2020-01-31 10:30:41 -08:00
module_signature.c
module_signing.c
module-internal.h
module.c kernel/module: Hide vermagic header file from general use 2020-04-21 13:27:37 -07:00
notifier.c x86/mm: split vmalloc_sync_all() 2020-03-21 18:56:06 -07:00
nsproxy.c ns: Introduce Time Namespace 2020-01-14 12:20:48 +01:00
padata.c crypto: pcrypt - simplify error handling in pcrypt_create_aead() 2020-03-06 12:28:24 +11:00
panic.c locking/refcount: Remove unused 'refcount_error_report()' function 2019-11-25 09:15:42 +01:00
params.c
pid_namespace.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
pid.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-04-10 12:59:56 -07:00
profile.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
ptrace.c ptrace: reintroduce usage of subjective credentials in ptrace_has_cap() 2020-01-18 13:51:39 +01:00
range.c
reboot.c
relay.c
resource.c mm/memory_hotplug.c: use PFN_UP / PFN_DOWN in walk_system_ram_range() 2019-09-24 15:54:09 -07:00
rseq.c rseq: Reject unknown flags on rseq unregister 2019-12-25 10:41:20 +01:00
seccomp.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
signal.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-04-23 13:30:18 -07:00
smp.c cpu/hotplug: Move bringup of secondary CPUs out of smp_init() 2020-03-25 12:59:37 +01:00
smpboot.c
smpboot.h
softirq.c lockdep: Rename trace_{hard,soft}{irq_context,irqs_enabled}() 2020-03-21 16:03:54 +01:00
stackleak.c
stacktrace.c stacktrace: Get rid of unneeded '!!' pattern 2019-11-11 10:30:59 +01:00
stop_machine.c stop_machine: Make stop_cpus() static 2020-01-17 10:19:21 +01:00
sys_ni.c y2038: allow disabling time32 system calls 2019-11-15 14:38:30 +01:00
sys.c sys/sysinfo: Respect boottime inside time namespace 2020-03-03 19:34:32 +01:00
sysctl_binary.c sysctl: Remove the sysctl system call 2019-11-26 13:03:56 -06:00
sysctl-test.c kunit: allow kunit tests to be loaded as a module 2020-01-09 16:42:29 -07:00
sysctl.c sysctl: Fix unused function warning 2020-05-05 11:59:32 -07:00
task_work.c task_work_run: don't take ->pi_lock unconditionally 2020-03-02 14:06:33 -07:00
taskstats.c taskstats: fix data-race 2019-12-04 15:18:39 +01:00
test_kprobes.c
torture.c CPU (hotplug) updates: 2020-03-30 18:06:39 -07:00
tracepoint.c
tsacct.c tsacct: add 64-bit btime field 2019-12-18 18:07:31 +01:00
ucount.c ucount: Make sure ucounts in /proc/sys/user don't regress again 2020-04-07 21:51:27 +02:00
uid16.c
uid16.h
umh.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
up.c smp/up: Make smp_call_function_single() match SMP semantics 2020-02-07 15:34:12 +01:00
user_namespace.c
user-return-notifier.c
user.c
utsname_sysctl.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
utsname.c
watchdog_hld.c
watchdog.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
workqueue_internal.h
workqueue.c workqueue: Remove the warning in wq_worker_sleeping() 2020-04-08 11:35:20 +02:00