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Daniel Borkmann 01c5774d82 bpf: Allow for map-in-map with dynamic inner array map entries 
Recent work in f4d05259213f ("bpf: Add map_meta_equal map ops") and 134fede4eecf
("bpf: Relax max_entries check for most of the inner map types") added support
for dynamic inner max elements for most map-in-map types. Exceptions were maps
like array or prog array where the map_gen_lookup() callback uses the maps'
max_entries field as a constant when emitting instructions.

We recently implemented Maglev consistent hashing into Cilium's load balancer
which uses map-in-map with an outer map being hash and inner being array holding
the Maglev backend table for each service. This has been designed this way in
order to reduce overall memory consumption given the outer hash map allows to
avoid preallocating a large, flat memory area for all services. Also, the
number of service mappings is not always known a-priori.

The use case for dynamic inner array map entries is to further reduce memory
overhead, for example, some services might just have a small number of back
ends while others could have a large number. Right now the Maglev backend table
for small and large number of backends would need to have the same inner array
map entries which adds a lot of unneeded overhead.

Dynamic inner array map entries can be realized by avoiding the inlined code
generation for their lookup. The lookup will still be efficient since it will
be calling into array_map_lookup_elem() directly and thus avoiding retpoline.
The patch adds a BPF_F_INNER_MAP flag to map creation which therefore skips
inline code generation and relaxes array_map_meta_equal() check to ignore both
maps' max_entries. This also still allows to have faster lookups for map-in-map
when BPF_F_INNER_MAP is not specified and hence dynamic max_entries not needed.

Example code generation where inner map is dynamic sized array:

  # bpftool p d x i 125
  int handle__sys_enter(void * ctx):
  ; int handle__sys_enter(void *ctx)
     0: (b4) w1 = 0
  ; int key = 0;
     1: (63) *(u32 *)(r10 -4) = r1
     2: (bf) r2 = r10
  ;
     3: (07) r2 += -4
  ; inner_map = bpf_map_lookup_elem(&outer_arr_dyn, &key);
     4: (18) r1 = map[id:468]
     6: (07) r1 += 272
     7: (61) r0 = *(u32 *)(r2 +0)
     8: (35) if r0 >= 0x3 goto pc+5
     9: (67) r0 <<= 3
    10: (0f) r0 += r1
    11: (79) r0 = *(u64 *)(r0 +0)
    12: (15) if r0 == 0x0 goto pc+1
    13: (05) goto pc+1
    14: (b7) r0 = 0
    15: (b4) w6 = -1
  ; if (!inner_map)
    16: (15) if r0 == 0x0 goto pc+6
    17: (bf) r2 = r10
  ;
    18: (07) r2 += -4
  ; val = bpf_map_lookup_elem(inner_map, &key);
    19: (bf) r1 = r0                               | No inlining but instead
    20: (85) call array_map_lookup_elem#149280     | call to array_map_lookup_elem()
  ; return val ? *val : -1;                        | for inner array lookup.
    21: (15) if r0 == 0x0 goto pc+1
  ; return val ? *val : -1;
    22: (61) r6 = *(u32 *)(r0 +0)
  ; }
    23: (bc) w0 = w6
    24: (95) exit

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201010234006.7075-4-daniel@iogearbox.net
 		2022-08-30 11:33:35 +08:00
..
bpf bpf: Allow for map-in-map with dynamic inner array map entries 2022-08-30 11:33:35 +08:00
cgroup bpf: Refactor bpf_link update handling 2022-08-30 11:33:22 +08:00
configs Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
debug kdb: Make memory allocations more robust 2021-04-12 12:52:10 +08:00
dma swiotlb: fix "x86: Don't panic if can not alloc buffer for swiotlb" 2021-03-16 16:40:57 +08:00
events perf: Expose get/put_callchain_entry() 2022-08-30 11:33:26 +08:00
gcov gcov: re-fix clang-11+ support 2021-05-20 16:06:55 +08:00
irq genirq/matrix: Prevent allocation counter corruption 2021-05-20 16:07:24 +08:00
livepatch Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
locking locking/qspinlock: Introduce llc aware spinlock 2022-03-02 10:48:05 +08:00
power PM: EM: postpone creating the debugfs dir till fs_initcall 2021-04-12 12:53:30 +08:00
printk printk: fix deadlock when kernel panic 2021-04-12 12:52:39 +08:00
rcu rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-04-12 12:52:37 +08:00
sched rq-qos: restore the kabi to compatible with 0009.2 2022-07-25 15:05:10 +08:00
time posix-timers: Preserve return value in clock_adjtime32() 2021-05-20 16:07:22 +08:00
tkernel Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
trace selftests/bpf: sync fentry/fexit test from upstream 2022-08-30 11:33:31 +08:00
.gitignore kbuild: update config_data.gz only when the content of .config is changed 2021-05-20 16:07:35 +08:00
Kconfig.freezer Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Kconfig.hz Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Kconfig.locks Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Kconfig.preempt Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Makefile kbuild: update config_data.gz only when the content of .config is changed 2021-05-20 16:07:35 +08:00
acct.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
async.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
audit.c audit: fix a net reference leak in audit_list_rules_send() 2021-03-16 16:29:25 +08:00
audit.h audit: fix a net reference leak in audit_list_rules_send() 2021-03-16 16:29:25 +08:00
audit_fsnotify.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
audit_tree.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
audit_watch.c audit: CONFIG_CHANGE don't log internal bookkeeping as an event 2021-03-16 16:36:51 +08:00
auditfilter.c audit: fix a net reference leak in audit_list_rules_send() 2021-03-16 16:29:25 +08:00
auditsc.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
backtracetest.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
bounds.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
capability.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
compat.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
configs.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
context_tracking.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
cpu.c kernel/cpu: add arch override for clear_tasks_mm_cpumask() mm handling 2021-03-16 16:42:28 +08:00
cpu_pm.c kernel/cpu_pm: Fix uninitted local in cpu_pm 2021-03-16 16:29:48 +08:00
crash_core.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
crash_dump.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
cred.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
delayacct.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
dma.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
exec_domain.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
exit.c don't dump the threads that had been already exiting when zapped. 2021-03-16 16:40:57 +08:00
extable.c bpf: Add support for BTF pointers to x86 JIT 2022-08-30 11:33:17 +08:00
fail_function.c fail_function: Remove a redundant mutex unlock 2021-03-16 16:41:23 +08:00
fork.c exec: Transform exec_update_mutex into a rw_semaphore 2021-04-12 12:51:05 +08:00
freezer.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
futex.c Revert 337f13046ff0 ("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op") 2021-05-20 16:07:35 +08:00
gen_kheaders.sh kbuild: add variables for compression tools 2021-03-16 16:35:19 +08:00
groups.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
hung_task.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
iomem.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
irq_work.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
jump_label.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
kallsyms.c kallsyms: Refactor kallsyms_show_value() to take cred 2021-03-16 16:31:37 +08:00
kcmp.c exec: Transform exec_update_mutex into a rw_semaphore 2021-04-12 12:51:05 +08:00
kcov.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
kexec.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
kexec_core.c kernel: kexec: remove the lock operation of system_transition_mutex 2021-04-12 12:51:43 +08:00
kexec_elf.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
kexec_file.c ima: Free IMA measurement buffer after kexec syscall 2021-04-12 12:52:21 +08:00
kexec_internal.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
kheaders.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
kmod.c kmod: make request_module() return an error when autoloading is disabled 2021-03-16 16:26:15 +08:00
kprobes.c tracing/kprobe: Fix to support kretprobe events on unloaded modules 2021-04-12 12:51:58 +08:00
ksysfs.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
kthread.c kthread: Fix PF_KTHREAD vs to_kthread() race 2022-03-02 10:48:07 +08:00
latencytop.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
module-internal.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
module.c kabi: check modver major version and features 2021-06-23 07:24:18 +00:00
module_signature.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
module_signing.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
notifier.c kernel/notifier.c: intercept duplicate registrations to avoid infinite loops 2021-03-16 16:36:43 +08:00
nsproxy.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
padata.c padata: add separate cpuhp node for CPUHP_PADATA_DEAD 2021-03-16 16:28:57 +08:00
panic.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
params.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
pid.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
pid_namespace.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
profile.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
ptrace.c ptrace: Set PF_SUPERPRIV when checking capability 2021-03-16 16:41:32 +08:00
range.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
reboot.c reboot: fix overflow parsing reboot cpu number 2021-03-16 16:40:55 +08:00
relay.c kernel/relay.c: fix memleak on destroy relay channel 2021-03-16 16:34:28 +08:00
resource.c /dev/mem: Revoke mappings when a driver claims the region 2021-03-16 16:30:25 +08:00
rseq.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
seccomp.c seccomp: Add missing return in non-void function 2021-04-12 12:52:36 +08:00
signal.c ptrace: fix task_join_group_stop() for the case when current is traced 2021-03-16 16:40:18 +08:00
smp.c smp: Fix smp_call_function_single_async prototype 2021-05-20 16:08:01 +08:00
smpboot.c kthread: Extract KTHREAD_IS_PER_CPU 2021-04-12 12:51:51 +08:00
smpboot.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
softirq.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
stackleak.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
stacktrace.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
stop_machine.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
sys.c kernel/sys.c: avoid copying possible padding bytes in copy_to_user 2021-03-16 16:36:43 +08:00
sys_ni.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
sysctl-test.c kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec() 2021-03-16 16:36:31 +08:00
sysctl.c bpf: Sharing bpf runtime stats with BPF_ENABLE_STATS 2022-08-30 11:33:25 +08:00
sysctl_binary.c net: change TCP_TIMEWAIT_LEN on runtime 2021-03-16 16:43:58 +08:00
task_work.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
taskstats.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
test_kprobes.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
torture.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
tracepoint.c tracepoint: Do not fail unregistering a probe due to memory failure 2021-04-12 12:52:27 +08:00
tsacct.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
ucount.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
uid16.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
uid16.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
umh.c usermodehelper: reset umask to default before executing user process 2021-03-16 16:37:54 +08:00
up.c smp: Fix smp_call_function_single_async prototype 2021-05-20 16:08:01 +08:00
user-return-notifier.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
user.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
user_namespace.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
utsname.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
utsname_sysctl.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
watchdog.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
watchdog_hld.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
workqueue.c workqueue: Move the position of debug_work_activate() in __queue_work() 2021-05-20 16:07:02 +08:00
workqueue_internal.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00