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5 Commits

Author SHA1 Message Date
Yang Shi
ac00881f92 bpf: convert hashtab lock to raw lock
When running bpf samples on rt kernel, it reports the below warning:

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
in_atomic(): 1, irqs_disabled(): 128, pid: 477, name: ping
Preemption disabled at:[<ffff80000017db58>] kprobe_perf_func+0x30/0x228

CPU: 3 PID: 477 Comm: ping Not tainted 4.1.10-rt8 
Hardware name: Freescale Layerscape 2085a RDB Board (DT)
Call trace:
[<ffff80000008a5b0>] dump_backtrace+0x0/0x128
[<ffff80000008a6f8>] show_stack+0x20/0x30
[<ffff8000007da90c>] dump_stack+0x7c/0xa0
[<ffff8000000e4830>] ___might_sleep+0x188/0x1a0
[<ffff8000007e2200>] rt_spin_lock+0x28/0x40
[<ffff80000018bf9c>] htab_map_update_elem+0x124/0x320
[<ffff80000018c718>] bpf_map_update_elem+0x40/0x58
[<ffff800000187658>] __bpf_prog_run+0xd48/0x1640
[<ffff80000017ca6c>] trace_call_bpf+0x8c/0x100
[<ffff80000017db58>] kprobe_perf_func+0x30/0x228
[<ffff80000017dd84>] kprobe_dispatcher+0x34/0x58
[<ffff8000007e399c>] kprobe_handler+0x114/0x250
[<ffff8000007e3bf4>] kprobe_breakpoint_handler+0x1c/0x30
[<ffff800000085b80>] brk_handler+0x88/0x98
[<ffff8000000822f0>] do_debug_exception+0x50/0xb8
Exception stack(0xffff808349687460 to 0xffff808349687580)
7460: 4ca2b600 ffff8083 4a3a7000 ffff8083 49687620 ffff8083 0069c5f8 ffff8000
7480: 00000001 00000000 007e0628 ffff8000 496874b0 ffff8083 007e1de8 ffff8000
74a0: 496874d0 ffff8083 0008e04c ffff8000 00000001 00000000 4ca2b600 ffff8083
74c0: 00ba2e80 ffff8000 49687528 ffff8083 49687510 ffff8083 000e5c70 ffff8000
74e0: 00c22348 ffff8000 00000000 ffff8083 49687510 ffff8083 000e5c74 ffff8000
7500: 4ca2b600 ffff8083 49401800 ffff8083 00000001 00000000 00000000 00000000
7520: 496874d0 ffff8083 00000000 00000000 00000000 00000000 00000000 00000000
7540: 2f2e2d2c 33323130 00000000 00000000 4c944500 ffff8083 00000000 00000000
7560: 00000000 00000000 008751e0 ffff8000 00000001 00000000 124e2d1d 00107b77

Convert hashtab lock to raw lock to avoid such warning.

Signed-off-by: Yang Shi <yang.shi@linaro.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-11-02 15:45:43 -05:00
Alexei Starovoitov
aaac3ba95e bpf: charge user for creation of BPF maps and programs
since eBPF programs and maps use kernel memory consider it 'locked' memory
from user accounting point of view and charge it against RLIMIT_MEMLOCK limit.
This limit is typically set to 64Kbytes by distros, so almost all
bpf+tracing programs would need to increase it, since they use maps,
but kernel charges maximum map size upfront.
For example the hash map of 1024 elements will be charged as 64Kbyte.
It's inconvenient for current users and changes current behavior for root,
but probably worth doing to be consistent root vs non-root.

Similar accounting logic is done by mmap of perf_event.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-12 19:13:36 -07:00
Daniel Borkmann
a2c83fff58 ebpf: constify various function pointer structs
We can move bpf_map_ops and bpf_verifier_ops and other structs into ro
section, bpf_map_type_list and bpf_prog_type_list into read mostly.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 14:05:18 -05:00
Alexei Starovoitov
daaf427c6a bpf: fix arraymap NULL deref and missing overflow and zero size checks
- fix NULL pointer dereference:
kernel/bpf/arraymap.c:41 array_map_alloc() error: potential null dereference 'array'.  (kzalloc returns null)
kernel/bpf/arraymap.c:41 array_map_alloc() error: we previously assumed 'array' could be null (see line 40)

- integer overflow check was missing in arraymap
(hashmap checks for overflow via kmalloc_array())

- arraymap can round_up(value_size, 8) to zero. check was missing.

- hashmap was missing zero size check as well, since roundup_pow_of_two() can
truncate into zero

- found a typo in the arraymap comment and unnecessary empty line

Fix all of these issues and make both overflow checks explicit U32 in size.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-11-19 15:40:00 -05:00
Alexei Starovoitov
0f8e4bd8a1 bpf: add hashtable type of eBPF maps
add new map type BPF_MAP_TYPE_HASH and its implementation

- maps are created/destroyed by userspace. Both userspace and eBPF programs
  can lookup/update/delete elements from the map

- eBPF programs can be called in_irq(), so use spin_lock_irqsave() mechanism
  for concurrent updates

- key/value are opaque range of bytes (aligned to 8 bytes)

- user space provides 3 configuration attributes via BPF syscall:
  key_size, value_size, max_entries

- map takes care of allocating/freeing key/value pairs

- map_update_elem() must fail to insert new element when max_entries
  limit is reached to make sure that eBPF programs cannot exhaust memory

- map_update_elem() replaces elements in an atomic way

- optimized for speed of lookup() which can be called multiple times from
  eBPF program which itself is triggered by high volume of events
  . in the future JIT compiler may recognize lookup() call and optimize it
    further, since key_size is constant for life of eBPF program

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-11-18 13:43:25 -05:00