linux.git/tools/testing/selftests/bpf/test_maps.c, branch v4.13

bpf, tests: add a test for htab lookup + update traversal

2017-06-10T23:05:46+00:00

Add a test case to track behaviour when traversing and updating the
htab map. We recently used such traversal, so it's quite useful to
keep it as an example in selftests.

Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

bpf: provide a generic macro for percpu values for selftests

2017-04-28T19:48:15+00:00

To overcome bugs as described and fixed in 89087c456fb5 ("bpf: Fix
values type used in test_maps"), provide a generic BPF_DECLARE_PERCPU()
and bpf_percpu() accessor macro for all percpu map values used in
tests.

Declaring variables works as follows (also works for structs):

  BPF_DECLARE_PERCPU(uint32_t, my_value);

They can then be accessed normally as uint32_t type through:

  bpf_percpu(my_value, )

For example:

  bpf_percpu(my_value, 0)++;

Implicitly, we make sure that the passed type is allocated and aligned
by gcc at least on a 8-byte boundary, so that it works together with
the map lookup/update syscall for percpu maps. We use it as a usage
example in test_maps, so that others are free to adapt this into their
code when necessary.

Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

bpf: map_get_next_key to return first key on NULL

2017-04-25T15:57:45+00:00

When iterating through a map, we need to find a key that does not exist
in the map so map_get_next_key will give us the first key of the map.
This often requires a lot of guessing in production systems.

This patch makes map_get_next_key return the first key when the key
pointer in the parameter is NULL.

Signed-off-by: Teng Qin 
Signed-off-by: Alexei Starovoitov 
Acked-by: Daniel Borkmann 
Signed-off-by: David S. Miller

bpf: Fix values type used in test_maps

2017-04-21T19:16:46+00:00

Maps of per-cpu type have their value element size adjusted to 8 if it
is specified smaller during various map operations.

This makes test_maps as a 32-bit binary fail, in fact the kernel
writes past the end of the value's array on the user's stack.

To be quite honest, I think the kernel should reject creation of a
per-cpu map that doesn't have a value size of at least 8 if that's
what the kernel is going to silently adjust to later.

If the user passed something smaller, it is a sizeof() calcualtion
based upon the type they will actually use (just like in this testcase
code) in later calls to the map operations.

Fixes: df570f577231 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_ARRAY")
Signed-off-by: David S. Miller 
Acked-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov

bpf: fix hashmap extra_elems logic

2017-03-22T21:12:18+00:00

In both kmalloc and prealloc mode the bpf_map_update_elem() is using
per-cpu extra_elems to do atomic update when the map is full.
There are two issues with it. The logic can be misused, since it allows
max_entries+num_cpus elements to be present in the map. And alloc_extra_elems()
at map creation time can fail percpu alloc for large map values with a warn:
WARNING: CPU: 3 PID: 2752 at ../mm/percpu.c:892 pcpu_alloc+0x119/0xa60
illegal size (32824) or align (8) for percpu allocation

The fixes for both of these issues are different for kmalloc and prealloc modes.
For prealloc mode allocate extra num_possible_cpus elements and store
their pointers into extra_elems array instead of actual elements.
Hence we can use these hidden(spare) elements not only when the map is full
but during bpf_map_update_elem() that replaces existing element too.
That also improves performance, since pcpu_freelist_pop/push is avoided.
Unfortunately this approach cannot be used for kmalloc mode which needs
to kfree elements after rcu grace period. Therefore switch it back to normal
kmalloc even when full and old element exists like it was prior to
commit 6c9059817432 ("bpf: pre-allocate hash map elements").

Add tests to check for over max_entries and large map values.

Reported-by: Dave Jones 
Fixes: 6c9059817432 ("bpf: pre-allocate hash map elements")
Signed-off-by: Alexei Starovoitov 
Acked-by: Daniel Borkmann 
Acked-by: Martin KaFai Lau 
Signed-off-by: David S. Miller

bpf: Remove bpf_sys.h from selftests

2017-02-10T20:56:08+00:00

Add require dependency headers.

Signed-off-by: Mickaël Salaün 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Shuah Khan 
Signed-off-by: David S. Miller

bpf: Use bpf_create_map() from the library

2017-02-10T20:56:07+00:00

Replace bpf_map_create() with bpf_create_map() calls.

Signed-off-by: Mickaël Salaün 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Shuah Khan 
Signed-off-by: David S. Miller

bpf: Use bpf_map_get_next_key() from the library

2017-02-10T20:56:07+00:00

Replace bpf_map_next_key() with bpf_map_get_next_key() calls.

Signed-off-by: Mickaël Salaün 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Shuah Khan 
Signed-off-by: David S. Miller

bpf: Use bpf_map_delete_elem() from the library

2017-02-10T20:56:07+00:00

Replace bpf_map_delete() with bpf_map_delete_elem() calls.

Signed-off-by: Mickaël Salaün 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Shuah Khan 
Signed-off-by: David S. Miller

bpf: Use bpf_map_lookup_elem() from the library

2017-02-10T20:56:07+00:00

Replace bpf_map_lookup() with bpf_map_lookup_elem() calls.

Signed-off-by: Mickaël Salaün 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Shuah Khan 
Signed-off-by: David S. Miller