linux/tools/lib
Eric Leblond 4708bbda5c tools lib bpf: Fix maps resolution
It is not correct to assimilate the elf data of the maps section to an
array of map definition. In fact the sizes differ. The offset provided
in the symbol section has to be used instead.

This patch fixes a bug causing a elf with two maps not to load
correctly.

Wang Nan added:

This patch requires a name for each BPF map, so array of BPF maps is not
allowed. This restriction is reasonable, because kernel verifier forbid
indexing BPF map from such array unless the index is a fixed value, but
if the index is fixed why not merging it into name?

For example:

Program like this:
  ...
  unsigned long cpu = get_smp_processor_id();
  int *pval = map_lookup_elem(&map_array[cpu], &key);
  ...

Generates bytecode like this:

0: (b7) r1 = 0
1: (63) *(u32 *)(r10 -4) = r1
2: (b7) r1 = 680997
3: (63) *(u32 *)(r10 -8) = r1
4: (85) call 8
5: (67) r0 <<= 4
6: (18) r1 = 0x112dd000
8: (0f) r0 += r1
9: (bf) r2 = r10
10: (07) r2 += -4
11: (bf) r1 = r0
12: (85) call 1

Where instruction 8 is the computation, 8 and 11 render r1 to an invalid
value for function map_lookup_elem, causes verifier report error.

Signed-off-by: Eric Leblond <eric@regit.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Wang Nan <wangnan0@huawei.com>
[ Merge bpf_object__init_maps_name into bpf_object__init_maps.
  Fix segfault for buggy BPF script Validate obj->maps ]
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161115040617.69788-5-wangnan0@huawei.com
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-11-25 11:27:33 -03:00
..
api tools lib api fs: Add hugetlbfs filesystem detector 2016-09-08 12:34:43 -03:00
bpf tools lib bpf: Fix maps resolution 2016-11-25 11:27:33 -03:00
lockdep tools/lib/lockdep: Fix unsupported 'basename -s' in run_tests.sh 2016-03-30 12:45:56 +02:00
subcmd tools lib subcmd: Suppport cascading options 2016-10-25 10:12:16 -03:00
symbol tools lib symbol: Introduce kallsyms2elf_type 2015-09-30 18:34:31 -03:00
traceevent tools lib traceevent: Add retrieval of preempt count and latency flags 2016-11-23 10:44:03 -03:00
bitmap.c tools lib: Add bitmap_and function 2016-08-02 16:33:27 -03:00
find_bit.c tools lib: Add for_each_clear_bit macro 2016-10-24 11:07:33 -03:00
hweight.c tools: Copy lib/hweight.c from the kernel sources 2015-07-09 16:29:56 -03:00
rbtree.c tools: Copy lib/rbtree.c to tools/lib/ 2015-07-05 22:48:21 -03:00
str_error_r.c tools: Introduce str_error_r() 2016-07-12 15:19:47 -03:00
string.c perf tools: Move strlcpy() from perf to tools/lib/string.c 2015-12-16 16:09:39 -03:00
vsprintf.c perf tools: Uninline scnprintf() and vscnprint() 2016-07-12 15:20:24 -03:00