`ulp patches` skip livepatchable libraries

[giulianobelinassi]

Because of:

libpulp/tools/patches.c

Line 441 in fd16e1b

int len = MIN(obj->num_symbols, 64);

libcrypto.so.1.1 is not being listed as a livepatchable library in SLE-15-SP4. Find another way of finding if a loaded library is livepatchable in the target process.

[giulianobelinassi]

One way of fixing this is by not limiting the number of symbols to 64. But that slows down patchable considerably because glibc is huge.

[giulianobelinassi]

A safe value for this seems to be 8192:

[giulianobelinassi]

The above graph was generated by simulating how many symbols patches would have to read to decide if a library is livepatchable or not on all libraries in /usr/lib64/ and its subdirectories.

[giulianobelinassi]

Some libraries have up to 50.000 symbols, so limiting to 8000 may still have some speedups.