libbpf: Support Debian in resolve_full_path()

attach_probe selftest fails on Debian-based distros with `failed to
resolve full path for 'libc.so.6'`. The reason is that these distros
embraced multiarch to the point where even for the "main" architecture
they store libc in /lib/<triple>.

This is configured in /etc/ld.so.conf and in theory it's possible to
replicate the loader's parsing and processing logic in libbpf, however
a much simpler solution is to just enumerate the known library paths.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220404225020.51029-1-iii@linux.ibm.com
This commit is contained in:
Ilya Leoshkevich 2022-04-05 00:50:20 +02:00 committed by Andrii Nakryiko
parent d298761746
commit 568189310c

View File

@ -10707,15 +10707,53 @@ out:
return ret;
}
static const char *arch_specific_lib_paths(void)
{
/*
* Based on https://packages.debian.org/sid/libc6.
*
* Assume that the traced program is built for the same architecture
* as libbpf, which should cover the vast majority of cases.
*/
#if defined(__x86_64__)
return "/lib/x86_64-linux-gnu";
#elif defined(__i386__)
return "/lib/i386-linux-gnu";
#elif defined(__s390x__)
return "/lib/s390x-linux-gnu";
#elif defined(__s390__)
return "/lib/s390-linux-gnu";
#elif defined(__arm__) && defined(__SOFTFP__)
return "/lib/arm-linux-gnueabi";
#elif defined(__arm__) && !defined(__SOFTFP__)
return "/lib/arm-linux-gnueabihf";
#elif defined(__aarch64__)
return "/lib/aarch64-linux-gnu";
#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 64
return "/lib/mips64el-linux-gnuabi64";
#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 32
return "/lib/mipsel-linux-gnu";
#elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return "/lib/powerpc64le-linux-gnu";
#elif defined(__sparc__) && defined(__arch64__)
return "/lib/sparc64-linux-gnu";
#elif defined(__riscv) && __riscv_xlen == 64
return "/lib/riscv64-linux-gnu";
#else
return NULL;
#endif
}
/* Get full path to program/shared library. */
static int resolve_full_path(const char *file, char *result, size_t result_sz)
{
const char *search_paths[2];
const char *search_paths[3] = {};
int i;
if (strstr(file, ".so")) {
search_paths[0] = getenv("LD_LIBRARY_PATH");
search_paths[1] = "/usr/lib64:/usr/lib";
search_paths[2] = arch_specific_lib_paths();
} else {
search_paths[0] = getenv("PATH");
search_paths[1] = "/usr/bin:/usr/sbin";