Commit 56818931 authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Andrii Nakryiko
Browse files

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: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220404225020.51029-1-iii@linux.ibm.com
parent d2987617

tools/lib/bpf/libbpf.c

+39 −1
Original line number Diff line number Diff line
@@ -10707,15 +10707,53 @@ static long elf_find_func_offset(const char *binary_path, const char *name) 
	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";