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author | Yonghong Song <yhs@fb.com> | 2021-09-24 05:58:56 +0300 |
---|---|---|
committer | Andrii Nakryiko <andrii@kernel.org> | 2021-09-25 01:35:03 +0300 |
commit | 091037fb770e1771a52246f9b68dc76082178a3c (patch) | |
tree | 0b827250f3093b12efbf31aa3247985ea4424fb9 /tools | |
parent | c86216bc96aa2a61ee5248d99d0bd15e69cf52d1 (diff) | |
download | linux-091037fb770e1771a52246f9b68dc76082178a3c.tar.xz |
selftests/bpf: Fix btf_dump __int128 test failure with clang build kernel
With clang build kernel (adding LLVM=1 to kernel and selftests/bpf build
command line), I hit the following test failure:
$ ./test_progs -t btf_dump
...
btf_dump_data:PASS:ensure expected/actual match 0 nsec
btf_dump_data:FAIL:find type id unexpected find type id: actual -2 < expected 0
btf_dump_data:FAIL:find type id unexpected find type id: actual -2 < expected 0
test_btf_dump_int_data:FAIL:dump __int128 unexpected error: -2 (errno 2)
#15/9 btf_dump/btf_dump: int_data:FAIL
Further analysis showed gcc build kernel has type "__int128" in dwarf/BTF
and it doesn't exist in clang build kernel. Code searching for kernel code
found the following:
arch/s390/include/asm/types.h: unsigned __int128 pair;
crypto/ecc.c: unsigned __int128 m = (unsigned __int128)left * right;
include/linux/math64.h: return (u64)(((unsigned __int128)a * mul) >> shift);
include/linux/math64.h: return (u64)(((unsigned __int128)a * mul) >> shift);
lib/ubsan.h:typedef __int128 s_max;
lib/ubsan.h:typedef unsigned __int128 u_max;
In my case, CONFIG_UBSAN is not enabled. Even if we only have "unsigned __int128"
in the code, somehow gcc still put "__int128" in dwarf while clang didn't.
Hence current test works fine for gcc but not for clang.
Enabling CONFIG_UBSAN is an option to provide __int128 type into dwarf
reliably for both gcc and clang, but not everybody enables CONFIG_UBSAN
in their kernel build. So the best choice is to use "unsigned __int128" type
which is available in both clang and gcc build kernels. But clang and gcc
dwarf encoded names for "unsigned __int128" are different:
[$ ~] cat t.c
unsigned __int128 a;
[$ ~] gcc -g -c t.c && llvm-dwarfdump t.o | grep __int128
DW_AT_type (0x00000031 "__int128 unsigned")
DW_AT_name ("__int128 unsigned")
[$ ~] clang -g -c t.c && llvm-dwarfdump t.o | grep __int128
DW_AT_type (0x00000033 "unsigned __int128")
DW_AT_name ("unsigned __int128")
The test change in this patch tries to test type name before
doing actual test.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20210924025856.2192476-1-yhs@fb.com
Diffstat (limited to 'tools')
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/btf_dump.c | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/btf_dump.c b/tools/testing/selftests/bpf/prog_tests/btf_dump.c index 52ccf0cf35e1..87f9df653e4e 100644 --- a/tools/testing/selftests/bpf/prog_tests/btf_dump.c +++ b/tools/testing/selftests/bpf/prog_tests/btf_dump.c @@ -358,12 +358,27 @@ static void test_btf_dump_int_data(struct btf *btf, struct btf_dump *d, TEST_BTF_DUMP_DATA_OVER(btf, d, NULL, str, int, sizeof(int)-1, "", 1); #ifdef __SIZEOF_INT128__ - TEST_BTF_DUMP_DATA(btf, d, NULL, str, __int128, BTF_F_COMPACT, - "(__int128)0xffffffffffffffff", - 0xffffffffffffffff); - ASSERT_OK(btf_dump_data(btf, d, "__int128", NULL, 0, &i, 16, str, - "(__int128)0xfffffffffffffffffffffffffffffffe"), - "dump __int128"); + /* gcc encode unsigned __int128 type with name "__int128 unsigned" in dwarf, + * and clang encode it with name "unsigned __int128" in dwarf. + * Do an availability test for either variant before doing actual test. + */ + if (btf__find_by_name(btf, "unsigned __int128") > 0) { + TEST_BTF_DUMP_DATA(btf, d, NULL, str, unsigned __int128, BTF_F_COMPACT, + "(unsigned __int128)0xffffffffffffffff", + 0xffffffffffffffff); + ASSERT_OK(btf_dump_data(btf, d, "unsigned __int128", NULL, 0, &i, 16, str, + "(unsigned __int128)0xfffffffffffffffffffffffffffffffe"), + "dump unsigned __int128"); + } else if (btf__find_by_name(btf, "__int128 unsigned") > 0) { + TEST_BTF_DUMP_DATA(btf, d, NULL, str, __int128 unsigned, BTF_F_COMPACT, + "(__int128 unsigned)0xffffffffffffffff", + 0xffffffffffffffff); + ASSERT_OK(btf_dump_data(btf, d, "__int128 unsigned", NULL, 0, &i, 16, str, + "(__int128 unsigned)0xfffffffffffffffffffffffffffffffe"), + "dump unsigned __int128"); + } else { + ASSERT_TRUE(false, "unsigned_int128_not_found"); + } #endif } |