[PATCH 5.4 129/214] libbpf: Handle GCC built-in types for Arm NEON

Greg Kroah-Hartman
2020-09-01T16:19:38Z

From: Jean-Philippe Brucker <jean-philippe@linaro.org>

[ Upstream commit 702eddc77a905782083b14ccd05b23840675fd18 ]

When building Arm NEON (SIMD) code from lib/raid6/neon.uc, GCC emits
DWARF information using a base type "__Poly8_t", which is internal to
GCC and not recognized by Clang. This causes build failures when
building with Clang a vmlinux.h generated from an arm64 kernel that was
built with GCC.

vmlinux.h:47284:9: error: unknown type name '__Poly8_t'
typedef __Poly8_t poly8x16_t[16];
^~~~~~~~~

The polyX_t types are defined as unsigned integers in the "Arm C
Language Extension" document (101028_Q220_00_en). Emit typedefs based on
standard integer types for the GCC internal types, similar to those
emitted by Clang.

Including linux/kernel.h to use ARRAY_SIZE() incidentally redefined
max(), causing a build bug due to different types, hence the seemingly
unrelated change.

Reported-by: Jakov Petrina <jakov.petrina@sartura.hr>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200812143909.3293280-1-jean-philippe@linaro.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/btf_dump.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index d9e386b8f47ed..07fcc8e79662d 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -13,6 +13,7 @@
#include <errno.h>
#include <linux/err.h>
#include <linux/btf.h>
+#include <linux/kernel.h>
#include "btf.h"
#include "hashmap.h"
#include "libbpf.h"
@@ -543,6 +544,9 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
}
}

+static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
+ const struct btf_type *t);
+
static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
const struct btf_type *t);
static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id,
@@ -665,6 +669,9 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)

switch (kind) {
case BTF_KIND_INT:
+ /* Emit type alias definitions if necessary */
+ btf_dump_emit_missing_aliases(d, id, t);
+
tstate->emit_state = EMITTED;
break;
case BTF_KIND_ENUM:
@@ -899,7 +906,7 @@ static void btf_dump_emit_struct_def(struct btf_dump *d,
btf_dump_printf(d, ": %d", m_sz);
off = m_off + m_sz;
} else {
- m_sz = max(0, btf__resolve_size(d->btf, m->type));
+ m_sz = max(0LL, btf__resolve_size(d->btf, m->type));
off = m_off + m_sz * 8;
}
btf_dump_printf(d, ";");
@@ -919,6 +926,32 @@ static void btf_dump_emit_struct_def(struct btf_dump *d,
btf_dump_printf(d, " __attribute__((packed))");
}

+static const char *missing_base_types[][2] = {
+ /*
+ * GCC emits typedefs to its internal __PolyX_t types when compiling Arm
+ * SIMD intrinsics. Alias them to standard base types.
+ */
+ { "__Poly8_t", "unsigned char" },
+ { "__Poly16_t", "unsigned short" },
+ { "__Poly64_t", "unsigned long long" },
+ { "__Poly128_t", "unsigned __int128" },
+};
+
+static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
+ const struct btf_type *t)
+{
+ const char *name = btf_dump_type_name(d, id);
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(missing_base_types); i++) {
+ if (strcmp(name, missing_base_types[i][0]) == 0) {
+ btf_dump_printf(d, "typedef %s %s;\n\n",
+ missing_base_types[i][1], name);
+ break;
+ }
+ }
+}
+
static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
const struct btf_type *t)
{
--
2.25.1