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libbpf: Handle GCC built-in types for Arm NEON 

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
This commit is contained in:
Jean-Philippe Brucker 2020-08-12 16:39:10 +02:00 committed by Alexei Starovoitov
parent 8faf7fc597
commit 702eddc77a
1 changed files with 34 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
tools/lib/bpf/btf_dump.c
View File

@ -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"
@ -549,6 +550,9 @@ 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,
@ -671,6 +675,9 @@ 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:
@ -870,7 +877,7 @@ 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, ";");
@ -890,6 +897,32 @@ 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)
{