linux/tools/perf/util/jitdump.h
Gustavo A. R. Silva 6549a8c0c3 perf tools: Replace zero-length array with flexible-array
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array
member[1][2], introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gustavo A. R. Silva <gustavo@embeddedor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200515172926.GA31976@embeddedor
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-05-28 10:03:27 -03:00

141 lines
2.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* jitdump.h: jitted code info encapsulation file format
*
* Adapted from OProfile GPLv2 support jidump.h:
* Copyright 2007 OProfile authors
* Jens Wilke
* Daniel Hansel
* Copyright IBM Corporation 2007
*/
#ifndef JITDUMP_H
#define JITDUMP_H
#include <sys/time.h>
#include <time.h>
#include <stdint.h>
/* JiTD */
#define JITHEADER_MAGIC 0x4A695444
#define JITHEADER_MAGIC_SW 0x4454694A
#define PADDING_8ALIGNED(x) ((((x) + 7) & 7) ^ 7)
#define ALIGN_8(x) (((x) + 7) & (~7))
#define JITHEADER_VERSION 1
enum jitdump_flags_bits {
JITDUMP_FLAGS_ARCH_TIMESTAMP_BIT,
JITDUMP_FLAGS_MAX_BIT,
};
#define JITDUMP_FLAGS_ARCH_TIMESTAMP (1ULL << JITDUMP_FLAGS_ARCH_TIMESTAMP_BIT)
#define JITDUMP_FLAGS_RESERVED (JITDUMP_FLAGS_MAX_BIT < 64 ? \
(~((1ULL << JITDUMP_FLAGS_MAX_BIT) - 1)) : 0)
struct jitheader {
uint32_t magic; /* characters "jItD" */
uint32_t version; /* header version */
uint32_t total_size; /* total size of header */
uint32_t elf_mach; /* elf mach target */
uint32_t pad1; /* reserved */
uint32_t pid; /* JIT process id */
uint64_t timestamp; /* timestamp */
uint64_t flags; /* flags */
};
enum jit_record_type {
JIT_CODE_LOAD = 0,
JIT_CODE_MOVE = 1,
JIT_CODE_DEBUG_INFO = 2,
JIT_CODE_CLOSE = 3,
JIT_CODE_UNWINDING_INFO = 4,
JIT_CODE_MAX,
};
/* record prefix (mandatory in each record) */
struct jr_prefix {
uint32_t id;
uint32_t total_size;
uint64_t timestamp;
};
struct jr_code_load {
struct jr_prefix p;
uint32_t pid;
uint32_t tid;
uint64_t vma;
uint64_t code_addr;
uint64_t code_size;
uint64_t code_index;
};
struct jr_code_close {
struct jr_prefix p;
};
struct jr_code_move {
struct jr_prefix p;
uint32_t pid;
uint32_t tid;
uint64_t vma;
uint64_t old_code_addr;
uint64_t new_code_addr;
uint64_t code_size;
uint64_t code_index;
};
struct debug_entry {
uint64_t addr;
int lineno; /* source line number starting at 1 */
int discrim; /* column discriminator, 0 is default */
const char name[]; /* null terminated filename, \xff\0 if same as previous entry */
};
struct jr_code_debug_info {
struct jr_prefix p;
uint64_t code_addr;
uint64_t nr_entry;
struct debug_entry entries[];
};
struct jr_code_unwinding_info {
struct jr_prefix p;
uint64_t unwinding_size;
uint64_t eh_frame_hdr_size;
uint64_t mapped_size;
const char unwinding_data[];
};
union jr_entry {
struct jr_code_debug_info info;
struct jr_code_close close;
struct jr_code_load load;
struct jr_code_move move;
struct jr_prefix prefix;
struct jr_code_unwinding_info unwinding;
};
static inline struct debug_entry *
debug_entry_next(struct debug_entry *ent)
{
void *a = ent + 1;
size_t l = strlen(ent->name) + 1;
return a + l;
}
static inline char *
debug_entry_file(struct debug_entry *ent)
{
void *a = ent + 1;
return a;
}
#endif /* !JITDUMP_H */