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