forked from Minki/linux
0284fecd13
This record is intended to provide unwinding information in the
eh_frame format. This is required to unwind JITed code which
does not maintain the frame pointer register during function calls.
The eh_frame unwinding information can be emitted by V8 / Chromium
when the --perf_prof_unwinding_info is passed.
A record of type jr_code_unwinding_info comes before the jr_code_load
it referred to and contains both the .eh_frame and .eh_frame_hdr.
The fields in the header have the following meaning:
* unwinding_size: size of the eh_frame and eh_frame_hdr, necessary
for distinguishing the content from the padding.
* eh_frame_hdr_size: as the name says.
* mapped_size: size of the payload that was in memory at runtime.
typically unwinding_size if the .eh_frame_hdr and .eh_frame were
mapped, or 0 if they weren't. It should always be the former case,
since the .eh_frame is guaranteed to be mapped in memory. However,
certain JITs might want to inject an .eh_frame_hdr with an empty LUT
to trigger fp-based unwinding fallback in libunwind. The only part
of the .eh_frame_hdr that libunwind reads from remote memory is the
LUT, and since there is none, mapping the unwinding info in memory
is not necessary, and 0 in this field signifies that it wasn't.
This practical hack allows to save bytes in code memory for those
JIT compilers that might or might not maintain a valid frame pointer.
The payload that follows is assumed to contain first the .eh_frame and
then the .eh_header_hdr, with no padding between the two.
Signed-off-by: Stefano Sanfilippo <ssanfilippo@chromium.org>
Signed-off-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Stephane Eranian <eranian@google.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1476356383-30100-7-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
140 lines
2.8 KiB
C
140 lines
2.8 KiB
C
/*
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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[0]; /* 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[0];
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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[0];
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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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