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snapshot: add size info for builtins on Posix

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Lack of size information can cause debugging and observability tools to
misbehave or to fail. We can see the size for all builtins is zero with
objdump:

  $ objdump -t d8 | grep Builtins_ArgumentsAdaptorTrampoline
  0000000001084a00 l     F .text  0000000000000000              Builtins_ArgumentsAdaptorTrampoline
                                  ^
                                  Size is zero

Tools like bpftrace rely on the function size to guarantee a tracepoint
is added within function boundaries. Without size information, those
tools can't guarantee a tracepoint will be added safely.

Add .size directive for each builtin function, as described in
https://sourceware.org/binutils/docs-2.24/as/Size.html#Size, to fix this
issue. We can see with objdump that the size is properly set:

  $ objdump -t d8 | grep Builtins_ArgumentsAdaptorTrampoline
  00000000010bf820 l     F .text  0000000000000140              Builtins_ArgumentsAdaptorTrampoline

R=bmeurer@chromium.org, hpayer@chromium.org, verwaest@chromium.org, yangguo@chromium.org

Change-Id: I4cd2b0a12b629498dd9d7465cc1002dda37028c7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1898807
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64824}
This commit is contained in:
Matheus Marchini 2019-11-05 10:04:06 -08:00 committed by Commit Bot
parent 73110f6e69
commit 48d964af83
10 changed files with 25 additions and 12 deletions
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3
src/snapshot/embedded/embedded-file-writer.cc
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@ -31,7 +31,8 @@ void EmbeddedFileWriter::WriteBuiltin(PlatformEmbeddedFileWriterBase* w,
// Isolate::SetEmbeddedBlob that the blob layout remains unchanged, i.e.
// that labels do not insert bytes into the middle of the blob byte
// stream.
w->DeclareFunctionBegin(builtin_symbol.begin());
w->DeclareFunctionBegin(builtin_symbol.begin(),
blob->InstructionSizeOfBuiltin(builtin_id));
const std::vector<byte>& current_positions = source_positions_[builtin_id];
// The code below interleaves bytes of assembly code for the builtin

4
src/snapshot/embedded/platform-embedded-file-writer-aix.cc
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@ -82,7 +82,9 @@ void PlatformEmbeddedFileWriterAIX::SourceInfo(int fileid, const char* filename,
fprintf(fp_, ".xline %d, \"%s\"\n", line, filename);
}
void PlatformEmbeddedFileWriterAIX::DeclareFunctionBegin(const char* name) {
// TODO(mmarchini): investigate emitting size annotations for AIX
void PlatformEmbeddedFileWriterAIX::DeclareFunctionBegin(const char* name,
uint32_t size) {
Newline();
DeclareSymbolGlobal(name);
fprintf(fp_, ".csect %s[DS]\n", name); // function descriptor

2
src/snapshot/embedded/platform-embedded-file-writer-aix.h
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@ -34,7 +34,7 @@ class PlatformEmbeddedFileWriterAIX : public PlatformEmbeddedFileWriterBase {
void DeclareLabel(const char* name) override;
void SourceInfo(int fileid, const char* filename, int line) override;
void DeclareFunctionBegin(const char* name) override;
void DeclareFunctionBegin(const char* name, uint32_t size) override;
void DeclareFunctionEnd(const char* name) override;
int HexLiteral(uint64_t value) override;

2
src/snapshot/embedded/platform-embedded-file-writer-base.h
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@ -63,7 +63,7 @@ class PlatformEmbeddedFileWriterBase {
virtual void DeclareLabel(const char* name) = 0;
virtual void SourceInfo(int fileid, const char* filename, int line) = 0;
virtual void DeclareFunctionBegin(const char* name) = 0;
virtual void DeclareFunctionBegin(const char* name, uint32_t size) = 0;
virtual void DeclareFunctionEnd(const char* name) = 0;
// Returns the number of printed characters.

4
src/snapshot/embedded/platform-embedded-file-writer-generic.cc
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@ -95,7 +95,8 @@ void PlatformEmbeddedFileWriterGeneric::SourceInfo(int fileid,
fprintf(fp_, ".loc %d %d\n", fileid, line);
}
void PlatformEmbeddedFileWriterGeneric::DeclareFunctionBegin(const char* name) {
void PlatformEmbeddedFileWriterGeneric::DeclareFunctionBegin(const char* name,
uint32_t size) {
DeclareLabel(name);
if (target_arch_ == EmbeddedTargetArch::kArm ||
@ -108,6 +109,7 @@ void PlatformEmbeddedFileWriterGeneric::DeclareFunctionBegin(const char* name) {
// to create a DWARF subprogram entry.
fprintf(fp_, ".type %s, @function\n", name);
}
fprintf(fp_, ".size %s, %u\n", name, size);
}
void PlatformEmbeddedFileWriterGeneric::DeclareFunctionEnd(const char* name) {}

2
src/snapshot/embedded/platform-embedded-file-writer-generic.h
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@ -36,7 +36,7 @@ class PlatformEmbeddedFileWriterGeneric
void DeclareLabel(const char* name) override;
void SourceInfo(int fileid, const char* filename, int line) override;
void DeclareFunctionBegin(const char* name) override;
void DeclareFunctionBegin(const char* name, uint32_t size) override;
void DeclareFunctionEnd(const char* name) override;
int HexLiteral(uint64_t value) override;

4
src/snapshot/embedded/platform-embedded-file-writer-mac.cc
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@ -78,7 +78,9 @@ void PlatformEmbeddedFileWriterMac::SourceInfo(int fileid, const char* filename,
fprintf(fp_, ".loc %d %d\n", fileid, line);
}
void PlatformEmbeddedFileWriterMac::DeclareFunctionBegin(const char* name) {
// TODO(mmarchini): investigate emitting size annotations for OS X
void PlatformEmbeddedFileWriterMac::DeclareFunctionBegin(const char* name,
uint32_t size) {
DeclareLabel(name);
// TODO(mvstanton): Investigate the proper incantations to mark the label as

2
src/snapshot/embedded/platform-embedded-file-writer-mac.h
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@ -34,7 +34,7 @@ class PlatformEmbeddedFileWriterMac : public PlatformEmbeddedFileWriterBase {
void DeclareLabel(const char* name) override;
void SourceInfo(int fileid, const char* filename, int line) override;
void DeclareFunctionBegin(const char* name) override;
void DeclareFunctionBegin(const char* name, uint32_t size) override;
void DeclareFunctionEnd(const char* name) override;
int HexLiteral(uint64_t value) override;

12
src/snapshot/embedded/platform-embedded-file-writer-win.cc
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@ -418,7 +418,9 @@ void PlatformEmbeddedFileWriterWin::SourceInfo(int fileid, const char* filename,
// Its syntax is #line <line> "<filename>"
}
void PlatformEmbeddedFileWriterWin::DeclareFunctionBegin(const char* name) {
// TODO(mmarchini): investigate emitting size annotations for Windows
void PlatformEmbeddedFileWriterWin::DeclareFunctionBegin(const char* name,
uint32_t size) {
fprintf(fp_, "%s%s PROC\n", SYMBOL_PREFIX, name);
}
@ -522,7 +524,9 @@ void PlatformEmbeddedFileWriterWin::SourceInfo(int fileid, const char* filename,
// Its syntax is #line <line> "<filename>"
}
void PlatformEmbeddedFileWriterWin::DeclareFunctionBegin(const char* name) {
// TODO(mmarchini): investigate emitting size annotations for Windows
void PlatformEmbeddedFileWriterWin::DeclareFunctionBegin(const char* name,
uint32_t size) {
fprintf(fp_, "%s%s FUNCTION\n", SYMBOL_PREFIX, name);
}
@ -638,7 +642,9 @@ void PlatformEmbeddedFileWriterWin::SourceInfo(int fileid, const char* filename,
// Windows.
}
void PlatformEmbeddedFileWriterWin::DeclareFunctionBegin(const char* name) {
// TODO(mmarchini): investigate emitting size annotations for Windows
void PlatformEmbeddedFileWriterWin::DeclareFunctionBegin(const char* name,
uint32_t size) {
DeclareLabel(name);
if (target_arch_ == EmbeddedTargetArch::kArm64) {

2
src/snapshot/embedded/platform-embedded-file-writer-win.h
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@ -33,7 +33,7 @@ class PlatformEmbeddedFileWriterWin : public PlatformEmbeddedFileWriterBase {
void DeclareLabel(const char* name) override;
void SourceInfo(int fileid, const char* filename, int line) override;
void DeclareFunctionBegin(const char* name) override;
void DeclareFunctionBegin(const char* name, uint32_t size) override;
void DeclareFunctionEnd(const char* name) override;
int HexLiteral(uint64_t value) override;