Commit Graph

6 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith b3a66691f8 IR: Make metadata typeless in assembly, clang side
Match LLVM changes from r224257.

llvm-svn: 224259
2014-12-15 19:10:08 +00:00
Alexey Samsonov a0ac3c2bf0 [ASan] Improve blacklisting of global variables.
This commit changes the way we blacklist global variables in ASan.
Now the global is excluded from instrumentation (either regular
bounds checking, or initialization-order checking) if:

1) Global is explicitly blacklisted by its mangled name.
This part is left unchanged.

2) SourceLocation of a global is in blacklisted source file.
This changes the old behavior, where instead of looking at the
SourceLocation of a variable we simply considered llvm::Module
identifier. This was wrong, as identifier may not correspond to
the file name, and we incorrectly disabled instrumentation
for globals coming from #include'd files.

3) Global is blacklisted by type.
Now we build the type of a global variable using Clang machinery
(QualType::getAsString()), instead of llvm::StructType::getName().

After this commit, the active users of ASan blacklist files
may have to revisit them (this is a backwards-incompatible change).

llvm-svn: 220097
2014-10-17 22:37:33 +00:00
Alexey Samsonov d9ad5cec0c [ASan] Use metadata to pass source-level information from Clang to ASan.
Instead of creating global variables for source locations and global names,
just create metadata nodes and strings. They will be transformed into actual
globals in the instrumentation pass (if necessary). This approach is more
flexible:
1) we don't have to ensure that our custom globals survive all the optimizations
2) if globals are discarded for some reason, we will simply ignore metadata for them
   and won't have to erase corresponding globals
3) metadata for source locations can be reused for other purposes: e.g. we may
   attach source location metadata to alloca instructions and provide better descriptions
   for stack variables in ASan error reports.

No functionality change.

llvm-svn: 214604
2014-08-02 00:35:50 +00:00
Alexey Samsonov 15c9669615 [ASan] Collect unmangled names of global variables in Clang to print them in error reports.
Currently ASan instrumentation pass creates a string with global name
for each instrumented global (to include global names in the error report). Global
name is already mangled at this point, and we may not be able to demangle it
at runtime (e.g. there is no __cxa_demangle on Android).

Instead, create a string with fully qualified global name in Clang, and pass it
to ASan instrumentation pass in llvm.asan.globals metadata. If there is no metadata
for some global, ASan will use the original algorithm.

This fixes https://code.google.com/p/address-sanitizer/issues/detail?id=264.

llvm-svn: 212872
2014-07-12 00:42:52 +00:00
Alexey Samsonov e7a8ccfaad [Sanitizer] Reduce the usage of sanitizer blacklist in CodeGenModule
Get rid of cached CodeGenModule::SanOpts, which was used to turn off
sanitizer codegen options if current LLVM Module is blacklisted, and use
plain LangOpts.Sanitize instead.

1) Some codegen decisions (turning TBAA or writable strings on/off)
   shouldn't depend on the contents of blacklist.

2) llvm.asan.globals should *always* be created, even if the module
   is blacklisted - soon Clang's CodeGen where we read sanitizer
   blacklist files, so we should properly report which globals are
   blacklisted to the backend.

llvm-svn: 212499
2014-07-07 23:34:34 +00:00
Alexey Samsonov 4f319cca42 [ASan] Print exact source location of global variables in error reports.
See https://code.google.com/p/address-sanitizer/issues/detail?id=299 for the
original feature request.

Introduce llvm.asan.globals metadata, which Clang (or any other frontend)
may use to report extra information about global variables to ASan
instrumentation pass in the backend. This metadata replaces
llvm.asan.dynamically_initialized_globals that was used to detect init-order
bugs. llvm.asan.globals contains the following data for each global:
  1) source location (file/line/column info);
  2) whether it is dynamically initialized;
  3) whether it is blacklisted (shouldn't be instrumented).

Source location data is then emitted in the binary and can be picked up
by ASan runtime in case it needs to print error report involving some global.
For example:

  0x... is located 4 bytes to the right of global variable 'C::array' defined in '/path/to/file:17:8' (0x...) of size 40

These source locations are printed even if the binary doesn't have any
debug info.

This is an ABI-breaking change. ASan initialization is renamed to
__asan_init_v4(). Pre-built libraries compiled with older Clang will not work
with the fresh runtime.

llvm-svn: 212188
2014-07-02 16:54:41 +00:00