[XRay][compiler-rt] Update use of internal_mmap

Summary:
The implementation of `internal_mmap(...)` deviates from the contract of
`mmap(...)` -- i.e. error returns are actually the equivalent of `errno`
results. We update how XRay uses `internal_mmap(...)` to better handle
these error conditions.

In the process, we change the default pointers we're using from `char*`
to `uint8_t*` to prevent potential usage of the pointers in the string
library functions that expect to operate on `char*`.

We also take the chance to "promote" sizes of individual `internal_mmap`
requests to at least page size bytes, consistent with the expectations
of calls to `mmap`.

Reviewers: cryptoad, mboerger

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D52361

llvm-svn: 342745

1 files changed, 2 insertions, 1 deletions

diff --git a/compiler-rt/lib/xray/xray_buffer_queue.h b/compiler-rt/lib/xray/xray_buffer_queue.h
index bfb091e3f83..c1fa9fab768 100644
--- a/compiler-rt/lib/xray/xray_buffer_queue.h
+++ b/compiler-rt/lib/xray/xray_buffer_queue.h
@@ -20,6 +20,7 @@
 #include "sanitizer_common/sanitizer_mutex.h"
 #include "xray_defs.h"
 #include <cstddef>
+#include <cstdint>
 
 namespace __xray {
 
@@ -114,7 +115,7 @@ private:
 
   // A pointer to a contiguous block of memory to serve as the backing store for
   // all the individual buffers handed out.
-  void *BackingStore;
+  uint8_t *BackingStore;
 
   // A dynamically allocated array of BufferRep instances.
   BufferRep *Buffers;