commit 2c06869f7c456464fa795bb11ec04c5bfd23f83c
author Siva Chandra Reddy <sivachandra@google.com> Mon Mar 08 15:12:22 2021 -0800
committer Copybara-Service <copybara-worker@google.com> Thu Mar 18 00:20:24 2021 -0700
tree ce0939d80708c744b7e9ea7e7a56582ab7e88094
parent 95fbd51f9ed288b5cda1a508c3d5d2a5f342521a

[libc][NFC] Make x86_64 fenv functions msan safe.

These functions used inline asm to read FPU state. This change adds
explicit unpoisoning in these functions as the sanitizers don't see the
read operations.

GitOrigin-RevId: 001a12ed59c354aa759ff3e104748c36803cfaa2

src/__support/CMakeLists.txt

diff --git a/src/__support/CMakeLists.txt b/src/__support/CMakeLists.txt
index 980b510..32f538e 100644
--- a/src/__support/CMakeLists.txt
+++ b/src/__support/CMakeLists.txt
@@ -2,4 +2,5 @@
   common
   HDRS
     common.h
+    sanitizer_annotations.h
 )

utils/FPUtil/CMakeLists.txt

diff --git a/utils/FPUtil/CMakeLists.txt b/utils/FPUtil/CMakeLists.txt
index 2c1c166..43ee643 100644
--- a/utils/FPUtil/CMakeLists.txt
+++ b/utils/FPUtil/CMakeLists.txt
@@ -31,6 +31,7 @@
     libc.include.math
     libc.include.errno
     libc.include.fenv
+    libc.src.__support.common
     libc.utils.CPP.standalone_cpp
 )
 

utils/FPUtil/x86_64/FEnv.h

diff --git a/utils/FPUtil/x86_64/FEnv.h b/utils/FPUtil/x86_64/FEnv.h
index 3fb4881..1196aba 100644
--- a/utils/FPUtil/x86_64/FEnv.h
+++ b/utils/FPUtil/x86_64/FEnv.h
@@ -12,6 +12,8 @@
 #include <fenv.h>
 #include <stdint.h>
 
+#include "src/__support/sanitizer_annotations.h"
+
 namespace __llvm_libc {
 namespace fputil {
 
@@ -95,6 +97,7 @@
 static inline uint16_t getX87ControlWord() {
   uint16_t w;
   __asm__ __volatile__("fnstcw %0" : "=m"(w)::);
+  SANITIZER_MEMORY_INITIALIZED(&w, sizeof(w));
   return w;
 }
 
@@ -105,6 +108,7 @@
 static inline uint16_t getX87StatusWord() {
   uint16_t w;
   __asm__ __volatile__("fnstsw %0" : "=m"(w)::);
+  SANITIZER_MEMORY_INITIALIZED(&w, sizeof(w));
   return w;
 }
 
@@ -115,6 +119,7 @@
 static inline uint32_t getMXCSR() {
   uint32_t w;
   __asm__ __volatile__("stmxcsr %0" : "=m"(w)::);
+  SANITIZER_MEMORY_INITIALIZED(&w, sizeof(w));
   return w;
 }
 
@@ -124,6 +129,7 @@
 
 static inline void getX87StateDescriptor(X87StateDescriptor &s) {
   __asm__ __volatile__("fnstenv %0" : "=m"(s));
+  SANITIZER_MEMORY_INITIALIZED(&s, sizeof(s));
 }
 
 static inline void writeX87StateDescriptor(const X87StateDescriptor &s) {