[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.

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

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

diff --git a/libc/utils/FPUtil/x86_64/FEnv.h b/libc/utils/FPUtil/x86_64/FEnv.h
index 3fb4881..1196aba 100644 (file)
--- a/libc/utils/FPUtil/x86_64/FEnv.h
+++ b/libc/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_assert(
 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 void writeX87ControlWord(uint16_t w) {
 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 void clearX87Exceptions() {
 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 writeMXCSR(uint32_t w) {
 
 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) {