[PATCH] D67329: Add getauxval() compat for NetBSD

[Kamil Rytarowski via Phabricator via llvm-commits]

krytarowski created this revision.
krytarowski added reviewers: vitalybuka, dvyukov, mgorny, joerg.
krytarowski added a project: Sanitizers.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

getauxval() is not available on NetBSD and there is no a direct equivalent.

Add a function that implements the same semantics with NetBSD internals.

Reorder the GetPageSize() functions to prefer the sysctl approach for NetBSD.
It no longer makes a difference which approach is better. Avoid changing
conditional code path.


Repository:
  rL LLVM

https://reviews.llvm.org/D67329

Files:
  lib/sanitizer_common/sanitizer_getauxval.h
  lib/sanitizer_common/sanitizer_linux.cpp


Index: lib/sanitizer_common/sanitizer_linux.cpp
===================================================================
--- lib/sanitizer_common/sanitizer_linux.cpp
+++ lib/sanitizer_common/sanitizer_linux.cpp
@@ -1062,8 +1062,6 @@
 uptr GetPageSize() {
 #if SANITIZER_LINUX && (defined(__x86_64__) || defined(__i386__))
   return EXEC_PAGESIZE;
-#elif SANITIZER_USE_GETAUXVAL
-  return getauxval(AT_PAGESZ);
 #elif SANITIZER_FREEBSD || SANITIZER_NETBSD
 // Use sysctl as sysconf can trigger interceptors internally.
   int pz = 0;
@@ -1072,6 +1070,8 @@
   int rv = internal_sysctl(mib, 2, &pz, &pzl, nullptr, 0);
   CHECK_EQ(rv, 0);
   return (uptr)pz;
+#elif SANITIZER_USE_GETAUXVAL
+  return getauxval(AT_PAGESZ);
 #else
   return sysconf(_SC_PAGESIZE);  // EXEC_PAGESIZE may not be trustworthy.
 #endif
Index: lib/sanitizer_common/sanitizer_getauxval.h
===================================================================
--- lib/sanitizer_common/sanitizer_getauxval.h
+++ lib/sanitizer_common/sanitizer_getauxval.h
@@ -9,6 +9,7 @@
 // Common getauxval() guards and definitions.
 // getauxval() is not defined until glibc version 2.16, or until API level 21
 // for Android.
+// Implement the getauxval() compat function for NetBSD.
 //
 //===----------------------------------------------------------------------===//
 
@@ -42,6 +43,23 @@
 unsigned long getauxval(unsigned long type);  // NOLINT
 # endif
 
-#endif // SANITIZER_LINUX || SANITIZER_FUCHSIA
+#elif SANITIZER_NETBSD
+
+#define SANITIZER_USE_GETAUXVAL 1
+
+#include <dlfcn.h>
+#include <elf.h>
+
+static inline decltype(AuxInfo::a_v) getauxval(decltype(AuxInfo::a_type) type) {
+  for (const AuxInfo *aux = (const AuxInfo *)_dlauxinfo();
+       aux->a_type != AT_NULL; ++aux) {
+    if (type == aux->a_type)
+      return aux->a_v;
+  }
+
+  return 0;
+}
+
+#endif
 
 #endif // SANITIZER_GETAUXVAL_H


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