[PATCH] D68794: libhwasan initialisation include kernel syscall ABI relaxation
Matthew Malcomson via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Oct 11 06:40:32 PDT 2019
mmalcomson updated this revision to Diff 224582.
mmalcomson edited the summary of this revision.
mmalcomson added a comment.
Run `prctl` syscall for Android, but ignore EINVAL failures.
NOTE: I don't believe this distinguishes between running on a kernel with with the tagged address ABI unconditional or running on a newer kernel or on a kernel with `sysctl abi.tagged_addr_disabled=1`
(https://android.googlesource.com/kernel/common/+/690c4ca8a5715644370384672f24d95b042db74a/Documentation/arm64/tagged-address-abi.rst)
I doubt this will be much of a concern -- there was already a requirement of having the correct Android kernel for things to work -- but am mentioning it for posterity.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D68794/new/
https://reviews.llvm.org/D68794
Files:
compiler-rt/lib/hwasan/hwasan.cpp
compiler-rt/lib/hwasan/hwasan.h
compiler-rt/lib/hwasan/hwasan_linux.cpp
Index: compiler-rt/lib/hwasan/hwasan_linux.cpp
===================================================================
--- compiler-rt/lib/hwasan/hwasan_linux.cpp
+++ compiler-rt/lib/hwasan/hwasan_linux.cpp
@@ -34,6 +34,7 @@
#include <sys/time.h>
#include <unistd.h>
#include <unwind.h>
+#include <sys/prctl.h>
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_procmaps.h"
@@ -144,6 +145,33 @@
FindDynamicShadowStart(shadow_size_bytes);
}
+void InitPrctl() {
+ // This function uses the prctl interface to ask the kernel to accept
+ // tagged pointers.
+ //
+ // Here we unconditionally request that the PR_TAGGED_ADDR_ENABLE value is
+ // turned on, there is nothing else that can be done.
+#define PR_SET_TAGGED_ADDR_CTRL 55
+#define PR_GET_TAGGED_ADDR_CTRL 56
+#define PR_TAGGED_ADDR_ENABLE (1UL << 0)
+ if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0) == -1
+ || ! prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0)) {
+#if SANITIZER_ANDROID
+ // Some older Android kernels have the tagged pointer ABI on
+ // unconditionally, and hence don't have the tagged-addr prctl.
+ //
+ // In order to handle those we ignore getting EINVAL. */
+ if (errno == EINVAL)
+ return;
+#endif
+ Printf("FATAL: HWAddressSanitizer failed to enable tagged pointer syscall ABI.\n");
+ Die();
+ }
+#undef PR_SET_TAGGED_ADDR_CTRL
+#undef PR_GET_TAGGED_ADDR_CTRL
+#undef PR_TAGGED_ADDR_ENABLE
+}
+
bool InitShadow() {
// Define the entire memory range.
kHighMemEnd = GetHighMemEnd();
Index: compiler-rt/lib/hwasan/hwasan.h
===================================================================
--- compiler-rt/lib/hwasan/hwasan.h
+++ compiler-rt/lib/hwasan/hwasan.h
@@ -74,6 +74,7 @@
bool ProtectRange(uptr beg, uptr end);
bool InitShadow();
+void InitPrctl();
void InitThreads();
void MadviseShadow();
char *GetProcSelfMaps();
Index: compiler-rt/lib/hwasan/hwasan.cpp
===================================================================
--- compiler-rt/lib/hwasan/hwasan.cpp
+++ compiler-rt/lib/hwasan/hwasan.cpp
@@ -354,6 +354,8 @@
hwasan_init_is_running = 1;
SanitizerToolName = "HWAddressSanitizer";
+ InitPrctl();
+
InitTlsSize();
CacheBinaryName();
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