[HWAsan] Add hwasan_sys_page_size command option to support 4K/8K/16K/64K page size system

[XiaodongLoong]

Summary

There is a few passes or other code that need to know the page size of the target system in advance.
And due to cross compilation, the page size might be different on host and target system. So we
need to specify the page size of the target system explicitly.

For example, HWAsan has a ring buffer that is a multiple of the page size. HWAsan pass doesnot know
the page size of the target system, but 4K page size is specified by default. As shown in D123910.

[XiaodongLoong]

Delete blank line

[MaskRay]

Please provide justification for this new config.

[XiaodongLoong]

In D123908#3455948, @MaskRay wrote:

Please provide justification for this new config.

OK，I add summary information about it. Thank you!

[lebedev.ri]

If this is meant to specify the value for the target system, then certainly,
this is still hardcoding some value, that will still not be always right.
I would guess the solution should be to read it from the IR metadata.

[MaskRay]

Hard-coded build page size values may work for your system, but generally isn't reliable. For example, AT_PAGESZ was invented for retrieving the run-time value. I don't think the build system should know the page size.

[XiaodongLoong]

In D123908#3456330, @lebedev.ri wrote:

If this is meant to specify the value for the target system, then certainly,
this is still hardcoding some value, that will still not be always right.
I would guess the solution should be to read it from the IR metadata.

I need to do a invetigation on IR metadata. Is there a similar example about it?
Thank you!

[XiaodongLoong]

In D123908#3457563, @MaskRay wrote:

Hard-coded build page size values may work for your system, but generally isn't reliable. For example, AT_PAGESZ was invented for retrieving the run-time value. I don't think the build system should know the page size.

Yes, you are right. I'll change this revision.

[XiaodongLoong]

update revision that doesn't change CMakeLists.txt

[XiaodongLoong]

If this is meant to specify the value for the target system, then certainly,
this is still hardcoding some value, that will still not be always right.

Hard-coded build page size values may work for your system, but generally isn't reliable.

Yes, you are right. It is not reliable. I have no better idea on it by now. I defined a new command option "hwasan-sys-page-size", It can be used as following:

$ clang -fsanitize=hwaddress -mllvm -hwasan-sys-page-size=8k example.c

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

 static const size_t kNumberOfAccessSizes = 5;
 
 static const size_t kDefaultShadowScale = 4;
 static const uint64_t kDynamicShadowSentinel =
     std::numeric_limits<uint64_t>::max();
 
 static const unsigned kShadowBaseAlignment = 32;
 
+static cl::opt<std::string> ClSystemPageSize(
+    "hwasan-sys-page-size",
+    cl::desc("System page size for ring buffer, such as 4K/8K/16K/64K"),
+    cl::Hidden, cl::init("4k"));
+
 static cl::opt<std::string>
     ClMemoryAccessCallbackPrefix("hwasan-memory-access-callback-prefix",
                                  cl::desc("Prefix for memory access callbacks"),
                                  cl::Hidden, cl::init("__hwasan_"));
 
 static cl::opt<bool> ClKasanMemIntrinCallbackPrefix(
     "hwasan-kernel-mem-intrinsic-prefix",
     cl::desc("Use prefix for memory intrinsics in KASAN mode"), cl::Hidden,
bool shouldUseStackSafetyAnalysis(const Triple &TargetTriple,
   return shouldInstrumentStack(TargetTriple) &&
          mightUseStackSafetyAnalysis(DisableOptimization);
 }
 
 bool shouldDetectUseAfterScope(const Triple &TargetTriple) {
   return ClUseAfterScope && shouldInstrumentStack(TargetTriple);
 }
 
+static uint64_t getSystemPageSizeBits() {
+  StringRef PageSizeStr(ClSystemPageSize.getValue());
+  if (PageSizeStr.equals_insensitive("4k"))
+    return 12;
+  else if (PageSizeStr.equals_insensitive("8k"))
+    return 13;
+  else if (PageSizeStr.equals_insensitive("16k"))
+    return 14;
+  else if (PageSizeStr.equals_insensitive("64k"))
+    return 16;
+  else
+    report_fatal_error("unsupported page size: " + PageSizeStr);
+}
+
 /// An instrumentation pass implementing detection of addressability bugs
 /// using tagged pointers.
 class HWAddressSanitizer {
 public:
   HWAddressSanitizer(Module &M, bool CompileKernel, bool Recover,
                      const StackSafetyGlobalInfo *SSI)
       : M(M), SSI(SSI) {
     this->Recover = ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover;