[llvm-exegesis] Validate that address annotations are aligned

llvm/test/tools/llvm-exegesis/X86/latency/memory-annotations-alignment-page-boundary.s

@@ -0,0 +1,14 @@
+# REQUIRES: exegesis-can-measure-latency, x86_64-linux
+
+# Test that we error out if the requested address is not aligned to a page
+# boundary. Here we test out mapping at 2^12+4, which is off from a page
+# boundary by four bytes.
+
+# RUN: not llvm-exegesis -mtriple=x86_64-unknown-unknown -mode=latency -snippets-file=%s -execution-mode=subprocess 2>&1 | FileCheck %s
+
+# LLVM-EXEGESIS-MEM-DEF test1 4096 414D47
+# LLVM-EXEGESIS-MEM-MAP test1 65540
+
+nop
+
+# CHECK: invalid comment 'LLVM-EXEGESIS-MEM-MAP  test1 65540', expected <ADDRESS> to be a multiple of the platform page size. 

llvm/test/tools/llvm-exegesis/X86/latency/memory-annotations-snippet-alignment-page-boundary.s

@@ -0,0 +1,13 @@
+# REQUIRES: exegesis-can-measure-latency, x86_64-linux
+
+# Test that we error out if the requested snippet address is not aligned to
+# a page boundary. Here we test out mapping at 2^12+4 which is off from a page
+# boundary by four bytes.
+
+# RUN: not llvm-exegesis -mtriple=x86_64-unknown-unknown -mode=latency -snippets-file=%s -execution-mode=subprocess 2>&1 | FileCheck %s
+
+# LLVM-EXEGESIS-SNIPPET-ADDRESS 65540
+
+nop
+
+# CHECK: invalid comment 'LLVM-EXEGESIS-SNIPPET-ADDRESS 65540, expected <ADDRESS> to be a multiple of the platform page size.

llvm/tools/llvm-exegesis/lib/Assembler.cpp

@@ -36,6 +36,10 @@
 #include "perfmon/perf_event.h"
 #endif // HAVE_LIBPFM
 
+#ifdef __linux__
+#include <unistd.h>
+#endif
+
 namespace llvm {
 namespace exegesis {
 
@@ -53,6 +57,13 @@ static bool generateSnippetSetupCode(
   if (GenerateMemoryInstructions) {
     BBF.addInstructions(ET.generateMemoryInitialSetup());
     for (const MemoryMapping &MM : Key.MemoryMappings) {
+#ifdef __linux__
+      // The frontend that generates that parses the memory mapping information
+      // from the user should validate that the requested address is a multiple
+      // of the page size. Assert that this is true here.
+      assert(MM.Address % getpagesize() == 0 &&
+             "Memory mappings need to be aligned to page boundaries.");
+#endif
       BBF.addInstructions(ET.generateMmap(
           MM.Address, Key.MemoryValues.at(MM.MemoryValueName).SizeBytes,
           ET.getAuxiliaryMemoryStartAddress() +

llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp

@@ -418,6 +418,12 @@ class SubProcessFunctionExecutorImpl
       exit(ChildProcessExitCodeE::RSeqDisableFailed);
 #endif // GLIBC_INITS_RSEQ
 
+    // The frontend that generates the memory annotation structures should
+    // validate that the address to map the snippet in at is a multiple of
+    // the page size. Assert that this is true here.
+    assert(Key.SnippetAddress % getpagesize() == 0 &&
+           "The snippet address needs to be aligned to a page boundary.");
+
     size_t FunctionDataCopySize = this->Function.FunctionBytes.size();
     void *MapAddress = NULL;
     int MapFlags = MAP_PRIVATE | MAP_ANONYMOUS;

llvm/tools/llvm-exegesis/lib/SnippetFile.cpp

@@ -23,6 +23,10 @@
 #include "llvm/Support/SourceMgr.h"
 #include <string>
 
+#ifdef __linux__
+#include <unistd.h>
+#endif // __linux__
+
 namespace llvm {
 namespace exegesis {
 namespace {
@@ -118,6 +122,19 @@ class BenchmarkCodeStreamer : public MCStreamer, public AsmCommentConsumer {
       MemoryMapping MemMap;
       MemMap.MemoryValueName = Parts[0].trim().str();
       MemMap.Address = std::stol(Parts[1].trim().str());
+
+#ifdef __linux__
+      // Validate that the annotation is a multiple of the platform's page
+      // size.
+      if (MemMap.Address % getpagesize() != 0) {
+        errs() << "invalid comment 'LLVM-EXEGESIS-MEM-MAP " << CommentText
+               << "', expected <ADDRESS> to be a multiple of the platform page "
+                  "size.";
+        ++InvalidComments;
+        return;
+      }
+#endif // __linux__
+
       // validate that the annotation refers to an already existing memory
       // definition
       auto MemValIT = Result->Key.MemoryValues.find(Parts[0].trim().str());
@@ -142,6 +159,20 @@ class BenchmarkCodeStreamer : public MCStreamer, public AsmCommentConsumer {
         ++InvalidComments;
         return;
       }
+
+#ifdef __linux__
+      // Validate that the address in the annotation is a multiple of the
+      // platform's page size.
+      if (Result->Key.SnippetAddress % getpagesize() != 0) {
+        errs() << "invalid comment 'LLVM-EXEGESIS-SNIPPET-ADDRESS "
+               << CommentText
+               << ", expected <ADDRESS> to be a multiple of the platform page "
+                  "size.";
+        ++InvalidComments;
+        return;
+      }
+#endif // __linux__
+
       return;
     }
   }