Log more info in an mprotect record mismatch

rr-debugger · Jan 2, 2024 · 12398d3 · 12398d3
1 parent d142cc9
commit 12398d3
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Showing 4 changed files with 35 additions and 14 deletions.
diff --git a/src/DumpCommand.cc b/src/DumpCommand.cc
@@ -156,18 +156,8 @@ static void dump_syscallbuf_data(TraceReader& trace, FILE* out,
   }
   if (flags.dump_mmaps) {
     for (auto& record : frame.event().SyscallbufFlush().mprotect_records) {
-      char prot_flags[] = "rwx";
-      if (!(record.prot & PROT_READ)) {
-        prot_flags[0] = '-';
-      }
-      if (!(record.prot & PROT_WRITE)) {
-        prot_flags[1] = '-';
-      }
-      if (!(record.prot & PROT_EXEC)) {
-        prot_flags[2] = '-';
-      }
-      fprintf(out, "  { start:'%p', size:'%" PRIx64 "', prot:%s }\n",
-              (void*)record.start, record.size, prot_flags);
+      fprintf(out, "  { start:%p, size:%" PRIx64 ", prot:'%s' }\n",
+              (void*)record.start, record.size, prot_flags_string(record.prot).c_str());
       if (flags.raw_dump) {
         fprintf(out, "  ");
         for (unsigned long i = 0; i < sizeof(record); ++i) {

diff --git a/src/ReplaySession.cc b/src/ReplaySession.cc
@@ -1285,6 +1285,13 @@ void ReplaySession::prepare_syscallbuf_records(ReplayTask* t, Ticks ticks) {
     REMOTE_PTR_FIELD_MINUS_OFFSET(t->preload_globals, f,          \
       SYSCALLBUF_FDS_DISABLED_SIZE - t->session().syscallbuf_fds_disabled_size())
 
+static string mprotect_record_string(const mprotect_record& record) {
+  stringstream s;
+  s << HEX(record.start) << "," << HEX(record.size) << ","
+    << prot_flags_string(record.prot);
+  return s.str();
+}
+
 /**
  * Returns mprotect_record_count
  */
@@ -1315,8 +1322,9 @@ static uint32_t apply_mprotect_records(ReplayTask* t,
         ASSERT(t, r.start == recorded_r.start &&
                r.size == recorded_r.size &&
                r.prot == recorded_r.prot)
-          << "Trace mprotect records don't match the mprotect records "
-          "generated by execution";
+          << "Mismatched mprotect record " << (i + skip_mprotect_records)
+          << ": recorded " << mprotect_record_string(recorded_r)
+          << ", got " << mprotect_record_string(r);
       }
       t->vm()->protect(t, r.start, r.size, r.prot);
       if (running_under_rr()) {

diff --git a/src/kernel_metadata.cc b/src/kernel_metadata.cc
@@ -7,6 +7,8 @@
 #include <signal.h>
 #include <syscall.h>
 
+#include <sstream>
+
 #include "kernel_abi.h"
 #include "kernel_supplement.h"
 #include "log.h"
@@ -560,4 +562,23 @@ NativeArch::siginfo_t convert_to_native_siginfo(SupportedArch arch,
   RR_ARCH_FUNCTION(convert_to_native_siginfo_arch, arch, data, size);
 }
 
+string prot_flags_string(int prot) {
+  char prot_flags[] = "rwx";
+  if (!(prot & PROT_READ)) {
+    prot_flags[0] = '-';
+  }
+  if (!(prot & PROT_WRITE)) {
+    prot_flags[1] = '-';
+  }
+  if (!(prot & PROT_EXEC)) {
+    prot_flags[2] = '-';
+  }
+  stringstream ret;
+  ret << prot_flags;
+  if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC)) {
+    ret << " (" << HEX(prot) << ")";
+  }
+  return ret.str();
+}
+
 } // namespace rr
diff --git a/src/kernel_metadata.h b/src/kernel_metadata.h
@@ -79,6 +79,8 @@ bool is_coredumping_signal(int signo);
 NativeArch::siginfo_t convert_to_native_siginfo(SupportedArch arch,
     const void* data, size_t size);
 
+std::string prot_flags_string(int prot);
+
 } // namespace rr
 
 #endif