32 bit fixes

src/PerfCounters.cc

@@ -21,6 +21,7 @@
 #include <bpf/libbpf.h>
 #endif
 #include <linux/hw_breakpoint.h>
+#include <sys/utsname.h>
 
 #include <algorithm>
 #include <fstream>
@@ -1243,6 +1244,19 @@ static struct perf_event_attr init_hw_breakpoint_attr() {
   attr.wakeup_events = 1;
   attr.precise_ip = 3;
   attr.disabled = 1;
+
+#if defined(__i386__)
+  struct utsname buf;
+  if (uname(&buf) != 0) {
+    FATAL() << "Failed to call uname";
+  }
+  if (strcmp(buf.machine, "x86_64") == 0) {
+    /* A 32-bit rr running at a 64-bit kernel
+     * needs to set bp_len as needed by the kernel. */
+    attr.bp_len = HW_BREAKPOINT_LEN_8;
+  }
+#endif
+
   return attr;
 }
 

src/record_syscall.cc

@@ -6375,7 +6375,7 @@ static void check_outside_mappings(const KernelMapping& tracee_km, const RecordS
 #if defined(__i386__)
   struct utsname buf;
   if (uname(&buf) != 0) {
-    FATAL() << "Failed to read /proc";
+    FATAL() << "Failed to call uname";
   }
   if (sizeof(void*) == 4 && strcmp(buf.machine, "x86_64") == 0) {
       /* Running 32-bit rr at a 64-bit kernel is not going to work because

src/test/fd_leak.run

@@ -1,4 +1,7 @@
 source `dirname $0`/util.sh
+
+skip_if_rr_32_bit_with_shell_64_bit
+
 num_baseline=$(ls -la /proc/self/fd | wc -l)
 just_record $(which rr) "record --nested=detach ls -la /proc/self/fd"
 replay

src/test/rlimit.c

@@ -2,6 +2,19 @@
 
 #include "util.h"
 
+int kernel_is_32bit_x86(void)
+{
+#if defined(__i386__)
+  struct utsname buf;
+  if (uname(&buf) != 0)
+    return 0;
+
+  if (strcmp(buf.machine, "i686") == 0) // running at a 32bit kernel
+    return 1;
+#endif
+  return 0;
+}
+
 int main(void) {
   struct rlimit* r;
   struct rlimit* r2;
@@ -14,6 +27,11 @@ int main(void) {
   test_assert(r->rlim_max > 0);
   VERIFY_GUARD(r);
 
+  /* When running a 32-bit kernel and using the 64-bit rlimit struct,
+   * a value above 0xfffffffe fails. */
+  if (kernel_is_32bit_x86())
+    r->rlim_cur &= 0xffffffff;
+
   r->rlim_cur /= 2;
   test_assert(0 == setrlimit(RLIMIT_FSIZE, r));
   VERIFY_GUARD(r);

src/test/unmap_vdso.run

@@ -1,4 +1,7 @@
 source `dirname $0`/util.sh
+
+skip_if_rr_32_bit_with_shell_64_bit
+
 RECORD_ARGS="--unmap-vdso"
 just_record cat /proc/self/maps
 if grep "vdso" record.out; then