[PATCH 3/4] fuzz: add mangled object name to linker script

[Alexander Bulekov <alxndr@bu.edu>]

Previously, we relied on "FuzzerTracePC*(.bss*)" to place libfuzzer's
fuzzer::TPC object into our contiguous shared-memory region. This does
not work for some libfuzzer builds, so this addition identifies the
region by its mangled name: *(.bss._ZN6fuzzer3TPCE);

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
 tests/qtest/fuzz/fork_fuzz.ld | 5 +++++
 1 file changed, 5 insertions(+)

This isn't ideal, but I looked at the libfuzzer builds packaged for
debian, for versions 6, 7, 8, 9, 10 and 11 and this (mangled) object
name appears consistently in the symbol tables.

diff --git a/tests/qtest/fuzz/fork_fuzz.ld b/tests/qtest/fuzz/fork_fuzz.ld
index e086bba873..bfb667ed06 100644
--- a/tests/qtest/fuzz/fork_fuzz.ld
+++ b/tests/qtest/fuzz/fork_fuzz.ld
@@ -28,6 +28,11 @@ SECTIONS
 
       /* Internal Libfuzzer TracePC object which contains the ValueProfileMap */
       FuzzerTracePC*(.bss*);
+      /*
+       * In case the above line fails, explicitly specify the (mangled) name of
+       * the object we care about
+       */
+       *(.bss._ZN6fuzzer3TPCE);
   }
   .data.fuzz_end : ALIGN(4K)
   {
-- 
2.26.2