symtab reader: fix up alternative addresses

CFI symbols need special interpretation and this work is performed by
the add_alternative_address_lookups method.

Some symbol addresses need to be "tweaked" to be correctly interpreted
and this must also happen in add_alternative_address_lookups.

In particular, this commit fixes ARM32 CFI symbol interpretation.

	* src/abg-symtab-reader.cc
	(symtab::add_alternative_address_lookups): Tweak function
	addresses in the same manner as done in symtab::load_.

Signed-off-by: Giuliano Procida <gprocida@google.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/abg-symtab-reader.cc b/src/abg-symtab-reader.cc
index 0f4d0b65..04e8b23c 100644
--- a/src/abg-symtab-reader.cc
+++ b/src/abg-symtab-reader.cc
@@ -351,6 +351,7 @@ symtab::load_(Elf*	       elf_handle,
               elf_helpers::maybe_adjust_et_rel_sym_addr_to_abs_addr(elf_handle,
                                                                     sym);
 
+          // See also symtab::add_alternative_address_lookups.
           if (symbol_sptr->is_function())
             {
               if (is_arm32)
@@ -581,6 +582,9 @@ symtab::update_function_entry_address_symbol_map(
 void
 symtab::add_alternative_address_lookups(Elf* elf_handle)
 {
+  const bool is_arm32 = elf_helpers::architecture_is_arm32(elf_handle);
+  const bool is_ppc64 = elf_helpers::architecture_is_ppc64(elf_handle);
+
   Elf_Scn* symtab_section = elf_helpers::find_symtab_section(elf_handle);
   if (!symtab_section)
     return;
@@ -634,6 +638,19 @@ symtab::add_alternative_address_lookups(Elf* elf_handle)
                   elf_helpers::maybe_adjust_et_rel_sym_addr_to_abs_addr(
                       elf_handle, sym);
 
+              // See also symtab::load_.
+              if (symbol_sptr->is_function())
+                {
+                  if (is_arm32)
+                    // Clear bit zero of ARM32 addresses as per "ELF for the Arm
+                    // Architecture" section 5.5.3.
+                    // https://static.docs.arm.com/ihi0044/g/aaelf32.pdf
+                    symbol_value &= ~1;
+                  else if (is_ppc64)
+                    update_function_entry_address_symbol_map(elf_handle, sym,
+                                                             symbol_sptr);
+                }
+
               const auto result =
                   addr_symbol_map_.emplace(symbol_value, symbol_sptr);
               ABG_ASSERT(result.second);