libdwfl: Add minisymtab support.

Add an auxiliary symbol table dwfl_file aux_sym to Dwfl_Module if all we
have is the dynsym table.  The main file might contain a .gnu_debugdata
section. The .gnu_debugdata section is a compressed embedded ELF file
that contains the text (code) section symbols from the symtab table
that are not in the main file dynsym table. dwfl_module_getsymtab (),
dwfl_module_addrsym () and dwfl_module_getsym () will use the auxiliary
symbol table when available (and no full symtab is available from the
debug file).

    * libdwflP.h (struct Dwfl_Module): Add aux_sym, aux_symdata,
    aux_syments, aux_symstrdata, aux_symxndxdata and aux_first_global.
    (dwfl_adjusted_aux_sym_addr): New function.
    (dwfl_deadjust_aux_sym_addr): Likewise.
    (dwfl_adjusted_st_value): Take and check symfile argument.
    (dwfl_deadjust_st_value): Likewise.
    * dwfl_module_getdwarf.c (find_prelink_address_sync): Take and
    use dwfl_file as argument to set address_sync.
    (find_debuginfo): Call find_prelink_address_sync with debug file.
    (find_aux_sym): New function.
    (find_symtab): Use find_aux_sym if all we have is the dynsym table
    and fill in aux DwflModule fields.
    (dwfl_module_getsymtab): Return syments plus aux_syments.
    (load_symtab): Always set first_global.
    * dwfl_module_addrsym.c (dwfl_module_addrsym): Check symfile
    when using same_section. Calculate first_global based on both
    mod->first_global and mod->aux_first_global.
    * dwfl_module.c (__libdwfl_module_free): Free aux_sym.
    * dwfl_module_getsym.c (dwfl_module_getsym): Use auxsym table
    to retrieve symbol and name if necessary, making sure all locals
    from any table come before any globals.
    * dwfl_module_info.c (dwfl_module_info): Call dwfl_adjusted_st_value
    with symfile.
    * relocate.c (resolve_symbol): Likewise.

https://fedoraproject.org/wiki/Features/MiniDebugInfo

Signed-off-by: Mark Wielaard <mjw@redhat.com>

1 files changed, 34 insertions, 7 deletions

diff --git a/libdwfl/libdwflP.h b/libdwfl/libdwflP.h
index 806ebcd9..5aaa7785 100644
--- a/libdwfl/libdwflP.h
+++ b/libdwfl/libdwflP.h
@@ -142,7 +142,7 @@ struct Dwfl_Module
   char *name;			/* Iterator name for this module.  */
   GElf_Addr low_addr, high_addr;
 
-  struct dwfl_file main, debug;
+  struct dwfl_file main, debug, aux_sym;
   GElf_Addr main_bias;
   Ebl *ebl;
   GElf_Half e_type;		/* GElf_Ehdr.e_type cache.  */
@@ -152,10 +152,15 @@ struct Dwfl_Module
 
   struct dwfl_file *symfile;	/* Either main or debug.  */
   Elf_Data *symdata;		/* Data in the ELF symbol table section.  */
+  Elf_Data *aux_symdata;	/* Data in the auxiliary ELF symbol table.  */
   size_t syments;		/* sh_size / sh_entsize of that section.  */
+  size_t aux_syments;		/* sh_size / sh_entsize of aux_sym section.  */
   int first_global;		/* Index of first global symbol of table.  */
+  int aux_first_global;		/* Index of first global of aux_sym table.  */
   Elf_Data *symstrdata;		/* Data for its string table.  */
+  Elf_Data *aux_symstrdata;	/* Data for aux_sym string table.  */
   Elf_Data *symxndxdata;	/* Data in the extended section index table. */
+  Elf_Data *aux_symxndxdata;	/* Data in the extended auxiliary table. */
 
   Dwarf *dw;			/* libdw handle for its debugging info.  */
 
@@ -255,20 +260,42 @@ dwfl_deadjust_dwarf_addr (Dwfl_Module *mod, Dwarf_Addr addr)
 	  + mod->debug.address_sync);
 }
 
+static inline Dwarf_Addr
+dwfl_adjusted_aux_sym_addr (Dwfl_Module *mod, Dwarf_Addr addr)
+{
+  return dwfl_adjusted_address (mod, (addr
+				      - mod->aux_sym.address_sync
+				      + mod->main.address_sync));
+}
+
+static inline Dwarf_Addr
+dwfl_deadjust_aux_sym_addr (Dwfl_Module *mod, Dwarf_Addr addr)
+{
+  return (dwfl_deadjust_address (mod, addr)
+	  - mod->main.address_sync
+	  + mod->aux_sym.address_sync);
+}
+
 static inline GElf_Addr
-dwfl_adjusted_st_value (Dwfl_Module *mod, GElf_Addr addr)
+dwfl_adjusted_st_value (Dwfl_Module *mod, struct dwfl_file *symfile,
+			GElf_Addr addr)
 {
-  if (mod->symfile == &mod->main)
+  if (symfile == &mod->main)
     return dwfl_adjusted_address (mod, addr);
-  return dwfl_adjusted_dwarf_addr (mod, addr);
+  if (symfile == &mod->debug)
+    return dwfl_adjusted_dwarf_addr (mod, addr);
+  return dwfl_adjusted_aux_sym_addr (mod, addr);
 }
 
 static inline GElf_Addr
-dwfl_deadjust_st_value (Dwfl_Module *mod, GElf_Addr addr)
+dwfl_deadjust_st_value (Dwfl_Module *mod, struct dwfl_file *symfile,
+			GElf_Addr addr)
 {
-  if (mod->symfile == &mod->main)
+  if (symfile == &mod->main)
     return dwfl_deadjust_address (mod, addr);
-  return dwfl_deadjust_dwarf_addr (mod, addr);
+  if (symfile == &mod->debug)
+    return dwfl_deadjust_dwarf_addr (mod, addr);
+  return dwfl_deadjust_aux_sym_addr (mod, addr);
 }
 
 /* This describes a contiguous address range that lies in a single CU.