hppa: Fix bind-now audit (BZ #28857)

On hppa, a function pointer returned by la_symbind is actually a function
descriptor has the plabel bit set (bit 30).  This must be cleared to get
the actual address of the descriptor.  If the descriptor has been bound,
the first word of the descriptor is the physical address of theA function,
otherwise, the first word of the descriptor points to a trampoline in the
PLT.

This patch also adds a workaround on tests because on hppa (and it seems
to be the only ABI I have see it), some shared library adds a dynamic PLT
relocation to am empty symbol name:

$ readelf -r elf/tst-audit25mod1.so
[...]
Relocation section '.rela.plt' at offset 0x464 contains 6 entries:
 Offset     Info    Type            Sym.Value  Sym. Name + Addend
00002008  00000081 R_PARISC_IPLT                508
[...]

It breaks some assumptions on the test, where a symbol with an empty
name ("") is passed on la_symbind.

Checked on x86_64-linux-gnu and hppa-linux-gnu.

elf/Makefile

@@ -2210,7 +2210,7 @@ $(objpfx)tst-audit24c.out: $(objpfx)tst-auditmod24c.so
 $(objpfx)tst-audit24c: $(objpfx)tst-audit24amod1.so \
 		       $(objpfx)tst-audit24amod2.so
 tst-audit24c-ENV = LD_BIND_NOW=1 LD_AUDIT=$(objpfx)tst-auditmod24c.so
-LDFLAGS-tst-audit24b = -Wl,-z,lazy
+LDFLAGS-tst-audit24c = -Wl,-z,lazy
 
 $(objpfx)tst-audit24d.out: $(objpfx)tst-auditmod24d.so
 $(objpfx)tst-audit24d: $(objpfx)tst-audit24dmod1.so \

elf/dl-audit.c

@@ -257,7 +257,8 @@ _dl_audit_symbind (struct link_map *l, struct reloc_result *reloc_result,
       reloc_result->flags = flags;
     }
 
-  DL_FIXUP_BINDNOW_RELOC (value, new_value, sym.st_value);
+  if (flags & LA_SYMB_ALTVALUE)
+    DL_FIXUP_BINDNOW_RELOC (value, new_value, sym.st_value);
 }
 
 void

elf/tst-auditmod24a.c

@@ -110,5 +110,7 @@ la_symbind32 (Elf32_Sym *sym, unsigned int ndx,
       return sym->st_value;
     }
 
-  abort ();
+  if (symname[0] != '\0')
+    abort ();
+  return sym->st_value;
 }

elf/tst-auditmod24d.c

@@ -116,5 +116,7 @@ la_symbind32 (Elf32_Sym *sym, unsigned int ndx,
 	}
     }
 
-  abort ();
+  if (symname[0] != '\0')
+    abort ();
+  return sym->st_value;
 }

elf/tst-auditmod25.c

@@ -72,7 +72,7 @@ la_symbind32 (Elf32_Sym *sym, unsigned int ndx,
 	      unsigned int *flags, const char *symname)
 #endif
 {
-  if (*refcook != -1 && *defcook != -1)
+  if (*refcook != -1 && *defcook != -1 && symname[0] != '\0')
     fprintf (stderr, "la_symbind: %s %u\n", symname,
 	     *flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT) ? 1 : 0);
   return sym->st_value;

sysdeps/hppa/dl-lookupcfg.h

@@ -79,7 +79,9 @@ void attribute_hidden _dl_unmap (struct link_map *map);
 /* Extract the code address from a fixup value */
 #define DL_FIXUP_VALUE_CODE_ADDR(value) ((value).ip)
 #define DL_FIXUP_VALUE_ADDR(value) ((uintptr_t) &(value))
-#define DL_FIXUP_ADDR_VALUE(addr) (*(struct fdesc *) (addr))
+/* Clear the plabel bit to get the actual address of the descriptor.  */
+#define DL_FIXUP_ADDR_VALUE(addr) \
+  (*(DL_FIXUP_VALUE_TYPE *) ((uintptr_t) (addr) & ~2))
 #define DL_FIXUP_BINDNOW_ADDR_VALUE(addr) (addr)
-#define DL_FIXUP_BINDNOW_RELOC(value, new_value, st_value) \
-  (*value) = *(struct fdesc *) (st_value)
+#define DL_FIXUP_BINDNOW_RELOC(value, new_value, st_value)	\
+  *(value) = *(DL_FIXUP_VALUE_TYPE *) ((uintptr_t) (new_value) & ~2)