Fix nommu handling of DT_TEXTREL

We have a problem with DT_TEXTREL shared libraries on nommu machines.
The dynamic linker's strategy is to map the text segment read-only
first, then look for DT_TEXTREL, and use mprotect to change protections
if necessary. This fails on nommu, since a nommu kernel can decide to
share the memory for private read-only file mappings, and mprotect
doesn't (can't) do anything about this sharing. Existing nommu targets
apparently have no need for this, but on C6X, we may need to assign
library indices at run-time if no --dsbt-index option was passed to the
linker at build time.

Hence, the following patch, which instead of using mprotect, redoes the
mapping with PF_W set.

Signed-off-by: Bernd Schmidt <bernds@codesourcery.com>

2 files changed, 35 insertions, 8 deletions

diff --git a/ldso/ldso/bfin/dl-inlines.h b/ldso/ldso/bfin/dl-inlines.h
index 6524f5edc..969986218 100644
--- a/ldso/ldso/bfin/dl-inlines.h
+++ b/ldso/ldso/bfin/dl-inlines.h
@@ -88,14 +88,39 @@ __dl_init_loadaddr_hdr (struct elf32_fdpic_loadaddr loadaddr, void *addr,
   segdata->p_memsz = phdr->p_memsz;
 
 #if defined (__SUPPORT_LD_DEBUG__)
-  {
-    extern char *_dl_debug;
-    extern int _dl_debug_file;
-    if (_dl_debug)
-      _dl_dprintf(_dl_debug_file, "%i: mapped %x at %x, size %x\n",
-		  loadaddr.map->nsegs-1,
-		  segdata->p_vaddr, segdata->addr, segdata->p_memsz);
-  }
+  if (_dl_debug)
+    _dl_dprintf(_dl_debug_file, "%i: mapped %x at %x, size %x\n",
+		loadaddr.map->nsegs-1,
+		segdata->p_vaddr, segdata->addr, segdata->p_memsz);
+#endif
+}
+
+/* Replace an existing entry in the load map.  */
+static __always_inline void
+__dl_update_loadaddr_hdr (struct elf32_fdpic_loadaddr loadaddr, void *addr,
+			  Elf32_Phdr *phdr)
+{
+  struct elf32_fdpic_loadseg *segdata;
+  void *oldaddr;
+  int i;
+
+  for (i = 0; i < loadaddr.map->nsegs; i++)
+    if (loadaddr.map->segs[i].p_vaddr == phdr->p_vaddr
+	&& loadaddr.map->segs[i].p_memsz == phdr->p_memsz)
+      break;
+  if (i == loadaddr.map->nsegs)
+    _dl_exit (-1);
+
+  segdata = loadaddr.map->segs + i;
+  oldaddr = (void *)segdata->addr;
+  _dl_munmap (oldaddr, segdata->p_memsz);
+  segdata->addr = (Elf32_Addr) addr;
+
+#if defined (__SUPPORT_LD_DEBUG__)
+  if (_dl_debug)
+    _dl_dprintf(_dl_debug_file, "%i: changed mapping %x at %x (old %x), size %x\n",
+		loadaddr.map->nsegs-1,
+		segdata->p_vaddr, segdata->addr, oldaddr, segdata->p_memsz);
 #endif
 }
 
diff --git a/ldso/ldso/bfin/dl-sysdep.h b/ldso/ldso/bfin/dl-sysdep.h
index 50c750990..168e5c89a 100644
--- a/ldso/ldso/bfin/dl-sysdep.h
+++ b/ldso/ldso/bfin/dl-sysdep.h
@@ -120,6 +120,8 @@ struct funcdesc_ht;
 #define DL_INIT_LOADADDR_HDR(LOADADDR, ADDR, PHDR) \
   (__dl_init_loadaddr_hdr ((LOADADDR), (ADDR), (PHDR), \
 			   dl_init_loadaddr_load_count))
+#define DL_UPDATE_LOADADDR_HDR(LOADADDR, ADDR, PHDR) \
+  (__dl_update_loadaddr_hdr ((LOADADDR), (ADDR), (PHDR)))
 #define DL_LOADADDR_UNMAP(LOADADDR, LEN) \
   (__dl_loadaddr_unmap ((LOADADDR), (NULL)))
 #define DL_LIB_UNMAP(LIB, LEN) \