Revert "Allocate bss section within proper range of other sections"

This reverts commit e019ec94f12268dd92ea5d5204e9e57e7ebf10ca.

This sadly breaks the external interpreter on i386.

For instance, see https://circleci.com/gh/ghc/ghc/10925.

1 files changed, 30 insertions, 43 deletions

diff --git a/rts/linker/Elf.c b/rts/linker/Elf.c
index 0a7ffaec21..fe87aed0b0 100644
--- a/rts/linker/Elf.c
+++ b/rts/linker/Elf.c
@@ -579,7 +579,7 @@ ocVerifyImage_ELF ( ObjectCode* oc )
 /* Figure out what kind of section it is.  Logic derived from
    Figure 1.14 ("Special Sections") of the ELF document
    ("Portable Formats Specification, Version 1.1"). */
-static SectionKind getSectionKind_ELF( Elf_Shdr *hdr, int *is_bss )
+static int getSectionKind_ELF( Elf_Shdr *hdr, int *is_bss )
 {
     *is_bss = false;
 
@@ -681,31 +681,23 @@ ocGetNames_ELF ( ObjectCode* oc )
       StgWord mapped_size = 0, mapped_offset = 0;
       StgWord size = shdr[i].sh_size;
       StgWord offset = shdr[i].sh_offset;
-      StgWord align = shdr[i].sh_addralign;
 
       if (is_bss && size > 0) {
          /* This is a non-empty .bss section.  Allocate zeroed space for
             it, and set its .sh_offset field such that
             ehdrC + .sh_offset == addr_of_zeroed_space.  */
-#if defined(NEED_GOT) || RTS_LINKER_USE_MMAP
-          if (USE_CONTIGUOUS_MMAP || RtsFlags.MiscFlags.linkerAlwaysPic) {
-              /* The space for bss sections is already preallocated */
-              ASSERT(oc->bssBegin != NULL);
-              alloc = SECTION_NOMEM;
-              start =
-                oc->image + roundUpToAlign(oc->bssBegin - oc->image, align);
-              oc->bssBegin = (char*)start + size;
-              ASSERT(oc->bssBegin <= oc->bssEnd);
-          } else {
-              /* Use mmapForLinker to allocate .bss, otherwise the malloced
-               * address might be out of range for sections that are mmaped.
-               */
-              alloc = SECTION_MMAP;
-              start = mmapForLinker(size, MAP_ANONYMOUS, -1, 0);
-              mapped_start = start;
-              mapped_offset = 0;
-              mapped_size = roundUpToPage(size);
-          }
+#if defined(NEED_GOT)
+          /* always use mmap if we use GOT slots.  Otherwise the malloced
+           * address might be out of range for sections that are mmaped.
+           */
+          alloc = SECTION_MMAP;
+          start = mmap(NULL, size,
+                       PROT_READ | PROT_WRITE | PROT_EXEC,
+                       MAP_ANON | MAP_PRIVATE,
+                       -1, 0);
+          mapped_start = start;
+          mapped_offset = 0;
+          mapped_size = roundUpToPage(size);
 #else
           alloc = SECTION_MALLOC;
           start = stgCallocBytes(1, size, "ocGetNames_ELF(BSS)");
@@ -1881,27 +1873,22 @@ int ocRunInit_ELF( ObjectCode *oc )
 
 #if defined(NEED_SYMBOL_EXTRAS)
 
-int ocAllocateExtras_ELF( ObjectCode *oc )
+int ocAllocateSymbolExtras_ELF( ObjectCode *oc )
 {
-  Elf_Ehdr *ehdr = (Elf_Ehdr *) oc->image;
-  Elf_Shdr* shdr = (Elf_Shdr *) ( ((char *)oc->image) + ehdr->e_shoff );
-  Elf_Shdr* symtab = NULL;
-  Elf_Word shnum = elf_shnum(ehdr);
-  int bssSize = 0;
-
-  for (Elf_Word i = 0; i < shnum; ++i) {
-    if(shdr[i].sh_type == SHT_SYMTAB) {
-      symtab = &shdr[i];
-    } else {
-      int isBss = 0;
-      getSectionKind_ELF(&shdr[i], &isBss);
-      if (isBss && shdr[i].sh_size > 0) {
-        bssSize += roundUpToAlign(shdr[i].sh_size, shdr[i].sh_addralign);
-      }
-    }
-  }
+  Elf_Ehdr *ehdr;
+  Elf_Shdr* shdr;
+  Elf_Word i, shnum;
+
+  ehdr = (Elf_Ehdr *) oc->image;
+  shdr = (Elf_Shdr *) ( ((char *)oc->image) + ehdr->e_shoff );
+
+  shnum = elf_shnum(ehdr);
+
+  for( i = 0; i < shnum; i++ )
+    if( shdr[i].sh_type == SHT_SYMTAB )
+      break;
 
-  if (symtab == NULL)
+  if( i == shnum )
   {
     // Not having a symbol table is not in principle a problem.
     // When an object file has no symbols then the 'strip' program
@@ -1911,15 +1898,15 @@ int ocAllocateExtras_ELF( ObjectCode *oc )
     return 1;
   }
 
-  if( symtab->sh_entsize != sizeof( Elf_Sym ) )
+  if( shdr[i].sh_entsize != sizeof( Elf_Sym ) )
   {
     errorBelch( "The entry size (%d) of the symtab isn't %d\n",
-      (int) symtab->sh_entsize, (int) sizeof( Elf_Sym ) );
+      (int) shdr[i].sh_entsize, (int) sizeof( Elf_Sym ) );
 
     return 0;
   }
 
-  return ocAllocateExtras(oc, symtab->sh_size / sizeof( Elf_Sym ), 0, bssSize);
+  return ocAllocateSymbolExtras( oc, shdr[i].sh_size / sizeof( Elf_Sym ), 0 );
 }
 
 #endif /* NEED_SYMBOL_EXTRAS */