Merge "iommu: free io pgtable during domain detach."

[sagit-ice-cold/kernel_xiaomi_msm8998.git] / fs / binfmt_elf.c

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 6c031dd..8a0243e 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -905,17 +905,60 @@ static int load_elf_binary(struct linux_binprm *bprm)
                elf_flags = MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE;
 
                vaddr = elf_ppnt->p_vaddr;
+               /*
+                * If we are loading ET_EXEC or we have already performed
+                * the ET_DYN load_addr calculations, proceed normally.
+                */
                if (loc->elf_ex.e_type == ET_EXEC || load_addr_set) {
                        elf_flags |= MAP_FIXED;
                } else if (loc->elf_ex.e_type == ET_DYN) {
-                       /* Try and get dynamic programs out of the way of the
-                        * default mmap base, as well as whatever program they
-                        * might try to exec.  This is because the brk will
-                        * follow the loader, and is not movable.  */
-                       load_bias = ELF_ET_DYN_BASE - vaddr;
-                       if (current->flags & PF_RANDOMIZE)
-                               load_bias += arch_mmap_rnd();
-                       load_bias = ELF_PAGESTART(load_bias);
+                       /*
+                        * This logic is run once for the first LOAD Program
+                        * Header for ET_DYN binaries to calculate the
+                        * randomization (load_bias) for all the LOAD
+                        * Program Headers, and to calculate the entire
+                        * size of the ELF mapping (total_size). (Note that
+                        * load_addr_set is set to true later once the
+                        * initial mapping is performed.)
+                        *
+                        * There are effectively two types of ET_DYN
+                        * binaries: programs (i.e. PIE: ET_DYN with INTERP)
+                        * and loaders (ET_DYN without INTERP, since they
+                        * _are_ the ELF interpreter). The loaders must
+                        * be loaded away from programs since the program
+                        * may otherwise collide with the loader (especially
+                        * for ET_EXEC which does not have a randomized
+                        * position). For example to handle invocations of
+                        * "./ld.so someprog" to test out a new version of
+                        * the loader, the subsequent program that the
+                        * loader loads must avoid the loader itself, so
+                        * they cannot share the same load range. Sufficient
+                        * room for the brk must be allocated with the
+                        * loader as well, since brk must be available with
+                        * the loader.
+                        *
+                        * Therefore, programs are loaded offset from
+                        * ELF_ET_DYN_BASE and loaders are loaded into the
+                        * independently randomized mmap region (0 load_bias
+                        * without MAP_FIXED).
+                        */
+                       if (elf_interpreter) {
+                               load_bias = ELF_ET_DYN_BASE;
+                               if (current->flags & PF_RANDOMIZE)
+                                       load_bias += arch_mmap_rnd();
+                               elf_flags |= MAP_FIXED;
+                       } else
+                               load_bias = 0;
+
+                       /*
+                        * Since load_bias is used for all subsequent loading
+                        * calculations, we must lower it by the first vaddr
+                        * so that the remaining calculations based on the
+                        * ELF vaddrs will be correctly offset. The result
+                        * is then page aligned.
+                        */
+                       load_bias = ELF_PAGESTART(load_bias - vaddr);
+
                        total_size = total_mapping_size(elf_phdata,
                                                        loc->elf_ex.e_phnum);
                        if (!total_size) {