From 8514218c136c9a21a5ed4f123d2c49f21ef86947 Mon Sep 17 00:00:00 2001 From: Alan Davis Date: Thu, 26 May 2011 18:15:06 +0200 Subject: Correct a bug when remapping textrel segments on nommu From: Alan Davis On C6X, when trying to execute a program that has a textrel DSO, it fails to load. The telltale line in the LD_DEBUG output is: _dl_get_ready_to_run:779: file=''; needed by './a.out' The corresponding DT_NEEDED entry has 'libc.so.0', but here the filename is empty. This is what is happening in _dl_elf_shared_library(): First, map all segments according to their permissions. Text gets initially mapped read-only. Then, parse the dynamic information. The dynamic table is in RW but some of the tags may point to RO. For example, DT_NEEDED points to a string in .dynstr which is in RO. These pointers get computed according to the loadmap from the original mapping. Then, in response to a DT_TEXTREL tag, the RO segment gets remapped, thereby invaliding anything that points to it, in particular certain dynamic tags such as DT_NEEDED. The following patch re-parses the dynamic info after the remapping so as to re-compute any invalid pointers. Signed-off-by: Alan Davis Signed-off-by: Bernd Schmidt --- ldso/ldso/dl-elf.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c index 7b5d75146..09b3aaf01 100644 --- a/ldso/ldso/dl-elf.c +++ b/ldso/ldso/dl-elf.c @@ -714,6 +714,9 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure, DL_UPDATE_LOADADDR_HDR(lib_loadaddr, new_addr + (ppnt->p_vaddr & ADDR_ALIGN), ppnt); + /* This has invalidated all pointers into the previously readonly segment. + Update any them to point into the remapped segment. */ + _dl_parse_dynamic_info(dpnt, dynamic_info, NULL, lib_loadaddr); #endif } } -- cgit v1.2.3