d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

rtld: populate DT_DEBUG iff DYNAMIC segment is writable

Browse Source 
MIPS has/had a read-only DYNAMIC segment, and uses an extra level of
indirection (through MIPS_RLD_MAP) to locate the debugger rendezvous
data.

Some linkers (e.g. LLVM's lld) may produce MIPS binaries with a writable
DYNAMIC segment, which would allow us to eventually drop a special case.

Therefore, instead of hardcoding knowledge that DYNAMIC is not writable
on MIPS just check the permissions on the segment.

Reviewed by:	kib
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D4791
This commit is contained in:
Ed Maste 2016-01-05 15:52:16 +00:00
parent 1041e09089
commit 7a2ff73d68
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
libexec/rtld-elf/rtld.c
View File

@ -1144,13 +1144,13 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
* is mapped read-only. DT_MIPS_RLD_MAP is used instead.
*/
#ifndef __mips__
case DT_DEBUG:
if (!obj->writable_dynamic)
break;
if (!early)
dbg("Filling in DT_DEBUG entry");
((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
break;
#endif
case DT_FLAGS:
if (dynp->d_un.d_val & DF_ORIGIN)
@ -1331,6 +1331,8 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
break;
case PT_DYNAMIC:
if (ph->p_flags & PROT_WRITE)
obj->writable_dynamic = true;
obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
break;