[PATCH] ldso: fix standalone execution on x86_64 architecture

=?UTF-8?q?C=C3=A9dric=20VINCENT?= cedric.vincent at st.com
Mon Apr 7 08:04:40 UTC 2014

If the dynamic linker is built with LDSO_STANDALONE_SUPPORT=y, it can
load then run a dynamically linked program when explicitly invoked
from the command line.  This is used for test and prelink purposes,
and also by other tools like PRoot to force the kernel to load the
right ELF interpreter.

This feature is currently broken on x86_64 since the number of command
line arguments (ie. argc) passed from the kernel is an "elf_addr_t"
(64 bit on x86_64), whereas it is read as an "unsigned int" (32 bit on

Ref: https://github.com/cedric-vincent/PRoot/issues/45
Signed-off-by: Cédric VINCENT <cedric.vincent at st.com>

v2: use "ElfW(Addr)", as suggested by Bernhard Reutner-Fischer
 ldso/ldso/ldso.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ldso/ldso/ldso.c b/ldso/ldso/ldso.c
index becabd3..a3745c3 100644
--- a/ldso/ldso/ldso.c
+++ b/ldso/ldso/ldso.c
@@ -526,8 +526,8 @@ void *_dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
 	if (_start == (void *) auxvt[AT_ENTRY].a_un.a_val) {
-		unsigned int *aux_dat = (unsigned int *) argv;
-		int argc = aux_dat[-1];
+		ElfW(Addr) *aux_dat = (ElfW(Addr) *) argv;
+		int argc = (int) aux_dat[-1];
 		tpnt->libname = argv[0];
 		while (argc > 1)

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