Message ID | 20210818022847.2041537-1-hjl.tools@gmail.com |
---|---|
State | New |
Headers | show |
Series | elf: Copy l_addr/l_ld when adding ld.so to a new namespace | expand |
On Tue, Aug 17, 2021 at 7:28 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > When add ld.so to a new namespace, we don't actually load ld.so. We > create a new link map and refers the real one for almost everything. > Copy l_addr and l_ld from the real ld.so link map to avoid GDB warning: > > warning: .dynamic section for ".../elf/ld-linux-x86-64.so.2" is not at the expected address (wrong library or version mismatch?) > > when handling shared library loaded by dlmopen. > --- > elf/dl-load.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/elf/dl-load.c b/elf/dl-load.c > index cb0618b7fc..aab290bea6 100644 > --- a/elf/dl-load.c > +++ b/elf/dl-load.c > @@ -1026,6 +1026,10 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > /* Refer to the real descriptor. */ > l->l_real = &GL(dl_rtld_map); > > + /* Also copy l_addr and l_ld. */ > + l->l_addr = l->l_real->l_addr; > + l->l_ld = l->l_real->l_ld; > + > /* No need to bump the refcount of the real object, ld.so will > never be unloaded. */ > __close_nocancel (fd); > -- > 2.31.1 > PING.
On Mon, Sep 20, 2021 at 9:52 AM H.J. Lu <hjl.tools@gmail.com> wrote: > > On Tue, Aug 17, 2021 at 7:28 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > > > When add ld.so to a new namespace, we don't actually load ld.so. We > > create a new link map and refers the real one for almost everything. > > Copy l_addr and l_ld from the real ld.so link map to avoid GDB warning: > > > > warning: .dynamic section for ".../elf/ld-linux-x86-64.so.2" is not at the expected address (wrong library or version mismatch?) > > > > when handling shared library loaded by dlmopen. > > --- > > elf/dl-load.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/elf/dl-load.c b/elf/dl-load.c > > index cb0618b7fc..aab290bea6 100644 > > --- a/elf/dl-load.c > > +++ b/elf/dl-load.c > > @@ -1026,6 +1026,10 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > > /* Refer to the real descriptor. */ > > l->l_real = &GL(dl_rtld_map); > > > > + /* Also copy l_addr and l_ld. */ > > + l->l_addr = l->l_real->l_addr; > > + l->l_ld = l->l_real->l_ld; > > + > > /* No need to bump the refcount of the real object, ld.so will > > never be unloaded. */ > > __close_nocancel (fd); > > -- > > 2.31.1 > > > > PING. > Any comments on this patch?
On 17/08/2021 23:28, H.J. Lu via Libc-alpha wrote: > When add ld.so to a new namespace, we don't actually load ld.so. We > create a new link map and refers the real one for almost everything. > Copy l_addr and l_ld from the real ld.so link map to avoid GDB warning: > > warning: .dynamic section for ".../elf/ld-linux-x86-64.so.2" is not at the expected address (wrong library or version mismatch?) > > when handling shared library loaded by dlmopen. LGTM, thanks. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> > --- > elf/dl-load.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/elf/dl-load.c b/elf/dl-load.c > index cb0618b7fc..aab290bea6 100644 > --- a/elf/dl-load.c > +++ b/elf/dl-load.c > @@ -1026,6 +1026,10 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > /* Refer to the real descriptor. */ > l->l_real = &GL(dl_rtld_map); > > + /* Also copy l_addr and l_ld. */ This comments seems obvious, maybe add it is required to avoid a GDB warning with dlmopen(); > + l->l_addr = l->l_real->l_addr; > + l->l_ld = l->l_real->l_ld; > + > /* No need to bump the refcount of the real object, ld.so will > never be unloaded. */ > __close_nocancel (fd); >
On Wed, Sep 29, 2021 at 11:57 AM Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote: > > On 17/08/2021 23:28, H.J. Lu via Libc-alpha wrote: > > When add ld.so to a new namespace, we don't actually load ld.so. We > > create a new link map and refers the real one for almost everything. > > Copy l_addr and l_ld from the real ld.so link map to avoid GDB warning: > > > > warning: .dynamic section for ".../elf/ld-linux-x86-64.so.2" is not at the expected address (wrong library or version mismatch?) > > > > when handling shared library loaded by dlmopen. > > LGTM, thanks. > > Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> > > > --- > > elf/dl-load.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/elf/dl-load.c b/elf/dl-load.c > > index cb0618b7fc..aab290bea6 100644 > > --- a/elf/dl-load.c > > +++ b/elf/dl-load.c > > @@ -1026,6 +1026,10 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > > /* Refer to the real descriptor. */ > > l->l_real = &GL(dl_rtld_map); > > > > + /* Also copy l_addr and l_ld. */ > > This comments seems obvious, maybe add it is required to avoid a > GDB warning with dlmopen(); Changed to /* Copy l_addr and l_ld to avoid a GDB warning with dlmopen(). */ > > + l->l_addr = l->l_real->l_addr; > > + l->l_ld = l->l_real->l_ld; > > + > > /* No need to bump the refcount of the real object, ld.so will > > never be unloaded. */ > > __close_nocancel (fd); > > This is the patch I am checking in. Thanks.
diff --git a/elf/dl-load.c b/elf/dl-load.c index cb0618b7fc..aab290bea6 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -1026,6 +1026,10 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, /* Refer to the real descriptor. */ l->l_real = &GL(dl_rtld_map); + /* Also copy l_addr and l_ld. */ + l->l_addr = l->l_real->l_addr; + l->l_ld = l->l_real->l_ld; + /* No need to bump the refcount of the real object, ld.so will never be unloaded. */ __close_nocancel (fd);