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Re: [PATCH] [BZ #19178] ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA conflict
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>, mark dot hatle at windriver dot com
- Date: Wed, 28 Oct 2015 16:18:27 -0700
- Subject: Re: [PATCH] [BZ #19178] ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA conflict
- Authentication-results: sourceware.org; auth=none
- References: <20151028114906 dot GA7686 at gmail dot com> <CAMe9rOquOovFN=ZaD+6AFUm=XVer8nj+sQzu-6q+1mDC_CRjtw at mail dot gmail dot com> <CAMe9rOqtF_9qSfftHHSd22ig7FwsSM_pK_9dOPufHd6zChAjcg at mail dot gmail dot com>
On Wed, Oct 28, 2015 at 3:04 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Oct 28, 2015 at 6:42 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Wed, Oct 28, 2015 at 4:49 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> _dl_debug_bindings updates relocation type class with 4 and 8. But
>>> ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA may be defined to 4. This patch
>>> adds ELF_RTYPE_CLASS_TLS/ELF_RTYPE_CLASS_IFUNC and use them in
>>> _dl_debug_bindings.
>>>
>>> Tested on i686 and x86-64. OK for master and 2.22 branch?
>>>
>>>
>>> H.J.
>>> --
>>> [BZ #19178]
>>> * dl-lookup.c (_dl_debug_bindings): Replace 4 and 8 with
>>> ELF_RTYPE_CLASS_TLS and ELF_RTYPE_CLASS_IFUNC.
>>> * sysdeps/generic/ldsodefs.h (ELF_RTYPE_CLASS_TLS): New.
>>> (ELF_RTYPE_CLASS_IFUNC): Likewise.
>>
>>
>> It doesn't work with prelink.
>>
>
> Here is the correct patch. Verified with prelink. OK for master
> and 2.22 branch?
Here is the updated patch to keep only ELF_RTYPE_CLASS_PLT and
ELF_RTYPE_CLASS_COPY bits for prelink.
Mark, can you verify it with prelink?
Thanks.
--
H.J.
From 7f16bc353495e6c2ec101abeee4ba26525e6c725 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 28 Oct 2015 07:49:44 -0700
Subject: [PATCH] Keep only ELF_RTYPE_CLASS_{PLT|COPY} bits for prelink
prelink runs ld.so with the environment variable LD_TRACE_PRELINKING
set to dump the relocation type class from _dl_debug_bindings. prelink
has the following relocation type classes:
#define RTYPE_CLASS_VALID 8
#define RTYPE_CLASS_PLT (8|1)
#define RTYPE_CLASS_COPY (8|2)
#define RTYPE_CLASS_TLS (8|4)
where ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA has a conflict with
RTYPE_CLASS_TLS.
Since prelink only uses ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY
bits, we should clear the other bits when the DL_DEBUG_PRELINK bit is
set.
[BZ #19178]
* elf/dl-lookup.c (RTYPE_CLASS_VALID): New.
(RTYPE_CLASS_PLT): Likewise.
(RTYPE_CLASS_COPY): Likewise.
(RTYPE_CLASS_TLS): Likewise.
(_dl_debug_bindings): Use RTYPE_CLASS_TLS and RTYPE_CLASS_VALID
to set relocation type class for DL_DEBUG_PRELINK. Keep only
ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY bits for
DL_DEBUG_PRELINK.
---
elf/dl-lookup.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 581fb20..6ae6cc3 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -1016,6 +1016,18 @@ _dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
#ifdef SHARED
if (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK)
{
+/* ELF_RTYPE_CLASS_XXX must match RTYPE_CLASS_XXX used by prelink with
+ LD_TRACE_PRELINKING. */
+#define RTYPE_CLASS_VALID 8
+#define RTYPE_CLASS_PLT (8|1)
+#define RTYPE_CLASS_COPY (8|2)
+#define RTYPE_CLASS_TLS (8|4)
+#if ELF_RTYPE_CLASS_PLT != 0 && ELF_RTYPE_CLASS_PLT != 1
+# error ELF_RTYPE_CLASS_PLT must be 0 or 1!
+#endif
+#if ELF_RTYPE_CLASS_COPY != 0 && ELF_RTYPE_CLASS_COPY != 2
+# error ELF_RTYPE_CLASS_COPY must be 0 or 2!
+#endif
int conflict = 0;
struct sym_val val = { NULL, NULL };
@@ -1071,12 +1083,17 @@ _dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
if (value->s)
{
+ /* Keep only ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY
+ bits since since prelink only uses them. */
+ type_class &= ELF_RTYPE_CLASS_PLT | ELF_RTYPE_CLASS_COPY;
if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info)
== STT_TLS))
- type_class = 4;
+ /* Clear the RTYPE_CLASS_VALID bit in RTYPE_CLASS_TLS. */
+ type_class = RTYPE_CLASS_TLS & ~RTYPE_CLASS_VALID;
else if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info)
== STT_GNU_IFUNC))
- type_class |= 8;
+ /* Set the RTYPE_CLASS_VALID bit. */
+ type_class |= RTYPE_CLASS_VALID;
}
if (conflict
--
2.4.3