[v14,5/9] nptl: add rtld_hidden_proto to __rseq_size and __rseq_offset
Checks
| Context |
Check |
Description |
| redhat-pt-bot/TryBot-apply_patch |
success
|
Patch applied to master at the time it was sent
|
Commit Message
This allows accessing the internal aliases of __rseq_size and
__rseq_offset from ld.so without ifdefs and avoids a PLT entry in ld.so
for both variables.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
sysdeps/unix/sysv/linux/dl-rseq-symbols.S | 27 ++++++++++++++++-------
sysdeps/unix/sysv/linux/rseq-internal.h | 16 ++++++++------
2 files changed, 28 insertions(+), 15 deletions(-)
@@ -27,14 +27,18 @@
/* Some targets define a macro to denote the zero register. */
#undef zero
-/* Define 2 symbols: '__rseq_size' is public const and '_rseq_size' (an
- alias of '__rseq_size') is hidden and writable for internal use by the
- dynamic linker which will initialize the value both symbols point to
- before copy relocations take place. */
+/* Define 3 symbols: '__rseq_size' is public const and then '_rseq_size' and
+ '__GI___rseq_size' (both aliases of '__rseq_size') are hidden, '_rseq_size'
+ is writable for internal use by the dynamic linker which will initialize
+ the value the symbols point to before copy relocations take place. */
.globl __rseq_size
.type __rseq_size, %object
.size __rseq_size, 4
+ .hidden __GI___rseq_size
+ .globl __GI___rseq_size
+ .type __GI___rseq_size, %object
+ .size __GI___rseq_size, 4
.hidden _rseq_size
.globl _rseq_size
.type _rseq_size, %object
@@ -42,17 +46,23 @@
.section .data.rel.ro
.balign 4
__rseq_size:
+__GI___rseq_size:
_rseq_size:
.zero 4
-/* Define 2 symbols: '__rseq_offset' is public const and '_rseq_offset' (an
- alias of '__rseq_offset') is hidden and writable for internal use by the
- dynamic linker which will initialize the value both symbols point to
- before copy relocations take place. */
+/* Define 3 symbols: '__rseq_offset' is public const and then '_rseq_offset'
+ and '__GI___rseq_offset' (both aliases of '__rseq_offset') are hidden,
+ '_rseq_offset' is writable for internal use by the dynamic linker which will
+ initialize the value the symbols point to before copy relocations take
+ place. */
.globl __rseq_offset
.type __rseq_offset, %object
.size __rseq_offset, RSEQ_OFFSET_SIZE
+ .hidden __GI___rseq_offset
+ .globl __GI___rseq_offset
+ .type __GI___rseq_offset, %object
+ .size __GI___rseq_offset, RSEQ_OFFSET_SIZE
.hidden _rseq_offset
.globl _rseq_offset
.type _rseq_offset, %object
@@ -60,5 +70,6 @@ _rseq_size:
.section .data.rel.ro
.balign RSEQ_OFFSET_SIZE
__rseq_offset:
+__GI___rseq_offset:
_rseq_offset:
.zero RSEQ_OFFSET_SIZE
@@ -24,6 +24,7 @@
#include <stdbool.h>
#include <stdio.h>
#include <sys/rseq.h>
+#include <ldsodefs.h>
/* Minimum size of the rseq area allocation required by the syscall. The
actually used rseq feature size may be less (20 bytes initially). */
@@ -52,19 +53,20 @@ extern unsigned int _rseq_size attribute_hidden;
In .data.relro but not yet write-protected. */
extern ptrdiff_t _rseq_offset attribute_hidden;
+/* We want to use rtld_hidden_proto in order to call the internal aliases
+ of __rseq_size and __rseq_offset from ld.so. This avoids a PLT entry in
+ ld.so for both variables. */
+rtld_hidden_proto (__rseq_size)
+rtld_hidden_proto (__rseq_offset)
+
#ifdef RSEQ_SIG
static inline bool
rseq_register_current_thread (struct pthread *self, bool do_rseq)
{
if (do_rseq)
{
- unsigned int size;
-#if IS_IN (rtld)
- /* Use the hidden symbol in ld.so. */
- size = _rseq_size;
-#else
- size = __rseq_size;
-#endif
+ unsigned int size = __rseq_size;
+
if (size < RSEQ_AREA_SIZE_INITIAL)
/* The initial implementation used only 20 bytes out of 32,
but still expected size 32. */