[PATCH] x32: Use THREAD_SELF for RSEQ_* accessors

[H.J. Lu]

Use THREAD_SELF to get the %fs register to work around the GCC bug:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121613

with the negative offset from the %fs register.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
 sysdeps/x86_64/x32/nptl/rseq-access.h | 110 ++++++++++++--------------
 1 file changed, 49 insertions(+), 61 deletions(-)

diff --git a/sysdeps/x86_64/x32/nptl/rseq-access.h b/sysdeps/x86_64/x32/nptl/rseq-access.h
index 8386ebd4bf..0baf4e8ea1 100644
--- a/sysdeps/x86_64/x32/nptl/rseq-access.h
+++ b/sysdeps/x86_64/x32/nptl/rseq-access.h
@@ -16,70 +16,58 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+/* Read member of the RSEQ area directly.  */
+#define RSEQ_GETMEM(member) \
+  ({								\
+     _Static_assert (sizeof (RSEQ_SELF()->member) == 1		\
+		     || sizeof (RSEQ_SELF()->member) == 4	\
+		     || sizeof (RSEQ_SELF()->member) == 8,	\
+		     "size of rseq data");			\
+     void *__self = THREAD_SELF;				\
+     asm ("" ::: "memory");					\
+     (*(__typeof (RSEQ_SELF()->member) *)			\
+      (((uintptr_t) __self) + __rseq_offset			\
+       + offsetof (struct rseq_area, member)));			\
+  })
+
 /* Read member of the RSEQ area directly, with single-copy atomicity semantics.  */
 #define RSEQ_GETMEM_ONCE(member) \
-  ({ __typeof (RSEQ_SELF()->member) __value;				      \
-     _Static_assert (sizeof (__value) == 1				      \
-		     || sizeof (__value) == 4				      \
-		     || sizeof (__value) == 8,				      \
-		     "size of rseq data");			      \
-     if (sizeof (__value) == 1)						      \
-       asm volatile ("movb %%fs:%P2(%q3),%b0"				      \
-		     : "=q" (__value)					      \
-		     : "0" (0), "i" (offsetof (struct rseq_area, member)),    \
-		       "r" ((long long int) __rseq_offset));		      \
-     else if (sizeof (__value) == 4)					      \
-       asm volatile ("movl %%fs:%P1(%q2),%0"				      \
-		     : "=r" (__value)					      \
-		     : "i" (offsetof (struct rseq_area, member)),	      \
-		       "r" ((long long int) __rseq_offset));		      \
-     else /* 8 */							      \
-       {								      \
-	 asm volatile ("movq %%fs:%P1(%q2),%q0"				      \
-		       : "=r" (__value)					      \
-		       : "i" (offsetof (struct rseq_area, member)),	      \
-		         "r" ((long long int) __rseq_offset));		      \
-       }								      \
-     __value; })
-
-/* Read member of the RSEQ area directly.  */
-#define RSEQ_GETMEM(member) RSEQ_GETMEM_ONCE(member)
+  ({								\
+     _Static_assert (sizeof (RSEQ_SELF()->member) == 1		\
+		     || sizeof (RSEQ_SELF()->member) == 4	\
+		     || sizeof (RSEQ_SELF()->member) == 8,	\
+		     "size of rseq data");			\
+     void *__self = THREAD_SELF;				\
+     asm ("" ::: "memory");					\
+     (*(volatile __typeof (RSEQ_SELF()->member) *)		\
+      (((uintptr_t) __self) + __rseq_offset			\
+       + offsetof (struct rseq_area, member)));			\
+  })
 
-/* Loading addresses of objects on x86-64 needs to be treated special
-   when generating PIC code.  */
-#ifdef __pic__
-# define IMM_MODE "nr"
-#else
-# define IMM_MODE "ir"
-#endif
+/* Set member of the RSEQ area directly.  */
+#define RSEQ_SETMEM(member, value) \
+  ({								\
+     _Static_assert (sizeof (RSEQ_SELF()->member) == 1		\
+		     || sizeof (RSEQ_SELF()->member) == 4	\
+		     || sizeof (RSEQ_SELF()->member) == 8,	\
+		     "size of rseq data");			\
+     void *__self = THREAD_SELF;				\
+     asm ("" ::: "memory");					\
+     (*(__typeof (RSEQ_SELF()->member) *)			\
+      (((uintptr_t) __self) + __rseq_offset			\
+       + offsetof (struct rseq_area, member))) = (value);	\
+  })
 
 /* Set member of the RSEQ area directly, with single-copy atomicity semantics.  */
 #define RSEQ_SETMEM_ONCE(member, value) \
-  ({									      \
-     _Static_assert (sizeof (RSEQ_SELF()->member) == 1			      \
-		     || sizeof (RSEQ_SELF()->member) == 4		      \
-		     || sizeof (RSEQ_SELF()->member) == 8,		      \
-		     "size of rseq data");			      \
-     if (sizeof (RSEQ_SELF()->member) == 1)				      \
-       asm volatile ("movb %b0,%%fs:%P1(%q2)" :				      \
-		     : "iq" (value),					      \
-		       "i" (offsetof (struct rseq_area, member)),	      \
-		       "r" ((long long int) __rseq_offset));		      \
-     else if (sizeof (RSEQ_SELF()->member) == 4)			      \
-       asm volatile ("movl %0,%%fs:%P1(%q2)" :				      \
-		     : IMM_MODE (value),				      \
-		       "i" (offsetof (struct rseq_area, member)),	      \
-		       "r" ((long long int) __rseq_offset));		      \
-     else /* 8 */							      \
-       {								      \
-	 /* Since movq takes a signed 32-bit immediate or a register source   \
-	    operand, use "er" constraint for 32-bit signed integer constant   \
-	    or register.  */						      \
-	 asm volatile ("movq %q0,%%fs:%P1(%q2)" :			      \
-		       : "er" ((uint64_t) cast_to_integer (value)),	      \
-			 "i" (offsetof (struct rseq_area, member)),	      \
-		         "r" ((long long int) __rseq_offset));		      \
-       }})
-
-/* Set member of the RSEQ area directly.  */
-#define RSEQ_SETMEM(member, value) RSEQ_SETMEM_ONCE(member, value)
+  ({								\
+     _Static_assert (sizeof (RSEQ_SELF()->member) == 1		\
+		     || sizeof (RSEQ_SELF()->member) == 4	\
+		     || sizeof (RSEQ_SELF()->member) == 8,	\
+		     "size of rseq data");			\
+     void *__self = THREAD_SELF;				\
+     asm ("" ::: "memory");					\
+     (*(volatile __typeof (RSEQ_SELF()->member) *)		\
+      (((uintptr_t) __self) + __rseq_offset			\
+       + offsetof (struct rseq_area, member))) = (value);	\
+  })
-- 
2.50.1