svn commit: r327097 - in head/sys/mips: include mips

[Konstantin Belousov]

Author: kib
Date: Fri Dec 22 23:27:03 2017
New Revision: 327097
URL: https://svnweb.freebsd.org/changeset/base/327097

Log:
  Remove mips MD atomic_load_64 and atomic_store_64.
  
  The only users of the functions were db_read_bytes() and
  db_write_bytes() ddb(4) interfaces.  Replace the calls with direct
  reads and writes, which are automatically atomic on 64bits and n32.
  
  Note that removed assembler implementation for mips32 is not atomic
  anyway.
  
  Reviewed by:	jhb
  Discussed with:	imp
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week
  Differential revision:	https://reviews.freebsd.org/D13586

Modified:
  head/sys/mips/include/atomic.h
  head/sys/mips/mips/db_interface.c
  head/sys/mips/mips/support.S

Modified: head/sys/mips/include/atomic.h
==============================================================================
--- head/sys/mips/include/atomic.h	Fri Dec 22 21:54:39 2017	(r327096)
+++ head/sys/mips/include/atomic.h	Fri Dec 22 23:27:03 2017	(r327097)
@@ -341,24 +341,6 @@ atomic_store_rel_##WIDTH(__volatile uint##WIDTH##_t *p
 
 ATOMIC_STORE_LOAD(32)
 ATOMIC_STORE_LOAD(64)
-#if !defined(__mips_n64) && !defined(__mips_n32)
-void atomic_store_64(__volatile uint64_t *, uint64_t);
-uint64_t atomic_load_64(__volatile uint64_t *);
-#elif defined (__mips_n32)
-static __inline void
-atomic_store_64(__volatile uint64_t *p, uint64_t v)
-{
-	*p = v;
-}
-
-static __inline uint64_t
-atomic_load_64(__volatile uint64_t *p)
-{
-	return (*p);
-}
-/* #else atomic_common.h definitions of atomic_load/store_64 are used */
-#endif
-
 #undef ATOMIC_STORE_LOAD
 
 /*

Modified: head/sys/mips/mips/db_interface.c
==============================================================================
--- head/sys/mips/mips/db_interface.c	Fri Dec 22 21:54:39 2017	(r327096)
+++ head/sys/mips/mips/db_interface.c	Fri Dec 22 23:27:03 2017	(r327097)
@@ -152,6 +152,7 @@ db_read_bytes(vm_offset_t addr, size_t size, char *dat
 		/*
 		 * 'addr' could be a memory-mapped I/O address.  Try to
 		 * do atomic load/store in unit of size requested.
+		 * size == 8 is only atomic on 64bit or n32 kernel.
 		 */
 		if ((size == 2 || size == 4 || size == 8) &&
 		    ((addr & (size -1)) == 0) &&
@@ -164,8 +165,7 @@ db_read_bytes(vm_offset_t addr, size_t size, char *dat
 				*(uint32_t *)data = *(uint32_t *)addr;
 				break;
 			case 8:
-				*(uint64_t *)data = atomic_load_64(
-				    (void *)addr);
+				*(uint64_t *)data = *(uint64_t *)addr;
 				break;
 			}
 		} else {
@@ -195,6 +195,7 @@ db_write_bytes(vm_offset_t addr, size_t size, char *da
 		/*
 		 * 'addr' could be a memory-mapped I/O address.  Try to
 		 * do atomic load/store in unit of size requested.
+		 * size == 8 is only atomic on 64bit or n32 kernel.
 		 */
 		if ((size == 2 || size == 4 || size == 8) &&
 		    ((addr & (size -1)) == 0) &&
@@ -207,8 +208,7 @@ db_write_bytes(vm_offset_t addr, size_t size, char *da
 				*(uint32_t *)addr = *(uint32_t *)data;
 				break;
 			case 8:
-				atomic_store_64((uint64_t *)addr,
-				    *(uint64_t *)data);
+				*(uint64_t *)addr = *(uint64_t *)data;
 				break;
 			}
 		} else {

Modified: head/sys/mips/mips/support.S
==============================================================================
--- head/sys/mips/mips/support.S	Fri Dec 22 21:54:39 2017	(r327096)
+++ head/sys/mips/mips/support.S	Fri Dec 22 23:27:03 2017	(r327097)
@@ -839,74 +839,7 @@ LEAF(atomic_subtract_8)
 	nop
 END(atomic_subtract_8)
 
-/*
- *	atomic 64-bit register read/write assembly language support routines.
- */
-
 	.set	noreorder		# Noreorder is default style!
-
-#if !defined(__mips_n64) && !defined(__mips_n32)	
-	/*
-	 * I don't know if these routines have the right number of
-	 * NOPs in it for all processors.  XXX
-	 *
-	 * Maybe it would be better to just leave this undefined in that case.
-	 *
-	 * XXX These routines are not safe in the case of a TLB miss on a1 or
-	 *     a0 unless the trapframe is 64-bit, which it just isn't with O32.
-	 *     If we take any exception, not just an interrupt, the upper
-	 *     32-bits will be clobbered.  Use only N32 and N64 kernels if you
-	 *     want to use 64-bit registers while interrupts are enabled or
-	 *     with memory operations.  Since this isn't even using load-linked
-	 *     and store-conditional, perhaps it should just use two registers
-	 *     instead, as is right and good with the O32 ABI.
-	 */
-LEAF(atomic_store_64)
-	mfc0	t1, MIPS_COP_0_STATUS
-	and	t2, t1, ~MIPS_SR_INT_IE
-	mtc0	t2, MIPS_COP_0_STATUS
-	nop
-	nop
-	nop
-	nop
-	ld	t0, (a1)
-	nop
-	nop
-	sd	t0, (a0)
-	nop
-	nop
-	mtc0	t1,MIPS_COP_0_STATUS
-	nop
-	nop
-	nop
-	nop
-	j	ra
-	nop
-END(atomic_store_64)
-
-LEAF(atomic_load_64)
-	mfc0	t1, MIPS_COP_0_STATUS
-	and	t2, t1, ~MIPS_SR_INT_IE
-	mtc0	t2, MIPS_COP_0_STATUS
-	nop
-	nop
-	nop
-	nop
-	ld	t0, (a0)
-	nop
-	nop
-	sd	t0, (a1)
-	nop
-	nop
-	mtc0	t1,MIPS_COP_0_STATUS
-	nop
-	nop
-	nop
-	nop
-	j	ra
-	nop
-END(atomic_load_64)
-#endif
 
 #if defined(DDB) || defined(DEBUG)