Date: Tue, 12 Sep 2000 23:13:25 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: John Baldwin <jhb@pike.osd.bsdi.com> Cc: alpha@freebsd.org Subject: Re: Mutex's aren't recursing Message-ID: <Pine.BSF.4.21.0009122312550.86297-100000@salmon.nlsystems.com> In-Reply-To: <200009122143.OAA08606@pike.osd.bsdi.com>
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On Tue, 12 Sep 2000, John Baldwin wrote:
> Doug Rabson wrote:
> > I sent you some mail yesterday about this. I got the constraints wrong for
> > the inline assembler in atomic_cmpset. I disassembled some of the code in
> > interrupt.c which is trying to enter the mutex. You can clearly see that
> > it is misusing t1 as both an input and output to the inline.
>
> Thanks! I'll try this out. Also, I just discovered that swtch.s didn't import
> sched_lock, so cpu_switch was modifying a private copy of sched_lock instead
> of the global variable (I think). I'll have some feedback on this in just a
> sec.
BTW, this is my current version of atomic.h:
Index: atomic.h
===================================================================
RCS file: /home/ncvs/src/sys/alpha/include/atomic.h,v
retrieving revision 1.3
diff -u -r1.3 atomic.h
--- atomic.h 2000/09/06 11:20:53 1.3
+++ atomic.h 2000/09/12 20:46:23
@@ -44,15 +44,149 @@
void atomic_add_16(volatile u_int16_t *, u_int16_t);
void atomic_subtract_16(volatile u_int16_t *, u_int16_t);
-void atomic_set_32(volatile u_int32_t *, u_int32_t);
-void atomic_clear_32(volatile u_int32_t *, u_int32_t);
-void atomic_add_32(volatile u_int32_t *, u_int32_t);
-void atomic_subtract_32(volatile u_int32_t *, u_int32_t);
-
-void atomic_set_64(volatile u_int64_t *, u_int64_t);
-void atomic_clear_64(volatile u_int64_t *, u_int64_t);
-void atomic_add_64(volatile u_int64_t *, u_int64_t);
-void atomic_subtract_64(volatile u_int64_t *, u_int64_t);
+static __inline void atomic_set_32(volatile u_int32_t *p, u_int32_t v)
+{
+ u_int32_t temp;
+
+ __asm __volatile (
+ "1:\tldl_l %0, %2\n\t" /* load old value */
+ "bis %0, %3, %0\n\t" /* calculate new value */
+ "stl_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
+
+static __inline void atomic_clear_32(volatile u_int32_t *p, u_int32_t v)
+{
+ u_int32_t temp;
+
+ __asm __volatile (
+ "1:\tldl_l %0, %2\n\t" /* load old value */
+ "bic %0, %3, %0\n\t" /* calculate new value */
+ "stl_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
+
+static __inline void atomic_add_32(volatile u_int32_t *p, u_int32_t v)
+{
+ u_int32_t temp;
+
+ __asm __volatile (
+ "1:\tldl_l %0, %2\n\t" /* load old value */
+ "addl %0, %3, %0\n\t" /* calculate new value */
+ "stl_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
+
+static __inline void atomic_subtract_32(volatile u_int32_t *p, u_int32_t v)
+{
+ u_int32_t temp;
+
+ __asm __volatile (
+ "1:\tldl_l %0, %2\n\t" /* load old value */
+ "subl %0, %3, %0\n\t" /* calculate new value */
+ "stl_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
+
+static __inline void atomic_set_64(volatile u_int64_t *p, u_int64_t v)
+{
+ u_int64_t temp;
+
+ __asm __volatile (
+ "1:\tldq_l %0, %2\n\t" /* load old value */
+ "bis %0, %3, %0\n\t" /* calculate new value */
+ "stq_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
+
+static __inline void atomic_clear_64(volatile u_int64_t *p, u_int64_t v)
+{
+ u_int64_t temp;
+
+ __asm __volatile (
+ "1:\tldq_l %0, %2\n\t" /* load old value */
+ "bic %0, %3, %0\n\t" /* calculate new value */
+ "stq_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
+
+static __inline void atomic_add_64(volatile u_int64_t *p, u_int64_t v)
+{
+ u_int64_t temp;
+
+ __asm __volatile (
+ "1:\tldq_l %0, %2\n\t" /* load old value */
+ "addq %0, %3, %0\n\t" /* calculate new value */
+ "stq_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
+
+static __inline void atomic_subtract_64(volatile u_int64_t *p, u_int64_t v)
+{
+ u_int64_t temp;
+
+ __asm __volatile (
+ "1:\tldq_l %0, %2\n\t" /* load old value */
+ "subq %0, %3, %0\n\t" /* calculate new value */
+ "stq_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 2f\n\t" /* spin if failed */
+ "mb\n\t" /* drain to memory */
+ ".section .text3,\"ax\"\n" /* improve branch prediction */
+ "2:\tbr 1b\n" /* try again */
+ ".previous\n"
+ : "=&r" (temp), "=m" (*p)
+ : "m" (*p), "r" (v)
+ : "memory");
+}
#define atomic_set_char atomic_set_8
#define atomic_clear_char atomic_clear_8
@@ -82,20 +216,20 @@
static __inline u_int32_t
atomic_cmpset_32(volatile u_int32_t* p, u_int32_t cmpval, u_int32_t newval)
{
- u_int32_t ret, temp;
+ u_int32_t ret;
__asm __volatile (
- "1:\tldl_l %1, %5\n\t" /* load old value */
- "cmpeq %1, %3, %0\n\t" /* compare */
+ "1:\tldl_l %0, %4\n\t" /* load old value */
+ "cmpeq %0, %2, %0\n\t" /* compare */
"beq %0, 2f\n\t" /* exit if not equal */
- "mov %4, %1\n\t" /* value to store */
- "stl_c %1, %2\n\t" /* attempt to store */
- "beq %1, 3f\n\t" /* if it failed, spin */
+ "mov %3, %0\n\t" /* value to store */
+ "stl_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 3f\n\t" /* if it failed, spin */
"2:\n" /* done */
".section .text3,\"ax\"\n" /* improve branch prediction */
"3:\tbr 1b\n" /* try again */
".previous\n"
- : "=&r" (ret), "=r" (temp), "=m" (*p)
+ : "=&r" (ret), "=m" (*p)
: "r" (cmpval), "r" (newval), "m" (*p)
: "memory");
@@ -110,20 +244,20 @@
static __inline u_int64_t
atomic_cmpset_64(volatile u_int64_t* p, u_int64_t cmpval, u_int64_t newval)
{
- u_int64_t ret, temp;
+ u_int64_t ret;
__asm __volatile (
- "1:\tldq_l %1, %5\n\t" /* load old value */
- "cmpeq %1, %3, %0\n\t" /* compare */
+ "1:\tldq_l %0, %4\n\t" /* load old value */
+ "cmpeq %0, %2, %0\n\t" /* compare */
"beq %0, 2f\n\t" /* exit if not equal */
- "mov %4, %1\n\t" /* value to store */
- "stq_c %1, %2\n\t" /* attempt to store */
- "beq %1, 3f\n\t" /* if it failed, spin */
+ "mov %3, %0\n\t" /* value to store */
+ "stq_c %0, %1\n\t" /* attempt to store */
+ "beq %0, 3f\n\t" /* if it failed, spin */
"2:\n" /* done */
".section .text3,\"ax\"\n" /* improve branch prediction */
"3:\tbr 1b\n" /* try again */
".previous\n"
- : "=&r" (ret), "=r" (temp), "=m" (*p)
+ : "=&r" (ret), "=m" (*p)
: "r" (cmpval), "r" (newval), "m" (*p)
: "memory");
--
Doug Rabson Mail: dfr@nlsystems.com
Nonlinear Systems Ltd. Phone: +44 20 8348 3944
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