From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by oss.sgi.com (8.11.2/8.11.3) id g11IetR15686 for linux-mips-outgoing; Fri, 1 Feb 2002 10:40:55 -0800 Received: from ocean.lucon.org (12-234-19-19.client.attbi.com [12.234.19.19]) by oss.sgi.com (8.11.2/8.11.3) with SMTP id g11IeSd15683 for ; Fri, 1 Feb 2002 10:40:28 -0800 Received: by ocean.lucon.org (Postfix, from userid 1000) id 78793125C3; Fri, 1 Feb 2002 09:40:25 -0800 (PST) Date: Fri, 1 Feb 2002 09:40:25 -0800 From: "H . J . Lu" To: "Maciej W. Rozycki" Cc: Hiroyuki Machida , libc-alpha@sources.redhat.com, linux-mips@oss.sgi.com Subject: Re: PATCH: Fix ll/sc for mips Message-ID: <20020201094025.A10392@lucon.org> References: <20020201.123523.50041631.machida@sm.sony.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from macro@ds2.pg.gda.pl on Fri, Feb 01, 2002 at 12:50:48PM +0100 Sender: owner-linux-mips@oss.sgi.com Precedence: bulk On Fri, Feb 01, 2002 at 12:50:48PM +0100, Maciej W. Rozycki wrote: > On Fri, 1 Feb 2002, Hiroyuki Machida wrote: > > > > It will fail if *p is not same as oldval. > > > > Please note that "sc" may fail even if nobody write the > > variable. (See P.211 "8.4.2 Load-Linked/Sotre-Conditional" of "See > > MIPS RUN" for more detail.) > > So, after your patch applied, compare_and_swap() may fail, even if > > *p is equal to oldval. > > That's exactly what I meant -- "sc" may fail to execute the store, while > "cmpxchgl" may not. > Here is the updated patch. H.J. --- 2002-01-31 H.J. Lu * sysdeps/mips/pspinlock.c (__pthread_spin_lock): Use a different register in the delayed slot. * sysdeps/mips/pt-machine.h (testandset): Call _test_and_set. (__compare_and_swap): Return 0 only when failed to compare. 2002-01-31 H.J. Lu * sysdeps/mips/atomicity.h (compare_and_swap): Return 0 only when failed to compare. * sysdeps/unix/sysv/linux/mips/sys/tas.h (_test_and_set): Fill the delay slot. --- glibc-2.2.4/linuxthreads/sysdeps/mips/pspinlock.c.llsc Thu Jan 31 10:49:37 2002 +++ glibc-2.2.4/linuxthreads/sysdeps/mips/pspinlock.c Thu Jan 31 10:49:37 2002 @@ -29,20 +29,21 @@ int __pthread_spin_lock (pthread_spinlock_t *lock) { - unsigned int tmp; + unsigned int tmp1, tmp2; asm volatile ("\t\t\t# spin_lock\n\t" - "1:\n\t" - "ll %1,%2\n\t" ".set push\n\t" - ".set noreorder\n\t" + ".set noreorder\n" + "1:\n\t" + "ll %1,%3\n\t" "bnez %1,1b\n\t" - " li %1,1\n\t" - ".set pop\n\t" - "sc %1,%0\n\t" - "beqz %1,1b" - : "=m" (*lock), "=&r" (tmp) + "li %2,1\n\t" + "sc %2,%0\n\t" + "beqz %2,1b\n\t" + "nop\n\t" + ".set pop" + : "=m" (*lock), "=&r" (tmp1), "=&r" (tmp2) : "m" (*lock) : "memory"); --- glibc-2.2.4/linuxthreads/sysdeps/mips/pt-machine.h.llsc Sat Dec 9 08:55:34 2000 +++ glibc-2.2.4/linuxthreads/sysdeps/mips/pt-machine.h Fri Feb 1 09:19:44 2002 @@ -33,41 +33,11 @@ /* Spinlock implementation; required. */ -#if (_MIPS_ISA >= _MIPS_ISA_MIPS2) - -PT_EI long int -testandset (int *spinlock) -{ - long int ret, temp; - - __asm__ __volatile__ - ("/* Inline spinlock test & set */\n\t" - "1:\n\t" - "ll %0,%3\n\t" - ".set push\n\t" - ".set noreorder\n\t" - "bnez %0,2f\n\t" - " li %1,1\n\t" - ".set pop\n\t" - "sc %1,%2\n\t" - "beqz %1,1b\n" - "2:\n\t" - "/* End spinlock test & set */" - : "=&r" (ret), "=&r" (temp), "=m" (*spinlock) - : "m" (*spinlock) - : "memory"); - - return ret; -} - -#else /* !(_MIPS_ISA >= _MIPS_ISA_MIPS2) */ - PT_EI long int testandset (int *spinlock) { return _test_and_set (spinlock, 1); } -#endif /* !(_MIPS_ISA >= _MIPS_ISA_MIPS2) */ /* Get some notion of the current stack. Need not be exactly the top @@ -84,22 +54,24 @@ register char * stack_pointer __asm__ (" PT_EI int __compare_and_swap (long int *p, long int oldval, long int newval) { - long int ret; + long int ret, temp; __asm__ __volatile__ - ("/* Inline compare & swap */\n\t" + ("/* Inline compare & swap */\n" "1:\n\t" - "ll %0,%4\n\t" - ".set push\n" + "ll %1,%5\n\t" + ".set push\n\t" ".set noreorder\n\t" - "bne %0,%2,2f\n\t" - " move %0,%3\n\t" - ".set pop\n\t" - "sc %0,%1\n\t" - "beqz %0,1b\n" + "bne %1,%3,2f\n\t" + "move %0,$0\n\t" + "move %0,%4\n\t" + "sc %0,%2\n\t" + "beqz %0,1b\n\t" + "nop\n\t" + ".set pop\n" "2:\n\t" "/* End compare & swap */" - : "=&r" (ret), "=m" (*p) + : "=&r" (ret), "=&r" (temp), "=m" (*p) : "r" (oldval), "r" (newval), "m" (*p) : "memory"); --- glibc-2.2.4/sysdeps/mips/atomicity.h.llsc Mon Jul 9 11:58:19 2001 +++ glibc-2.2.4/sysdeps/mips/atomicity.h Fri Feb 1 09:21:41 2002 @@ -32,12 +32,16 @@ exchange_and_add (volatile uint32_t *mem int result, tmp; __asm__ __volatile__ - ("/* Inline exchange & add */\n\t" + ("/* Inline exchange & add */\n" "1:\n\t" "ll %0,%3\n\t" "addu %1,%4,%0\n\t" "sc %1,%2\n\t" + ".set push\n\t" + ".set noreorder\n\t" "beqz %1,1b\n\t" + "nop\n\t" + ".set pop\n\t" "/* End exchange & add */" : "=&r"(result), "=&r"(tmp), "=m"(*mem) : "m" (*mem), "r"(val) @@ -53,12 +57,16 @@ atomic_add (volatile uint32_t *mem, int int result; __asm__ __volatile__ - ("/* Inline atomic add */\n\t" + ("/* Inline atomic add */\n" "1:\n\t" "ll %0,%2\n\t" "addu %0,%3,%0\n\t" "sc %0,%1\n\t" + ".set push\n\t" + ".set noreorder\n\t" "beqz %0,1b\n\t" + "nop\n\t" + ".set pop\n\t" "/* End atomic add */" : "=&r"(result), "=m"(*mem) : "m" (*mem), "r"(val) @@ -69,22 +77,24 @@ static inline int __attribute__ ((unused)) compare_and_swap (volatile long int *p, long int oldval, long int newval) { - long int ret; + long int ret, temp; __asm__ __volatile__ - ("/* Inline compare & swap */\n\t" + ("/* Inline compare & swap */\n" "1:\n\t" - "ll %0,%4\n\t" - ".set push\n" + "ll %1,%5\n\t" + ".set push\n\t" ".set noreorder\n\t" - "bne %0,%2,2f\n\t" - "move %0,%3\n\t" - ".set pop\n\t" - "sc %0,%1\n\t" - "beqz %0,1b\n" + "bne %1,%3,2f\n\t" + "move %0,$0\n\t" + "move %0,%4\n\t" + "sc %0,%2\n\t" + "beqz %0,1b\n\t" + "nop\n\t" + ".set pop\n" "2:\n\t" "/* End compare & swap */" - : "=&r" (ret), "=m" (*p) + : "=&r" (ret), "=&r" (temp), "=m" (*p) : "r" (oldval), "r" (newval), "m" (*p) : "memory"); --- glibc-2.2.4/sysdeps/unix/sysv/linux/mips/sys/tas.h.llsc Mon Jul 9 11:58:45 2001 +++ glibc-2.2.4/sysdeps/unix/sysv/linux/mips/sys/tas.h Thu Jan 31 10:49:37 2002 @@ -42,16 +42,17 @@ _test_and_set (int *p, int v) __THROW int r, t; __asm__ __volatile__ - ("1:\n\t" + (".set push\n\t" + ".set noreorder\n" + "1:\n\t" "ll %0,%3\n\t" - ".set push\n\t" - ".set noreorder\n\t" "beq %0,%4,2f\n\t" - " move %1,%4\n\t" - ".set pop\n\t" + "move %1,%4\n\t" "sc %1,%2\n\t" - "beqz %1,1b\n" - "2:\n" + "beqz %1,1b\n\t" + "nop\n" + "2:\n\t" + ".set pop" : "=&r" (r), "=&r" (t), "=m" (*p) : "m" (*p), "r" (v) : "memory");