--- /dev/null
+diff -Naur linux-2.6.11/arch/i386/Kconfig linux-2.6.11.post/arch/i386/Kconfig
+--- linux-2.6.11/arch/i386/Kconfig 2005-03-02 07:37:49.000000000 +0000
++++ linux-2.6.11.post/arch/i386/Kconfig 2005-06-10 13:42:35.000000000 +0100
+@@ -481,6 +481,19 @@
+
+ If you don't know what to do here, say N.
+
++config SMP_ALTERNATIVES
++ bool "SMP alternatives support (EXPERIMENTAL)"
++ depends on SMP && EXPERIMENTAL
++ help
++ Try to reduce the overhead of running an SMP kernel on a uniprocessor
++ host slightly by replacing certain key instruction sequences
++ according to whether we currently have more than one CPU available.
++ This should provide a noticeable boost to performance when
++ running SMP kernels on UP machines, and have negligible impact
++ when running on an true SMP host.
++
++ If unsure, say N.
++
+ config NR_CPUS
+ int "Maximum number of CPUs (2-255)"
+ range 2 255
+diff -Naur linux-2.6.11/arch/i386/kernel/Makefile linux-2.6.11.post/arch/i386/kernel/Makefile
+--- linux-2.6.11/arch/i386/kernel/Makefile 2005-03-02 07:37:49.000000000 +0000
++++ linux-2.6.11.post/arch/i386/kernel/Makefile 2005-06-16 11:16:18.555332435 +0100
+@@ -32,6 +32,7 @@
+ obj-$(CONFIG_HPET_TIMER) += time_hpet.o
+ obj-$(CONFIG_EFI) += efi.o efi_stub.o
+ obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
++obj-$(CONFIG_SMP_ALTERNATIVES) += smpalts.o
+
+ EXTRA_AFLAGS := -traditional
+
+diff -Naur linux-2.6.11/arch/i386/kernel/smpalts.c linux-2.6.11.post/arch/i386/kernel/smpalts.c
+--- linux-2.6.11/arch/i386/kernel/smpalts.c 1970-01-01 01:00:00.000000000 +0100
++++ linux-2.6.11.post/arch/i386/kernel/smpalts.c 2005-06-16 11:23:39.300902424 +0100
+@@ -0,0 +1,76 @@
++#include <linux/kernel.h>
++#include <asm/system.h>
++#include <asm/smp_alt.h>
++#include <asm/processor.h>
++#include <asm/string.h>
++
++struct smp_replacement_record {
++ unsigned char targ_size;
++ unsigned char smp1_size;
++ unsigned char smp2_size;
++ unsigned char up_size;
++ unsigned char feature;
++ unsigned char data[0];
++};
++
++struct smp_alternative_record {
++ void *targ_start;
++ struct smp_replacement_record *repl;
++};
++
++extern struct smp_alternative_record __start_smp_alternatives_table,
++ __stop_smp_alternatives_table;
++
++void prepare_for_smp(void)
++{
++ struct smp_alternative_record *r;
++ printk(KERN_INFO "Enabling SMP...\n");
++ for (r = &__start_smp_alternatives_table;
++ r != &__stop_smp_alternatives_table;
++ r++) {
++ BUG_ON(r->repl->targ_size < r->repl->smp1_size);
++ BUG_ON(r->repl->targ_size < r->repl->smp2_size);
++ BUG_ON(r->repl->targ_size < r->repl->up_size);
++ if (r->repl->feature != (unsigned char)-1 &&
++ boot_cpu_has(r->repl->feature)) {
++ memcpy(r->targ_start,
++ r->repl->data + r->repl->smp1_size,
++ r->repl->smp2_size);
++ memset(r->targ_start + r->repl->smp2_size,
++ 0x90,
++ r->repl->targ_size - r->repl->smp2_size);
++ } else {
++ memcpy(r->targ_start,
++ r->repl->data,
++ r->repl->smp1_size);
++ memset(r->targ_start + r->repl->smp1_size,
++ 0x90,
++ r->repl->targ_size - r->repl->smp1_size);
++ }
++ }
++ /* Paranoia */
++ asm volatile ("jmp 1f\n1:");
++ mb();
++}
++
++void unprepare_for_smp(void)
++{
++ struct smp_alternative_record *r;
++ printk(KERN_INFO "Disabling SMP...\n");
++ for (r = &__start_smp_alternatives_table;
++ r != &__stop_smp_alternatives_table;
++ r++) {
++ BUG_ON(r->repl->targ_size < r->repl->smp1_size);
++ BUG_ON(r->repl->targ_size < r->repl->smp2_size);
++ BUG_ON(r->repl->targ_size < r->repl->up_size);
++ memcpy(r->targ_start,
++ r->repl->data + r->repl->smp1_size + r->repl->smp2_size,
++ r->repl->up_size);
++ memset(r->targ_start + r->repl->up_size,
++ 0x90,
++ r->repl->targ_size - r->repl->up_size);
++ }
++ /* Paranoia */
++ asm volatile ("jmp 1f\n1:");
++ mb();
++}
+diff -Naur linux-2.6.11/arch/i386/kernel/smpboot.c linux-2.6.11.post/arch/i386/kernel/smpboot.c
+--- linux-2.6.11/arch/i386/kernel/smpboot.c 2005-03-02 07:38:09.000000000 +0000
++++ linux-2.6.11.post/arch/i386/kernel/smpboot.c 2005-06-16 11:17:09.287064617 +0100
+@@ -1003,6 +1003,11 @@
+ if (max_cpus <= cpucount+1)
+ continue;
+
++#ifdef CONFIG_SMP_ALTERNATIVES
++ if (kicked == 1)
++ prepare_for_smp();
++#endif
++
+ if (do_boot_cpu(apicid))
+ printk("CPU #%d not responding - cannot use it.\n",
+ apicid);
+@@ -1118,6 +1123,11 @@
+ return -EIO;
+ }
+
++#ifdef CONFIG_SMP_ALTERNATIVES
++ if (num_online_cpus() == 1)
++ prepare_for_smp();
++#endif
++
+ local_irq_enable();
+ /* Unleash the CPU! */
+ cpu_set(cpu, smp_commenced_mask);
+diff -Naur linux-2.6.11/arch/i386/kernel/vmlinux.lds.S linux-2.6.11.post/arch/i386/kernel/vmlinux.lds.S
+--- linux-2.6.11/arch/i386/kernel/vmlinux.lds.S 2005-03-02 07:38:37.000000000 +0000
++++ linux-2.6.11.post/arch/i386/kernel/vmlinux.lds.S 2005-06-10 11:14:14.000000000 +0100
+@@ -30,6 +30,13 @@
+ __ex_table : { *(__ex_table) }
+ __stop___ex_table = .;
+
++ . = ALIGN(16);
++ __start_smp_alternatives_table = .;
++ __smp_alternatives : { *(__smp_alternatives) }
++ __stop_smp_alternatives_table = .;
++
++ __smp_replacements : { *(__smp_replacements) }
++
+ RODATA
+
+ /* writeable */
+diff -Naur linux-2.6.11/include/asm-i386/atomic.h linux-2.6.11.post/include/asm-i386/atomic.h
+--- linux-2.6.11/include/asm-i386/atomic.h 2005-03-02 07:37:51.000000000 +0000
++++ linux-2.6.11.post/include/asm-i386/atomic.h 2005-06-13 10:10:39.000000000 +0100
+@@ -4,18 +4,13 @@
+ #include <linux/config.h>
+ #include <linux/compiler.h>
+ #include <asm/processor.h>
++#include <asm/smp_alt.h>
+
+ /*
+ * Atomic operations that C can't guarantee us. Useful for
+ * resource counting etc..
+ */
+
+-#ifdef CONFIG_SMP
+-#define LOCK "lock ; "
+-#else
+-#define LOCK ""
+-#endif
+-
+ /*
+ * Make sure gcc doesn't try to be clever and move things around
+ * on us. We need to use _exactly_ the address the user gave us,
+diff -Naur linux-2.6.11/include/asm-i386/bitops.h linux-2.6.11.post/include/asm-i386/bitops.h
+--- linux-2.6.11/include/asm-i386/bitops.h 2005-03-02 07:38:12.000000000 +0000
++++ linux-2.6.11.post/include/asm-i386/bitops.h 2005-06-13 10:11:54.000000000 +0100
+@@ -7,6 +7,7 @@
+
+ #include <linux/config.h>
+ #include <linux/compiler.h>
++#include <asm/smp_alt.h>
+
+ /*
+ * These have to be done with inline assembly: that way the bit-setting
+@@ -16,12 +17,6 @@
+ * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
+ */
+
+-#ifdef CONFIG_SMP
+-#define LOCK_PREFIX "lock ; "
+-#else
+-#define LOCK_PREFIX ""
+-#endif
+-
+ #define ADDR (*(volatile long *) addr)
+
+ /**
+@@ -41,7 +36,7 @@
+ */
+ static inline void set_bit(int nr, volatile unsigned long * addr)
+ {
+- __asm__ __volatile__( LOCK_PREFIX
++ __asm__ __volatile__( LOCK
+ "btsl %1,%0"
+ :"=m" (ADDR)
+ :"Ir" (nr));
+@@ -76,7 +71,7 @@
+ */
+ static inline void clear_bit(int nr, volatile unsigned long * addr)
+ {
+- __asm__ __volatile__( LOCK_PREFIX
++ __asm__ __volatile__( LOCK
+ "btrl %1,%0"
+ :"=m" (ADDR)
+ :"Ir" (nr));
+@@ -121,7 +116,7 @@
+ */
+ static inline void change_bit(int nr, volatile unsigned long * addr)
+ {
+- __asm__ __volatile__( LOCK_PREFIX
++ __asm__ __volatile__( LOCK
+ "btcl %1,%0"
+ :"=m" (ADDR)
+ :"Ir" (nr));
+@@ -140,7 +135,7 @@
+ {
+ int oldbit;
+
+- __asm__ __volatile__( LOCK_PREFIX
++ __asm__ __volatile__( LOCK
+ "btsl %2,%1\n\tsbbl %0,%0"
+ :"=r" (oldbit),"=m" (ADDR)
+ :"Ir" (nr) : "memory");
+@@ -180,7 +175,7 @@
+ {
+ int oldbit;
+
+- __asm__ __volatile__( LOCK_PREFIX
++ __asm__ __volatile__( LOCK
+ "btrl %2,%1\n\tsbbl %0,%0"
+ :"=r" (oldbit),"=m" (ADDR)
+ :"Ir" (nr) : "memory");
+@@ -231,7 +226,7 @@
+ {
+ int oldbit;
+
+- __asm__ __volatile__( LOCK_PREFIX
++ __asm__ __volatile__( LOCK
+ "btcl %2,%1\n\tsbbl %0,%0"
+ :"=r" (oldbit),"=m" (ADDR)
+ :"Ir" (nr) : "memory");
+diff -Naur linux-2.6.11/include/asm-i386/rwsem.h linux-2.6.11.post/include/asm-i386/rwsem.h
+--- linux-2.6.11/include/asm-i386/rwsem.h 2005-03-02 07:38:08.000000000 +0000
++++ linux-2.6.11.post/include/asm-i386/rwsem.h 2005-06-13 10:13:06.000000000 +0100
+@@ -40,6 +40,7 @@
+
+ #include <linux/list.h>
+ #include <linux/spinlock.h>
++#include <asm/smp_alt.h>
+
+ struct rwsem_waiter;
+
+@@ -99,7 +100,7 @@
+ {
+ __asm__ __volatile__(
+ "# beginning down_read\n\t"
+-LOCK_PREFIX " incl (%%eax)\n\t" /* adds 0x00000001, returns the old value */
++LOCK " incl (%%eax)\n\t" /* adds 0x00000001, returns the old value */
+ " js 2f\n\t" /* jump if we weren't granted the lock */
+ "1:\n\t"
+ LOCK_SECTION_START("")
+@@ -130,7 +131,7 @@
+ " movl %1,%2\n\t"
+ " addl %3,%2\n\t"
+ " jle 2f\n\t"
+-LOCK_PREFIX " cmpxchgl %2,%0\n\t"
++LOCK " cmpxchgl %2,%0\n\t"
+ " jnz 1b\n\t"
+ "2:\n\t"
+ "# ending __down_read_trylock\n\t"
+@@ -150,7 +151,7 @@
+ tmp = RWSEM_ACTIVE_WRITE_BIAS;
+ __asm__ __volatile__(
+ "# beginning down_write\n\t"
+-LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" /* subtract 0x0000ffff, returns the old value */
++LOCK " xadd %%edx,(%%eax)\n\t" /* subtract 0x0000ffff, returns the old value */
+ " testl %%edx,%%edx\n\t" /* was the count 0 before? */
+ " jnz 2f\n\t" /* jump if we weren't granted the lock */
+ "1:\n\t"
+@@ -188,7 +189,7 @@
+ __s32 tmp = -RWSEM_ACTIVE_READ_BIAS;
+ __asm__ __volatile__(
+ "# beginning __up_read\n\t"
+-LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" /* subtracts 1, returns the old value */
++LOCK " xadd %%edx,(%%eax)\n\t" /* subtracts 1, returns the old value */
+ " js 2f\n\t" /* jump if the lock is being waited upon */
+ "1:\n\t"
+ LOCK_SECTION_START("")
+@@ -214,7 +215,7 @@
+ __asm__ __volatile__(
+ "# beginning __up_write\n\t"
+ " movl %2,%%edx\n\t"
+-LOCK_PREFIX " xaddl %%edx,(%%eax)\n\t" /* tries to transition 0xffff0001 -> 0x00000000 */
++LOCK " xaddl %%edx,(%%eax)\n\t" /* tries to transition 0xffff0001 -> 0x00000000 */
+ " jnz 2f\n\t" /* jump if the lock is being waited upon */
+ "1:\n\t"
+ LOCK_SECTION_START("")
+@@ -239,7 +240,7 @@
+ {
+ __asm__ __volatile__(
+ "# beginning __downgrade_write\n\t"
+-LOCK_PREFIX " addl %2,(%%eax)\n\t" /* transitions 0xZZZZ0001 -> 0xYYYY0001 */
++LOCK " addl %2,(%%eax)\n\t" /* transitions 0xZZZZ0001 -> 0xYYYY0001 */
+ " js 2f\n\t" /* jump if the lock is being waited upon */
+ "1:\n\t"
+ LOCK_SECTION_START("")
+@@ -263,7 +264,7 @@
+ static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
+ {
+ __asm__ __volatile__(
+-LOCK_PREFIX "addl %1,%0"
++LOCK "addl %1,%0"
+ : "=m"(sem->count)
+ : "ir"(delta), "m"(sem->count));
+ }
+@@ -276,7 +277,7 @@
+ int tmp = delta;
+
+ __asm__ __volatile__(
+-LOCK_PREFIX "xadd %0,(%2)"
++LOCK "xadd %0,(%2)"
+ : "+r"(tmp), "=m"(sem->count)
+ : "r"(sem), "m"(sem->count)
+ : "memory");
+diff -Naur linux-2.6.11/include/asm-i386/smp_alt.h linux-2.6.11.post/include/asm-i386/smp_alt.h
+--- linux-2.6.11/include/asm-i386/smp_alt.h 1970-01-01 01:00:00.000000000 +0100
++++ linux-2.6.11.post/include/asm-i386/smp_alt.h 2005-06-16 11:16:50.109433206 +0100
+@@ -0,0 +1,32 @@
++#ifndef __ASM_SMP_ALT_H__
++#define __ASM_SMP_ALT_H__
++
++#include <linux/config.h>
++
++#ifdef CONFIG_SMP
++#if defined(CONFIG_SMP_ALTERNATIVES) && !defined(MODULE)
++#define LOCK \
++ "6677: nop\n" \
++ ".section __smp_alternatives,\"a\"\n" \
++ ".long 6677b\n" \
++ ".long 6678f\n" \
++ ".previous\n" \
++ ".section __smp_replacements,\"a\"\n" \
++ "6678: .byte 1\n" \
++ ".byte 1\n" \
++ ".byte 0\n" \
++ ".byte 1\n" \
++ ".byte -1\n" \
++ "lock\n" \
++ "nop\n" \
++ ".previous\n"
++void prepare_for_smp(void);
++void unprepare_for_smp(void);
++#else
++#define LOCK "lock ; "
++#endif
++#else
++#define LOCK ""
++#endif
++
++#endif /* __ASM_SMP_ALT_H__ */
+diff -Naur linux-2.6.11/include/asm-i386/spinlock.h linux-2.6.11.post/include/asm-i386/spinlock.h
+--- linux-2.6.11/include/asm-i386/spinlock.h 2005-03-02 07:37:50.000000000 +0000
++++ linux-2.6.11.post/include/asm-i386/spinlock.h 2005-06-13 14:13:52.000000000 +0100
+@@ -6,6 +6,7 @@
+ #include <asm/page.h>
+ #include <linux/config.h>
+ #include <linux/compiler.h>
++#include <asm/smp_alt.h>
+
+ asmlinkage int printk(const char * fmt, ...)
+ __attribute__ ((format (printf, 1, 2)));
+@@ -47,8 +48,9 @@
+ #define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x))
+
+ #define spin_lock_string \
+- "\n1:\t" \
+- "lock ; decb %0\n\t" \
++ "1:\n" \
++ LOCK \
++ "decb %0\n\t" \
+ "jns 3f\n" \
+ "2:\t" \
+ "rep;nop\n\t" \
+@@ -58,8 +60,9 @@
+ "3:\n\t"
+
+ #define spin_lock_string_flags \
+- "\n1:\t" \
+- "lock ; decb %0\n\t" \
++ "1:\n" \
++ LOCK \
++ "decb %0\n\t" \
+ "jns 4f\n\t" \
+ "2:\t" \
+ "testl $0x200, %1\n\t" \
+@@ -121,10 +124,34 @@
+ static inline int _raw_spin_trylock(spinlock_t *lock)
+ {
+ char oldval;
++#ifdef CONFIG_SMP_ALTERNATIVES
+ __asm__ __volatile__(
+- "xchgb %b0,%1"
++ "1:movb %1,%b0\n"
++ "movb $0,%1\n"
++ "2:"
++ ".section __smp_alternatives,\"a\"\n"
++ ".long 1b\n"
++ ".long 3f\n"
++ ".previous\n"
++ ".section __smp_replacements,\"a\"\n"
++ "3: .byte 2b - 1b\n"
++ ".byte 5f-4f\n"
++ ".byte 0\n"
++ ".byte 6f-5f\n"
++ ".byte -1\n"
++ "4: xchgb %b0,%1\n"
++ "5: movb %1,%b0\n"
++ "movb $0,%1\n"
++ "6:\n"
++ ".previous\n"
+ :"=q" (oldval), "=m" (lock->slock)
+ :"0" (0) : "memory");
++#else
++ __asm__ __volatile__(
++ "xchgb %b0,%1\n"
++ :"=q" (oldval), "=m" (lock->slock)
++ :"0" (0) : "memory");
++#endif
+ return oldval > 0;
+ }
+
+@@ -225,8 +252,8 @@
+ __build_write_lock(rw, "__write_lock_failed");
+ }
+
+-#define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
+-#define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
++#define _raw_read_unlock(rw) asm volatile(LOCK "incl %0" :"=m" ((rw)->lock) : : "memory")
++#define _raw_write_unlock(rw) asm volatile(LOCK "addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
+
+ static inline int _raw_read_trylock(rwlock_t *lock)
+ {
+diff -Naur linux-2.6.11/include/asm-i386/system.h linux-2.6.11.post/include/asm-i386/system.h
+--- linux-2.6.11/include/asm-i386/system.h 2005-03-02 07:37:30.000000000 +0000
++++ linux-2.6.11.post/include/asm-i386/system.h 2005-06-15 13:21:40.000000000 +0100
+@@ -5,7 +5,7 @@
+ #include <linux/kernel.h>
+ #include <asm/segment.h>
+ #include <asm/cpufeature.h>
+-#include <linux/bitops.h> /* for LOCK_PREFIX */
++#include <asm/smp_alt.h>
+
+ #ifdef __KERNEL__
+
+@@ -249,19 +249,19 @@
+ unsigned long prev;
+ switch (size) {
+ case 1:
+- __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
++ __asm__ __volatile__(LOCK "cmpxchgb %b1,%2"
+ : "=a"(prev)
+ : "q"(new), "m"(*__xg(ptr)), "0"(old)
+ : "memory");
+ return prev;
+ case 2:
+- __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
++ __asm__ __volatile__(LOCK "cmpxchgw %w1,%2"
+ : "=a"(prev)
+ : "q"(new), "m"(*__xg(ptr)), "0"(old)
+ : "memory");
+ return prev;
+ case 4:
+- __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
++ __asm__ __volatile__(LOCK "cmpxchgl %1,%2"
+ : "=a"(prev)
+ : "q"(new), "m"(*__xg(ptr)), "0"(old)
+ : "memory");
+@@ -425,11 +425,55 @@
+ #endif
+
+ #ifdef CONFIG_SMP
+-#define smp_mb() mb()
+-#define smp_rmb() rmb()
+ #define smp_wmb() wmb()
+-#define smp_read_barrier_depends() read_barrier_depends()
++#if defined(CONFIG_SMP_ALTERNATIVES) && !defined(MODULE)
++#define smp_alt_mb(instr) \
++__asm__ __volatile__("6667:\nnop\nnop\nnop\nnop\nnop\nnop\n6668:\n" \
++ ".section __smp_alternatives,\"a\"\n" \
++ ".long 6667b\n" \
++ ".long 6673f\n" \
++ ".previous\n" \
++ ".section __smp_replacements,\"a\"\n" \
++ "6673:.byte 6668b-6667b\n" \
++ ".byte 6670f-6669f\n" \
++ ".byte 6671f-6670f\n" \
++ ".byte 0\n" \
++ ".byte %c0\n" \
++ "6669:lock;addl $0,0(%%esp)\n" \
++ "6670:" instr "\n" \
++ "6671:\n" \
++ ".previous\n" \
++ : \
++ : "i" (X86_FEATURE_XMM2) \
++ : "memory")
++#define smp_rmb() smp_alt_mb("lfence")
++#define smp_mb() smp_alt_mb("mfence")
++#define set_mb(var, value) do { \
++unsigned long __set_mb_temp; \
++__asm__ __volatile__("6667:movl %1, %0\n6668:\n" \
++ ".section __smp_alternatives,\"a\"\n" \
++ ".long 6667b\n" \
++ ".long 6673f\n" \
++ ".previous\n" \
++ ".section __smp_replacements,\"a\"\n" \
++ "6673: .byte 6668b-6667b\n" \
++ ".byte 6670f-6669f\n" \
++ ".byte 0\n" \
++ ".byte 6671f-6670f\n" \
++ ".byte -1\n" \
++ "6669: xchg %1, %0\n" \
++ "6670:movl %1, %0\n" \
++ "6671:\n" \
++ ".previous\n" \
++ : "=m" (var), "=r" (__set_mb_temp) \
++ : "1" (value) \
++ : "memory"); } while (0)
++#else
++#define smp_rmb() rmb()
++#define smp_mb() mb()
+ #define set_mb(var, value) do { xchg(&var, value); } while (0)
++#endif
++#define smp_read_barrier_depends() read_barrier_depends()
+ #else
+ #define smp_mb() barrier()
+ #define smp_rmb() barrier()
projects / xen.git / commitdiff