[patch] SMP alternatives, take #2

From: Gerd Knorr
Date: Wed Nov 30 2005 - 05:20:19 EST

Hi,

Here next version of the SMP alternatives patch.

Had a more detailed look at the bits generated, the vast majority in the smp alternatives table where simply lock prefixes. So I decided to specical-case these to keep the table sizes small. There are three elf sections now:

.smp_altinstructions
.smp_altinstr_replacement
These are pretty much the same like the existing non-smp
alternative bits, with the exception that the replacement
table also has some space to keep the original instruction, to
allow patching both SMP->UP and back UP->SMP. It's used to patch
the code for spinlocks with simpler UP versions.

.smp_locks
List of pointers to the lock prefixes to be NOP'ed for UP.

For the core kernel these three sections are grouped together and are page-aligned, so they can be freed. Freeing happens automatically in some cases where they not needed any more after booting up (UP system found, kernel without CONFIG_HOTPLUG_CPU). There is also a kernel cmd line option to force the tables being released.

For modules only the .smp_locks section is handled, the other ones simply don't appear in modules ;)

cheers,

Gerd diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/kernel/Makefile work-2.6.14/arch/i386/kernel/Makefile
--- linux-2.6.14/arch/i386/kernel/Makefile 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/arch/i386/kernel/Makefile 2005-11-21 09:19:52.000000000 +0100
@@ -7,7 +7,7 @@
obj-y := process.o semaphore.o signal.o entry.o traps.o irq.o vm86.o \
ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_i386.o \
pci-dma.o i386_ksyms.o i387.o dmi_scan.o bootflag.o \
- doublefault.o quirks.o i8237.o
+ doublefault.o quirks.o i8237.o alternative.o

obj-y += cpu/
obj-y += timers/
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/kernel/alternative.c work-2.6.14/arch/i386/kernel/alternative.c
--- linux-2.6.14/arch/i386/kernel/alternative.c 1970-01-01 01:00:00.000000000 +0100
+++ work-2.6.14/arch/i386/kernel/alternative.c 2005-11-25 14:02:40.000000000 +0100
@@ -0,0 +1,320 @@
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <asm/alternative.h>
+
+#define DEBUG 0
+#if DEBUG
+# define DPRINTK(fmt, args...) printk(fmt, args)
+#else
+# define DPRINTK(fmt, args...)
+#endif
+
+/* Use inline assembly to define this because the nops are defined
+ as inline assembly strings in the include files and we cannot
+ get them easily into strings. */
+asm("\t.data\nintelnops: "
+ GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6
+ GENERIC_NOP7 GENERIC_NOP8);
+asm("\t.data\nk8nops: "
+ K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6
+ K8_NOP7 K8_NOP8);
+asm("\t.data\nk7nops: "
+ K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6
+ K7_NOP7 K7_NOP8);
+
+extern unsigned char intelnops[], k8nops[], k7nops[];
+static unsigned char *intel_nops[ASM_NOP_MAX+1] = {
+ NULL,
+ intelnops,
+ intelnops + 1,
+ intelnops + 1 + 2,
+ intelnops + 1 + 2 + 3,
+ intelnops + 1 + 2 + 3 + 4,
+ intelnops + 1 + 2 + 3 + 4 + 5,
+ intelnops + 1 + 2 + 3 + 4 + 5 + 6,
+ intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+};
+static unsigned char *k8_nops[ASM_NOP_MAX+1] = {
+ NULL,
+ k8nops,
+ k8nops + 1,
+ k8nops + 1 + 2,
+ k8nops + 1 + 2 + 3,
+ k8nops + 1 + 2 + 3 + 4,
+ k8nops + 1 + 2 + 3 + 4 + 5,
+ k8nops + 1 + 2 + 3 + 4 + 5 + 6,
+ k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+};
+static unsigned char *k7_nops[ASM_NOP_MAX+1] = {
+ NULL,
+ k7nops,
+ k7nops + 1,
+ k7nops + 1 + 2,
+ k7nops + 1 + 2 + 3,
+ k7nops + 1 + 2 + 3 + 4,
+ k7nops + 1 + 2 + 3 + 4 + 5,
+ k7nops + 1 + 2 + 3 + 4 + 5 + 6,
+ k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+};
+static struct nop {
+ int cpuid;
+ unsigned char **noptable;
+} noptypes[] = {
+ { X86_FEATURE_K8, k8_nops },
+ { X86_FEATURE_K7, k7_nops },
+ { -1, NULL }
+};
+
+
+extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
+extern struct alt_instr __smp_alt_instructions[], __smp_alt_instructions_end[];
+extern u8 *__smp_locks[], *__smp_locks_end[];
+
+extern u8 _text[], _etext[];
+extern u8 __smp_alt_begin[], __smp_alt_end[];
+
+
+static unsigned char** find_nop_table(void)
+{
+ unsigned char **noptable = intel_nops;
+ int i;
+
+ for (i = 0; noptypes[i].cpuid >= 0; i++) {
+ if (boot_cpu_has(noptypes[i].cpuid)) {
+ noptable = noptypes[i].noptable;
+ break;
+ }
+ }
+ return noptable;
+}
+
+/* Replace instructions with better alternatives for this CPU type.
+ This runs before SMP is initialized to avoid SMP problems with
+ self modifying code. This implies that assymetric systems where
+ APs have less capabilities than the boot processor are not handled.
+ Tough. Make sure you disable such features by hand. */
+
+void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
+{
+ unsigned char **noptable = find_nop_table();
+ struct alt_instr *a;
+ int diff, i, k;
+
+ DPRINTK("%s: alt table %p -> %p\n", __FUNCTION__, start, end);
+ for (a = start; a < end; a++) {
+ BUG_ON(a->replacementlen > a->instrlen);
+ if (!boot_cpu_has(a->cpuid))
+ continue;
+ memcpy(a->instr, a->replacement, a->replacementlen);
+ diff = a->instrlen - a->replacementlen;
+ /* Pad the rest with nops */
+ for (i = a->replacementlen; diff > 0; diff -= k, i += k) {
+ k = diff;
+ if (k > ASM_NOP_MAX)
+ k = ASM_NOP_MAX;
+ memcpy(a->instr + i, noptable[k], k);
+ }
+ }
+}
+
+static void alternatives_smp_save(struct alt_instr *start, struct alt_instr *end)
+{
+ struct alt_instr *a;
+
+ DPRINTK("%s: alt table %p-%p\n", __FUNCTION__, start, end);
+ for (a = start; a < end; a++) {
+ memcpy(a->replacement + a->replacementlen,
+ a->instr,
+ a->instrlen);
+ }
+}
+
+static void alternatives_smp_apply(struct alt_instr *start, struct alt_instr *end)
+{
+ struct alt_instr *a;
+
+ for (a = start; a < end; a++) {
+ memcpy(a->instr,
+ a->replacement + a->replacementlen,
+ a->instrlen);
+ }
+}
+
+static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
+{
+ u8 **ptr;
+
+ for (ptr = start; ptr < end; ptr++) {
+ if (*ptr < text)
+ continue;
+ if (*ptr > text_end)
+ continue;
+ **ptr = 0xf0; /* lock prefix */
+ };
+}
+
+static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end)
+{
+ unsigned char **noptable = find_nop_table();
+ u8 **ptr;
+
+ for (ptr = start; ptr < end; ptr++) {
+ if (*ptr < text)
+ continue;
+ if (*ptr > text_end)
+ continue;
+ **ptr = noptable[1][0];
+ };
+}
+
+struct smp_alt_module {
+ /* what is this ??? */
+ struct module *mod;
+ char *name;
+
+ /* ptrs to lock prefixes */
+ u8 **locks;
+ u8 **locks_end;
+
+ /* .text segment, needed to avoid patching init code ;) */
+ u8 *text;
+ u8 *text_end;
+
+ struct list_head next;
+};
+static LIST_HEAD(smp_alt_modules);
+static DEFINE_SPINLOCK(smp_alt);
+
+static int smp_alt_once = 0;
+static int __init bootonly(char *str)
+{
+ smp_alt_once = 1;
+ return 1;
+}
+__setup("smp-alt-boot", bootonly);
+
+void alternatives_smp_module_add(struct module *mod, char *name,
+ void *locks, void *locks_end,
+ void *text, void *text_end)
+{
+ struct smp_alt_module *smp;
+ unsigned long flags;
+
+ if (smp_alt_once) {
+ if (boot_cpu_has(X86_FEATURE_UP))
+ alternatives_smp_unlock(locks, locks_end,
+ text, text_end);
+ return;
+ }
+
+ smp = kzalloc(sizeof(*smp), GFP_KERNEL);
+ if (NULL == smp)
+ return; /* we'll run the (safe but slow) SMP code then ... */
+
+ smp->mod = mod;
+ smp->name = name;
+ smp->locks = locks;
+ smp->locks_end = locks_end;
+ smp->text = text;
+ smp->text_end = text_end;
+ DPRINTK("%s: locks %p -> %p, text %p -> %p, name %s\n",
+ __FUNCTION__, smp->locks, smp->locks_end,
+ smp->text, smp->text_end, smp->name);
+
+ spin_lock_irqsave(&smp_alt, flags);
+ list_add_tail(&smp->next, &smp_alt_modules);
+ if (boot_cpu_has(X86_FEATURE_UP))
+ alternatives_smp_unlock(smp->locks, smp->locks_end,
+ smp->text, smp->text_end);
+ spin_unlock_irqrestore(&smp_alt, flags);
+}
+
+void alternatives_smp_module_del(struct module *mod)
+{
+ struct smp_alt_module *item;
+ unsigned long flags;
+
+ if (smp_alt_once)
+ return;
+
+ spin_lock_irqsave(&smp_alt, flags);
+ list_for_each_entry(item, &smp_alt_modules, next) {
+ if (mod != item->mod)
+ continue;
+ list_del(&item->next);
+ spin_unlock_irqrestore(&smp_alt, flags);
+ DPRINTK("%s: %s\n", __FUNCTION__, item->name);
+ kfree(item);
+ return;
+ }
+ spin_unlock_irqrestore(&smp_alt, flags);
+}
+
+void alternatives_smp_switch(int smp)
+{
+ struct smp_alt_module *mod;
+ unsigned long flags;
+
+ if (smp_alt_once)
+ return;
+ BUG_ON(!smp && (num_online_cpus() > 1));
+
+ spin_lock_irqsave(&smp_alt, flags);
+ if (smp) {
+ printk(KERN_INFO "SMP alternatives: switching to SMP code\n");
+ clear_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability);
+ alternatives_smp_apply(__smp_alt_instructions,
+ __smp_alt_instructions_end);
+ list_for_each_entry(mod, &smp_alt_modules, next)
+ alternatives_smp_lock(mod->locks, mod->locks_end,
+ mod->text, mod->text_end);
+ } else {
+ printk(KERN_INFO "SMP alternatives: switching to UP code\n");
+ set_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability);
+ apply_alternatives(__smp_alt_instructions,
+ __smp_alt_instructions_end);
+ list_for_each_entry(mod, &smp_alt_modules, next)
+ alternatives_smp_unlock(mod->locks, mod->locks_end,
+ mod->text, mod->text_end);
+ }
+ spin_unlock_irqrestore(&smp_alt, flags);
+}
+
+extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
+
+void __init alternative_instructions(void)
+{
+ apply_alternatives(__alt_instructions, __alt_instructions_end);
+
+ /* switch to patch-once-at-boottime-only mode and free the
+ * tables in case we know the number of CPUs will never ever
+ * change */
+#ifdef CONFIG_HOTPLUG_CPU
+ if (num_possible_cpus() < 2)
+ smp_alt_once = 1;
+#else
+ smp_alt_once = 1;
+#endif
+
+ if (smp_alt_once) {
+ if (1 == num_possible_cpus()) {
+ printk(KERN_INFO "SMP alternatives: switching to UP code\n");
+ set_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability);
+ apply_alternatives(__smp_alt_instructions,
+ __smp_alt_instructions_end);
+ alternatives_smp_unlock(__smp_locks, __smp_locks_end,
+ _text, _etext);
+ }
+ free_init_pages("SMP alternatives",
+ (unsigned long)__smp_alt_begin,
+ (unsigned long)__smp_alt_end);
+ } else {
+ alternatives_smp_save(__smp_alt_instructions,
+ __smp_alt_instructions_end);
+ alternatives_smp_module_add(NULL, "core kernel",
+ __smp_locks, __smp_locks_end,
+ _text, _etext);
+ alternatives_smp_switch(0);
+ }
+}
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/kernel/module.c work-2.6.14/arch/i386/kernel/module.c
--- linux-2.6.14/arch/i386/kernel/module.c 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/arch/i386/kernel/module.c 2005-11-25 11:31:21.000000000 +0100
@@ -104,26 +104,38 @@
return -ENOEXEC;
}

-extern void apply_alternatives(void *start, void *end);
-
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
- const Elf_Shdr *s;
+ const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL;
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

- /* look for .altinstructions to patch */
for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
- void *seg;
- if (strcmp(".altinstructions", secstrings + s->sh_name))
- continue;
- seg = (void *)s->sh_addr;
- apply_alternatives(seg, seg + s->sh_size);
- }
+ if (!strcmp(".text", secstrings + s->sh_name))
+ text = s;
+ if (!strcmp(".altinstructions", secstrings + s->sh_name))
+ alt = s;
+ if (!strcmp(".smp_locks", secstrings + s->sh_name))
+ locks= s;
+ }
+
+ if (alt) {
+ /* patch .altinstructions */
+ void *aseg = (void *)alt->sh_addr;
+ apply_alternatives(aseg, aseg + alt->sh_size);
+ }
+ if (locks && text) {
+ void *lseg = (void *)locks->sh_addr;
+ void *tseg = (void *)text->sh_addr;
+ alternatives_smp_module_add(me, me->name,
+ lseg, lseg + locks->sh_size,
+ tseg, tseg + text->sh_size);
+ }
return 0;
}

void module_arch_cleanup(struct module *mod)
{
+ alternatives_smp_module_del(mod);
}
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/kernel/semaphore.c work-2.6.14/arch/i386/kernel/semaphore.c
--- linux-2.6.14/arch/i386/kernel/semaphore.c 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/arch/i386/kernel/semaphore.c 2005-11-25 11:49:54.000000000 +0100
@@ -110,11 +110,11 @@
".align 4\n"
".globl __write_lock_failed\n"
"__write_lock_failed:\n\t"
- LOCK "addl $" RW_LOCK_BIAS_STR ",(%eax)\n"
+ LOCK_PREFIX "addl $" RW_LOCK_BIAS_STR ",(%eax)\n"
"1: rep; nop\n\t"
"cmpl $" RW_LOCK_BIAS_STR ",(%eax)\n\t"
"jne 1b\n\t"
- LOCK "subl $" RW_LOCK_BIAS_STR ",(%eax)\n\t"
+ LOCK_PREFIX "subl $" RW_LOCK_BIAS_STR ",(%eax)\n\t"
"jnz __write_lock_failed\n\t"
"ret"
);
@@ -124,11 +124,11 @@
".align 4\n"
".globl __read_lock_failed\n"
"__read_lock_failed:\n\t"
- LOCK "incl (%eax)\n"
+ LOCK_PREFIX "incl (%eax)\n"
"1: rep; nop\n\t"
"cmpl $1,(%eax)\n\t"
"js 1b\n\t"
- LOCK "decl (%eax)\n\t"
+ LOCK_PREFIX "decl (%eax)\n\t"
"js __read_lock_failed\n\t"
"ret"
);
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/kernel/setup.c work-2.6.14/arch/i386/kernel/setup.c
--- linux-2.6.14/arch/i386/kernel/setup.c 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/arch/i386/kernel/setup.c 2005-11-21 09:10:40.000000000 +0100
@@ -1361,101 +1361,6 @@
pci_mem_start, gapstart, gapsize);
}

-/* Use inline assembly to define this because the nops are defined
- as inline assembly strings in the include files and we cannot
- get them easily into strings. */
-asm("\t.data\nintelnops: "
- GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6
- GENERIC_NOP7 GENERIC_NOP8);
-asm("\t.data\nk8nops: "
- K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6
- K8_NOP7 K8_NOP8);
-asm("\t.data\nk7nops: "
- K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6
- K7_NOP7 K7_NOP8);
-
-extern unsigned char intelnops[], k8nops[], k7nops[];
-static unsigned char *intel_nops[ASM_NOP_MAX+1] = {
- NULL,
- intelnops,
- intelnops + 1,
- intelnops + 1 + 2,
- intelnops + 1 + 2 + 3,
- intelnops + 1 + 2 + 3 + 4,
- intelnops + 1 + 2 + 3 + 4 + 5,
- intelnops + 1 + 2 + 3 + 4 + 5 + 6,
- intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
-};
-static unsigned char *k8_nops[ASM_NOP_MAX+1] = {
- NULL,
- k8nops,
- k8nops + 1,
- k8nops + 1 + 2,
- k8nops + 1 + 2 + 3,
- k8nops + 1 + 2 + 3 + 4,
- k8nops + 1 + 2 + 3 + 4 + 5,
- k8nops + 1 + 2 + 3 + 4 + 5 + 6,
- k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
-};
-static unsigned char *k7_nops[ASM_NOP_MAX+1] = {
- NULL,
- k7nops,
- k7nops + 1,
- k7nops + 1 + 2,
- k7nops + 1 + 2 + 3,
- k7nops + 1 + 2 + 3 + 4,
- k7nops + 1 + 2 + 3 + 4 + 5,
- k7nops + 1 + 2 + 3 + 4 + 5 + 6,
- k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
-};
-static struct nop {
- int cpuid;
- unsigned char **noptable;
-} noptypes[] = {
- { X86_FEATURE_K8, k8_nops },
- { X86_FEATURE_K7, k7_nops },
- { -1, NULL }
-};
-
-/* Replace instructions with better alternatives for this CPU type.
-
- This runs before SMP is initialized to avoid SMP problems with
- self modifying code. This implies that assymetric systems where
- APs have less capabilities than the boot processor are not handled.
- Tough. Make sure you disable such features by hand. */
-void apply_alternatives(void *start, void *end)
-{
- struct alt_instr *a;
- int diff, i, k;
- unsigned char **noptable = intel_nops;
- for (i = 0; noptypes[i].cpuid >= 0; i++) {
- if (boot_cpu_has(noptypes[i].cpuid)) {
- noptable = noptypes[i].noptable;
- break;
- }
- }
- for (a = start; (void *)a < end; a++) {
- if (!boot_cpu_has(a->cpuid))
- continue;
- BUG_ON(a->replacementlen > a->instrlen);
- memcpy(a->instr, a->replacement, a->replacementlen);
- diff = a->instrlen - a->replacementlen;
- /* Pad the rest with nops */
- for (i = a->replacementlen; diff > 0; diff -= k, i += k) {
- k = diff;
- if (k > ASM_NOP_MAX)
- k = ASM_NOP_MAX;
- memcpy(a->instr + i, noptable[k], k);
- }
- }
-}
-
-void __init alternative_instructions(void)
-{
- extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
- apply_alternatives(__alt_instructions, __alt_instructions_end);
-}
-
static char * __init machine_specific_memory_setup(void);

#ifdef CONFIG_MCA
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/kernel/smpboot.c work-2.6.14/arch/i386/kernel/smpboot.c
--- linux-2.6.14/arch/i386/kernel/smpboot.c 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/arch/i386/kernel/smpboot.c 2005-11-25 12:16:49.000000000 +0100
@@ -874,6 +874,7 @@
unsigned short nmi_high = 0, nmi_low = 0;

++cpucount;
+ alternatives_smp_switch(1);

/*
* We can't use kernel_thread since we must avoid to
@@ -1315,6 +1316,9 @@
fixup_irqs(map);
/* It's now safe to remove this processor from the online map */
cpu_clear(cpu, cpu_online_map);
+
+ if (1 == num_online_cpus())
+ alternatives_smp_switch(0);
return 0;
}

diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/kernel/vmlinux.lds.S work-2.6.14/arch/i386/kernel/vmlinux.lds.S
--- linux-2.6.14/arch/i386/kernel/vmlinux.lds.S 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/arch/i386/kernel/vmlinux.lds.S 2005-11-24 16:26:51.000000000 +0100
@@ -68,6 +68,26 @@
*(.data.init_task)
}

+ /* might get freed after init */
+ . = ALIGN(4096);
+ __smp_alt_begin = .;
+ __smp_alt_instructions = .;
+ .smp_altinstructions : AT(ADDR(.smp_altinstructions) - LOAD_OFFSET) {
+ *(.smp_altinstructions)
+ }
+ __smp_alt_instructions_end = .;
+ . = ALIGN(4);
+ __smp_locks = .;
+ .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
+ *(.smp_locks)
+ }
+ __smp_locks_end = .;
+ .smp_altinstr_replacement : AT(ADDR(.smp_altinstr_replacement) - LOAD_OFFSET) {
+ *(.smp_altinstr_replacement)
+ }
+ . = ALIGN(4096);
+ __smp_alt_end = .;
+
/* will be freed after init */
. = ALIGN(4096); /* Init code and data */
__init_begin = .;
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/arch/i386/mm/init.c work-2.6.14/arch/i386/mm/init.c
--- linux-2.6.14/arch/i386/mm/init.c 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/arch/i386/mm/init.c 2005-11-24 12:07:44.000000000 +0100
@@ -667,31 +667,30 @@
return flag;
}

-void free_initmem(void)
+void free_init_pages(char *what, unsigned long begin, unsigned long end)
{
unsigned long addr;

- addr = (unsigned long)(&__init_begin);
- for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
+ for (addr = begin; addr < end; addr += PAGE_SIZE) {
ClearPageReserved(virt_to_page(addr));
set_page_count(virt_to_page(addr), 1);
memset((void *)addr, 0xcc, PAGE_SIZE);
free_page(addr);
totalram_pages++;
}
- printk (KERN_INFO "Freeing unused kernel memory: %dk freed\n", (__init_end - __init_begin) >> 10);
+ printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
+}
+
+void free_initmem(void)
+{
+ free_init_pages("unused kernel memory",
+ (unsigned long)(&__init_begin),
+ (unsigned long)(&__init_end));
}

#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
- if (start < end)
- printk (KERN_INFO "Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
- for (; start < end; start += PAGE_SIZE) {
- ClearPageReserved(virt_to_page(start));
- set_page_count(virt_to_page(start), 1);
- free_page(start);
- totalram_pages++;
- }
+ free_init_pages("initrd memory", start, end);
}
#endif
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/alternative.h work-2.6.14/include/asm-i386/alternative.h
--- linux-2.6.14/include/asm-i386/alternative.h 1970-01-01 01:00:00.000000000 +0100
+++ work-2.6.14/include/asm-i386/alternative.h 2005-11-25 13:58:19.000000000 +0100
@@ -0,0 +1,129 @@
+#ifndef _I386_ALTERNATIVE_H
+#define _I386_ALTERNATIVE_H
+
+#ifdef __KERNEL__
+
+struct alt_instr {
+ u8 *instr; /* original instruction */
+ u8 *replacement;
+ u8 cpuid; /* cpuid bit set for replacement */
+ u8 instrlen; /* length of original instruction */
+ u8 replacementlen; /* length of new instruction, <= instrlen */
+ u8 pad;
+};
+
+extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
+
+struct module;
+extern void alternatives_smp_module_add(struct module *mod, char *name,
+ void *locks, void *locks_end,
+ void *text, void *text_end);
+extern void alternatives_smp_module_del(struct module *mod);
+extern void alternatives_smp_switch(int smp);
+
+#endif
+
+/*
+ * Alternative instructions for different CPU types or capabilities.
+ *
+ * This allows to use optimized instructions even on generic binary
+ * kernels.
+ *
+ * length of oldinstr must be longer or equal the length of newinstr
+ * It can be padded with nops as needed.
+ *
+ * For non barrier like inlines please define new variants
+ * without volatile and memory clobber.
+ */
+#define alternative(oldinstr, newinstr, feature) \
+ asm volatile ("661:\n\t" oldinstr "\n662:\n" \
+ ".section .altinstructions,\"a\"\n" \
+ " .align 4\n" \
+ " .long 661b\n" /* label */ \
+ " .long 663f\n" /* new instruction */ \
+ " .byte %c0\n" /* feature bit */ \
+ " .byte 662b-661b\n" /* sourcelen */ \
+ " .byte 664f-663f\n" /* replacementlen */ \
+ ".previous\n" \
+ ".section .altinstr_replacement,\"ax\"\n" \
+ "663:\n\t" newinstr "\n664:\n" /* replacement */ \
+ ".previous" :: "i" (feature) : "memory")
+
+/*
+ * Alternative inline assembly with input.
+ *
+ * Pecularities:
+ * No memory clobber here.
+ * Argument numbers start with 1.
+ * Best is to use constraints that are fixed size (like (%1) ... "r")
+ * If you use variable sized constraints like "m" or "g" in the
+ * replacement maake sure to pad to the worst case length.
+ */
+#define alternative_input(oldinstr, newinstr, feature, input...) \
+ asm volatile ("661:\n\t" oldinstr "\n662:\n" \
+ ".section .altinstructions,\"a\"\n" \
+ " .align 4\n" \
+ " .long 661b\n" /* label */ \
+ " .long 663f\n" /* new instruction */ \
+ " .byte %c0\n" /* feature bit */ \
+ " .byte 662b-661b\n" /* sourcelen */ \
+ " .byte 664f-663f\n" /* replacementlen */ \
+ ".previous\n" \
+ ".section .altinstr_replacement,\"ax\"\n" \
+ "663:\n\t" newinstr "\n664:\n" /* replacement */ \
+ ".previous" :: "i" (feature), ##input)
+
+/*
+ * Alternative inline assembly for SMP.
+ *
+ * alternative_smp() takes two versions (SMP first, UP second) and is
+ * for more complex stuff such as spinlocks.
+ *
+ * The LOCK_PREFIX macro defined here replaces the LOCK and
+ * LOCK_PREFIX macros used everywhere in the source tree.
+ *
+ * SMP alternatives use the same data structures as the other
+ * alternatives and the X86_FEATURE_UP flag to indicate the case of a
+ * UP system running a SMP kernel. The existing apply_alternatives()
+ * works fine for patching a SMP kernel for UP.
+ *
+ * The SMP alternative tables can be kept after boot and contain both
+ * UP and SMP versions of the instructions to allow switching back to
+ * SMP at runtime, when hotplugging in a new CPU, which is especially
+ * useful in virtualized environments.
+ *
+ * The very common lock prefix is handled as special case in a
+ * separate table which is a pure address list without replacement ptr
+ * and size information. That keeps the table sizes small.
+ */
+
+#ifdef CONFIG_SMP
+#define alternative_smp(smpinstr, upinstr, args...) \
+ asm volatile ("661:\n\t" smpinstr "\n662:\n" \
+ ".section .smp_altinstructions,\"a\"\n" \
+ " .align 4\n" \
+ " .long 661b\n" /* label */ \
+ " .long 663f\n" /* new instruction */ \
+ " .byte 0x68\n" /* X86_FEATURE_UP */ \
+ " .byte 662b-661b\n" /* sourcelen */ \
+ " .byte 664f-663f\n" /* replacementlen */ \
+ ".previous\n" \
+ ".section .smp_altinstr_replacement,\"awx\"\n" \
+ "663:\n\t" upinstr "\n" /* replacement */ \
+ "664:\n\t.fill 662b-661b,1,0x42\n" /* space for original */ \
+ ".previous" : args)
+
+#define LOCK_PREFIX \
+ ".section .smp_locks,\"a\"\n" \
+ " .align 4\n" \
+ " .long 661f\n" /* address */ \
+ ".previous\n" \
+ "661:\n\tlock; "
+
+#else /* ! CONFIG_SMP */
+#define alternative_smp(smpinstr, upinstr, args...) \
+ asm volatile (upinstr : args)
+#define LOCK_PREFIX ""
+#endif
+
+#endif /* _I386_ALTERNATIVE_H */
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/atomic.h work-2.6.14/include/asm-i386/atomic.h
--- linux-2.6.14/include/asm-i386/atomic.h 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/include/asm-i386/atomic.h 2005-11-25 11:43:05.000000000 +0100
@@ -10,12 +10,6 @@
* 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,
@@ -52,7 +46,7 @@
static __inline__ void atomic_add(int i, atomic_t *v)
{
__asm__ __volatile__(
- LOCK "addl %1,%0"
+ LOCK_PREFIX "addl %1,%0"
:"=m" (v->counter)
:"ir" (i), "m" (v->counter));
}
@@ -67,7 +61,7 @@
static __inline__ void atomic_sub(int i, atomic_t *v)
{
__asm__ __volatile__(
- LOCK "subl %1,%0"
+ LOCK_PREFIX "subl %1,%0"
:"=m" (v->counter)
:"ir" (i), "m" (v->counter));
}
@@ -86,7 +80,7 @@
unsigned char c;

__asm__ __volatile__(
- LOCK "subl %2,%0; sete %1"
+ LOCK_PREFIX "subl %2,%0; sete %1"
:"=m" (v->counter), "=qm" (c)
:"ir" (i), "m" (v->counter) : "memory");
return c;
@@ -101,7 +95,7 @@
static __inline__ void atomic_inc(atomic_t *v)
{
__asm__ __volatile__(
- LOCK "incl %0"
+ LOCK_PREFIX "incl %0"
:"=m" (v->counter)
:"m" (v->counter));
}
@@ -115,7 +109,7 @@
static __inline__ void atomic_dec(atomic_t *v)
{
__asm__ __volatile__(
- LOCK "decl %0"
+ LOCK_PREFIX "decl %0"
:"=m" (v->counter)
:"m" (v->counter));
}
@@ -133,7 +127,7 @@
unsigned char c;

__asm__ __volatile__(
- LOCK "decl %0; sete %1"
+ LOCK_PREFIX "decl %0; sete %1"
:"=m" (v->counter), "=qm" (c)
:"m" (v->counter) : "memory");
return c != 0;
@@ -152,7 +146,7 @@
unsigned char c;

__asm__ __volatile__(
- LOCK "incl %0; sete %1"
+ LOCK_PREFIX "incl %0; sete %1"
:"=m" (v->counter), "=qm" (c)
:"m" (v->counter) : "memory");
return c != 0;
@@ -172,7 +166,7 @@
unsigned char c;

__asm__ __volatile__(
- LOCK "addl %2,%0; sets %1"
+ LOCK_PREFIX "addl %2,%0; sets %1"
:"=m" (v->counter), "=qm" (c)
:"ir" (i), "m" (v->counter) : "memory");
return c;
@@ -195,7 +189,7 @@
/* Modern 486+ processor */
__i = i;
__asm__ __volatile__(
- LOCK "xaddl %0, %1;"
+ LOCK_PREFIX "xaddl %0, %1;"
:"=r"(i)
:"m"(v->counter), "0"(i));
return i + __i;
@@ -220,11 +214,11 @@

/* These are x86-specific, used by some header files */
#define atomic_clear_mask(mask, addr) \
-__asm__ __volatile__(LOCK "andl %0,%1" \
+__asm__ __volatile__(LOCK_PREFIX "andl %0,%1" \
: : "r" (~(mask)),"m" (*addr) : "memory")

#define atomic_set_mask(mask, addr) \
-__asm__ __volatile__(LOCK "orl %0,%1" \
+__asm__ __volatile__(LOCK_PREFIX "orl %0,%1" \
: : "r" (mask),"m" (*(addr)) : "memory")

/* Atomic operations are already serializing on x86 */
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/bitops.h work-2.6.14/include/asm-i386/bitops.h
--- linux-2.6.14/include/asm-i386/bitops.h 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/include/asm-i386/bitops.h 2005-11-25 11:39:49.000000000 +0100
@@ -7,6 +7,7 @@

#include <linux/config.h>
#include <linux/compiler.h>
+#include <asm/alternative.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)

/**
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/cpufeature.h work-2.6.14/include/asm-i386/cpufeature.h
--- linux-2.6.14/include/asm-i386/cpufeature.h 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/include/asm-i386/cpufeature.h 2005-11-16 09:43:47.000000000 +0100
@@ -70,6 +70,8 @@
#define X86_FEATURE_P3 (3*32+ 6) /* P3 */
#define X86_FEATURE_P4 (3*32+ 7) /* P4 */

+#define X86_FEATURE_UP (3*32+ 8) /* smp kernel running on up */
+
/* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
#define X86_FEATURE_XMM3 (4*32+ 0) /* Streaming SIMD Extensions-3 */
#define X86_FEATURE_MWAIT (4*32+ 3) /* Monitor/Mwait support */
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/rwlock.h work-2.6.14/include/asm-i386/rwlock.h
--- linux-2.6.14/include/asm-i386/rwlock.h 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/include/asm-i386/rwlock.h 2005-11-17 09:44:53.000000000 +0100
@@ -21,21 +21,23 @@
#define RW_LOCK_BIAS_STR "0x01000000"

#define __build_read_lock_ptr(rw, helper) \
- asm volatile(LOCK "subl $1,(%0)\n\t" \
- "jns 1f\n" \
- "call " helper "\n\t" \
- "1:\n" \
- ::"a" (rw) : "memory")
+ alternative_smp("lock; subl $1,(%0)\n\t" \
+ "jns 1f\n" \
+ "call " helper "\n\t" \
+ "1:\n", \
+ "subl $1,(%0)\n\t", \
+ :"a" (rw) : "memory")

#define __build_read_lock_const(rw, helper) \
- asm volatile(LOCK "subl $1,%0\n\t" \
- "jns 1f\n" \
- "pushl %%eax\n\t" \
- "leal %0,%%eax\n\t" \
- "call " helper "\n\t" \
- "popl %%eax\n\t" \
- "1:\n" \
- :"=m" (*(volatile int *)rw) : : "memory")
+ alternative_smp("lock; subl $1,%0\n\t" \
+ "jns 1f\n" \
+ "pushl %%eax\n\t" \
+ "leal %0,%%eax\n\t" \
+ "call " helper "\n\t" \
+ "popl %%eax\n\t" \
+ "1:\n", \
+ "subl $1,%0\n\t", \
+ "=m" (*(volatile int *)rw) : : "memory")

#define __build_read_lock(rw, helper) do { \
if (__builtin_constant_p(rw)) \
@@ -45,21 +47,23 @@
} while (0)

#define __build_write_lock_ptr(rw, helper) \
- asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
- "jz 1f\n" \
- "call " helper "\n\t" \
- "1:\n" \
- ::"a" (rw) : "memory")
+ alternative_smp("lock; subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
+ "jz 1f\n" \
+ "call " helper "\n\t" \
+ "1:\n", \
+ "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t", \
+ :"a" (rw) : "memory")

#define __build_write_lock_const(rw, helper) \
- asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",%0\n\t" \
- "jz 1f\n" \
- "pushl %%eax\n\t" \
- "leal %0,%%eax\n\t" \
- "call " helper "\n\t" \
- "popl %%eax\n\t" \
- "1:\n" \
- :"=m" (*(volatile int *)rw) : : "memory")
+ alternative_smp("lock; subl $" RW_LOCK_BIAS_STR ",%0\n\t" \
+ "jz 1f\n" \
+ "pushl %%eax\n\t" \
+ "leal %0,%%eax\n\t" \
+ "call " helper "\n\t" \
+ "popl %%eax\n\t" \
+ "1:\n", \
+ "subl $" RW_LOCK_BIAS_STR ",%0\n\t", \
+ "=m" (*(volatile int *)rw) : : "memory")

#define __build_write_lock(rw, helper) do { \
if (__builtin_constant_p(rw)) \
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/semaphore.h work-2.6.14/include/asm-i386/semaphore.h
--- linux-2.6.14/include/asm-i386/semaphore.h 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/include/asm-i386/semaphore.h 2005-11-25 11:48:04.000000000 +0100
@@ -102,7 +102,7 @@
might_sleep();
__asm__ __volatile__(
"# atomic down operation\n\t"
- LOCK "decl %0\n\t" /* --sem->count */
+ LOCK_PREFIX "decl %0\n\t" /* --sem->count */
"js 2f\n"
"1:\n"
LOCK_SECTION_START("")
@@ -126,7 +126,7 @@
might_sleep();
__asm__ __volatile__(
"# atomic interruptible down operation\n\t"
- LOCK "decl %1\n\t" /* --sem->count */
+ LOCK_PREFIX "decl %1\n\t" /* --sem->count */
"js 2f\n\t"
"xorl %0,%0\n"
"1:\n"
@@ -151,7 +151,7 @@

__asm__ __volatile__(
"# atomic interruptible down operation\n\t"
- LOCK "decl %1\n\t" /* --sem->count */
+ LOCK_PREFIX "decl %1\n\t" /* --sem->count */
"js 2f\n\t"
"xorl %0,%0\n"
"1:\n"
@@ -176,7 +176,7 @@
{
__asm__ __volatile__(
"# atomic up operation\n\t"
- LOCK "incl %0\n\t" /* ++sem->count */
+ LOCK_PREFIX "incl %0\n\t" /* ++sem->count */
"jle 2f\n"
"1:\n"
LOCK_SECTION_START("")
diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/spinlock.h work-2.6.14/include/asm-i386/spinlock.h
--- linux-2.6.14/include/asm-i386/spinlock.h 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/include/asm-i386/spinlock.h 2005-11-25 11:44:47.000000000 +0100
@@ -48,18 +48,23 @@
"jmp 1b\n" \
"4:\n\t"

+#define __raw_spin_lock_string_up \
+ "\n\tdecb %0"
+
static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
- __asm__ __volatile__(
- __raw_spin_lock_string
- :"=m" (lock->slock) : : "memory");
+ alternative_smp(
+ __raw_spin_lock_string,
+ __raw_spin_lock_string_up,
+ "=m" (lock->slock) : : "memory");
}

static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
{
- __asm__ __volatile__(
- __raw_spin_lock_string_flags
- :"=m" (lock->slock) : "r" (flags) : "memory");
+ alternative_smp(
+ __raw_spin_lock_string_flags,
+ __raw_spin_lock_string_up,
+ "=m" (lock->slock) : "r" (flags) : "memory");
}

static inline int __raw_spin_trylock(raw_spinlock_t *lock)
@@ -178,12 +183,12 @@

static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
- asm volatile("lock ; incl %0" :"=m" (rw->lock) : : "memory");
+ asm volatile(LOCK_PREFIX "incl %0" :"=m" (rw->lock) : : "memory");
}

static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
- asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ", %0"
+ asm volatile(LOCK_PREFIX "addl $" RW_LOCK_BIAS_STR ", %0"
: "=m" (rw->lock) : : "memory");
}

diff -urN -x 'build-*' -x '*~' -x Make -x scripts linux-2.6.14/include/asm-i386/system.h work-2.6.14/include/asm-i386/system.h
--- linux-2.6.14/include/asm-i386/system.h 2005-10-28 02:02:08.000000000 +0200
+++ work-2.6.14/include/asm-i386/system.h 2005-11-25 11:41:22.000000000 +0100
@@ -292,67 +292,6 @@
((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
(unsigned long)(n),sizeof(*(ptr))))

-#ifdef __KERNEL__
-struct alt_instr {
- __u8 *instr; /* original instruction */
- __u8 *replacement;
- __u8 cpuid; /* cpuid bit set for replacement */
- __u8 instrlen; /* length of original instruction */
- __u8 replacementlen; /* length of new instruction, <= instrlen */
- __u8 pad;
-};
-#endif
-
-/*
- * Alternative instructions for different CPU types or capabilities.
- *
- * This allows to use optimized instructions even on generic binary
- * kernels.
- *
- * length of oldinstr must be longer or equal the length of newinstr
- * It can be padded with nops as needed.
- *
- * For non barrier like inlines please define new variants
- * without volatile and memory clobber.
- */
-#define alternative(oldinstr, newinstr, feature) \
- asm volatile ("661:\n\t" oldinstr "\n662:\n" \
- ".section .altinstructions,\"a\"\n" \
- " .align 4\n" \
- " .long 661b\n" /* label */ \
- " .long 663f\n" /* new instruction */ \
- " .byte %c0\n" /* feature bit */ \
- " .byte 662b-661b\n" /* sourcelen */ \
- " .byte 664f-663f\n" /* replacementlen */ \
- ".previous\n" \
- ".section .altinstr_replacement,\"ax\"\n" \
- "663:\n\t" newinstr "\n664:\n" /* replacement */ \
- ".previous" :: "i" (feature) : "memory")
-
-/*
- * Alternative inline assembly with input.
- *
- * Pecularities:
- * No memory clobber here.
- * Argument numbers start with 1.
- * Best is to use constraints that are fixed size (like (%1) ... "r")
- * If you use variable sized constraints like "m" or "g" in the
- * replacement maake sure to pad to the worst case length.
- */
-#define alternative_input(oldinstr, newinstr, feature, input...) \
- asm volatile ("661:\n\t" oldinstr "\n662:\n" \
- ".section .altinstructions,\"a\"\n" \
- " .align 4\n" \
- " .long 661b\n" /* label */ \
- " .long 663f\n" /* new instruction */ \
- " .byte %c0\n" /* feature bit */ \
- " .byte 662b-661b\n" /* sourcelen */ \
- " .byte 664f-663f\n" /* replacementlen */ \
- ".previous\n" \
- ".section .altinstr_replacement,\"ax\"\n" \
- "663:\n\t" newinstr "\n664:\n" /* replacement */ \
- ".previous" :: "i" (feature), ##input)
-
/*
* Force strict CPU ordering.
* And yes, this is required on UP too when we're talking