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linux/arch/x86/kernel/cpu/intel.c
Maciej W. Rozycki 593f4a788e x86: APIC: remove apic_write_around(); use alternatives 
Use alternatives to select the workaround for the 11AP Pentium erratum
for the affected steppings on the fly rather than build time.  Remove the
X86_GOOD_APIC configuration option and replace all the calls to
apic_write_around() with plain apic_write(), protecting accesses to the
ESR as appropriate due to the 3AP Pentium erratum.  Remove
apic_read_around() and all its invocations altogether as not needed.
Remove apic_write_atomic() and all its implementing backends.  The use of
ASM_OUTPUT2() is not strictly needed for input constraints, but I have
used it for readability's sake.

I had the feeling no one else was brave enough to do it, so I went ahead
and here it is.  Verified by checking the generated assembly and tested
with both a 32-bit and a 64-bit configuration, also with the 11AP
"feature" forced on and verified with gdb on /proc/kcore to work as
expected (as an 11AP machines are quite hard to get hands on these days).
Some script complained about the use of "volatile", but apic_write() needs
it for the same reason and is effectively a replacement for writel(), so I
have disregarded it.

I am not sure what the policy wrt defconfig files is, they are generated
and there is risk of a conflict resulting from an unrelated change, so I
have left changes to them out.  The option will get removed from them at
the next run.

Some testing with machines other than mine will be needed to avoid some
stupid mistake, but despite its volume, the change is not really that
intrusive, so I am fairly confident that because it works for me, it will
everywhere.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 12:51:21 +02:00

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#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/smp.h>
#include <linux/thread_info.h>
#include <linux/module.h>
#include <asm/processor.h>
#include <asm/pgtable.h>
#include <asm/msr.h>
#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/ds.h>
#include <asm/bugs.h>
#include "cpu.h"
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/mpspec.h>
#include <asm/apic.h>
#include <mach_apic.h>
#endif
#ifdef CONFIG_X86_INTEL_USERCOPY
/*
* Alignment at which movsl is preferred for bulk memory copies.
*/
struct movsl_mask movsl_mask __read_mostly;
#endif
static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
{
/* Netburst reports 64 bytes clflush size, but does IO in 128 bytes */
if (c->x86 == 15 && c->x86_cache_alignment == 64)
c->x86_cache_alignment = 128;
if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
(c->x86 == 0x6 && c->x86_model >= 0x0e))
set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
}
/*
* Early probe support logic for ppro memory erratum #50
*
* This is called before we do cpu ident work
*/
int __cpuinit ppro_with_ram_bug(void)
{
/* Uses data from early_cpu_detect now */
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
boot_cpu_data.x86 == 6 &&
boot_cpu_data.x86_model == 1 &&
boot_cpu_data.x86_mask < 8) {
printk(KERN_INFO "Pentium Pro with Errata#50 detected. Taking evasive action.\n");
return 1;
}
return 0;
}
/*
* P4 Xeon errata 037 workaround.
* Hardware prefetcher may cause stale data to be loaded into the cache.
*/
static void __cpuinit Intel_errata_workarounds(struct cpuinfo_x86 *c)
{
unsigned long lo, hi;
if ((c->x86 == 15) && (c->x86_model == 1) && (c->x86_mask == 1)) {
rdmsr(MSR_IA32_MISC_ENABLE, lo, hi);
if ((lo & (1<<9)) == 0) {
printk (KERN_INFO "CPU: C0 stepping P4 Xeon detected.\n");
printk (KERN_INFO "CPU: Disabling hardware prefetching (Errata 037)\n");
lo |= (1<<9); /* Disable hw prefetching */
wrmsr (MSR_IA32_MISC_ENABLE, lo, hi);
}
}
}
/*
* find out the number of processor cores on the die
*/
static int __cpuinit num_cpu_cores(struct cpuinfo_x86 *c)
{
unsigned int eax, ebx, ecx, edx;
if (c->cpuid_level < 4)
return 1;
/* Intel has a non-standard dependency on %ecx for this CPUID level. */
cpuid_count(4, 0, &eax, &ebx, &ecx, &edx);
if (eax & 0x1f)
return ((eax >> 26) + 1);
else
return 1;
}
#ifdef CONFIG_X86_F00F_BUG
static void __cpuinit trap_init_f00f_bug(void)
{
__set_fixmap(FIX_F00F_IDT, __pa(&idt_table), PAGE_KERNEL_RO);
/*
* Update the IDT descriptor and reload the IDT so that
* it uses the read-only mapped virtual address.
*/
idt_descr.address = fix_to_virt(FIX_F00F_IDT);
load_idt(&idt_descr);
}
#endif
static void __cpuinit init_intel(struct cpuinfo_x86 *c)
{
unsigned int l2 = 0;
char *p = NULL;
early_init_intel(c);
#ifdef CONFIG_X86_F00F_BUG
/*
* All current models of Pentium and Pentium with MMX technology CPUs
* have the F0 0F bug, which lets nonprivileged users lock up the system.
* Note that the workaround only should be initialized once...
*/
c->f00f_bug = 0;
if (!paravirt_enabled() && c->x86 == 5) {
static int f00f_workaround_enabled;
c->f00f_bug = 1;
if (!f00f_workaround_enabled) {
trap_init_f00f_bug();
printk(KERN_NOTICE "Intel Pentium with F0 0F bug - workaround enabled.\n");
f00f_workaround_enabled = 1;
}
}
#endif
l2 = init_intel_cacheinfo(c);
if (c->cpuid_level > 9) {
unsigned eax = cpuid_eax(10);
/* Check for version and the number of counters */
if ((eax & 0xff) && (((eax>>8) & 0xff) > 1))
set_cpu_cap(c, X86_FEATURE_ARCH_PERFMON);
}
/* SEP CPUID bug: Pentium Pro reports SEP but doesn't have it until model 3 mask 3 */
if ((c->x86<<8 | c->x86_model<<4 | c->x86_mask) < 0x633)
clear_cpu_cap(c, X86_FEATURE_SEP);
/*
* Names for the Pentium II/Celeron processors
* detectable only by also checking the cache size.
* Dixon is NOT a Celeron.
*/
if (c->x86 == 6) {
switch (c->x86_model) {
case 5:
if (c->x86_mask == 0) {
if (l2 == 0)
p = "Celeron (Covington)";
else if (l2 == 256)
p = "Mobile Pentium II (Dixon)";
}
break;
case 6:
if (l2 == 128)
p = "Celeron (Mendocino)";
else if (c->x86_mask == 0 || c->x86_mask == 5)
p = "Celeron-A";
break;
case 8:
if (l2 == 128)
p = "Celeron (Coppermine)";
break;
}
}
if (p)
strcpy(c->x86_model_id, p);
c->x86_max_cores = num_cpu_cores(c);
detect_ht(c);
/* Work around errata */
Intel_errata_workarounds(c);
#ifdef CONFIG_X86_INTEL_USERCOPY
/*
* Set up the preferred alignment for movsl bulk memory moves
*/
switch (c->x86) {
case 4: /* 486: untested */
break;
case 5: /* Old Pentia: untested */
break;
case 6: /* PII/PIII only like movsl with 8-byte alignment */
movsl_mask.mask = 7;
break;
case 15: /* P4 is OK down to 8-byte alignment */
movsl_mask.mask = 7;
break;
}
#endif
if (cpu_has_xmm2)
set_cpu_cap(c, X86_FEATURE_LFENCE_RDTSC);
if (c->x86 == 15) {
set_cpu_cap(c, X86_FEATURE_P4);
}
if (c->x86 == 6)
set_cpu_cap(c, X86_FEATURE_P3);
if (cpu_has_ds) {
unsigned int l1;
rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
if (!(l1 & (1<<11)))
set_cpu_cap(c, X86_FEATURE_BTS);
if (!(l1 & (1<<12)))
set_cpu_cap(c, X86_FEATURE_PEBS);
}
if (cpu_has_bts)
ds_init_intel(c);
/*
* See if we have a good local APIC by checking for buggy Pentia,
* i.e. all B steppings and the C2 stepping of P54C when using their
* integrated APIC (see 11AP erratum in "Pentium Processor
* Specification Update").
*/
if (cpu_has_apic && (c->x86<<8 | c->x86_model<<4) == 0x520 &&
(c->x86_mask < 0x6 || c->x86_mask == 0xb))
set_cpu_cap(c, X86_FEATURE_11AP);
#ifdef CONFIG_X86_NUMAQ
numaq_tsc_disable();
#endif
}
static unsigned int __cpuinit intel_size_cache(struct cpuinfo_x86 *c, unsigned int size)
{
/*
* Intel PIII Tualatin. This comes in two flavours.
* One has 256kb of cache, the other 512. We have no way
* to determine which, so we use a boottime override
* for the 512kb model, and assume 256 otherwise.
*/
if ((c->x86 == 6) && (c->x86_model == 11) && (size == 0))
size = 256;
return size;
}
static struct cpu_dev intel_cpu_dev __cpuinitdata = {
.c_vendor = "Intel",
.c_ident = { "GenuineIntel" },
.c_models = {
{ .vendor = X86_VENDOR_INTEL, .family = 4, .model_names =
{
[0] = "486 DX-25/33",
[1] = "486 DX-50",
[2] = "486 SX",
[3] = "486 DX/2",
[4] = "486 SL",
[5] = "486 SX/2",
[7] = "486 DX/2-WB",
[8] = "486 DX/4",
[9] = "486 DX/4-WB"
}
},
{ .vendor = X86_VENDOR_INTEL, .family = 5, .model_names =
{
[0] = "Pentium 60/66 A-step",
[1] = "Pentium 60/66",
[2] = "Pentium 75 - 200",
[3] = "OverDrive PODP5V83",
[4] = "Pentium MMX",
[7] = "Mobile Pentium 75 - 200",
[8] = "Mobile Pentium MMX"
}
},
{ .vendor = X86_VENDOR_INTEL, .family = 6, .model_names =
{
[0] = "Pentium Pro A-step",
[1] = "Pentium Pro",
[3] = "Pentium II (Klamath)",
[4] = "Pentium II (Deschutes)",
[5] = "Pentium II (Deschutes)",
[6] = "Mobile Pentium II",
[7] = "Pentium III (Katmai)",
[8] = "Pentium III (Coppermine)",
[10] = "Pentium III (Cascades)",
[11] = "Pentium III (Tualatin)",
}
},
{ .vendor = X86_VENDOR_INTEL, .family = 15, .model_names =
{
[0] = "Pentium 4 (Unknown)",
[1] = "Pentium 4 (Willamette)",
[2] = "Pentium 4 (Northwood)",
[4] = "Pentium 4 (Foster)",
[5] = "Pentium 4 (Foster)",
}
},
},
.c_early_init = early_init_intel,
.c_init = init_intel,
.c_size_cache = intel_size_cache,
};
cpu_vendor_dev_register(X86_VENDOR_INTEL, &intel_cpu_dev);
#ifndef CONFIG_X86_CMPXCHG
unsigned long cmpxchg_386_u8(volatile void *ptr, u8 old, u8 new)
{
u8 prev;
unsigned long flags;
/* Poor man's cmpxchg for 386. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u8 *)ptr;
if (prev == old)
*(u8 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_386_u8);
unsigned long cmpxchg_386_u16(volatile void *ptr, u16 old, u16 new)
{
u16 prev;
unsigned long flags;
/* Poor man's cmpxchg for 386. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u16 *)ptr;
if (prev == old)
*(u16 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_386_u16);
unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new)
{
u32 prev;
unsigned long flags;
/* Poor man's cmpxchg for 386. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u32 *)ptr;
if (prev == old)
*(u32 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_386_u32);
#endif
#ifndef CONFIG_X86_CMPXCHG64
unsigned long long cmpxchg_486_u64(volatile void *ptr, u64 old, u64 new)
{
u64 prev;
unsigned long flags;
/* Poor man's cmpxchg8b for 386 and 486. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u64 *)ptr;
if (prev == old)
*(u64 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_486_u64);
#endif
/* arch_initcall(intel_cpu_init); */
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