[PATCH] x86: Remove CONFIG_X86_OOSTORE

From: Dave Jones
Date: Mon Mar 10 2014 - 19:34:17 EST

This was an optimization that made memcpy type benchmarks a little faster
on ancient (Circa 1998) IDT Winchip CPUs. In real-life workloads, it
wasn't even noticable, and I doubt anyone is running benchmarks on 16 year old
silicon any more.

Given this code has likely seen very little use over the last decade, let's just remove it.

Signed-off-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index c026cca5602c..f3aaf231b4e5 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -341,10 +341,6 @@ config X86_USE_3DNOW
def_bool y
depends on (MCYRIXIII || MK7 || MGEODE_LX) && !UML

-config X86_OOSTORE
- def_bool y
- depends on (MWINCHIP3D || MWINCHIPC6) && MTRR
-
#
# P6_NOPs are a relatively minor optimization that require a family >=
# 6 processor, except that it is broken on certain VIA chips.
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index 04a48903b2eb..69bbb4845020 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -85,11 +85,7 @@
#else
# define smp_rmb() barrier()
#endif
-#ifdef CONFIG_X86_OOSTORE
-# define smp_wmb() wmb()
-#else
-# define smp_wmb() barrier()
-#endif
+#define smp_wmb() barrier()
#define smp_read_barrier_depends() read_barrier_depends()
#define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
#else /* !SMP */
@@ -100,7 +96,7 @@
#define set_mb(var, value) do { var = value; barrier(); } while (0)
#endif /* SMP */

-#if defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE)
+#if defined(CONFIG_X86_PPRO_FENCE)

/*
* For either of these options x86 doesn't have a strong TSO memory
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 34f69cb9350a..91d9c69a629e 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -237,7 +237,7 @@ memcpy_toio(volatile void __iomem *dst, const void *src, size_t count)

static inline void flush_write_buffers(void)
{
-#if defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE)
+#if defined(CONFIG_X86_PPRO_FENCE)
asm volatile("lock; addl $0,0(%%esp)": : :"memory");
#endif
}
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index bf156ded74b5..0f62f5482d91 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -26,10 +26,9 @@
# define LOCK_PTR_REG "D"
#endif

-#if defined(CONFIG_X86_32) && \
- (defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE))
+#if defined(CONFIG_X86_32) && (defined(CONFIG_X86_PPRO_FENCE))
/*
- * On PPro SMP or if we are using OOSTORE, we use a locked operation to unlock
+ * On PPro SMP, we use a locked operation to unlock
* (PPro errata 66, 92)
*/
# define UNLOCK_LOCK_PREFIX LOCK_PREFIX
diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c
index 8779edab684e..d8fba5c15fbd 100644
--- a/arch/x86/kernel/cpu/centaur.c
+++ b/arch/x86/kernel/cpu/centaur.c
@@ -8,236 +8,6 @@

#include "cpu.h"

-#ifdef CONFIG_X86_OOSTORE
-
-static u32 power2(u32 x)
-{
- u32 s = 1;
-
- while (s <= x)
- s <<= 1;
-
- return s >>= 1;
-}
-
-
-/*
- * Set up an actual MCR
- */
-static void centaur_mcr_insert(int reg, u32 base, u32 size, int key)
-{
- u32 lo, hi;
-
- hi = base & ~0xFFF;
- lo = ~(size-1); /* Size is a power of 2 so this makes a mask */
- lo &= ~0xFFF; /* Remove the ctrl value bits */
- lo |= key; /* Attribute we wish to set */
- wrmsr(reg+MSR_IDT_MCR0, lo, hi);
- mtrr_centaur_report_mcr(reg, lo, hi); /* Tell the mtrr driver */
-}
-
-/*
- * Figure what we can cover with MCR's
- *
- * Shortcut: We know you can't put 4Gig of RAM on a winchip
- */
-static u32 ramtop(void)
-{
- u32 clip = 0xFFFFFFFFUL;
- u32 top = 0;
- int i;
-
- for (i = 0; i < e820.nr_map; i++) {
- unsigned long start, end;
-
- if (e820.map[i].addr > 0xFFFFFFFFUL)
- continue;
- /*
- * Don't MCR over reserved space. Ignore the ISA hole
- * we frob around that catastrophe already
- */
- if (e820.map[i].type == E820_RESERVED) {
- if (e820.map[i].addr >= 0x100000UL &&
- e820.map[i].addr < clip)
- clip = e820.map[i].addr;
- continue;
- }
- start = e820.map[i].addr;
- end = e820.map[i].addr + e820.map[i].size;
- if (start >= end)
- continue;
- if (end > top)
- top = end;
- }
- /*
- * Everything below 'top' should be RAM except for the ISA hole.
- * Because of the limited MCR's we want to map NV/ACPI into our
- * MCR range for gunk in RAM
- *
- * Clip might cause us to MCR insufficient RAM but that is an
- * acceptable failure mode and should only bite obscure boxes with
- * a VESA hole at 15Mb
- *
- * The second case Clip sometimes kicks in is when the EBDA is marked
- * as reserved. Again we fail safe with reasonable results
- */
- if (top > clip)
- top = clip;
-
- return top;
-}
-
-/*
- * Compute a set of MCR's to give maximum coverage
- */
-static int centaur_mcr_compute(int nr, int key)
-{
- u32 mem = ramtop();
- u32 root = power2(mem);
- u32 base = root;
- u32 top = root;
- u32 floor = 0;
- int ct = 0;
-
- while (ct < nr) {
- u32 fspace = 0;
- u32 high;
- u32 low;
-
- /*
- * Find the largest block we will fill going upwards
- */
- high = power2(mem-top);
-
- /*
- * Find the largest block we will fill going downwards
- */
- low = base/2;
-
- /*
- * Don't fill below 1Mb going downwards as there
- * is an ISA hole in the way.
- */
- if (base <= 1024*1024)
- low = 0;
-
- /*
- * See how much space we could cover by filling below
- * the ISA hole
- */
-
- if (floor == 0)
- fspace = 512*1024;
- else if (floor == 512*1024)
- fspace = 128*1024;
-
- /* And forget ROM space */
-
- /*
- * Now install the largest coverage we get
- */
- if (fspace > high && fspace > low) {
- centaur_mcr_insert(ct, floor, fspace, key);
- floor += fspace;
- } else if (high > low) {
- centaur_mcr_insert(ct, top, high, key);
- top += high;
- } else if (low > 0) {
- base -= low;
- centaur_mcr_insert(ct, base, low, key);
- } else
- break;
- ct++;
- }
- /*
- * We loaded ct values. We now need to set the mask. The caller
- * must do this bit.
- */
- return ct;
-}
-
-static void centaur_create_optimal_mcr(void)
-{
- int used;
- int i;
-
- /*
- * Allocate up to 6 mcrs to mark as much of ram as possible
- * as write combining and weak write ordered.
- *
- * To experiment with: Linux never uses stack operations for
- * mmio spaces so we could globally enable stack operation wc
- *
- * Load the registers with type 31 - full write combining, all
- * writes weakly ordered.
- */
- used = centaur_mcr_compute(6, 31);
-
- /*
- * Wipe unused MCRs
- */
- for (i = used; i < 8; i++)
- wrmsr(MSR_IDT_MCR0+i, 0, 0);
-}
-
-static void winchip2_create_optimal_mcr(void)
-{
- u32 lo, hi;
- int used;
- int i;
-
- /*
- * Allocate up to 6 mcrs to mark as much of ram as possible
- * as write combining, weak store ordered.
- *
- * Load the registers with type 25
- * 8 - weak write ordering
- * 16 - weak read ordering
- * 1 - write combining
- */
- used = centaur_mcr_compute(6, 25);
-
- /*
- * Mark the registers we are using.
- */
- rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
- for (i = 0; i < used; i++)
- lo |= 1<<(9+i);
- wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
-
- /*
- * Wipe unused MCRs
- */
-
- for (i = used; i < 8; i++)
- wrmsr(MSR_IDT_MCR0+i, 0, 0);
-}
-
-/*
- * Handle the MCR key on the Winchip 2.
- */
-static void winchip2_unprotect_mcr(void)
-{
- u32 lo, hi;
- u32 key;
-
- rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
- lo &= ~0x1C0; /* blank bits 8-6 */
- key = (lo>>17) & 7;
- lo |= key<<6; /* replace with unlock key */
- wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
-}
-
-static void winchip2_protect_mcr(void)
-{
- u32 lo, hi;
-
- rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
- lo &= ~0x1C0; /* blank bits 8-6 */
- wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
-}
-#endif /* CONFIG_X86_OOSTORE */
-
#define ACE_PRESENT (1 << 6)
#define ACE_ENABLED (1 << 7)
#define ACE_FCR (1 << 28) /* MSR_VIA_FCR */
@@ -362,20 +132,6 @@ static void init_centaur(struct cpuinfo_x86 *c)
fcr_clr = DPDC;
printk(KERN_NOTICE "Disabling bugged TSC.\n");
clear_cpu_cap(c, X86_FEATURE_TSC);
-#ifdef CONFIG_X86_OOSTORE
- centaur_create_optimal_mcr();
- /*
- * Enable:
- * write combining on non-stack, non-string
- * write combining on string, all types
- * weak write ordering
- *
- * The C6 original lacks weak read order
- *
- * Note 0x120 is write only on Winchip 1
- */
- wrmsr(MSR_IDT_MCR_CTRL, 0x01F0001F, 0);
-#endif
break;
case 8:
switch (c->x86_mask) {
@@ -392,40 +148,12 @@ static void init_centaur(struct cpuinfo_x86 *c)
fcr_set = ECX8|DSMC|DTLOCK|EMMX|EBRPRED|ERETSTK|
E2MMX|EAMD3D;
fcr_clr = DPDC;
-#ifdef CONFIG_X86_OOSTORE
- winchip2_unprotect_mcr();
- winchip2_create_optimal_mcr();
- rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
- /*
- * Enable:
- * write combining on non-stack, non-string
- * write combining on string, all types
- * weak write ordering
- */
- lo |= 31;
- wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
- winchip2_protect_mcr();
-#endif
break;
case 9:
name = "3";
fcr_set = ECX8|DSMC|DTLOCK|EMMX|EBRPRED|ERETSTK|
E2MMX|EAMD3D;
fcr_clr = DPDC;
-#ifdef CONFIG_X86_OOSTORE
- winchip2_unprotect_mcr();
- winchip2_create_optimal_mcr();
- rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
- /*
- * Enable:
- * write combining on non-stack, non-string
- * write combining on string, all types
- * weak write ordering
- */
- lo |= 31;
- wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
- winchip2_protect_mcr();
-#endif
break;
default:
name = "??";
diff --git a/arch/x86/um/asm/barrier.h b/arch/x86/um/asm/barrier.h
index 7d01b8c56c00..cc04e67bfd05 100644
--- a/arch/x86/um/asm/barrier.h
+++ b/arch/x86/um/asm/barrier.h
@@ -40,11 +40,7 @@
#define smp_rmb() barrier()
#endif /* CONFIG_X86_PPRO_FENCE */

-#ifdef CONFIG_X86_OOSTORE
-#define smp_wmb() wmb()
-#else /* CONFIG_X86_OOSTORE */
#define smp_wmb() barrier()
-#endif /* CONFIG_X86_OOSTORE */

#define smp_read_barrier_depends() read_barrier_depends()
#define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
--
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