kernel_optimize_test/arch/powerpc/mm/slb.c
Anton Blanchard de4376c284 powerpc: Preload application text segment instead of TASK_UNMAPPED_BASE
TASK_UNMAPPED_BASE is not used with the new top down mmap layout. We can
reuse this preload slot by loading in the segment at 0x10000000, where almost
all PowerPC binaries are linked at.

On a microbenchmark that bounces a token between two 64bit processes over pipes
and calls gettimeofday each iteration (to access the VDSO), both the 32bit and
64bit context switch rate improves (tested on a 4GHz POWER6):

32bit: 273k/sec -> 283k/sec
64bit: 277k/sec -> 284k/sec

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-08-20 10:12:26 +10:00

316 lines
9.6 KiB
C

/*
* PowerPC64 SLB support.
*
* Copyright (C) 2004 David Gibson <dwg@au.ibm.com>, IBM
* Based on earlier code written by:
* Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
* Copyright (c) 2001 Dave Engebretsen
* Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/paca.h>
#include <asm/cputable.h>
#include <asm/cacheflush.h>
#include <asm/smp.h>
#include <asm/firmware.h>
#include <linux/compiler.h>
#include <asm/udbg.h>
extern void slb_allocate_realmode(unsigned long ea);
extern void slb_allocate_user(unsigned long ea);
static void slb_allocate(unsigned long ea)
{
/* Currently, we do real mode for all SLBs including user, but
* that will change if we bring back dynamic VSIDs
*/
slb_allocate_realmode(ea);
}
#define slb_esid_mask(ssize) \
(((ssize) == MMU_SEGSIZE_256M)? ESID_MASK: ESID_MASK_1T)
static inline unsigned long mk_esid_data(unsigned long ea, int ssize,
unsigned long slot)
{
return (ea & slb_esid_mask(ssize)) | SLB_ESID_V | slot;
}
#define slb_vsid_shift(ssize) \
((ssize) == MMU_SEGSIZE_256M? SLB_VSID_SHIFT: SLB_VSID_SHIFT_1T)
static inline unsigned long mk_vsid_data(unsigned long ea, int ssize,
unsigned long flags)
{
return (get_kernel_vsid(ea, ssize) << slb_vsid_shift(ssize)) | flags |
((unsigned long) ssize << SLB_VSID_SSIZE_SHIFT);
}
static inline void slb_shadow_update(unsigned long ea, int ssize,
unsigned long flags,
unsigned long entry)
{
/*
* Clear the ESID first so the entry is not valid while we are
* updating it. No write barriers are needed here, provided
* we only update the current CPU's SLB shadow buffer.
*/
get_slb_shadow()->save_area[entry].esid = 0;
get_slb_shadow()->save_area[entry].vsid = mk_vsid_data(ea, ssize, flags);
get_slb_shadow()->save_area[entry].esid = mk_esid_data(ea, ssize, entry);
}
static inline void slb_shadow_clear(unsigned long entry)
{
get_slb_shadow()->save_area[entry].esid = 0;
}
static inline void create_shadowed_slbe(unsigned long ea, int ssize,
unsigned long flags,
unsigned long entry)
{
/*
* Updating the shadow buffer before writing the SLB ensures
* we don't get a stale entry here if we get preempted by PHYP
* between these two statements.
*/
slb_shadow_update(ea, ssize, flags, entry);
asm volatile("slbmte %0,%1" :
: "r" (mk_vsid_data(ea, ssize, flags)),
"r" (mk_esid_data(ea, ssize, entry))
: "memory" );
}
void slb_flush_and_rebolt(void)
{
/* If you change this make sure you change SLB_NUM_BOLTED
* appropriately too. */
unsigned long linear_llp, vmalloc_llp, lflags, vflags;
unsigned long ksp_esid_data, ksp_vsid_data;
WARN_ON(!irqs_disabled());
linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
lflags = SLB_VSID_KERNEL | linear_llp;
vflags = SLB_VSID_KERNEL | vmalloc_llp;
ksp_esid_data = mk_esid_data(get_paca()->kstack, mmu_kernel_ssize, 2);
if ((ksp_esid_data & ~0xfffffffUL) <= PAGE_OFFSET) {
ksp_esid_data &= ~SLB_ESID_V;
ksp_vsid_data = 0;
slb_shadow_clear(2);
} else {
/* Update stack entry; others don't change */
slb_shadow_update(get_paca()->kstack, mmu_kernel_ssize, lflags, 2);
ksp_vsid_data = get_slb_shadow()->save_area[2].vsid;
}
/*
* We can't take a PMU exception in the following code, so hard
* disable interrupts.
*/
hard_irq_disable();
/* We need to do this all in asm, so we're sure we don't touch
* the stack between the slbia and rebolting it. */
asm volatile("isync\n"
"slbia\n"
/* Slot 1 - first VMALLOC segment */
"slbmte %0,%1\n"
/* Slot 2 - kernel stack */
"slbmte %2,%3\n"
"isync"
:: "r"(mk_vsid_data(VMALLOC_START, mmu_kernel_ssize, vflags)),
"r"(mk_esid_data(VMALLOC_START, mmu_kernel_ssize, 1)),
"r"(ksp_vsid_data),
"r"(ksp_esid_data)
: "memory");
}
void slb_vmalloc_update(void)
{
unsigned long vflags;
vflags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_vmalloc_psize].sllp;
slb_shadow_update(VMALLOC_START, mmu_kernel_ssize, vflags, 1);
slb_flush_and_rebolt();
}
/* Helper function to compare esids. There are four cases to handle.
* 1. The system is not 1T segment size capable. Use the GET_ESID compare.
* 2. The system is 1T capable, both addresses are < 1T, use the GET_ESID compare.
* 3. The system is 1T capable, only one of the two addresses is > 1T. This is not a match.
* 4. The system is 1T capable, both addresses are > 1T, use the GET_ESID_1T macro to compare.
*/
static inline int esids_match(unsigned long addr1, unsigned long addr2)
{
int esid_1t_count;
/* System is not 1T segment size capable. */
if (!cpu_has_feature(CPU_FTR_1T_SEGMENT))
return (GET_ESID(addr1) == GET_ESID(addr2));
esid_1t_count = (((addr1 >> SID_SHIFT_1T) != 0) +
((addr2 >> SID_SHIFT_1T) != 0));
/* both addresses are < 1T */
if (esid_1t_count == 0)
return (GET_ESID(addr1) == GET_ESID(addr2));
/* One address < 1T, the other > 1T. Not a match */
if (esid_1t_count == 1)
return 0;
/* Both addresses are > 1T. */
return (GET_ESID_1T(addr1) == GET_ESID_1T(addr2));
}
/* Flush all user entries from the segment table of the current processor. */
void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
{
unsigned long offset = get_paca()->slb_cache_ptr;
unsigned long slbie_data = 0;
unsigned long pc = KSTK_EIP(tsk);
unsigned long stack = KSTK_ESP(tsk);
unsigned long exec_base;
if (!cpu_has_feature(CPU_FTR_NO_SLBIE_B) &&
offset <= SLB_CACHE_ENTRIES) {
int i;
asm volatile("isync" : : : "memory");
for (i = 0; i < offset; i++) {
slbie_data = (unsigned long)get_paca()->slb_cache[i]
<< SID_SHIFT; /* EA */
slbie_data |= user_segment_size(slbie_data)
<< SLBIE_SSIZE_SHIFT;
slbie_data |= SLBIE_C; /* C set for user addresses */
asm volatile("slbie %0" : : "r" (slbie_data));
}
asm volatile("isync" : : : "memory");
} else {
slb_flush_and_rebolt();
}
/* Workaround POWER5 < DD2.1 issue */
if (offset == 1 || offset > SLB_CACHE_ENTRIES)
asm volatile("slbie %0" : : "r" (slbie_data));
get_paca()->slb_cache_ptr = 0;
get_paca()->context = mm->context;
/*
* preload some userspace segments into the SLB.
* Almost all 32 and 64bit PowerPC executables are linked at
* 0x10000000 so it makes sense to preload this segment.
*/
exec_base = 0x10000000;
if (is_kernel_addr(pc) || is_kernel_addr(stack) ||
is_kernel_addr(exec_base))
return;
slb_allocate(pc);
if (!esids_match(pc, stack))
slb_allocate(stack);
if (!esids_match(pc, exec_base) &&
!esids_match(stack, exec_base))
slb_allocate(exec_base);
}
static inline void patch_slb_encoding(unsigned int *insn_addr,
unsigned int immed)
{
/* Assume the instruction had a "0" immediate value, just
* "or" in the new value
*/
*insn_addr |= immed;
flush_icache_range((unsigned long)insn_addr, 4+
(unsigned long)insn_addr);
}
void slb_initialize(void)
{
unsigned long linear_llp, vmalloc_llp, io_llp;
unsigned long lflags, vflags;
static int slb_encoding_inited;
extern unsigned int *slb_miss_kernel_load_linear;
extern unsigned int *slb_miss_kernel_load_io;
extern unsigned int *slb_compare_rr_to_size;
#ifdef CONFIG_SPARSEMEM_VMEMMAP
extern unsigned int *slb_miss_kernel_load_vmemmap;
unsigned long vmemmap_llp;
#endif
/* Prepare our SLB miss handler based on our page size */
linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
io_llp = mmu_psize_defs[mmu_io_psize].sllp;
vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
get_paca()->vmalloc_sllp = SLB_VSID_KERNEL | vmalloc_llp;
#ifdef CONFIG_SPARSEMEM_VMEMMAP
vmemmap_llp = mmu_psize_defs[mmu_vmemmap_psize].sllp;
#endif
if (!slb_encoding_inited) {
slb_encoding_inited = 1;
patch_slb_encoding(slb_miss_kernel_load_linear,
SLB_VSID_KERNEL | linear_llp);
patch_slb_encoding(slb_miss_kernel_load_io,
SLB_VSID_KERNEL | io_llp);
patch_slb_encoding(slb_compare_rr_to_size,
mmu_slb_size);
pr_devel("SLB: linear LLP = %04lx\n", linear_llp);
pr_devel("SLB: io LLP = %04lx\n", io_llp);
#ifdef CONFIG_SPARSEMEM_VMEMMAP
patch_slb_encoding(slb_miss_kernel_load_vmemmap,
SLB_VSID_KERNEL | vmemmap_llp);
pr_devel("SLB: vmemmap LLP = %04lx\n", vmemmap_llp);
#endif
}
get_paca()->stab_rr = SLB_NUM_BOLTED;
/* On iSeries the bolted entries have already been set up by
* the hypervisor from the lparMap data in head.S */
if (firmware_has_feature(FW_FEATURE_ISERIES))
return;
lflags = SLB_VSID_KERNEL | linear_llp;
vflags = SLB_VSID_KERNEL | vmalloc_llp;
/* Invalidate the entire SLB (even slot 0) & all the ERATS */
asm volatile("isync":::"memory");
asm volatile("slbmte %0,%0"::"r" (0) : "memory");
asm volatile("isync; slbia; isync":::"memory");
create_shadowed_slbe(PAGE_OFFSET, mmu_kernel_ssize, lflags, 0);
create_shadowed_slbe(VMALLOC_START, mmu_kernel_ssize, vflags, 1);
/* For the boot cpu, we're running on the stack in init_thread_union,
* which is in the first segment of the linear mapping, and also
* get_paca()->kstack hasn't been initialized yet.
* For secondary cpus, we need to bolt the kernel stack entry now.
*/
slb_shadow_clear(2);
if (raw_smp_processor_id() != boot_cpuid &&
(get_paca()->kstack & slb_esid_mask(mmu_kernel_ssize)) > PAGE_OFFSET)
create_shadowed_slbe(get_paca()->kstack,
mmu_kernel_ssize, lflags, 2);
asm volatile("isync":::"memory");
}