linux/arch/arm/mm/cache-v6.S
Russell King 2ffe2da3e7 ARM: dma-mapping: fix for speculative prefetching
ARMv6 and ARMv7 CPUs can perform speculative prefetching, which makes
DMA cache coherency handling slightly more interesting.  Rather than
being able to rely upon the CPU not accessing the DMA buffer until DMA
has completed, we now must expect that the cache could be loaded with
possibly stale data from the DMA buffer.

Where DMA involves data being transferred to the device, we clean the
cache before handing it over for DMA, otherwise we invalidate the buffer
to get rid of potential writebacks.  On DMA Completion, if data was
transferred from the device, we invalidate the buffer to get rid of
any stale speculative prefetches.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-By: Santosh Shilimkar <santosh.shilimkar@ti.com>
2010-02-15 15:22:25 +00:00

306 lines
7.1 KiB
ArmAsm

/*
* linux/arch/arm/mm/cache-v6.S
*
* Copyright (C) 2001 Deep Blue Solutions Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This is the "shell" of the ARMv6 processor support.
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/unwind.h>
#include "proc-macros.S"
#define HARVARD_CACHE
#define CACHE_LINE_SIZE 32
#define D_CACHE_LINE_SIZE 32
#define BTB_FLUSH_SIZE 8
#ifdef CONFIG_ARM_ERRATA_411920
/*
* Invalidate the entire I cache (this code is a workaround for the ARM1136
* erratum 411920 - Invalidate Instruction Cache operation can fail. This
* erratum is present in 1136, 1156 and 1176. It does not affect the MPCore.
*
* Registers:
* r0 - set to 0
* r1 - corrupted
*/
ENTRY(v6_icache_inval_all)
mov r0, #0
mrs r1, cpsr
cpsid ifa @ disable interrupts
mcr p15, 0, r0, c7, c5, 0 @ invalidate entire I-cache
mcr p15, 0, r0, c7, c5, 0 @ invalidate entire I-cache
mcr p15, 0, r0, c7, c5, 0 @ invalidate entire I-cache
mcr p15, 0, r0, c7, c5, 0 @ invalidate entire I-cache
msr cpsr_cx, r1 @ restore interrupts
.rept 11 @ ARM Ltd recommends at least
nop @ 11 NOPs
.endr
mov pc, lr
#endif
/*
* v6_flush_cache_all()
*
* Flush the entire cache.
*
* It is assumed that:
*/
ENTRY(v6_flush_kern_cache_all)
mov r0, #0
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c14, 0 @ D cache clean+invalidate
#ifndef CONFIG_ARM_ERRATA_411920
mcr p15, 0, r0, c7, c5, 0 @ I+BTB cache invalidate
#else
b v6_icache_inval_all
#endif
#else
mcr p15, 0, r0, c7, c15, 0 @ Cache clean+invalidate
#endif
mov pc, lr
/*
* v6_flush_cache_all()
*
* Flush all TLB entries in a particular address space
*
* - mm - mm_struct describing address space
*/
ENTRY(v6_flush_user_cache_all)
/*FALLTHROUGH*/
/*
* v6_flush_cache_range(start, end, flags)
*
* Flush a range of TLB entries in the specified address space.
*
* - start - start address (may not be aligned)
* - end - end address (exclusive, may not be aligned)
* - flags - vm_area_struct flags describing address space
*
* It is assumed that:
* - we have a VIPT cache.
*/
ENTRY(v6_flush_user_cache_range)
mov pc, lr
/*
* v6_coherent_kern_range(start,end)
*
* Ensure that the I and D caches are coherent within specified
* region. This is typically used when code has been written to
* a memory region, and will be executed.
*
* - start - virtual start address of region
* - end - virtual end address of region
*
* It is assumed that:
* - the Icache does not read data from the write buffer
*/
ENTRY(v6_coherent_kern_range)
/* FALLTHROUGH */
/*
* v6_coherent_user_range(start,end)
*
* Ensure that the I and D caches are coherent within specified
* region. This is typically used when code has been written to
* a memory region, and will be executed.
*
* - start - virtual start address of region
* - end - virtual end address of region
*
* It is assumed that:
* - the Icache does not read data from the write buffer
*/
ENTRY(v6_coherent_user_range)
UNWIND(.fnstart )
#ifdef HARVARD_CACHE
bic r0, r0, #CACHE_LINE_SIZE - 1
1:
USER( mcr p15, 0, r0, c7, c10, 1 ) @ clean D line
add r0, r0, #CACHE_LINE_SIZE
2:
cmp r0, r1
blo 1b
#endif
mov r0, #0
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
#ifndef CONFIG_ARM_ERRATA_411920
mcr p15, 0, r0, c7, c5, 0 @ I+BTB cache invalidate
#else
b v6_icache_inval_all
#endif
#else
mcr p15, 0, r0, c7, c5, 6 @ invalidate BTB
#endif
mov pc, lr
/*
* Fault handling for the cache operation above. If the virtual address in r0
* isn't mapped, just try the next page.
*/
9001:
mov r0, r0, lsr #12
mov r0, r0, lsl #12
add r0, r0, #4096
b 2b
UNWIND(.fnend )
ENDPROC(v6_coherent_user_range)
ENDPROC(v6_coherent_kern_range)
/*
* v6_flush_kern_dcache_area(void *addr, size_t size)
*
* Ensure that the data held in the page kaddr is written back
* to the page in question.
*
* - addr - kernel address
* - size - region size
*/
ENTRY(v6_flush_kern_dcache_area)
add r1, r0, r1
1:
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c14, 1 @ clean & invalidate D line
#else
mcr p15, 0, r0, c7, c15, 1 @ clean & invalidate unified line
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
blo 1b
#ifdef HARVARD_CACHE
mov r0, #0
mcr p15, 0, r0, c7, c10, 4
#endif
mov pc, lr
/*
* v6_dma_inv_range(start,end)
*
* Invalidate the data cache within the specified region; we will
* be performing a DMA operation in this region and we want to
* purge old data in the cache.
*
* - start - virtual start address of region
* - end - virtual end address of region
*/
v6_dma_inv_range:
tst r0, #D_CACHE_LINE_SIZE - 1
bic r0, r0, #D_CACHE_LINE_SIZE - 1
#ifdef HARVARD_CACHE
mcrne p15, 0, r0, c7, c10, 1 @ clean D line
#else
mcrne p15, 0, r0, c7, c11, 1 @ clean unified line
#endif
tst r1, #D_CACHE_LINE_SIZE - 1
bic r1, r1, #D_CACHE_LINE_SIZE - 1
#ifdef HARVARD_CACHE
mcrne p15, 0, r1, c7, c14, 1 @ clean & invalidate D line
#else
mcrne p15, 0, r1, c7, c15, 1 @ clean & invalidate unified line
#endif
1:
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c6, 1 @ invalidate D line
#else
mcr p15, 0, r0, c7, c7, 1 @ invalidate unified line
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
mov pc, lr
/*
* v6_dma_clean_range(start,end)
* - start - virtual start address of region
* - end - virtual end address of region
*/
v6_dma_clean_range:
bic r0, r0, #D_CACHE_LINE_SIZE - 1
1:
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c10, 1 @ clean D line
#else
mcr p15, 0, r0, c7, c11, 1 @ clean unified line
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
mov pc, lr
/*
* v6_dma_flush_range(start,end)
* - start - virtual start address of region
* - end - virtual end address of region
*/
ENTRY(v6_dma_flush_range)
bic r0, r0, #D_CACHE_LINE_SIZE - 1
1:
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c14, 1 @ clean & invalidate D line
#else
mcr p15, 0, r0, c7, c15, 1 @ clean & invalidate line
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
mov pc, lr
/*
* dma_map_area(start, size, dir)
* - start - kernel virtual start address
* - size - size of region
* - dir - DMA direction
*/
ENTRY(v6_dma_map_area)
add r1, r1, r0
teq r2, #DMA_FROM_DEVICE
beq v6_dma_inv_range
b v6_dma_clean_range
ENDPROC(v6_dma_map_area)
/*
* dma_unmap_area(start, size, dir)
* - start - kernel virtual start address
* - size - size of region
* - dir - DMA direction
*/
ENTRY(v6_dma_unmap_area)
add r1, r1, r0
teq r2, #DMA_TO_DEVICE
bne v6_dma_inv_range
mov pc, lr
ENDPROC(v6_dma_unmap_area)
__INITDATA
.type v6_cache_fns, #object
ENTRY(v6_cache_fns)
.long v6_flush_kern_cache_all
.long v6_flush_user_cache_all
.long v6_flush_user_cache_range
.long v6_coherent_kern_range
.long v6_coherent_user_range
.long v6_flush_kern_dcache_area
.long v6_dma_map_area
.long v6_dma_unmap_area
.long v6_dma_flush_range
.size v6_cache_fns, . - v6_cache_fns