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linux/arch/arm/mm/cache-v4wb.S
Linus Walleij 7b749aad1f ARM: 9393/1: mm: Use conditionals for CFI branches 
Commit 9385/2 introduced a few branches inside function
prototypes when using CFI in order to deal with the situation
where CFI inserts a few bytes of function information in front
of the symbol.

This is not good for older CPUs where every cycle counts.

Commit 9386/2 alleviated the situation a bit by using aliases
for the cache functions with identical signatures.

This leaves the coherent cache flush functions
*_coherent_kern_range() with these branches to the corresponing
*_coherent_user_range() around, since their return type differ and
they therefore cannot be aliased.

Solve this by a simple ifdef so at least we can use fallthroughs
when compiling without CFI enabled.

Link: https://lore.kernel.org/linux-arm-kernel/Zi+e9M%2Ff5b%2FSto9H@shell.armlinux.org.uk/

Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
2024-05-07 10:30:24 +01:00

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* linux/arch/arm/mm/cache-v4wb.S
*
* Copyright (C) 1997-2002 Russell king
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/cfi_types.h>
#include <asm/assembler.h>
#include <asm/page.h>
#include "proc-macros.S"
/*
* The size of one data cache line.
*/
#define CACHE_DLINESIZE 32
/*
* The total size of the data cache.
*/
#if defined(CONFIG_CPU_SA110)
# define CACHE_DSIZE 16384
#elif defined(CONFIG_CPU_SA1100)
# define CACHE_DSIZE 8192
#else
# error Unknown cache size
#endif
/*
* This is the size at which it becomes more efficient to
* clean the whole cache, rather than using the individual
* cache line maintenance instructions.
*
* Size Clean (ticks) Dirty (ticks)
* 4096 21 20 21 53 55 54
* 8192 40 41 40 106 100 102
* 16384 77 77 76 140 140 138
* 32768 150 149 150 214 216 212 <---
* 65536 296 297 296 351 358 361
* 131072 591 591 591 656 657 651
* Whole 132 136 132 221 217 207 <---
*/
#define CACHE_DLIMIT (CACHE_DSIZE * 4)
.data
.align 2
flush_base:
.long FLUSH_BASE
.text
/*
* flush_icache_all()
*
* Unconditionally clean and invalidate the entire icache.
*/
SYM_TYPED_FUNC_START(v4wb_flush_icache_all)
mov r0, #0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
ret lr
SYM_FUNC_END(v4wb_flush_icache_all)
/*
* flush_user_cache_all()
*
* Clean and invalidate all cache entries in a particular address
* space.
*/
SYM_FUNC_ALIAS(v4wb_flush_user_cache_all, v4wb_flush_kern_cache_all)
/*
* flush_kern_cache_all()
*
* Clean and invalidate the entire cache.
*/
SYM_TYPED_FUNC_START(v4wb_flush_kern_cache_all)
mov ip, #0
mcr p15, 0, ip, c7, c5, 0 @ invalidate I cache
__flush_whole_cache:
ldr r3, =flush_base
ldr r1, [r3, #0]
eor r1, r1, #CACHE_DSIZE
str r1, [r3, #0]
add r2, r1, #CACHE_DSIZE
1: ldr r3, [r1], #32
cmp r1, r2
blo 1b
#ifdef FLUSH_BASE_MINICACHE
add r2, r2, #FLUSH_BASE_MINICACHE - FLUSH_BASE
sub r1, r2, #512 @ only 512 bytes
1: ldr r3, [r1], #32
cmp r1, r2
blo 1b
#endif
mcr p15, 0, ip, c7, c10, 4 @ drain write buffer
ret lr
SYM_FUNC_END(v4wb_flush_kern_cache_all)
/*
* flush_user_cache_range(start, end, flags)
*
* Invalidate a range of cache entries in the specified
* address space.
*
* - start - start address (inclusive, page aligned)
* - end - end address (exclusive, page aligned)
* - flags - vma_area_struct flags describing address space
*/
SYM_TYPED_FUNC_START(v4wb_flush_user_cache_range)
mov ip, #0
sub r3, r1, r0 @ calculate total size
tst r2, #VM_EXEC @ executable region?
mcrne p15, 0, ip, c7, c5, 0 @ invalidate I cache
cmp r3, #CACHE_DLIMIT @ total size >= limit?
bhs __flush_whole_cache @ flush whole D cache
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
mcr p15, 0, r0, c7, c6, 1 @ invalidate D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
tst r2, #VM_EXEC
mcrne p15, 0, ip, c7, c10, 4 @ drain write buffer
ret lr
SYM_FUNC_END(v4wb_flush_user_cache_range)
/*
* flush_kern_dcache_area(void *addr, size_t size)
*
* Ensure no D cache aliasing occurs, either with itself or
* the I cache
*
* - addr - kernel address
* - size - region size
*/
SYM_TYPED_FUNC_START(v4wb_flush_kern_dcache_area)
add r1, r0, r1
#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
b v4wb_coherent_user_range
#endif
SYM_FUNC_END(v4wb_flush_kern_dcache_area)
/*
* coherent_kern_range(start, end)
*
* Ensure coherency between the Icache and the Dcache in the
* region described by start. If you have non-snooping
* Harvard caches, you need to implement this function.
*
* - start - virtual start address
* - end - virtual end address
*/
SYM_TYPED_FUNC_START(v4wb_coherent_kern_range)
#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
b v4wb_coherent_user_range
#endif
SYM_FUNC_END(v4wb_coherent_kern_range)
/*
* coherent_user_range(start, end)
*
* Ensure coherency between the Icache and the Dcache in the
* region described by start. If you have non-snooping
* Harvard caches, you need to implement this function.
*
* - start - virtual start address
* - end - virtual end address
*/
SYM_TYPED_FUNC_START(v4wb_coherent_user_range)
bic r0, r0, #CACHE_DLINESIZE - 1
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
mcr p15, 0, r0, c7, c6, 1 @ invalidate D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
mcr p15, 0, r0, c7, c10, 4 @ drain WB
ret lr
SYM_FUNC_END(v4wb_coherent_user_range)
/*
* dma_inv_range(start, end)
*
* Invalidate (discard) the specified virtual address range.
* May not write back any entries. If 'start' or 'end'
* are not cache line aligned, those lines must be written
* back.
*
* - start - virtual start address
* - end - virtual end address
*/
v4wb_dma_inv_range:
tst r0, #CACHE_DLINESIZE - 1
bic r0, r0, #CACHE_DLINESIZE - 1
mcrne p15, 0, r0, c7, c10, 1 @ clean D entry
tst r1, #CACHE_DLINESIZE - 1
mcrne p15, 0, r1, c7, c10, 1 @ clean D entry
1: mcr p15, 0, r0, c7, c6, 1 @ invalidate D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
ret lr
/*
* dma_clean_range(start, end)
*
* Clean (write back) the specified virtual address range.
*
* - start - virtual start address
* - end - virtual end address
*/
v4wb_dma_clean_range:
bic r0, r0, #CACHE_DLINESIZE - 1
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
ret lr
/*
* dma_flush_range(start, end)
*
* Clean and invalidate the specified virtual address range.
*
* - start - virtual start address
* - end - virtual end address
*
* This is actually the same as v4wb_coherent_kern_range()
*/
.globl v4wb_dma_flush_range
.set v4wb_dma_flush_range, v4wb_coherent_kern_range
/*
* dma_map_area(start, size, dir)
* - start - kernel virtual start address
* - size - size of region
* - dir - DMA direction
*/
SYM_TYPED_FUNC_START(v4wb_dma_map_area)
add r1, r1, r0
cmp r2, #DMA_TO_DEVICE
beq v4wb_dma_clean_range
bcs v4wb_dma_inv_range
b v4wb_dma_flush_range
SYM_FUNC_END(v4wb_dma_map_area)
/*
* dma_unmap_area(start, size, dir)
* - start - kernel virtual start address
* - size - size of region
* - dir - DMA direction
*/
SYM_TYPED_FUNC_START(v4wb_dma_unmap_area)
ret lr
SYM_FUNC_END(v4wb_dma_unmap_area)
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