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linux/arch/arm/mm/proc-arm940.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/arm940.S: utility functions for ARM940T
*
* Copyright (C) 2004-2006 Hyok S. Choi (hyok.choi@samsung.com)
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/cfi_types.h>
#include <linux/pgtable.h>
#include <asm/assembler.h>
#include <asm/hwcap.h>
#include <asm/pgtable-hwdef.h>
#include <asm/ptrace.h>
#include "proc-macros.S"
/* ARM940T has a 4KB DCache comprising 256 lines of 4 words */
#define CACHE_DLINESIZE 16
#define CACHE_DSEGMENTS 4
#define CACHE_DENTRIES 64
.text
/*
* cpu_arm940_proc_init()
* cpu_arm940_switch_mm()
*
* These are not required.
*/
SYM_TYPED_FUNC_START(cpu_arm940_proc_init)
ret lr
SYM_FUNC_END(cpu_arm940_proc_init)
SYM_TYPED_FUNC_START(cpu_arm940_switch_mm)
ret lr
SYM_FUNC_END(cpu_arm940_switch_mm)
/*
* cpu_arm940_proc_fin()
*/
SYM_TYPED_FUNC_START(cpu_arm940_proc_fin)
mrc p15, 0, r0, c1, c0, 0 @ ctrl register
bic r0, r0, #0x00001000 @ i-cache
bic r0, r0, #0x00000004 @ d-cache
mcr p15, 0, r0, c1, c0, 0 @ disable caches
ret lr
SYM_FUNC_END(cpu_arm940_proc_fin)
/*
* cpu_arm940_reset(loc)
* Params : r0 = address to jump to
* Notes : This sets up everything for a reset
*/
.pushsection .idmap.text, "ax"
SYM_TYPED_FUNC_START(cpu_arm940_reset)
mov ip, #0
mcr p15, 0, ip, c7, c5, 0 @ flush I cache
mcr p15, 0, ip, c7, c6, 0 @ flush D cache
mcr p15, 0, ip, c7, c10, 4 @ drain WB
mrc p15, 0, ip, c1, c0, 0 @ ctrl register
bic ip, ip, #0x00000005 @ .............c.p
bic ip, ip, #0x00001000 @ i-cache
mcr p15, 0, ip, c1, c0, 0 @ ctrl register
ret r0
SYM_FUNC_END(cpu_arm940_reset)
.popsection
/*
* cpu_arm940_do_idle()
*/
.align 5
SYM_TYPED_FUNC_START(cpu_arm940_do_idle)
mcr p15, 0, r0, c7, c0, 4 @ Wait for interrupt
ret lr
SYM_FUNC_END(cpu_arm940_do_idle)
/*
* flush_icache_all()
*
* Unconditionally clean and invalidate the entire icache.
*/
SYM_TYPED_FUNC_START(arm940_flush_icache_all)
mov r0, #0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
ret lr
SYM_FUNC_END(arm940_flush_icache_all)
/*
* flush_user_cache_all()
*/
SYM_FUNC_ALIAS(arm940_flush_user_cache_all, arm940_flush_kern_cache_all)
/*
* flush_kern_cache_all()
*
* Clean and invalidate the entire cache.
*/
SYM_TYPED_FUNC_START(arm940_flush_kern_cache_all)
mov r2, #VM_EXEC
b arm940_flush_user_cache_range
SYM_FUNC_END(arm940_flush_kern_cache_all)
/*
* flush_user_cache_range(start, end, flags)
*
* There is no efficient way to flush a range of cache entries
* in the specified address range. Thus, flushes all.
*
* - start - start address (inclusive)
* - end - end address (exclusive)
* - flags - vm_flags describing address space
*/
SYM_TYPED_FUNC_START(arm940_flush_user_cache_range)
mov ip, #0
#ifdef CONFIG_CPU_DCACHE_WRITETHROUGH
mcr p15, 0, ip, c7, c6, 0 @ flush D cache
#else
mov r1, #(CACHE_DSEGMENTS - 1) << 4 @ 4 segments
1: orr r3, r1, #(CACHE_DENTRIES - 1) << 26 @ 64 entries
2: mcr p15, 0, r3, c7, c14, 2 @ clean/flush D index
subs r3, r3, #1 << 26
bcs 2b @ entries 63 to 0
subs r1, r1, #1 << 4
bcs 1b @ segments 3 to 0
#endif
tst r2, #VM_EXEC
mcrne p15, 0, ip, c7, c5, 0 @ invalidate I cache
mcrne p15, 0, ip, c7, c10, 4 @ drain WB
ret lr
SYM_FUNC_END(arm940_flush_user_cache_range)
/*
* coherent_kern_range(start, end)
*
* Ensure coherency between the Icache and the Dcache in the
* region described by start, end. 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(arm940_coherent_kern_range)
b arm940_flush_kern_dcache_area
SYM_FUNC_END(arm940_coherent_kern_range)
/*
* coherent_user_range(start, end)
*
* Ensure coherency between the Icache and the Dcache in the
* region described by start, end. 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(arm940_coherent_user_range)
#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
b arm940_flush_kern_dcache_area
#endif
SYM_FUNC_END(arm940_coherent_user_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(arm940_flush_kern_dcache_area)
mov r0, #0
mov r1, #(CACHE_DSEGMENTS - 1) << 4 @ 4 segments
1: orr r3, r1, #(CACHE_DENTRIES - 1) << 26 @ 64 entries
2: mcr p15, 0, r3, c7, c14, 2 @ clean/flush D index
subs r3, r3, #1 << 26
bcs 2b @ entries 63 to 0
subs r1, r1, #1 << 4
bcs 1b @ segments 7 to 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(arm940_flush_kern_dcache_area)
/*
* dma_inv_range(start, end)
*
* There is no efficient way to invalidate a specifid virtual
* address range. Thus, invalidates all.
*
* - start - virtual start address
* - end - virtual end address
*/
arm940_dma_inv_range:
mov ip, #0
mov r1, #(CACHE_DSEGMENTS - 1) << 4 @ 4 segments
1: orr r3, r1, #(CACHE_DENTRIES - 1) << 26 @ 64 entries
2: mcr p15, 0, r3, c7, c6, 2 @ flush D entry
subs r3, r3, #1 << 26
bcs 2b @ entries 63 to 0
subs r1, r1, #1 << 4
bcs 1b @ segments 7 to 0
mcr p15, 0, ip, c7, c10, 4 @ drain WB
ret lr
/*
* dma_clean_range(start, end)
*
* There is no efficient way to clean a specifid virtual
* address range. Thus, cleans all.
*
* - start - virtual start address
* - end - virtual end address
*/
arm940_dma_clean_range:
SYM_TYPED_FUNC_START(cpu_arm940_dcache_clean_area)
mov ip, #0
#ifndef CONFIG_CPU_DCACHE_WRITETHROUGH
mov r1, #(CACHE_DSEGMENTS - 1) << 4 @ 4 segments
1: orr r3, r1, #(CACHE_DENTRIES - 1) << 26 @ 64 entries
2: mcr p15, 0, r3, c7, c10, 2 @ clean D entry
subs r3, r3, #1 << 26
bcs 2b @ entries 63 to 0
subs r1, r1, #1 << 4
bcs 1b @ segments 7 to 0
#endif
mcr p15, 0, ip, c7, c10, 4 @ drain WB
ret lr
SYM_FUNC_END(cpu_arm940_dcache_clean_area)
/*
* dma_flush_range(start, end)
*
* There is no efficient way to clean and invalidate a specifid
* virtual address range.
*
* - start - virtual start address
* - end - virtual end address
*/
SYM_TYPED_FUNC_START(arm940_dma_flush_range)
mov ip, #0
mov r1, #(CACHE_DSEGMENTS - 1) << 4 @ 4 segments
1: orr r3, r1, #(CACHE_DENTRIES - 1) << 26 @ 64 entries
2:
#ifndef CONFIG_CPU_DCACHE_WRITETHROUGH
mcr p15, 0, r3, c7, c14, 2 @ clean/flush D entry
#else
mcr p15, 0, r3, c7, c6, 2 @ invalidate D entry
#endif
subs r3, r3, #1 << 26
bcs 2b @ entries 63 to 0
subs r1, r1, #1 << 4
bcs 1b @ segments 7 to 0
mcr p15, 0, ip, c7, c10, 4 @ drain WB
ret lr
SYM_FUNC_END(arm940_dma_flush_range)
/*
* dma_map_area(start, size, dir)
* - start - kernel virtual start address
* - size - size of region
* - dir - DMA direction
*/
SYM_TYPED_FUNC_START(arm940_dma_map_area)
add r1, r1, r0
cmp r2, #DMA_TO_DEVICE
beq arm940_dma_clean_range
bcs arm940_dma_inv_range
b arm940_dma_flush_range
SYM_FUNC_END(arm940_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(arm940_dma_unmap_area)
ret lr
SYM_FUNC_END(arm940_dma_unmap_area)
.type __arm940_setup, #function
__arm940_setup:
mov r0, #0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
mcr p15, 0, r0, c7, c6, 0 @ invalidate D cache
mcr p15, 0, r0, c7, c10, 4 @ drain WB
mcr p15, 0, r0, c6, c3, 0 @ disable data area 3~7
mcr p15, 0, r0, c6, c4, 0
mcr p15, 0, r0, c6, c5, 0
mcr p15, 0, r0, c6, c6, 0
mcr p15, 0, r0, c6, c7, 0
mcr p15, 0, r0, c6, c3, 1 @ disable instruction area 3~7
mcr p15, 0, r0, c6, c4, 1
mcr p15, 0, r0, c6, c5, 1
mcr p15, 0, r0, c6, c6, 1
mcr p15, 0, r0, c6, c7, 1
mov r0, #0x0000003F @ base = 0, size = 4GB
mcr p15, 0, r0, c6, c0, 0 @ set area 0, default
mcr p15, 0, r0, c6, c0, 1
ldr r0, =(CONFIG_DRAM_BASE & 0xFFFFF000) @ base[31:12] of RAM
ldr r7, =CONFIG_DRAM_SIZE >> 12 @ size of RAM (must be >= 4KB)
pr_val r3, r0, r7, #1
mcr p15, 0, r3, c6, c1, 0 @ set area 1, RAM
mcr p15, 0, r3, c6, c1, 1
ldr r0, =(CONFIG_FLASH_MEM_BASE & 0xFFFFF000) @ base[31:12] of FLASH
ldr r7, =CONFIG_FLASH_SIZE @ size of FLASH (must be >= 4KB)
pr_val r3, r0, r6, #1
mcr p15, 0, r3, c6, c2, 0 @ set area 2, ROM/FLASH
mcr p15, 0, r3, c6, c2, 1
mov r0, #0x06
mcr p15, 0, r0, c2, c0, 0 @ Region 1&2 cacheable
mcr p15, 0, r0, c2, c0, 1
#ifdef CONFIG_CPU_DCACHE_WRITETHROUGH
mov r0, #0x00 @ disable whole write buffer
#else
mov r0, #0x02 @ Region 1 write bufferred
#endif
mcr p15, 0, r0, c3, c0, 0
mov r0, #0x10000
sub r0, r0, #1 @ r0 = 0xffff
mcr p15, 0, r0, c5, c0, 0 @ all read/write access
mcr p15, 0, r0, c5, c0, 1
mrc p15, 0, r0, c1, c0 @ get control register
orr r0, r0, #0x00001000 @ I-cache
orr r0, r0, #0x00000005 @ MPU/D-cache
ret lr
.size __arm940_setup, . - __arm940_setup
__INITDATA
@ define struct processor (see <asm/proc-fns.h> and proc-macros.S)
define_processor_functions arm940, dabort=nommu_early_abort, pabort=legacy_pabort, nommu=1
.section ".rodata"
string cpu_arch_name, "armv4t"
string cpu_elf_name, "v4"
string cpu_arm940_name, "ARM940T"
.align
.section ".proc.info.init", "a"
.type __arm940_proc_info,#object
__arm940_proc_info:
.long 0x41009400
.long 0xff00fff0
.long 0
initfn __arm940_setup, __arm940_proc_info
.long cpu_arch_name
.long cpu_elf_name
.long HWCAP_SWP | HWCAP_HALF | HWCAP_THUMB
.long cpu_arm940_name
.long arm940_processor_functions
.long 0
.long 0
.long arm940_cache_fns
.size __arm940_proc_info, . - __arm940_proc_info
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