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With ARM64_SW_TTBR0_PAN enabled, the exception entry code checks the active ASID to decide whether user access was enabled (non-zero ASID) when the exception was taken. On return from exception, if user access was previously disabled, it re-instates TTBR0_EL1 from the per-thread saved value (updated in switch_mm() or efi_set_pgd()). Commit7655abb953("arm64: mm: Move ASID from TTBR0 to TTBR1") makes a TTBR0_EL1 + ASID switching non-atomic. Subsequently, commit27a921e757("arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN") changes the __uaccess_ttbr0_disable() function and asm macro to first write the reserved TTBR0_EL1 followed by the ASID=0 update in TTBR1_EL1. If an exception occurs between these two, the exception return code will re-instate a valid TTBR0_EL1. Similar scenario can happen in cpu_switch_mm() between setting the reserved TTBR0_EL1 and the ASID update in cpu_do_switch_mm(). This patch reverts the entry.S check for ASID == 0 to TTBR0_EL1 and disables the interrupts around the TTBR0_EL1 and ASID switching code in __uaccess_ttbr0_disable(). It also ensures that, when returning from the EFI runtime services, efi_set_pgd() doesn't leave a non-zero ASID in TTBR1_EL1 by using uaccess_ttbr0_{enable,disable}. The accesses to current_thread_info()->ttbr0 are updated to use READ_ONCE/WRITE_ONCE. As a safety measure, __uaccess_ttbr0_enable() always masks out any existing non-zero ASID TTBR1_EL1 before writing in the new ASID. Fixes:27a921e757("arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN") Acked-by: Will Deacon <will.deacon@arm.com> Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: James Morse <james.morse@arm.com> Tested-by: James Morse <james.morse@arm.com> Co-developed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
224 lines
5.2 KiB
ArmAsm
224 lines
5.2 KiB
ArmAsm
/*
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* Cache maintenance
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*
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* Copyright (C) 2001 Deep Blue Solutions Ltd.
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/errno.h>
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#include <linux/linkage.h>
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#include <linux/init.h>
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#include <asm/assembler.h>
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#include <asm/cpufeature.h>
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#include <asm/alternative.h>
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#include <asm/asm-uaccess.h>
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/*
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* flush_icache_range(start,end)
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*
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* Ensure that the I and D caches are coherent within specified region.
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* This is typically used when code has been written to a memory region,
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* and will be executed.
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*
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* - start - virtual start address of region
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* - end - virtual end address of region
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*/
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ENTRY(flush_icache_range)
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/* FALLTHROUGH */
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/*
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* __flush_cache_user_range(start,end)
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*
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* Ensure that the I and D caches are coherent within specified region.
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* This is typically used when code has been written to a memory region,
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* and will be executed.
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*
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* - start - virtual start address of region
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* - end - virtual end address of region
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*/
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ENTRY(__flush_cache_user_range)
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uaccess_ttbr0_enable x2, x3, x4
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dcache_line_size x2, x3
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sub x3, x2, #1
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bic x4, x0, x3
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1:
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user_alt 9f, "dc cvau, x4", "dc civac, x4", ARM64_WORKAROUND_CLEAN_CACHE
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add x4, x4, x2
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cmp x4, x1
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b.lo 1b
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dsb ish
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icache_line_size x2, x3
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sub x3, x2, #1
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bic x4, x0, x3
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1:
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USER(9f, ic ivau, x4 ) // invalidate I line PoU
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add x4, x4, x2
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cmp x4, x1
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b.lo 1b
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dsb ish
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isb
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mov x0, #0
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1:
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uaccess_ttbr0_disable x1, x2
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ret
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9:
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mov x0, #-EFAULT
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b 1b
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ENDPROC(flush_icache_range)
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ENDPROC(__flush_cache_user_range)
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/*
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* __flush_dcache_area(kaddr, size)
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*
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* Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
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* are cleaned and invalidated to the PoC.
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*
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* - kaddr - kernel address
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* - size - size in question
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*/
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ENTRY(__flush_dcache_area)
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dcache_by_line_op civac, sy, x0, x1, x2, x3
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ret
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ENDPIPROC(__flush_dcache_area)
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/*
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* __clean_dcache_area_pou(kaddr, size)
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*
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* Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
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* are cleaned to the PoU.
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*
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* - kaddr - kernel address
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* - size - size in question
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*/
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ENTRY(__clean_dcache_area_pou)
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dcache_by_line_op cvau, ish, x0, x1, x2, x3
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ret
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ENDPROC(__clean_dcache_area_pou)
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/*
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* __inval_dcache_area(kaddr, size)
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*
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* Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
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* are invalidated. Any partial lines at the ends of the interval are
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* also cleaned to PoC to prevent data loss.
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*
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* - kaddr - kernel address
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* - size - size in question
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*/
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ENTRY(__inval_dcache_area)
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/* FALLTHROUGH */
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/*
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* __dma_inv_area(start, size)
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* - start - virtual start address of region
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* - size - size in question
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*/
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__dma_inv_area:
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add x1, x1, x0
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dcache_line_size x2, x3
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sub x3, x2, #1
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tst x1, x3 // end cache line aligned?
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bic x1, x1, x3
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b.eq 1f
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dc civac, x1 // clean & invalidate D / U line
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1: tst x0, x3 // start cache line aligned?
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bic x0, x0, x3
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b.eq 2f
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dc civac, x0 // clean & invalidate D / U line
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b 3f
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2: dc ivac, x0 // invalidate D / U line
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3: add x0, x0, x2
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cmp x0, x1
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b.lo 2b
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dsb sy
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ret
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ENDPIPROC(__inval_dcache_area)
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ENDPROC(__dma_inv_area)
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/*
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* __clean_dcache_area_poc(kaddr, size)
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*
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* Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
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* are cleaned to the PoC.
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*
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* - kaddr - kernel address
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* - size - size in question
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*/
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ENTRY(__clean_dcache_area_poc)
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/* FALLTHROUGH */
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/*
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* __dma_clean_area(start, size)
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* - start - virtual start address of region
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* - size - size in question
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*/
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__dma_clean_area:
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dcache_by_line_op cvac, sy, x0, x1, x2, x3
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ret
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ENDPIPROC(__clean_dcache_area_poc)
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ENDPROC(__dma_clean_area)
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/*
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* __clean_dcache_area_pop(kaddr, size)
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*
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* Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
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* are cleaned to the PoP.
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*
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* - kaddr - kernel address
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* - size - size in question
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*/
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ENTRY(__clean_dcache_area_pop)
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dcache_by_line_op cvap, sy, x0, x1, x2, x3
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ret
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ENDPIPROC(__clean_dcache_area_pop)
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/*
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* __dma_flush_area(start, size)
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*
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* clean & invalidate D / U line
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*
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* - start - virtual start address of region
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* - size - size in question
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*/
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ENTRY(__dma_flush_area)
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dcache_by_line_op civac, sy, x0, x1, x2, x3
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ret
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ENDPIPROC(__dma_flush_area)
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/*
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* __dma_map_area(start, size, dir)
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* - start - kernel virtual start address
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* - size - size of region
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* - dir - DMA direction
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*/
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ENTRY(__dma_map_area)
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cmp w2, #DMA_FROM_DEVICE
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b.eq __dma_inv_area
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b __dma_clean_area
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ENDPIPROC(__dma_map_area)
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/*
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* __dma_unmap_area(start, size, dir)
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* - start - kernel virtual start address
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* - size - size of region
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* - dir - DMA direction
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*/
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ENTRY(__dma_unmap_area)
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cmp w2, #DMA_TO_DEVICE
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b.ne __dma_inv_area
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ret
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ENDPIPROC(__dma_unmap_area)
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