Re: [PATCH v2 09/31] arm64: Cache maintenance routines
From: Santosh Shilimkar
Date: Fri Aug 17 2012 - 05:58:14 EST
On Tuesday 14 August 2012 11:22 PM, Catalin Marinas wrote:
The patch adds functionality required for cache maintenance. The AArch64
architecture mandates non-aliasing VIPT or PIPT D-cache and VIPT (may
have aliases) or ASID-tagged VIVT I-cache. Cache maintenance operations
are automatically broadcast in hardware between CPUs.
Signed-off-by: Will Deacon<will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas<catalin.marinas@xxxxxxx>
---
arch/arm64/include/asm/cache.h | 32 ++++
arch/arm64/include/asm/cacheflush.h | 209 ++++++++++++++++++++++++++
arch/arm64/include/asm/cachetype.h | 48 ++++++
arch/arm64/mm/cache.S | 279 +++++++++++++++++++++++++++++++++++
arch/arm64/mm/flush.c | 132 +++++++++++++++++
5 files changed, 700 insertions(+), 0 deletions(-)
create mode 100644 arch/arm64/include/asm/cache.h
create mode 100644 arch/arm64/include/asm/cacheflush.h
create mode 100644 arch/arm64/include/asm/cachetype.h
create mode 100644 arch/arm64/mm/cache.S
create mode 100644 arch/arm64/mm/flush.c
diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
new file mode 100644
index 0000000..390308a
--- /dev/null
+++ b/arch/arm64/include/asm/cache.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012 ARM 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see<http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_CACHE_H
+#define __ASM_CACHE_H
+
+#define L1_CACHE_SHIFT 6
+#define L1_CACHE_BYTES (1<< L1_CACHE_SHIFT)
+
+/*
+ * Memory returned by kmalloc() may be used for DMA, so we must make
+ * sure that all such allocations are cache aligned. Otherwise,
+ * unrelated code may cause parts of the buffer to be read into the
+ * cache before the transfer is done, causing old data to be seen by
+ * the CPU.
+ */
+#define ARCH_DMA_MINALIGN L1_CACHE_BYTES
+#define ARCH_SLAB_MINALIGN 8
+
+#endif
diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
new file mode 100644
index 0000000..93b5590
--- /dev/null
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -0,0 +1,209 @@
+/*
+ * Based on arch/arm/include/asm/cacheflush.h
+ *
+ * Copyright (C) 1999-2002 Russell King.
+ * Copyright (C) 2012 ARM 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see<http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_CACHEFLUSH_H
+#define __ASM_CACHEFLUSH_H
+
+#include<linux/mm.h>
+
+/*
+ * This flag is used to indicate that the page pointed to by a pte is clean
+ * and does not require cleaning before returning it to the user.
+ */
+#define PG_dcache_clean PG_arch_1
+
+/*
+ * MM Cache Management
+ * ===================
+ *
+ * The arch/arm/mm/cache-*.S and arch/arm/mm/proc-*.S files
+ * implement these methods.
+ *
+ * Start addresses are inclusive and end addresses are exclusive;
+ * start addresses should be rounded down, end addresses up.
+ *
+ * See Documentation/cachetlb.txt for more information.
+ * Please note that the implementation of these, and the required
+ * effects are cache-type (VIVT/VIPT/PIPT) specific.
+ *
+ * flush_cache_kern_all()
+ *
+ * Unconditionally clean and invalidate the entire cache.
+ *
+ * flush_cache_user_mm(mm)
+ *
+ * Clean and invalidate all user space cache entries
+ * before a change of page tables.
+ *
+ * flush_cache_user_range(start, end, flags)
+ *
+ * Clean and invalidate a range of cache entries in the
+ * specified address space before a change of page tables.
+ * - start - user start address (inclusive, page aligned)
+ * - end - user end address (exclusive, page aligned)
+ * - flags - vma->vm_flags field
+ *
+ * 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
+ *
+ * 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
+ *
+ * flush_kern_dcache_area(kaddr, size)
+ *
+ * Ensure that the data held in page is written back.
+ * - kaddr - page address
+ * - size - region size
+ *
+ * DMA Cache Coherency
+ * ===================
+ *
+ * dma_flush_range(start, end)
+ *
+ * Clean and invalidate the specified virtual address range.
+ * - start - virtual start address
+ * - end - virtual end address
+ */
+extern void __cpuc_flush_kern_all(void);
+extern void __cpuc_flush_user_all(void);
+extern void __cpuc_flush_user_range(unsigned long, unsigned long, unsigned int);
+extern void __cpuc_coherent_kern_range(unsigned long, unsigned long);
+extern void __cpuc_coherent_user_range(unsigned long, unsigned long);
+extern void __cpuc_flush_dcache_area(void *, size_t);
+
+/*
+ * These are private to the dma-mapping API. Do not use directly.
+ * Their sole purpose is to ensure that data held in the cache
+ * is visible to DMA, or data written by DMA to system memory is
+ * visible to the CPU.
+ */
+extern void dmac_map_area(const void *, size_t, int);
+extern void dmac_unmap_area(const void *, size_t, int);
+extern void dmac_flush_range(const void *, const void *);
+
+/*
+ * Copy user data from/to a page which is mapped into a different
+ * processes address space. Really, we want to allow our "user
+ * space" model to handle this.
+ */
+extern void copy_to_user_page(struct vm_area_struct *, struct page *,
+ unsigned long, void *, const void *, unsigned long);
+#define copy_from_user_page(vma, page, vaddr, dst, src, len) \
+ do { \
+ memcpy(dst, src, len); \
+ } while (0)
+
+/*
+ * Convert calls to our calling convention.
+ */
+#define flush_cache_all() __cpuc_flush_kern_all()
+extern void flush_cache_mm(struct mm_struct *mm);
+extern void flush_cache_range(struct vm_area_struct *vma, unsigned long start, unsigned long end);
+extern void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr, unsigned long pfn);
+
+#define flush_cache_dup_mm(mm) flush_cache_mm(mm)
+
+/*
+ * flush_cache_user_range is used when we want to ensure that the
+ * Harvard caches are synchronised for the user space address range.
+ * This is used for the ARM private sys_cacheflush system call.
+ */
+#define flush_cache_user_range(start, end) \
+ __cpuc_coherent_user_range((start)& PAGE_MASK, PAGE_ALIGN(end))
+
+/*
+ * Perform necessary cache operations to ensure that data previously
+ * stored within this range of addresses can be executed by the CPU.
+ */
+#define flush_icache_range(s,e) __cpuc_coherent_kern_range(s,e)
+
+/*
+ * flush_dcache_page is used when the kernel has written to the page
+ * cache page at virtual address page->virtual.
+ *
+ * If this page isn't mapped (ie, page_mapping == NULL), or it might
+ * have userspace mappings, then we _must_ always clean + invalidate
+ * the dcache entries associated with the kernel mapping.
+ *
+ * Otherwise we can defer the operation, and clean the cache when we are
+ * about to change to user space. This is the same method as used on SPARC64.
+ * See update_mmu_cache for the user space part.
+ */
+#define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1
+extern void flush_dcache_page(struct page *);
+
+static inline void __flush_icache_all(void)
+{
+ asm("ic ialluis");
+}
+
+#define ARCH_HAS_FLUSH_ANON_PAGE
+static inline void flush_anon_page(struct vm_area_struct *vma,
+ struct page *page, unsigned long vmaddr)
+{
+ extern void __flush_anon_page(struct vm_area_struct *vma,
+ struct page *, unsigned long);
+ if (PageAnon(page))
+ __flush_anon_page(vma, page, vmaddr);
+}
+
+#define flush_dcache_mmap_lock(mapping) \
+ spin_lock_irq(&(mapping)->tree_lock)
+#define flush_dcache_mmap_unlock(mapping) \
+ spin_unlock_irq(&(mapping)->tree_lock)
+
+#define flush_icache_user_range(vma,page,addr,len) \
+ flush_dcache_page(page)
+
+/*
+ * We don't appear to need to do anything here. In fact, if we did, we'd
+ * duplicate cache flushing elsewhere performed by flush_dcache_page().
+ */
+#define flush_icache_page(vma,page) do { } while (0)
+
+/*
+ * flush_cache_vmap() is used when creating mappings (eg, via vmap,
+ * vmalloc, ioremap etc) in kernel space for pages. On non-VIPT
+ * caches, since the direct-mappings of these pages may contain cached
+ * data, we need to do a full cache flush to ensure that writebacks
+ * don't corrupt data placed into these pages via the new mappings.
+ */
+static inline void flush_cache_vmap(unsigned long start, unsigned long end)
+{
+ /*
+ * set_pte_at() called from vmap_pte_range() does not
+ * have a DSB after cleaning the cache line.
+ */
+ dsb();
+}
+
+static inline void flush_cache_vunmap(unsigned long start, unsigned long end)
+{
+}
+
+#endif
diff --git a/arch/arm64/include/asm/cachetype.h b/arch/arm64/include/asm/cachetype.h
new file mode 100644
index 0000000..85f5f51
--- /dev/null
+++ b/arch/arm64/include/asm/cachetype.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2012 ARM 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see<http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_CACHETYPE_H
+#define __ASM_CACHETYPE_H
+
+#include<asm/cputype.h>
+
+#define CTR_L1IP_SHIFT 14
+#define CTR_L1IP_MASK 3
+
+#define ICACHE_POLICY_RESERVED 0
+#define ICACHE_POLICY_AIVIVT 1
+#define ICACHE_POLICY_VIPT 2
+#define ICACHE_POLICY_PIPT 3
+
+static inline u32 icache_policy(void)
+{
+ return (read_cpuid_cachetype()>> CTR_L1IP_SHIFT)& CTR_L1IP_MASK;
+}
+
+/*
+ * Whilst the D-side always behaves as PIPT on AArch64, aliasing is
+ * permitted in the I-cache.
+ */
+static inline int icache_is_aliasing(void)
+{
+ return icache_policy() != ICACHE_POLICY_PIPT;
+}
+
+static inline int icache_is_aivivt(void)
+{
+ return icache_policy() == ICACHE_POLICY_AIVIVT;
+}
+
+#endif /* __ASM_CACHETYPE_H */
diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
new file mode 100644
index 0000000..f4efa04
--- /dev/null
+++ b/arch/arm64/mm/cache.S
@@ -0,0 +1,279 @@
+/*
+ * Cache maintenance
+ *
+ * Copyright (C) 2001 Deep Blue Solutions Ltd.
+ * Copyright (C) 2012 ARM 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see<http://www.gnu.org/licenses/>.
+ */
+
+#include<linux/linkage.h>
+#include<linux/init.h>
+#include<asm/assembler.h>
+
+#include "proc-macros.S"
+
+/*
+ * __cpuc_flush_dcache_all()
+ *
+ * Flush the whole D-cache.
+ *
+ * Corrupted registers: x0-x7, x9-x11
+ */
+ENTRY(__cpuc_flush_dcache_all)
+ dsb sy // ensure ordering with previous memory accesses
+ mrs x0, clidr_el1 // read clidr
+ and x3, x0, #0x7000000 // extract loc from clidr
+ lsr x3, x3, #23 // left align loc bit field
+ cbz x3, finished // if loc is 0, then no need to clean
+ mov x10, #0 // start clean at cache level 0
+loop1:
+ add x2, x10, x10, lsr #1 // work out 3x current cache level
+ lsr x1, x0, x2 // extract cache type bits from clidr
+ and x1, x1, #7 // mask of the bits for current cache only
+ cmp x1, #2 // see what cache we have at this level
+ b.lt skip // skip if no cache, or just i-cache
+ save_and_disable_irqs x9 // make CSSELR and CCSIDR access atomic
+ msr csselr_el1, x10 // select current cache level in csselr
+ isb // isb to sych the new cssr&csidr
+ mrs x1, ccsidr_el1 // read the new ccsidr
+ restore_irqs x9
+ and x2, x1, #7 // extract the length of the cache lines
+ add x2, x2, #4 // add 4 (line length offset)
+ mov x4, #0x3ff
+ and x4, x4, x1, lsr #3 // find maximum number on the way size
+ clz x5, x4 // find bit position of way size increment
+ mov x7, #0x7fff
+ and x7, x7, x1, lsr #13 // extract max number of the index size
+loop2:
+ mov x9, x4 // create working copy of max way size
+loop3:
+ lsl x6, x9, x5
+ orr x11, x10, x6 // factor way and cache number into x11
+ lsl x6, x7, x2
+ orr x11, x11, x6 // factor index number into x11
+ dc cisw, x11 // clean& invalidate by set/way
+ subs x9, x9, #1 // decrement the way
+ b.ge loop3
+ subs x7, x7, #1 // decrement the index
+ b.ge loop2
+skip:
+ add x10, x10, #2 // increment cache number
+ cmp x3, x10
+ b.gt loop1
+finished:
+ mov x10, #0 // swith back to cache level 0
+ msr csselr_el1, x10 // select current cache level in csselr
+ dsb sy
+ isb
+ ret
+ENDPROC(__cpuc_flush_dcache_all)
+
We have discussed the need of cache maintenance by
level kind of API for ARMv7 (A15).
Shouldn't we add such API for arm64 as well ?
Regards
Santosh
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