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    Subject[PATCH] flush cache fixes for ia64 [2/2] sync icache dcache
    flush icache for ia64 take4.
    This patch is against 2.6.23-rc1.

    Changes v3 -> v4:
    - avoid implementing flush_(i)cache_pages().
    - added sync_icache_dcache() call.
    - change Documentation/cachetlb.txt

    Current ia64 kernel flushes icache by lazy_mmu_prot_update() *after*
    set_pte(). This is wrong. This patch removes lazy_mmu_prot_update and
    add sync_icache_dcache(). sync_icache_dcache() is called before set_pte()
    if necessary and synchronize icache with dcache (fc.i instruction).

    This patch fixes SIGILL problem on NFS/ia64.

    About Icache-Dcache inconsistency in ia64
    - When the cache line is modified, Icache and Dcache are purged.

    - When I-cache misses, I-cache will access just the lower layer cache(memory).
    Then, If the lower_layer_cache is not up-to-date, I-cache will see
    old information. For avoiding this case, Icache-Dcache synchronization(fc.i)
    is necessary. (Icache-Dcache synchronization means making Dcache and lower
    layer unified cache(memory) consistent.)

    Details:
    - In general, cache flushing macro are used for virtually tagged caches.
    IA64 has physically tagged caches but doesn't guarantee consistency
    between Icache and Dcache. So, new macro, sync_icache_dcache() is added.
    This is NO-OP in other archs.
    - sync_icache_dcache() only works if pte is executable.
    - sync_icache_dcache must be called before set_pte().
    - A page which is consistent is marked as PG_arch_1.

    About changes in generic codes:
    - do_wp_page() ....need to sync newly-installed page.

    - do_anonymous_page() .... newly installed anon pages doesn't contains
    any instruction when set_pte() is executed, icache-dcache synchronization
    is not necessary.

    - __do_fault() .... need to sync newly-installed page.

    - handle_pte_fault() .... just changes access bit...then, no need to sync.

    - remove_migration_pte().... need to sync newly-installed page.


    - change_pte_range() .... need to sync icache-dcache. When a user writes
    instruction into the page and mod fies protection to be
    executable, it should be synced.

    - hugetlb_change_protection() .... Maybe cache will be expired...but
    it is safe to sync Icache before set_pte().

    - page_mkclean_one() .... no need to sync icache-dcache. There is no page
    contents modification. And there is no protection
    change.

    Thanks to Zoltan Menyhart for his advices.

    Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

    ---
    Documentation/cachetlb.txt | 11 +++++++----
    arch/ia64/mm/init.c | 6 ++----
    include/asm-generic/pgtable.h | 8 ++++----
    include/asm-ia64/pgtable.h | 15 ++++++++++-----
    mm/hugetlb.c | 3 +--
    mm/memory.c | 8 +++-----
    mm/migrate.c | 2 +-
    mm/mprotect.c | 2 +-
    mm/rmap.c | 1 -
    9 files changed, 29 insertions(+), 27 deletions(-)

    Index: linux-2.6.23-rc1.test/include/asm-generic/pgtable.h
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/include/asm-generic/pgtable.h
    +++ linux-2.6.23-rc1.test/include/asm-generic/pgtable.h
    @@ -124,14 +124,14 @@ static inline void ptep_set_wrprotect(st
    #define pgd_offset_gate(mm, addr) pgd_offset(mm, addr)
    #endif

    -#ifndef __HAVE_ARCH_LAZY_MMU_PROT_UPDATE
    -#define lazy_mmu_prot_update(pte) do { } while (0)
    -#endif
    -
    #ifndef __HAVE_ARCH_MOVE_PTE
    #define move_pte(pte, prot, old_addr, new_addr) (pte)
    #endif

    +#ifndef __HAVE_ARCH_SYNC_ICACHE_DCACHE
    +#define sync_icache_dcache(pte) do {} while (0)
    +#endif
    +
    /*
    * A facility to provide lazy MMU batching. This allows PTE updates and
    * page invalidations to be delayed until a call to leave lazy MMU mode
    Index: linux-2.6.23-rc1.test/include/asm-ia64/pgtable.h
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/include/asm-ia64/pgtable.h
    +++ linux-2.6.23-rc1.test/include/asm-ia64/pgtable.h
    @@ -484,11 +484,17 @@ extern struct page *zero_page_memmap_ptr
    #endif

    /*
    - * IA-64 doesn't have any external MMU info: the page tables contain all the necessary
    - * information. However, we use this routine to take care of any (delayed) i-cache
    - * flushing that may be necessary.
    + * IA-64 doesn't guarantee Icache is consistent with Dcache. For ensure
    + * Icache consistency, we have to synchronize them before setting pte
    + * as an executable pte.
    */
    -extern void lazy_mmu_prot_update (pte_t pte);
    +extern void __sync_icache_dcache(pte_t pte);
    +static inline void sync_icache_dcache(pte_t pte) {
    + if (pte_exec(pte))
    + __sync_icache_dcache(pte);
    +}
    +#define __HAVE_ARCH_SYNC_ICACHE_DCACHE
    +

    #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
    /*
    @@ -578,7 +584,6 @@ extern void lazy_mmu_prot_update (pte_t
    #define __HAVE_ARCH_PTEP_SET_WRPROTECT
    #define __HAVE_ARCH_PTE_SAME
    #define __HAVE_ARCH_PGD_OFFSET_GATE
    -#define __HAVE_ARCH_LAZY_MMU_PROT_UPDATE

    #ifndef CONFIG_PGTABLE_4
    #include <asm-generic/pgtable-nopud.h>
    Index: linux-2.6.23-rc1.test/Documentation/cachetlb.txt
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/Documentation/cachetlb.txt
    +++ linux-2.6.23-rc1.test/Documentation/cachetlb.txt
    @@ -133,11 +133,14 @@ changes occur:
    The ia64 sn2 platform is one example of a platform
    that uses this interface.

    -8) void lazy_mmu_prot_update(pte_t pte)
    - This interface is called whenever the protection on
    - any user PTEs change. This interface provides a notification
    - to architecture specific code to take appropriate action.
    +8) void sync_icache_dcache(pte_t pte)
    + This interface is used for synchronize icache and dcache.
    + Even if the cache is physically tagged, some archs doesn't
    + guarantee consistency between I-cache and D-cache. In such arch,
    + we need to synchronize I-cache and D-cache before installing
    + executable pages.

    + This is used only for ia64 now.

    Next, we have the cache flushing interfaces. In general, when Linux
    is changing an existing virtual-->physical mapping to a new value,
    Index: linux-2.6.23-rc1.test/mm/memory.c
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/mm/memory.c
    +++ linux-2.6.23-rc1.test/mm/memory.c
    @@ -1697,9 +1697,9 @@ static int do_wp_page(struct mm_struct *
    flush_cache_page(vma, address, pte_pfn(orig_pte));
    entry = pte_mkyoung(orig_pte);
    entry = maybe_mkwrite(pte_mkdirty(entry), vma);
    + sync_icache_dcache(entry);
    if (ptep_set_access_flags(vma, address, page_table, entry,1)) {
    update_mmu_cache(vma, address, entry);
    - lazy_mmu_prot_update(entry);
    }
    ret |= VM_FAULT_WRITE;
    goto unlock;
    @@ -1741,7 +1741,7 @@ gotten:
    flush_cache_page(vma, address, pte_pfn(orig_pte));
    entry = mk_pte(new_page, vma->vm_page_prot);
    entry = maybe_mkwrite(pte_mkdirty(entry), vma);
    - lazy_mmu_prot_update(entry);
    + sync_icache_dcache(entry);
    /*
    * Clear the pte entry and flush it first, before updating the
    * pte with the new entry. This will avoid a race condition
    @@ -2286,7 +2286,6 @@ static int do_anonymous_page(struct mm_s

    /* No need to invalidate - it was non-present before */
    update_mmu_cache(vma, address, entry);
    - lazy_mmu_prot_update(entry);
    unlock:
    pte_unmap_unlock(page_table, ptl);
    return 0;
    @@ -2419,6 +2418,7 @@ static int __do_fault(struct mm_struct *
    if (likely(pte_same(*page_table, orig_pte))) {
    flush_icache_page(vma, page);
    entry = mk_pte(page, vma->vm_page_prot);
    + sync_icache_dcache(entry);
    if (flags & FAULT_FLAG_WRITE)
    entry = maybe_mkwrite(pte_mkdirty(entry), vma);
    set_pte_at(mm, address, page_table, entry);
    @@ -2437,7 +2437,6 @@ static int __do_fault(struct mm_struct *

    /* no need to invalidate: a not-present page won't be cached */
    update_mmu_cache(vma, address, entry);
    - lazy_mmu_prot_update(entry);
    } else {
    if (anon)
    page_cache_release(page);
    @@ -2611,7 +2610,6 @@ static inline int handle_pte_fault(struc
    entry = pte_mkyoung(entry);
    if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
    update_mmu_cache(vma, address, entry);
    - lazy_mmu_prot_update(entry);
    } else {
    /*
    * This is needed only for protection faults but the arch code
    Index: linux-2.6.23-rc1.test/mm/migrate.c
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/mm/migrate.c
    +++ linux-2.6.23-rc1.test/mm/migrate.c
    @@ -173,6 +173,7 @@ static void remove_migration_pte(struct
    if (is_write_migration_entry(entry))
    pte = pte_mkwrite(pte);
    flush_icache_page(vma, new);
    + sync_icache_dcache(pte);
    set_pte_at(mm, addr, ptep, pte);

    if (PageAnon(new))
    @@ -182,7 +183,6 @@ static void remove_migration_pte(struct

    /* No need to invalidate - it was non-present before */
    update_mmu_cache(vma, addr, pte);
    - lazy_mmu_prot_update(pte);

    out:
    pte_unmap_unlock(ptep, ptl);
    Index: linux-2.6.23-rc1.test/mm/hugetlb.c
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/mm/hugetlb.c
    +++ linux-2.6.23-rc1.test/mm/hugetlb.c
    @@ -352,7 +352,6 @@ static void set_huge_ptep_writable(struc
    entry = pte_mkwrite(pte_mkdirty(*ptep));
    if (ptep_set_access_flags(vma, address, ptep, entry, 1)) {
    update_mmu_cache(vma, address, entry);
    - lazy_mmu_prot_update(entry);
    }
    }

    @@ -704,8 +703,8 @@ void hugetlb_change_protection(struct vm
    if (!pte_none(*ptep)) {
    pte = huge_ptep_get_and_clear(mm, address, ptep);
    pte = pte_mkhuge(pte_modify(pte, newprot));
    + sync_icache_dcache(pte);
    set_huge_pte_at(mm, address, ptep, pte);
    - lazy_mmu_prot_update(pte);
    }
    }
    spin_unlock(&mm->page_table_lock);
    Index: linux-2.6.23-rc1.test/arch/ia64/mm/init.c
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/arch/ia64/mm/init.c
    +++ linux-2.6.23-rc1.test/arch/ia64/mm/init.c
    @@ -54,15 +54,13 @@ struct page *zero_page_memmap_ptr; /* ma
    EXPORT_SYMBOL(zero_page_memmap_ptr);

    void
    -lazy_mmu_prot_update (pte_t pte)
    +__sync_icache_dcache (pte_t pte)
    {
    unsigned long addr;
    struct page *page;
    unsigned long order;

    - if (!pte_exec(pte))
    - return; /* not an executable page... */
    -
    + BUG_ON(!pte_exec(pte));
    page = pte_page(pte);
    addr = (unsigned long) page_address(page);

    Index: linux-2.6.23-rc1.test/mm/mprotect.c
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/mm/mprotect.c
    +++ linux-2.6.23-rc1.test/mm/mprotect.c
    @@ -52,8 +52,8 @@ static void change_pte_range(struct mm_s
    */
    if (dirty_accountable && pte_dirty(ptent))
    ptent = pte_mkwrite(ptent);
    + sync_icache_dcache(ptent);
    set_pte_at(mm, addr, pte, ptent);
    - lazy_mmu_prot_update(ptent);
    #ifdef CONFIG_MIGRATION
    } else if (!pte_file(oldpte)) {
    swp_entry_t entry = pte_to_swp_entry(oldpte);
    Index: linux-2.6.23-rc1.test/mm/rmap.c
    ===================================================================
    --- linux-2.6.23-rc1.test.orig/mm/rmap.c
    +++ linux-2.6.23-rc1.test/mm/rmap.c
    @@ -436,7 +436,6 @@ static int page_mkclean_one(struct page
    entry = pte_wrprotect(entry);
    entry = pte_mkclean(entry);
    set_pte_at(mm, address, pte, entry);
    - lazy_mmu_prot_update(entry);
    ret = 1;
    }


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