[parisc-linux] Re: [parisc-linux-cvs] linux-2.6 jejb
James Bottomley
James.Bottomley at steeleye.com
Sun Apr 4 20:49:15 MDT 2004
On Sun, 2004-04-04 at 22:47, James Bottomley wrote:
> CVSROOT: /var/cvs
> Module name: linux-2.6
> Changes by: jejb 04/04/04 20:47:40
>
> Modified files:
> . : Makefile
> arch/parisc/kernel: cache.c pacache.S
> include/asm-parisc: cache.h cacheflush.h
>
> Log message:
> Fix non current user process flushing.
>
> We have two problems:
>
> - There's a bug in __flush_dcache_page() that causes it to do nothing
> if the current process doesn't contain the page. This is incorrect
> since it will leave the congruent user pages incoherent with the
> kernel page.
>
> - flush_cache_page() flushes everything if the mm of the
> requested vma isn't current (this is correct, but cumbersome and is
> what gives us the abysmally slow ptrace performance).
>
> We can fix both of these by introducing a new API:
>
> flush_user_cache_page_non_current()
>
> Specifically designed to flush a page in a non-current process.
===== arch/parisc/kernel/cache.c 1.7 vs edited =====
--- 1.7/arch/parisc/kernel/cache.c Wed Dec 17 23:48:38 2003
+++ edited/arch/parisc/kernel/cache.c Sat Apr 3 20:24:33 2004
@@ -71,9 +71,9 @@
if (VALID_PAGE(page) && page->mapping &&
test_bit(PG_dcache_dirty, &page->flags)) {
- flush_kernel_dcache_page(page_address(page));
clear_bit(PG_dcache_dirty, &page->flags);
}
+ flush_kernel_dcache_page(page_address(page));
}
void
@@ -293,6 +293,185 @@
}
}
EXPORT_SYMBOL(__flush_dcache_page);
+
+/* set to max pages to flush before a full flush. Zero means no limit */
+#define MAX_FLUSH_PAGES 0
+#undef DEBUG_PAGE_FLUSHING
+
+#ifdef DEBUG_PAGE_FLUSHING
+#define DBG(a...) printk(a)
+#else
+#define DBG(...)
+#endif
+
+#if (MAX_FLUSH_PAGES != 0)
+
+/* we get to use the bottom 12 bits of the addr for flags since the
+ * address must be page aligned */
+#define ICACHE_FLUSH_FLAG 0x1
+
+void flush_cache_mm(struct mm_struct *mm)
+{
+ struct vm_area_struct *vma;
+ unsigned long count = 0, actual_count = 0;
+ unsigned long sr3 = mfsp(3), cr25 = mfctl(25);
+ unsigned long *pages;
+
+ preempt_disable();
+ if(mm != current->active_mm) {
+ DBG("flush_tlb_mm: current MM is not active ");
+ /* FIXME: awful hack: move the process the mm belongs
+ * to temporarily to being the active one. This only
+ * works because we can never get back into user
+ * context from here. */
+ mtctl(__pa(mm->pgd), 25);
+ mtsp(mm->context, 3);
+ }
+
+ pages = kmalloc(MAX_FLUSH_PAGES * sizeof(unsigned long), GFP_ATOMIC);
+ if(!pages) {
+ printk(KERN_ERR "flush_tlb_mm: allocation failed: full flush\n");
+ goto full_flush;
+ }
+
+ for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
+ unsigned long start;
+
+ pmd_t *pmd;
+ pgd_t *pgd;
+ pte_t *pte;
+
+ count += (vma->vm_end - vma->vm_start)/PAGE_SIZE;
+
+ for (start = vma->vm_start; start < vma->vm_end;
+ start += PAGE_SIZE) {
+ pgd = pgd_offset(mm, start);
+
+ if (pgd_none(*pgd)) {
+ start = (start & PGDIR_MASK) + PGDIR_SIZE - PAGE_SIZE;
+ continue;
+ }
+
+ pmd = pmd_offset(pgd, start);
+ if (pmd_none(*pmd)) {
+ start = (start & PMD_MASK) + PMD_SIZE - PAGE_SIZE;
+ continue;
+ }
+ pte = pte_offset_map(pmd, start);
+ if(pte_val(*pte)==0 || !pte_present(*pte))
+ continue;
+
+ /* FIXME: Here we could also skip over any
+ * shared mapping page (i.e. equivalently
+ * aliased) with at least one other user */
+
+ pages[actual_count] = start;
+
+ if (vma->vm_flags && VM_EXEC)
+ pages[actual_count] |= ICACHE_FLUSH_FLAG;
+ if(++actual_count >= MAX_FLUSH_PAGES)
+ goto full_flush_free;
+
+ }
+ }
+
+ DBG("FLUSHED %lu (actual %lu)\n", count, actual_count);
+ for(count = 0; count < actual_count; count++) {
+ unsigned long addr = pages[count] & PAGE_MASK;
+ flush_user_dcache_page(addr);
+ if(pages[count] & ICACHE_FLUSH_FLAG)
+ flush_user_icache_page(addr);
+ }
+ out_free:
+ kfree(pages);
+ out:
+ mtsp(sr3, 3);
+ mtctl(cr25, 25);
+ preempt_enable();
+ return;
+
+ full_flush_free:
+ DBG("flush_cache_mm: over max pages %ld (count %ld), flushing everything\n", actual_count, count);
+ flush_cache_all();
+ goto out_free;
+
+ full_flush:
+ flush_cache_all();
+ goto out;
+}
+
+#else
+
+void flush_cache_mm(struct mm_struct *mm)
+{
+ struct vm_area_struct *vma;
+ unsigned long count = 0, actual_count = 0;
+ unsigned long sr3 = mfsp(3), cr25 = mfctl(25);
+ static int flushed = 0;
+
+ if(unlikely(!flushed)) {
+ printk("flush_cache_mm: INIT FLUSH ALL\n");
+ flushed = 1;
+ flush_cache_all();
+ return;
+ }
+
+ preempt_disable();
+ if(mm != current->active_mm) {
+ DBG("flush_tlb_mm: current MM is not active ");
+ /* FIXME: awful hack: move the process the mm belongs
+ * to temporarily to being the active one. This only
+ * works because we can never get back into user
+ * context from here. */
+ mtctl(__pa(mm->pgd), 25);
+ mtsp(mm->context, 3);
+ }
+
+ for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
+ unsigned long start;
+
+ pmd_t *pmd;
+ pgd_t *pgd;
+ pte_t *pte;
+
+ count += (vma->vm_end - vma->vm_start)/PAGE_SIZE;
+
+ for (start = vma->vm_start; start < vma->vm_end;
+ start += PAGE_SIZE) {
+ pgd = pgd_offset(mm, start);
+
+ if (pgd_none(*pgd)) {
+ start = (start & PGDIR_MASK) + PGDIR_SIZE - PAGE_SIZE;
+ continue;
+ }
+
+ pmd = pmd_offset(pgd, start);
+ if (pmd_none(*pmd)) {
+ start = (start & PMD_MASK) + PMD_SIZE - PAGE_SIZE;
+ continue;
+ }
+ pte = pte_offset_map(pmd, start);
+ if(pte_val(*pte)==0 || !pte_present(*pte))
+ continue;
+
+ /* FIXME: Here we could also skip over any
+ * shared mapping page (i.e. equivalently
+ * aliased) with at least one other user */
+
+ flush_user_dcache_page(start);
+ if (vma->vm_flags && VM_EXEC)
+ flush_user_icache_page(start);
+ actual_count++;
+ }
+ }
+ mtsp(sr3, 3);
+ mtctl(cr25, 25);
+ preempt_enable();
+ DBG("FLUSHED %lu (actual %lu)\n", count, actual_count);
+}
+#endif
+
+EXPORT_SYMBOL(flush_cache_mm);
/* Defined in arch/parisc/kernel/pacache.S */
EXPORT_SYMBOL(flush_kernel_dcache_range_asm);
===== arch/parisc/kernel/pacache.S 1.4 vs edited =====
--- 1.4/arch/parisc/kernel/pacache.S Thu Mar 11 03:05:50 2004
+++ edited/arch/parisc/kernel/pacache.S Sat Apr 3 08:52:19 2004
@@ -574,6 +574,95 @@
.exit
.procend
+
+ .export flush_user_dcache_page
+
+flush_user_dcache_page:
+ .proc
+ .callinfo NO_CALLS
+ .entry
+
+ ldil L%dcache_stride,%r1
+ ldw R%dcache_stride(%r1),%r23
+
+#ifdef __LP64__
+ depdi,z 1,63-PAGE_SHIFT,1,%r25
+#else
+ depwi,z 1,31-PAGE_SHIFT,1,%r25
+#endif
+ add %r26,%r25,%r25
+ sub %r25,%r23,%r25
+
+
+1: fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ fdc,m %r23(%sr3,%r26)
+ CMPB<< %r26,%r25,1b
+ fdc,m %r23(%sr3,%r26)
+
+ sync
+ bv %r0(%r2)
+ nop
+ .exit
+
+ .procend
+
+ .export flush_user_icache_page
+
+flush_user_icache_page:
+ .proc
+ .callinfo NO_CALLS
+ .entry
+
+ ldil L%dcache_stride,%r1
+ ldw R%dcache_stride(%r1),%r23
+
+#ifdef __LP64__
+ depdi,z 1,63-PAGE_SHIFT,1,%r25
+#else
+ depwi,z 1,31-PAGE_SHIFT,1,%r25
+#endif
+ add %r26,%r25,%r25
+ sub %r25,%r23,%r25
+
+
+1: fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ fic,m %r23(%sr3,%r26)
+ CMPB<< %r26,%r25,1b
+ fic,m %r23(%sr3,%r26)
+
+ sync
+ bv %r0(%r2)
+ nop
+ .exit
+
+ .procend
+
.export purge_kernel_dcache_page
===== include/asm-parisc/cacheflush.h 1.6 vs edited =====
--- 1.6/include/asm-parisc/cacheflush.h Thu Oct 2 02:11:59 2003
+++ edited/include/asm-parisc/cacheflush.h Sat Apr 3 12:20:20 2004
@@ -12,7 +12,7 @@
#ifdef CONFIG_SMP
#define flush_cache_mm(mm) flush_cache_all()
#else
-#define flush_cache_mm(mm) flush_cache_all_local()
+extern void flush_cache_mm(struct mm_struct *);
#endif
#define flush_kernel_dcache_range(start,size) \
===== include/asm-parisc/page.h 1.5 vs edited =====
--- 1.5/include/asm-parisc/page.h Sat Sep 27 16:43:45 2003
+++ edited/include/asm-parisc/page.h Sat Apr 3 19:47:09 2004
@@ -20,6 +20,8 @@
extern void purge_kernel_dcache_page(unsigned long);
extern void copy_user_page_asm(void *to, void *from);
extern void clear_user_page_asm(void *page, unsigned long vaddr);
+extern void flush_user_dcache_page(unsigned long);
+extern void flush_user_icache_page(unsigned long);
static inline void
copy_user_page(void *vto, void *vfrom, unsigned long vaddr, struct page *pg)
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