x86/pmap: remove page table accounting

This kind of strict accounting can lead to a kind of thrashing where one
or more tables can get allocated and released very frequently. For now,
take the naive approach of not freeing page table pages until the complete
tree is torn down.

Remove the now irrelevant x86_pmap_remove_ptp test module.

1 files changed, 0 insertions, 128 deletions

diff --git a/test/test_x86_pmap_remove_ptp.c b/test/test_x86_pmap_remove_ptp.c
deleted file mode 100644
index 88acc96..0000000
--- a/test/test_x86_pmap_remove_ptp.c
+++ /dev/null
@@ -1,128 +0,0 @@
-/*
- * Copyright (c) 2014 Richard Braun.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * 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/>.
- *
- *
- * This test module checks whether the TLB is correctly invalidated when
- * the structure of page table pages change. It is specifically tailored
- * for the x86 pmap module. It starts by allocating a physical page and
- * a region of virtual memory. This region is aligned so that creating
- * a physical mapping at its address involves the allocation of PTPs.
- * It then creates the physical mapping and writes the page, causing the
- * processor to cache page table entries. It then removes the physical
- * mapping. After that, it allocates one dummy physical page. The purpose
- * of this allocation is to force the pmap module to use pages at different
- * physical addresses when allocating new PTPs. Finally, it recreates the
- * same physical mapping as at the beginning, and attempts another write
- * access. If the TLB isn't correctly handled, the second physical mapping
- * creation fails because of stale entries when accessing intermediate PTPs.
- *
- * Note that, because of the complex optimizations around translation caching
- * in modern processors, this test may report false positives. So far, best
- * results are achieved with QEMU (without KVM), which seems to have reliable
- * behaviour.
- */
-
-#include <kern/cpumap.h>
-#include <kern/error.h>
-#include <kern/panic.h>
-#include <kern/param.h>
-#include <kern/printk.h>
-#include <kern/stddef.h>
-#include <kern/string.h>
-#include <kern/thread.h>
-#include <machine/pmap.h>
-#include <test/test.h>
-#include <vm/vm_kmem.h>
-#include <vm/vm_map.h>
-#include <vm/vm_page.h>
-
-static void
-test_run(void *arg)
-{
-    struct vm_page *page, *dummy;
-    unsigned long va;
-    int error, flags;
-
-    (void)arg;
-
-    printk("creating mapping\n");
-    page = vm_page_alloc(0, VM_PAGE_KMEM);
-
-    if (page == NULL)
-        panic("vm_page_alloc: %s", error_str(ERROR_NOMEM));
-
-    va = 0;
-    flags = VM_MAP_FLAGS(VM_PROT_ALL, VM_PROT_ALL, VM_INHERIT_NONE,
-                         VM_ADV_DEFAULT, 0);
-    error = vm_map_enter(kernel_map, &va, (1UL << 22), (1UL << 22), flags,
-                         NULL, 0);
-    error_check(error, "vm_map_enter");
-    pmap_enter(kernel_pmap, va, vm_page_to_pa(page),
-               VM_PROT_READ | VM_PROT_WRITE, PMAP_PEF_GLOBAL);
-    pmap_update(kernel_pmap);
-
-    printk("writing page, va:%p\n", (void *)va);
-    memset((void *)va, 'a', PAGE_SIZE);
-
-    printk("removing mapping\n");
-    pmap_remove(kernel_pmap, va, cpumap_all());
-    pmap_update(kernel_pmap);
-
-    printk("allocating dummy physical page\n");
-    dummy = vm_page_alloc(0, VM_PAGE_KMEM);
-
-    if (dummy == NULL)
-        panic("vm_page_alloc: %s", error_str(ERROR_NOMEM));
-
-    printk("recreating mapping\n");
-    pmap_enter(kernel_pmap, va, vm_page_to_pa(page),
-               VM_PROT_READ | VM_PROT_WRITE, PMAP_PEF_GLOBAL);
-    pmap_update(kernel_pmap);
-
-    printk("rewriting page\n");
-    memset((void *)va, 'a', PAGE_SIZE);
-
-    printk("done\n");
-}
-
-void
-test_setup(void)
-{
-    struct thread_attr attr;
-    struct thread *thread;
-    struct cpumap *cpumap;
-    int error;
-
-    /*
-     * Bind to BSP and run at maximum priority to prevent anything else
-     * from doing a complete TLB flush, meddling with the test.
-     */
-
-    error = cpumap_create(&cpumap);
-    error_check(error, "cpumap_create");
-
-    cpumap_zero(cpumap);
-    cpumap_set(cpumap, 0);
-    thread_attr_init(&attr, "x15_test_run");
-    thread_attr_set_detached(&attr);
-    thread_attr_set_cpumap(&attr, cpumap);
-    thread_attr_set_policy(&attr, THREAD_SCHED_POLICY_FIFO);
-    thread_attr_set_priority(&attr, THREAD_SCHED_RT_PRIO_MAX);
-    error = thread_create(&thread, &attr, test_run, NULL);
-    error_check(error, "thread_create");
-
-    cpumap_destroy(cpumap);
-}