[PATCH CPA] [9/28] CPA: Add simple self test at boot

[Andi Kleen <ak@suse.de>]

Since change_page_attr() is tricky code it is good to have some regression
test code. This patch maps and unmaps some random pages in the direct mapping
at boot and then dumps the state.

One disadvantage is that the results currently have to be checked
manually, it would be better if it had a global passed/failed message.

Add it with a CONFIG option.

Optional patch, but I find it useful.

Signed-off-by: Andi Kleen <ak@suse.de>

---
 arch/x86/mm/Makefile_32     |    1 
 arch/x86/mm/Makefile_64     |    1 
 arch/x86/mm/pageattr-test.c |  187 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 189 insertions(+)

Index: linux/arch/x86/mm/Makefile_64
===================================================================
--- linux.orig/arch/x86/mm/Makefile_64
+++ linux/arch/x86/mm/Makefile_64
@@ -7,3 +7,4 @@ obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpag
 obj-$(CONFIG_NUMA) += numa_64.o
 obj-$(CONFIG_K8_NUMA) += k8topology_64.o
 obj-$(CONFIG_ACPI_NUMA) += srat_64.o
+obj-$(CONFIG_CPA_DEBUG) += pageattr-test.o
Index: linux/arch/x86/mm/pageattr-test.c
===================================================================
--- /dev/null
+++ linux/arch/x86/mm/pageattr-test.c
@@ -0,0 +1,187 @@
+/*
+ * self test for change_page_attr.
+ *
+ * Clears the global bit on random pages in the direct mapping, then reverts and
+ * compares page tables forwards and afterwards.
+ */
+
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <asm/cacheflush.h>
+#include <asm/pgtable.h>
+#include <asm/kdebug.h>
+
+enum {
+	NTEST = 25,
+#ifdef CONFIG_X86_64
+	LOWEST_LEVEL = 4,
+	LPS = (1 << PMD_SHIFT),
+#elif defined(CONFIG_X86_PAE)
+	LOWEST_LEVEL = 3,
+	LPS = (1 << PMD_SHIFT),
+#else
+	LOWEST_LEVEL = 3, /* lookup_address lies here */
+	LPS = (1 << 22),
+#endif
+	GPS = (1<<30)
+};
+
+#ifdef CONFIG_X86_64
+#include <asm/proto.h>
+#define max_mapped end_pfn_map
+#else
+#define max_mapped max_low_pfn
+#endif
+
+struct split_state {
+	long lpg, gpg, spg, nx;
+};
+
+static __init int print_split(struct split_state *s)
+{
+	int printed = 0;
+	long i, expected, missed = 0;
+	s->lpg = s->gpg = s->spg = s->nx = 0;
+	for (i = 0; i < max_mapped; ) {
+		int level;
+		pte_t *pte;
+		unsigned long adr = (unsigned long)__va(i << PAGE_SHIFT);
+
+		pte = lookup_address(adr, &level);
+		if (!pte) {
+			if (!printed) {
+				dump_pagetable(adr);
+				printk("CPA %lx no pte level %d\n", adr, level);
+				printed = 1;
+			}
+			missed++;
+			i++;
+			continue;
+		}
+
+		if (level == 2 && sizeof(long) == 8) {
+			s->gpg++;
+			i += GPS/PAGE_SIZE;
+		} else if (level != LOWEST_LEVEL) {
+			s->lpg++;
+			i += LPS/PAGE_SIZE;
+		} else {
+			s->spg++;
+			i++;
+		}
+		if (pte_val(*pte) & _PAGE_NX)
+			s->nx++;
+	}
+	printk("CPA direct mapping small %lu large %lu giga %lu nx %lu missed %lu\n",
+		s->spg, s->lpg, s->gpg, s->nx, missed);
+	expected = (s->gpg*GPS + s->lpg*LPS)/PAGE_SIZE + s->spg + missed;
+	if (expected != max_mapped) {
+		printk("CPA max_mapped %lu but expected %lu\n",
+			max_mapped, expected);
+		return 1;
+	}
+	return 0;
+}
+
+static __init int state_same(struct split_state *a, struct split_state *b)
+{
+	return a->lpg == b->lpg && a->gpg == b->gpg && a->spg == b->spg &&
+			a->nx == b->nx;
+}
+
+static unsigned long addr[NTEST] __initdata;
+static unsigned len[NTEST] __initdata;
+
+/* Change the global bit on random pages in the direct mapping */
+static __init int exercise_pageattr(void)
+{
+	int i;
+	pte_t *pte;
+	int level;
+	int err;
+	struct split_state sa, sb, sc;
+	int failed = 0;
+
+	printk("CPA exercising pageattr\n");
+	failed += print_split(&sa);
+	srandom32(100);
+	for (i = 0; i < NTEST; i++) {
+		unsigned long pfn = random32() % max_mapped;
+		addr[i] = (unsigned long)__va(pfn << PAGE_SHIFT);
+		len[i] = min_t(unsigned long, random32() % 100, max_mapped - pfn);
+		pte = lookup_address(addr[i], &level);
+		if (!pte) {
+			printk("lookup of %lx failed\n", addr[i]);
+			failed++;
+			continue;
+		}
+		if (pgprot_val(pte_pgprot(*pte)) == 0) {
+			addr[i] = 0;
+			continue;
+		}
+
+		err = change_page_attr(virt_to_page(addr[i]), len[i],
+			    pte_pgprot(pte_clrhuge(pte_clrglobal(*pte))));
+		if (err < 0) {
+			printk("cpa %d failed %d\n", i, err);
+			failed++;
+		}
+
+		pte = lookup_address(addr[i], &level);
+		if (!pte || pte_global(*pte) || pte_huge(*pte)) {
+			printk("%lx: bad pte %Lx\n", addr[i],
+				pte ? (u64)pte_val(*pte) : 0ULL);
+			failed++;
+		}
+		if (level != LOWEST_LEVEL) {
+			printk("%lx: unexpected level %d\n", addr[i], level);
+			failed++;
+		}
+
+	}
+	global_flush_tlb();
+
+	failed += print_split(&sb);
+
+	printk("CPA reverting everything\n");
+	for (i = 0; i < NTEST; i++) {
+		if (!addr[i])
+			continue;
+		pte = lookup_address(addr[i], &level);
+		if (!pte) {
+			printk("lookup of %lx failed\n", addr[i]);
+			failed++;
+			continue;
+		}
+		err = change_page_attr(virt_to_page(addr[i]), len[i],
+					  pte_pgprot(pte_mkglobal(*pte)));
+		if (err < 0) {
+			printk("cpa2 failed: %d\n", err);
+			failed++;
+		}
+		pte = lookup_address(addr[i], &level);
+		if (!pte || !pte_global(*pte)) {
+			printk("%lx: bad pte %Lx\n", addr[i],
+			       pte ? (u64)pte_val(*pte) : 0ULL);
+			failed++;
+		}
+
+	}
+	global_flush_tlb();
+
+	failed += print_split(&sc);
+	if (!state_same(&sa, &sc))
+		failed++;
+
+	if (failed)
+		printk("CPA selftests NOT PASSED. Please report.\n");
+	else
+		printk("CPA selftests PASSED\n");
+
+	return 0;
+}
+
+module_init(exercise_pageattr);
Index: linux/arch/x86/mm/Makefile_32
===================================================================
--- linux.orig/arch/x86/mm/Makefile_32
+++ linux/arch/x86/mm/Makefile_32
@@ -8,3 +8,4 @@ obj-$(CONFIG_NUMA) += discontig_32.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
 obj-$(CONFIG_HIGHMEM) += highmem_32.o
 obj-$(CONFIG_BOOT_IOREMAP) += boot_ioremap_32.o
+obj-$(CONFIG_CPA_DEBUG) += pageattr-test.o