From 971a52d66a3e87d4d2f5d3455e62680447cdb8e9 Mon Sep 17 00:00:00 2001 From: Ingo Molnar <mingo@elte.hu> Date: Wed, 6 Feb 2008 22:39:45 +0100 Subject: x86: delay CPA self-test and repeat it delay the CPA self-test so that any impact (corruption) of user-space pagetables can be triggered. Repeat the test every 30 seconds. this would have prevented the bug fixed by 8cb2a7c1e95e472b5, at its source. Signed-off-by: Ingo Molnar <mingo@elte.hu> --- arch/x86/Kconfig.debug | 4 +-- arch/x86/mm/pageattr-test.c | 65 +++++++++++++++++++++++++++++++++++---------- 2 files changed, 53 insertions(+), 16 deletions(-) diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index 2e1e3af28c3a..fa555148823d 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -220,9 +220,9 @@ config DEBUG_BOOT_PARAMS This option will cause struct boot_params to be exported via debugfs. config CPA_DEBUG - bool "CPA self test code" + bool "CPA self-test code" depends on DEBUG_KERNEL help - Do change_page_attr self tests at boot. + Do change_page_attr() self-tests every 30 seconds. endmenu diff --git a/arch/x86/mm/pageattr-test.c b/arch/x86/mm/pageattr-test.c index 398f3a578dde..ed8201600354 100644 --- a/arch/x86/mm/pageattr-test.c +++ b/arch/x86/mm/pageattr-test.c @@ -5,6 +5,7 @@ * and compares page tables forwards and afterwards. */ #include <linux/bootmem.h> +#include <linux/kthread.h> #include <linux/random.h> #include <linux/kernel.h> #include <linux/init.h> @@ -14,8 +15,13 @@ #include <asm/pgtable.h> #include <asm/kdebug.h> +/* + * Only print the results of the first pass: + */ +static __read_mostly int print = 1; + enum { - NTEST = 4000, + NTEST = 400, #ifdef CONFIG_X86_64 LPS = (1 << PMD_SHIFT), #elif defined(CONFIG_X86_PAE) @@ -31,7 +37,7 @@ struct split_state { long min_exec, max_exec; }; -static __init int print_split(struct split_state *s) +static int print_split(struct split_state *s) { long i, expected, missed = 0; int printed = 0; @@ -82,10 +88,13 @@ static __init int print_split(struct split_state *s) s->max_exec = addr; } } - printk(KERN_INFO - "CPA mapping 4k %lu large %lu gb %lu x %lu[%lx-%lx] miss %lu\n", - s->spg, s->lpg, s->gpg, s->exec, - s->min_exec != ~0UL ? s->min_exec : 0, s->max_exec, missed); + if (print) { + printk(KERN_INFO + " 4k %lu large %lu gb %lu x %lu[%lx-%lx] miss %lu\n", + s->spg, s->lpg, s->gpg, s->exec, + s->min_exec != ~0UL ? s->min_exec : 0, + s->max_exec, missed); + } expected = (s->gpg*GPS + s->lpg*LPS)/PAGE_SIZE + s->spg + missed; if (expected != i) { @@ -96,11 +105,11 @@ static __init int print_split(struct split_state *s) return err; } -static unsigned long __initdata addr[NTEST]; -static unsigned int __initdata len[NTEST]; +static unsigned long addr[NTEST]; +static unsigned int len[NTEST]; /* Change the global bit on random pages in the direct mapping */ -static __init int exercise_pageattr(void) +static int pageattr_test(void) { struct split_state sa, sb, sc; unsigned long *bm; @@ -110,7 +119,8 @@ static __init int exercise_pageattr(void) int i, k; int err; - printk(KERN_INFO "CPA exercising pageattr\n"); + if (print) + printk(KERN_INFO "CPA self-test:\n"); bm = vmalloc((max_pfn_mapped + 7) / 8); if (!bm) { @@ -186,7 +196,6 @@ static __init int exercise_pageattr(void) failed += print_split(&sb); - printk(KERN_INFO "CPA reverting everything\n"); for (i = 0; i < NTEST; i++) { if (!addr[i]) continue; @@ -214,12 +223,40 @@ static __init int exercise_pageattr(void) failed += print_split(&sc); if (failed) { - printk(KERN_ERR "CPA selftests NOT PASSED. Please report.\n"); + printk(KERN_ERR "NOT PASSED. Please report.\n"); WARN_ON(1); + return -EINVAL; } else { - printk(KERN_INFO "CPA selftests PASSED\n"); + if (print) + printk(KERN_INFO "ok.\n"); } return 0; } -module_init(exercise_pageattr); + +static int do_pageattr_test(void *__unused) +{ + while (!kthread_should_stop()) { + schedule_timeout_interruptible(HZ*30); + if (pageattr_test() < 0) + break; + if (print) + print--; + } + return 0; +} + +static int start_pageattr_test(void) +{ + struct task_struct *p; + + p = kthread_create(do_pageattr_test, NULL, "pageattr-test"); + if (!IS_ERR(p)) + wake_up_process(p); + else + WARN_ON(1); + + return 0; +} + +module_init(start_pageattr_test); -- cgit v1.2.3