From 402b08622d9ac6e32e25289573272e0f21bb58a7 Mon Sep 17 00:00:00 2001 From: Carsten Otte Date: Tue, 25 Mar 2008 18:47:10 +0100 Subject: s390: KVM preparation: provide hook to enable pgstes in user pagetable The SIE instruction on s390 uses the 2nd half of the page table page to virtualize the storage keys of a guest. This patch offers the s390_enable_sie function, which reorganizes the page tables of a single-threaded process to reserve space in the page table: s390_enable_sie makes sure that the process is single threaded and then uses dup_mm to create a new mm with reorganized page tables. The old mm is freed and the process has now a page status extended field after every page table. Code that wants to exploit pgstes should SELECT CONFIG_PGSTE. This patch has a small common code hit, namely making dup_mm non-static. Edit (Carsten): I've modified Martin's patch, following Jeremy Fitzhardinge's review feedback. Now we do have the prototype for dup_mm in include/linux/sched.h. Following Martin's suggestion, s390_enable_sie() does now call task_lock() to prevent race against ptrace modification of mm_users. Signed-off-by: Martin Schwidefsky Signed-off-by: Carsten Otte Acked-by: Andrew Morton Signed-off-by: Avi Kivity --- arch/s390/kernel/setup.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/s390/kernel') diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c index 7141147e6b63..2f35133ebc18 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -316,7 +316,11 @@ static int __init early_parse_ipldelay(char *p) early_param("ipldelay", early_parse_ipldelay); #ifdef CONFIG_S390_SWITCH_AMODE +#ifdef CONFIG_PGSTE +unsigned int switch_amode = 1; +#else unsigned int switch_amode = 0; +#endif EXPORT_SYMBOL_GPL(switch_amode); static void set_amode_and_uaccess(unsigned long user_amode, -- cgit v1.2.2