From af0ebc40a81c694ad25f034383c13a233c4a2f55 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 7 Oct 2013 16:15:29 +0200 Subject: s390/mm,kvm: fix software dirty bits vs. kvm for old machines For machines without enhanced supression on protection the software dirty bit code forces the pte dirty bit and clears the page protection bit in pgste_set_pte. This is done for all pte types, the check for present ptes is missing. As a result swap ptes and other not-present ptes can get corrupted. Add a check for the _PAGE_PRESENT bit to pgste_set_pte before modifying the pte value. Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/pgtable.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/s390/include') diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 9b60a36c348d..2204400d0bd5 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -748,7 +748,9 @@ static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry) static inline void pgste_set_pte(pte_t *ptep, pte_t entry) { - if (!MACHINE_HAS_ESOP && (pte_val(entry) & _PAGE_WRITE)) { + if (!MACHINE_HAS_ESOP && + (pte_val(entry) & _PAGE_PRESENT) && + (pte_val(entry) & _PAGE_WRITE)) { /* * Without enhanced suppression-on-protection force * the dirty bit on for all writable ptes. -- cgit v1.2.3 From 8c071b0f19dfa230335d22ce56a8fab5bd20cedc Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 17 Oct 2013 12:38:17 +0200 Subject: s390/time: correct use of store clock fast The result of the store-clock-fast (STCKF) instruction is a bit fuzzy. It can happen that the value stored on one CPU is smaller than the value stored on another CPU, although the order of the stores is the other way around. This can cause deltas of get_tod_clock() values to become negative when they should not be. We need to be more careful with store-clock-fast, this patch partially reverts git commit e4b7b4238e666682555461fa52eecd74652f36bb "time: always use stckf instead of stck if available". The get_tod_clock() function now uses the store-clock-extended (STCKE) instruction. get_tod_clock_fast() can be used if the fuzziness of store-clock-fast is acceptable e.g. for wait loops local to a CPU. Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/timex.h | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) (limited to 'arch/s390/include') diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h index 8ad8af915032..819b94d22720 100644 --- a/arch/s390/include/asm/timex.h +++ b/arch/s390/include/asm/timex.h @@ -71,30 +71,30 @@ static inline void local_tick_enable(unsigned long long comp) typedef unsigned long long cycles_t; -static inline unsigned long long get_tod_clock(void) -{ - unsigned long long clk; - -#ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES - asm volatile(".insn s,0xb27c0000,%0" : "=Q" (clk) : : "cc"); -#else - asm volatile("stck %0" : "=Q" (clk) : : "cc"); -#endif - return clk; -} - static inline void get_tod_clock_ext(char *clk) { asm volatile("stcke %0" : "=Q" (*clk) : : "cc"); } -static inline unsigned long long get_tod_clock_xt(void) +static inline unsigned long long get_tod_clock(void) { unsigned char clk[16]; get_tod_clock_ext(clk); return *((unsigned long long *)&clk[1]); } +static inline unsigned long long get_tod_clock_fast(void) +{ +#ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES + unsigned long long clk; + + asm volatile("stckf %0" : "=Q" (clk) : : "cc"); + return clk; +#else + return get_tod_clock(); +#endif +} + static inline cycles_t get_cycles(void) { return (cycles_t) get_tod_clock() >> 2; @@ -125,7 +125,7 @@ extern u64 sched_clock_base_cc; */ static inline unsigned long long get_tod_clock_monotonic(void) { - return get_tod_clock_xt() - sched_clock_base_cc; + return get_tod_clock() - sched_clock_base_cc; } /** -- cgit v1.2.3