From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Tue, 16 Jan 2018 07:03:44 +0100
Subject: s390/alternative: use a copy of the facility bit mask
Git-commit: cf1489984641369611556bf00c48f945c77bcf02
Patch-mainline: v4.16-rc1
References: LTC#164304, bsc#1084911

To be able to switch off specific CPU alternatives with kernel parameters
make a copy of the facility bit mask provided by STFLE and use the copy
for the decision to apply an alternative.

Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Petr Tesarik <ptesarik@suse.com>

---
 arch/s390/include/asm/facility.h | 18 ++++++++++++++++++
 arch/s390/include/asm/lowcore.h  |  3 ++-
 arch/s390/kernel/alternative.c   |  3 ++-
 arch/s390/kernel/early.c         |  3 +++
 arch/s390/kernel/setup.c         |  4 +++-
 arch/s390/kernel/smp.c           |  4 +++-
 6 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h
index fbe0c4be3cd8..99c8ce30b3cd 100644
--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -15,6 +15,24 @@
 
 #define MAX_FACILITY_BIT (sizeof(((struct lowcore *)0)->stfle_fac_list) * 8)
 
+static inline void __set_facility(unsigned long nr, void *facilities)
+{
+	unsigned char *ptr = (unsigned char *) facilities;
+
+	if (nr >= MAX_FACILITY_BIT)
+		return;
+	ptr[nr >> 3] |= 0x80 >> (nr & 7);
+}
+
+static inline void __clear_facility(unsigned long nr, void *facilities)
+{
+	unsigned char *ptr = (unsigned char *) facilities;
+
+	if (nr >= MAX_FACILITY_BIT)
+		return;
+	ptr[nr >> 3] &= ~(0x80 >> (nr & 7));
+}
+
 static inline int __test_facility(unsigned long nr, void *facilities)
 {
 	unsigned char *ptr;
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index ec6592e8ba36..c63986aee942 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -151,7 +151,8 @@ struct lowcore {
 	__u8	pad_0x0e20[0x0f00-0x0e20];	/* 0x0e20 */
 
 	/* Extended facility list */
-	__u64	stfle_fac_list[32];		/* 0x0f00 */
+	__u64	stfle_fac_list[16];		/* 0x0f00 */
+	__u64	alt_stfle_fac_list[16];		/* 0x0f80 */
 	__u8	pad_0x1000[0x11b0-0x1000];	/* 0x1000 */
 
 	/* Pointer to the machine check extended save area */
diff --git a/arch/s390/kernel/alternative.c b/arch/s390/kernel/alternative.c
index 574e77622c04..1abf4f35d059 100644
--- a/arch/s390/kernel/alternative.c
+++ b/arch/s390/kernel/alternative.c
@@ -75,7 +75,8 @@ static void __init_or_module __apply_alternatives(struct alt_instr *start,
 		instr = (u8 *)&a->instr_offset + a->instr_offset;
 		replacement = (u8 *)&a->repl_offset + a->repl_offset;
 
-		if (!test_facility(a->facility))
+		if (!__test_facility(a->facility,
+				     S390_lowcore.alt_stfle_fac_list))
 			continue;
 
 		if (unlikely(a->instrlen % 2 || a->replacementlen % 2)) {
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 497a92047591..510f2183a7e7 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -193,6 +193,9 @@ static noinline __init void setup_facility_list(void)
 {
 	stfle(S390_lowcore.stfle_fac_list,
 	      ARRAY_SIZE(S390_lowcore.stfle_fac_list));
+	memcpy(S390_lowcore.alt_stfle_fac_list,
+	       S390_lowcore.stfle_fac_list,
+	       sizeof(S390_lowcore.alt_stfle_fac_list));
 }
 
 static __init void detect_diag9c(void)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 793da97f9a6e..bcd2a4a3937e 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -340,7 +340,9 @@ static void __init setup_lowcore(void)
 	lc->preempt_count = S390_lowcore.preempt_count;
 	lc->stfl_fac_list = S390_lowcore.stfl_fac_list;
 	memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
-	       MAX_FACILITY_BIT/8);
+	       sizeof(lc->stfle_fac_list));
+	memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
+	       sizeof(lc->alt_stfle_fac_list));
 	if (MACHINE_HAS_VX || MACHINE_HAS_GS) {
 		unsigned long bits, size;
 
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index a919b2f0141d..fc28c9571647 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -266,7 +266,9 @@ static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 	__ctl_store(lc->cregs_save_area, 0, 15);
 	save_access_regs((unsigned int *) lc->access_regs_save_area);
 	memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
-	       MAX_FACILITY_BIT/8);
+	       sizeof(lc->stfle_fac_list));
+	memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
+	       sizeof(lc->alt_stfle_fac_list));
 }
 
 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
-- 
2.13.6