linux-kernel - [PATCH 4.9 33/74] s390/alternative: use a copy of the facility bit mask

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Date:   Fri, 27 Apr 2018 15:58:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>
Subject: [PATCH 4.9 33/74] s390/alternative: use a copy of the facility bit mask

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Schwidefsky <schwidefsky@...ibm.com>


[ Upstream commit cf1489984641369611556bf00c48f945c77bcf02 ]

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@...hat.com>
Reviewed-by: Cornelia Huck <cohuck@...hat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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(-)

--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -17,6 +17,24 @@
 
 #define MAX_FACILITY_BIT (256*8)	/* stfle_fac_list has 256 bytes */
 
+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;
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -150,7 +150,8 @@ 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 vector register save area */
--- a/arch/s390/kernel/alternative.c
+++ b/arch/s390/kernel/alternative.c
@@ -74,7 +74,8 @@ static void __init_or_module __apply_alt
 		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)) {
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -299,6 +299,9 @@ static noinline __init void setup_facili
 {
 	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)
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -336,7 +336,9 @@ static void __init setup_lowcore(void)
 	lc->machine_flags = S390_lowcore.machine_flags;
 	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)
 		lc->vector_save_area_addr =
 			(unsigned long) &lc->vector_save_area;
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -253,7 +253,9 @@ static void pcpu_prepare_secondary(struc
 	__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)