s390/smp: make absolute lowcore / cpu restart parameter accesses more robust

Setting the cpu restart parameters is done in three different fashions:
- directly setting the four parameters individually
- copying the four parameters with memcpy (using 4 * sizeof(long))
- copying the four parameters using a private structure

In addition code in entry*.S relies on a certain order of the restart
members of struct _lowcore.

Make all of this more robust to future changes by adding a
mem_absolute_assign(dest, val) define, which assigns val to dest
using absolute addressing mode. Also the load multiple instructions
in entry*.S have been split into separate load instruction so the
order of the struct _lowcore members doesn't matter anymore.

In addition move the prototypes of memcpy_real/absolute from uaccess.h
to processor.h. These memcpy* variants are not related to uaccess at all.
string.h doesn't seem to match as well, so lets use processor.h.

Also replace the eight byte array in struct _lowcore which represents a
misaliged u64 with a u64. The compiler will always create code that
handles the misaligned u64 correctly.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 489d1d8d96b0..49158cb19274 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -430,10 +430,11 @@ static void __init setup_lowcore(void)
 	lc->restart_source = -1UL;
 
 	/* Setup absolute zero lowcore */
-	memcpy_absolute(&S390_lowcore.restart_stack, &lc->restart_stack,
-			4 * sizeof(unsigned long));
-	memcpy_absolute(&S390_lowcore.restart_psw, &lc->restart_psw,
-			sizeof(lc->restart_psw));
+	mem_assign_absolute(S390_lowcore.restart_stack, lc->restart_stack);
+	mem_assign_absolute(S390_lowcore.restart_fn, lc->restart_fn);
+	mem_assign_absolute(S390_lowcore.restart_data, lc->restart_data);
+	mem_assign_absolute(S390_lowcore.restart_source, lc->restart_source);
+	mem_assign_absolute(S390_lowcore.restart_psw, lc->restart_psw);
 
 	set_prefix((u32)(unsigned long) lc);
 	lowcore_ptr[0] = lc;
@@ -598,9 +599,7 @@ static void __init setup_memory_end(void)
 static void __init setup_vmcoreinfo(void)
 {
 #ifdef CONFIG_KEXEC
-	unsigned long ptr = paddr_vmcoreinfo_note();
-
-	memcpy_absolute(&S390_lowcore.vmcore_info, &ptr, sizeof(ptr));
+	mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note());
 #endif
 }