On 2020-06-10 16:51, Thomas Huth wrote:
On 09/06/2020 17.01, Pierre Morel wrote:
On 2020-06-09 09:09, Thomas Huth wrote:
On 08/06/2020 10.12, Pierre Morel wrote:
Provide some definitions and library routines that can be used by
...snip...
+static inline int ssch(unsigned long schid, struct orb *addr)
+{
+ register long long reg1 asm("1") = schid;
+ int cc;
+
+ asm volatile(
+ " ssch 0(%2)\n"
+ " ipm %0\n"
+ " srl %0,28\n"
+ : "=d" (cc)
+ : "d" (reg1), "a" (addr), "m" (*addr)
Hmm... What's the "m" (*addr) here good for? %3 is not used in the
assembly code?
addr is %2
"m" (*addr) means memory pointed by addr is read
+ : "cc", "memory");
Why "memory" ? Can this instruction also change the orb?
The orb not but this instruction modifies memory as follow:
orb -> ccw -> data
The CCW can be a READ or a WRITE instruction and the data my be anywhere
in memory (<2G)
A compiler memory barrier is need to avoid write instructions started
before the SSCH instruction to occur after for a write
and memory read made after the instruction to be executed before for a
read.
Ok, makes sense now, thanks!
+static inline int msch(unsigned long schid, struct schib *addr)
+{
+ register unsigned long reg1 asm ("1") = schid;
+ int cc;
+
+ asm volatile(
+ " msch 0(%3)\n"
+ " ipm %0\n"
+ " srl %0,28"
+ : "=d" (cc), "=m" (*addr)
+ : "d" (reg1), "a" (addr)
I'm not an expert with these IO instructions, but this looks wrong to me
... Is MSCH reading or writing the SCHIB data?
MSCH is reading the SCHIB data in memory.
So if it is reading, you don't need the "=m" (*addr) in the output
list, do you? You should rather use "m" (*addr) in the input list instead?
Yes, absolutely, it should be the oposite of stsch(), not the same!
I change it to:
asm volatile(
" msch 0(%3)\n"
" ipm %0\n"
" srl %0,28"
: "=d" (cc)
: "d" (reg1), "m" (*addr), "a" (addr)
: "cc");
Thanks,
Pierre
Thomas
--
Pierre Morel
IBM Lab Boeblingen
