On 18/01/2021 15.03, Janosch Frank wrote:
On a program exception we usually skip the instruction that caused the
exception and continue. That won't work for UV calls since a "brc 3,0b"
will retry the instruction if the CC is > 1.
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
I know this isn't very pretty.
I'm open for suggestions.
---
lib/s390x/asm/uv.h | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/lib/s390x/asm/uv.h b/lib/s390x/asm/uv.h
index 4c2fc48..252f1a3 100644
--- a/lib/s390x/asm/uv.h
+++ b/lib/s390x/asm/uv.h
@@ -53,21 +53,23 @@ struct uv_cb_share {
static inline int uv_call(unsigned long r1, unsigned long r2)
{
int cc;
+ struct lowcore *lc = 0x0;
/*
- * The brc instruction will take care of the cc 2/3 case where
- * we need to continue the execution because we were
- * interrupted. The inline assembly will only return on
- * success/error i.e. cc 0/1.
- */
+ * CC 2 and 3 tell us to re-execute because the instruction
+ * hasn't yet finished.
+ */
+ lc->pgm_int_code = 0;
+retry:
asm volatile(
"0: .insn rrf,0xB9A40000,%[r1],%[r2],0,0\n"
- " brc 3,0b\n"
" ipm %[cc]\n"
" srl %[cc],28\n"
: [cc] "=d" (cc)
: [r1] "a" (r1), [r2] "a" (r2)
: "memory", "cc");
+ if (!lc->pgm_int_code && cc > 1)
+ goto retry;
Why not simply:
do {
asm volatile(...);
} while (!lc->pgm_int_code && cc > 1)
?
Thomas
