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target/s390x: fix PACK reading 1 byte less and writing 1 byte more 

PACK fails on the test from the Principles of Operation: F1F2F3F4
becomes 0000234C instead of 0001234C due to an off-by-one error.
Furthermore, it overwrites one extra byte to the left of F1.

If len_dest is 0, then we only want to flip the 1st byte and never loop
over the rest. Therefore, the loop condition should be > and not >=.

If len_src is 1, then we should flip the 1st byte and pack the 2nd.
Since len_src is already decremented before the loop, the first
condition should be >=, and not >.

Likewise for len_src == 2 and the second condition.

Signed-off-by: Pavel Zbitskiy <pavel.zbitskiy@gmail.com>
Message-Id: <20180821025104.19604-7-pavel.zbitskiy@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Pavel Zbitskiy 2018-08-20 22:51:03 -04:00 committed by Cornelia Huck
parent ad8c851d2e
commit 3cea09271b
3 changed files with 25 additions and 3 deletions
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6
target/s390x/mem_helper.c
View File

@ -1019,15 +1019,15 @@ void HELPER(pack)(CPUS390XState *env, uint32_t len, uint64_t dest, uint64_t src)
len_src--;
/* now pack every value */
while (len_dest >= 0) {
while (len_dest > 0) {
b = 0;
if (len_src > 0) {
if (len_src >= 0) {
b = cpu_ldub_data_ra(env, src, ra) & 0x0f;
src--;
len_src--;
}
if (len_src > 0) {
if (len_src >= 0) {
b |= cpu_ldub_data_ra(env, src, ra) << 4;
src--;
len_src--;

1
tests/tcg/s390x/Makefile.target
View File

@ -5,3 +5,4 @@ TESTS+=csst
TESTS+=ipm
TESTS+=exrl-trt
TESTS+=exrl-trtr
TESTS+=pack

21
tests/tcg/s390x/pack.c Normal file
View File

@ -0,0 +1,21 @@
#include <unistd.h>
int main(void)
{
char data[] = {0xaa, 0xaa, 0xf1, 0xf2, 0xf3, 0xc4, 0xaa, 0xaa};
char exp[] = {0xaa, 0xaa, 0x00, 0x01, 0x23, 0x4c, 0xaa, 0xaa};
int i;
asm volatile(
" pack 2(4,%[data]),2(4,%[data])\n"
:
: [data] "r" (&data[0])
: "memory");
for (i = 0; i < 8; i++) {
if (data[i] != exp[i]) {
write(1, "bad data\n", 9);
return 1;
}
}
return 0;
}