Commit 3cea0927 authored by Pavel Zbitskiy's avatar Pavel Zbitskiy Committed by Cornelia Huck
Browse files

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: default avatarPavel Zbitskiy <pavel.zbitskiy@gmail.com>
Message-Id: <20180821025104.19604-7-pavel.zbitskiy@gmail.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent ad8c851d

target/s390x/mem_helper.c

+3 −3
Original line number Diff line number Diff line
@@ -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--;

tests/tcg/s390x/Makefile.target

+1 −0
Original line number Diff line number Diff line
@@ -5,3 +5,4 @@ TESTS+=csst 
TESTS+=ipm

TESTS+=exrl-trt

TESTS+=exrl-trtr

TESTS+=pack

tests/tcg/s390x/pack.c

0 → 100644
+21 −0
Original line number Diff line number Diff line 
#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;

}