Commit bb36ed88 authored by David Hildenbrand's avatar David Hildenbrand
Browse files

s390x/tcg: MVST: Fault-safe handling 



Access at most single pages and document why. Using the access helpers
might over-indicate watchpoints within the same page, I guess we can
live with that.

Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
parent 6514f42b

target/s390x/mem_helper.c

+17 −7
Original line number Diff line number Diff line
@@ -866,23 +866,33 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2) 
/* string copy */

uint32_t HELPER(mvst)(CPUS390XState *env, uint32_t r1, uint32_t r2)

{

    const int mmu_idx = cpu_mmu_index(env, false);

    const uint64_t d = get_address(env, r1);

    const uint64_t s = get_address(env, r2);

    const uint8_t c = env->regs[0];

    const int len = MIN(-(d | TARGET_PAGE_MASK), -(s | TARGET_PAGE_MASK));

    S390Access srca, desta;

    uintptr_t ra = GETPC();

    uint32_t len;

    int i;



    if (env->regs[0] & 0xffffff00ull) {

        s390_program_interrupt(env, PGM_SPECIFICATION, ILEN_AUTO, ra);

    }



    /* Lest we fail to service interrupts in a timely manner, limit the

       amount of work we're willing to do.  For now, let's cap at 8k.  */

    for (len = 0; len < 0x2000; ++len) {

        uint8_t v = cpu_ldub_data_ra(env, s + len, ra);

        cpu_stb_data_ra(env, d + len, v, ra);

    /*

     * Our access should not exceed single pages, as we must not report access

     * exceptions exceeding the actually copied range (which we don't know at

     * this point). We might over-indicate watchpoints within the pages

     * (if we ever care, we have to limit processing to a single byte).

     */

    srca = access_prepare(env, s, len, MMU_DATA_LOAD, mmu_idx, ra);

    desta = access_prepare(env, d, len, MMU_DATA_STORE, mmu_idx, ra);

    for (i = 0; i < len; i++) {

        const uint8_t v = access_get_byte(env, &srca, i, ra);



        access_set_byte(env, &desta, i, v, ra);

        if (v == c) {

            set_address_zero(env, r1, d + len);

            set_address_zero(env, r1, d + i);

            return 1;

        }

    }