Commit 9bed521e authored by Peter Maydell's avatar Peter Maydell
Browse files

hw/timer/armv7m_systick: Forbid non-privileged accesses 



Like most of the v7M memory mapped system registers, the systick
registers are accessible to privileged code only and user accesses
must generate a BusFault. We implement that for registers in
the NVIC proper already, but missed it for systick since we
implement it as a separate device. Correct the omission.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190617175317.27557-6-peter.maydell@linaro.org
parent 2884fbb6

hw/timer/armv7m_systick.c

+20 −6
Original line number Diff line number Diff line
@@ -75,11 +75,17 @@ static void systick_timer_tick(void *opaque) 
    }

}



static uint64_t systick_read(void *opaque, hwaddr addr, unsigned size)

static MemTxResult systick_read(void *opaque, hwaddr addr, uint64_t *data,

                                unsigned size, MemTxAttrs attrs)

{

    SysTickState *s = opaque;

    uint32_t val;



    if (attrs.user) {

        /* Generate BusFault for unprivileged accesses */

        return MEMTX_ERROR;

    }



    switch (addr) {

    case 0x0: /* SysTick Control and Status.  */

        val = s->control;
@@ -121,14 +127,21 @@ static uint64_t systick_read(void *opaque, hwaddr addr, unsigned size) 
    }



    trace_systick_read(addr, val, size);

    return val;

    *data = val;

    return MEMTX_OK;

}



static void systick_write(void *opaque, hwaddr addr,

                          uint64_t value, unsigned size)

static MemTxResult systick_write(void *opaque, hwaddr addr,

                                 uint64_t value, unsigned size,

                                 MemTxAttrs attrs)

{

    SysTickState *s = opaque;



    if (attrs.user) {

        /* Generate BusFault for unprivileged accesses */

        return MEMTX_ERROR;

    }



    trace_systick_write(addr, value, size);



    switch (addr) {
@@ -172,11 +185,12 @@ static void systick_write(void *opaque, hwaddr addr, 
        qemu_log_mask(LOG_GUEST_ERROR,

                      "SysTick: Bad write offset 0x%" HWADDR_PRIx "\n", addr);

    }

    return MEMTX_OK;

}



static const MemoryRegionOps systick_ops = {

    .read = systick_read,

    .write = systick_write,

    .read_with_attrs = systick_read,

    .write_with_attrs = systick_write,

    .endianness = DEVICE_NATIVE_ENDIAN,

    .valid.min_access_size = 4,

    .valid.max_access_size = 4,