Commit 05068c0d authored by Peter Maydell's avatar Peter Maydell
Browse files

exec.c: Relax restrictions on watchpoint length and alignment 



The current implementation of watchpoints requires that they
have a power of 2 length which is not greater than TARGET_PAGE_SIZE
and that their address is a multiple of their length. Watchpoints
on ARM don't fit these restrictions, so change the implementation
so they can be relaxed.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
parent acf82361

exec.c

+31 −13
Original line number Diff line number Diff line
@@ -582,12 +582,10 @@ int cpu_watchpoint_insert(CPUState *cpu, vaddr addr, vaddr len, 
int cpu_watchpoint_insert(CPUState *cpu, vaddr addr, vaddr len,

                          int flags, CPUWatchpoint **watchpoint)

{

    vaddr len_mask = ~(len - 1);

    CPUWatchpoint *wp;



    /* sanity checks: allow power-of-2 lengths, deny unaligned watchpoints */

    if ((len & (len - 1)) || (addr & ~len_mask) ||

            len == 0 || len > TARGET_PAGE_SIZE) {

    /* forbid ranges which are empty or run off the end of the address space */

    if (len == 0 || (addr + len - 1) <= addr) {

        error_report("tried to set invalid watchpoint at %"

                     VADDR_PRIx ", len=%" VADDR_PRIu, addr, len);

        return -EINVAL;
@@ -595,7 +593,7 @@ int cpu_watchpoint_insert(CPUState *cpu, vaddr addr, vaddr len, 
    wp = g_malloc(sizeof(*wp));



    wp->vaddr = addr;

    wp->len_mask = len_mask;

    wp->len = len;

    wp->flags = flags;



    /* keep all GDB-injected watchpoints in front */
@@ -616,11 +614,10 @@ int cpu_watchpoint_insert(CPUState *cpu, vaddr addr, vaddr len, 
int cpu_watchpoint_remove(CPUState *cpu, vaddr addr, vaddr len,

                          int flags)

{

    vaddr len_mask = ~(len - 1);

    CPUWatchpoint *wp;



    QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {

        if (addr == wp->vaddr && len_mask == wp->len_mask

        if (addr == wp->vaddr && len == wp->len

                && flags == (wp->flags & ~BP_WATCHPOINT_HIT)) {

            cpu_watchpoint_remove_by_ref(cpu, wp);

            return 0;
@@ -650,6 +647,27 @@ void cpu_watchpoint_remove_all(CPUState *cpu, int mask) 
        }

    }

}



/* Return true if this watchpoint address matches the specified

 * access (ie the address range covered by the watchpoint overlaps

 * partially or completely with the address range covered by the

 * access).

 */

static inline bool cpu_watchpoint_address_matches(CPUWatchpoint *wp,

                                                  vaddr addr,

                                                  vaddr len)

{

    /* We know the lengths are non-zero, but a little caution is

     * required to avoid errors in the case where the range ends

     * exactly at the top of the address space and so addr + len

     * wraps round to zero.

     */

    vaddr wpend = wp->vaddr + wp->len - 1;

    vaddr addrend = addr + len - 1;



    return !(addr > wpend || wp->vaddr > addrend);

}



#endif



/* Add a breakpoint.  */
@@ -861,7 +879,7 @@ hwaddr memory_region_section_get_iotlb(CPUState *cpu, 
    /* Make accesses to pages with watchpoints go via the

       watchpoint trap routines.  */

    QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {

        if (vaddr == (wp->vaddr & TARGET_PAGE_MASK)) {

        if (cpu_watchpoint_address_matches(wp, vaddr, TARGET_PAGE_SIZE)) {

            /* Avoid trapping reads of pages with a write breakpoint. */

            if ((prot & PAGE_WRITE) || (wp->flags & BP_MEM_READ)) {

                iotlb = PHYS_SECTION_WATCH + paddr;
@@ -1625,7 +1643,7 @@ static const MemoryRegionOps notdirty_mem_ops = { 
};



/* Generate a debug exception if a watchpoint has been hit.  */

static void check_watchpoint(int offset, int len_mask, int flags)

static void check_watchpoint(int offset, int len, int flags)

{

    CPUState *cpu = current_cpu;

    CPUArchState *env = cpu->env_ptr;
@@ -1643,8 +1661,8 @@ static void check_watchpoint(int offset, int len_mask, int flags) 
    }

    vaddr = (cpu->mem_io_vaddr & TARGET_PAGE_MASK) + offset;

    QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {

        if ((vaddr == (wp->vaddr & len_mask) ||

             (vaddr & wp->len_mask) == wp->vaddr) && (wp->flags & flags)) {

        if (cpu_watchpoint_address_matches(wp, vaddr, len)

            && (wp->flags & flags)) {

            wp->flags |= BP_WATCHPOINT_HIT;

            if (!cpu->watchpoint_hit) {

                cpu->watchpoint_hit = wp;
@@ -1670,7 +1688,7 @@ static void check_watchpoint(int offset, int len_mask, int flags) 
static uint64_t watch_mem_read(void *opaque, hwaddr addr,

                               unsigned size)

{

    check_watchpoint(addr & ~TARGET_PAGE_MASK, ~(size - 1), BP_MEM_READ);

    check_watchpoint(addr & ~TARGET_PAGE_MASK, size, BP_MEM_READ);

    switch (size) {

    case 1: return ldub_phys(&address_space_memory, addr);

    case 2: return lduw_phys(&address_space_memory, addr);
@@ -1682,7 +1700,7 @@ static uint64_t watch_mem_read(void *opaque, hwaddr addr, 
static void watch_mem_write(void *opaque, hwaddr addr,

                            uint64_t val, unsigned size)

{

    check_watchpoint(addr & ~TARGET_PAGE_MASK, ~(size - 1), BP_MEM_WRITE);

    check_watchpoint(addr & ~TARGET_PAGE_MASK, size, BP_MEM_WRITE);

    switch (size) {

    case 1:

        stb_phys(&address_space_memory, addr, val);

include/qom/cpu.h

+1 −1
Original line number Diff line number Diff line
@@ -169,7 +169,7 @@ typedef struct CPUBreakpoint { 


typedef struct CPUWatchpoint {

    vaddr vaddr;

    vaddr len_mask;

    vaddr len;

    int flags; /* BP_* */

    QTAILQ_ENTRY(CPUWatchpoint) entry;

} CPUWatchpoint;

linux-user/main.c

+1 −2
Original line number Diff line number Diff line
@@ -3458,8 +3458,7 @@ CPUArchState *cpu_copy(CPUArchState *env) 
        cpu_breakpoint_insert(new_cpu, bp->pc, bp->flags, NULL);

    }

    QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {

        cpu_watchpoint_insert(new_cpu, wp->vaddr, (~wp->len_mask) + 1,

                              wp->flags, NULL);

        cpu_watchpoint_insert(new_cpu, wp->vaddr, wp->len, wp->flags, NULL);

    }

#endif