ARM DPM: support adding/removing HW breakpoints

Generalize the core of watchpoint setup so that it can handle
breakpoints too.  Create breakpoint add/remove routines which
will use that, and hook them up to target types which don't
provide their own breakpoint support (nothing, yet).

This suffices for hardware-only breakpoint support.  The ARM11
code will be able to switch over to this without much trouble,
since it doesn't yet handle software breakpoints.  Switching
Cortex-A8 will be a bit more involved.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

diff --git a/src/target/arm_dpm.c b/src/target/arm_dpm.c
index 3c18e6334b26326aa8d8974423d339e91a5de427..0b5e2558522e2c951feb88b1dedc654b70222102 100644 (file)
--- a/src/target/arm_dpm.c
+++ b/src/target/arm_dpm.c
@@ -320,14 +320,17 @@ static int dpm_maybe_update_bpwp(struct arm_dpm *dpm, bool bpwp,
                                xp->address, xp->control);
 
        if (retval != ERROR_OK)
-               LOG_ERROR("%s: can't %s HW bp/wp %d",
+               LOG_ERROR("%s: can't %s HW %spoint %d",
                                disable ? "disable" : "enable",
                                target_name(dpm->arm->target),
-                               xp->number);
+                               (xp->number < 16) ? "break" : "watch",
+                               xp->number & 0xf);
 done:
        return retval;
 }
 
+static int dpm_add_breakpoint(struct target *target, struct breakpoint *bp);
+
 /**
  * Writes all modified core registers for all processor modes.  In normal
  * operation this is called on exit from halting debug state.
@@ -354,7 +357,7 @@ int arm_dpm_write_dirty_registers(struct arm_dpm *dpm, bool bpwp)
         * we should be able to assume we handle them; but until then,
         * cope with the hand-crafted breakpoint code.
         */
-       if (0) {
+       if (arm->target->type->add_breakpoint == dpm_add_breakpoint) {
                for (unsigned i = 0; i < dpm->nbp; i++) {
                        struct dpm_bp *dbp = dpm->dbp + i;
                        struct breakpoint *bp = dbp->bp;
@@ -665,43 +668,26 @@ done:
  * fact isn't currently leveraged.
  */
 
-static int dpm_watchpoint_setup(struct arm_dpm *dpm, unsigned index,
-               struct watchpoint *wp)
+static int dpm_bpwp_setup(struct arm_dpm *dpm, struct dpm_bpwp *xp,
+               uint32_t addr, uint32_t length)
 {
-       uint32_t addr = wp->address;
        uint32_t control;
 
-       /* this hardware doesn't support data value matching or masking */
-       if (wp->value || wp->mask != ~(uint32_t)0) {
-               LOG_DEBUG("watchpoint values and masking not supported");
-               return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
-       }
-
        control = (1 << 0)      /* enable */
                | (3 << 1);     /* both user and privileged access */
 
-       switch (wp->rw) {
-       case WPT_READ:
-               control |= 1 << 3;
-               break;
-       case WPT_WRITE:
-               control |= 2 << 3;
-               break;
-       case WPT_ACCESS:
-               control |= 3 << 3;
-               break;
-       }
-
        /* Match 1, 2, or all 4 byte addresses in this word.
         *
-        * FIXME:  v7 hardware allows lengths up to 2 GB, and has eight
-        * byte address select bits.  Support larger wp->length, if addr
-        * is suitably aligned.
+        * FIXME:  v7 hardware allows lengths up to 2 GB for BP and WP.
+        * Support larger length, when addr is suitably aligned.  In
+        * particular, allow watchpoints on 8 byte "double" values.
+        *
+        * REVISIT allow watchpoints on unaligned 2-bit values; and on
+        * v7 hardware, unaligned 4-byte ones too.
         */
-       switch (wp->length) {
+       switch (length) {
        case 1:
                control |= (1 << (addr & 3)) << 5;
-               addr &= ~3;
                break;
        case 2:
                /* require 2-byte alignment */
@@ -718,26 +704,110 @@ static int dpm_watchpoint_setup(struct arm_dpm *dpm, unsigned index,
                }
                /* FALL THROUGH */
        default:
-               LOG_DEBUG("bad watchpoint length or alignment");
+               LOG_ERROR("unsupported {break,watch}point length/alignment");
                return ERROR_INVALID_ARGUMENTS;
        }
 
-       /* other control bits:
-        * bits 9:12 == 0 ... only checking up to four byte addresses (v7 only)
+       /* other shared control bits:
         * bits 15:14 == 0 ... both secure and nonsecure states (v6.1+ only)
         * bit 20 == 0 ... not linked to a context ID
         * bit 28:24 == 0 ... not ignoring N LSBs (v7 only)
         */
 
-       dpm->dwp[index].wp = wp;
-       dpm->dwp[index].bpwp.address = addr & ~3;
-       dpm->dwp[index].bpwp.control = control;
-       dpm->dwp[index].bpwp.dirty = true;
+       xp->address = addr & ~3;
+       xp->control = control;
+       xp->dirty = true;
+
+       LOG_DEBUG("BPWP: addr %8.8x, control %x, number %d",
+                       xp->address, control, xp->number);
 
        /* hardware is updated in write_dirty_registers() */
        return ERROR_OK;
 }
 
+static int dpm_add_breakpoint(struct target *target, struct breakpoint *bp)
+{
+       struct arm *arm = target_to_arm(target);
+       struct arm_dpm *dpm = arm->dpm;
+       int retval = ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
+
+       if (bp->length < 2)
+               return ERROR_INVALID_ARGUMENTS;
+       if (!dpm->bpwp_enable)
+               return retval;
+
+       /* FIXME we need a generic solution for software breakpoints. */
+       if (bp->type == BKPT_SOFT)
+               LOG_DEBUG("using HW bkpt, not SW...");
+
+       for (unsigned i = 0; i < dpm->nbp; i++) {
+               if (!dpm->dbp[i].bp) {
+                       retval = dpm_bpwp_setup(dpm, &dpm->dbp[i].bpwp,
+                                       bp->address, bp->length);
+                       if (retval == ERROR_OK)
+                               dpm->dbp[i].bp = bp;
+                       break;
+               }
+       }
+
+       return retval;
+}
+
+static int dpm_remove_breakpoint(struct target *target, struct breakpoint *bp)
+{
+       struct arm *arm = target_to_arm(target);
+       struct arm_dpm *dpm = arm->dpm;
+       int retval = ERROR_INVALID_ARGUMENTS;
+
+       for (unsigned i = 0; i < dpm->nbp; i++) {
+               if (dpm->dbp[i].bp == bp) {
+                       dpm->dbp[i].bp = NULL;
+                       dpm->dbp[i].bpwp.dirty = true;
+
+                       /* hardware is updated in write_dirty_registers() */
+                       retval = ERROR_OK;
+                       break;
+               }
+       }
+
+       return retval;
+}
+
+static int dpm_watchpoint_setup(struct arm_dpm *dpm, unsigned index,
+               struct watchpoint *wp)
+{
+       int retval;
+       struct dpm_wp *dwp = dpm->dwp + index;
+       uint32_t control;
+
+       /* this hardware doesn't support data value matching or masking */
+       if (wp->value || wp->mask != ~(uint32_t)0) {
+               LOG_DEBUG("watchpoint values and masking not supported");
+               return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
+       }
+
+       retval = dpm_bpwp_setup(dpm, &dwp->bpwp, wp->address, wp->length);
+       if (retval != ERROR_OK)
+               return retval;
+
+       control = dwp->bpwp.control;
+       switch (wp->rw) {
+       case WPT_READ:
+               control |= 1 << 3;
+               break;
+       case WPT_WRITE:
+               control |= 2 << 3;
+               break;
+       case WPT_ACCESS:
+               control |= 3 << 3;
+               break;
+       }
+       dwp->bpwp.control = control;
+
+       dpm->dwp[index].wp = wp;
+
+       return retval;
+}
 
 static int dpm_add_watchpoint(struct target *target, struct watchpoint *wp)
 {
@@ -865,11 +935,16 @@ int arm_dpm_setup(struct arm_dpm *dpm)
        arm->mrc = dpm_mrc;
        arm->mcr = dpm_mcr;
 
-       /* breakpoint and watchpoint setup */
+       /* breakpoint setup -- optional until it works everywhere */
+       if (!target->type->add_breakpoint) {
+               target->type->add_breakpoint = dpm_add_breakpoint;
+               target->type->remove_breakpoint = dpm_remove_breakpoint;
+       }
+
+       /* watchpoint setup */
        target->type->add_watchpoint = dpm_add_watchpoint;
        target->type->remove_watchpoint = dpm_remove_watchpoint;
 
-       /* FIXME add breakpoint support */
        /* FIXME add vector catch support */
 
        dpm->nbp = 1 + ((dpm->didr >> 24) & 0xf);