Cortex-A8: better context restore
[openocd.git] / src / target / cortex_a8.c
index d02fee9e17affa30f904c726d8a4913e9b59d9dc..168fe127ddb68b960bce21dcd50d9964be835397 100644 (file)
@@ -237,7 +237,7 @@ static int cortex_a8_dap_read_coreregister_u32(struct target *target,
        struct armv7a_common *armv7a = target_to_armv7a(target);
        struct swjdp_common *swjdp = &armv7a->swjdp_info;
 
-       if (reg > 16)
+       if (reg > 17)
                return retval;
 
        if (reg < 15)
@@ -251,10 +251,12 @@ static int cortex_a8_dap_read_coreregister_u32(struct target *target,
                cortex_a8_exec_opcode(target, 0xE1A0000F);
                cortex_a8_exec_opcode(target, ARMV4_5_MCR(14, 0, 0, 0, 5, 0));
        }
-       else if (reg == 16)
+       else
        {
-               /* "MRS r0, CPSR"; then move r0 to DCCTX */
-               cortex_a8_exec_opcode(target, ARMV4_5_MRS(0, 0));
+               /* "MRS r0, CPSR" or "MRS r0, SPSR"
+                * then move r0 to DCCTX
+                */
+               cortex_a8_exec_opcode(target, ARMV4_5_MRS(0, reg & 1));
                cortex_a8_exec_opcode(target, ARMV4_5_MCR(14, 0, 0, 0, 5, 0));
        }
 
@@ -268,11 +270,13 @@ static int cortex_a8_dap_read_coreregister_u32(struct target *target,
 
        retval = mem_ap_read_atomic_u32(swjdp,
                        armv7a->debug_base + CPUDBG_DTRTX, value);
+       LOG_DEBUG("read DCC 0x%08" PRIx32, *value);
 
        return retval;
 }
 
-static int cortex_a8_dap_write_coreregister_u32(struct target *target, uint32_t value, int regnum)
+static int cortex_a8_dap_write_coreregister_u32(struct target *target,
+               uint32_t value, int regnum)
 {
        int retval = ERROR_OK;
        uint8_t Rd = regnum&0xFF;
@@ -292,29 +296,39 @@ static int cortex_a8_dap_write_coreregister_u32(struct target *target, uint32_t
                cortex_a8_exec_opcode(target, ARMV4_5_MRC(14, 0, 0, 0, 5, 0));
        }
 
-       if (Rd > 16)
+       if (Rd > 17)
                return retval;
 
        /* Write to DCCRX */
+       LOG_DEBUG("write DCC 0x%08" PRIx32, value);
        retval = mem_ap_write_u32(swjdp,
                        armv7a->debug_base + CPUDBG_DTRRX, value);
 
        if (Rd < 15)
        {
-               /* DCCRX to Rd, MCR p14, 0, Rd, c0, c5, 0,  0xEE000E15 */
+               /* DCCRX to Rn, "MCR p14, 0, Rn, c0, c5, 0", 0xEE00nE15 */
                cortex_a8_exec_opcode(target, ARMV4_5_MRC(14, 0, Rd, 0, 5, 0));
        }
        else if (Rd == 15)
        {
+               /* DCCRX to R0, "MCR p14, 0, R0, c0, c5, 0", 0xEE000E15
+                * then "mov r15, r0"
+                */
                cortex_a8_exec_opcode(target, ARMV4_5_MRC(14, 0, 0, 0, 5, 0));
                cortex_a8_exec_opcode(target, 0xE1A0F000);
        }
-       else if (Rd == 16)
+       else
        {
+               /* DCCRX to R0, "MCR p14, 0, R0, c0, c5, 0", 0xEE000E15
+                * then "MSR CPSR_cxsf, r0" or "MSR SPSR_cxsf, r0" (all fields)
+                */
                cortex_a8_exec_opcode(target, ARMV4_5_MRC(14, 0, 0, 0, 5, 0));
-               cortex_a8_exec_opcode(target, ARMV4_5_MSR_GP(0, 0xF, 0));
-               /* Execute a PrefetchFlush instruction through the ITR. */
-               cortex_a8_exec_opcode(target, ARMV4_5_MCR(15, 0, 0, 7, 5, 4));
+               cortex_a8_exec_opcode(target, ARMV4_5_MSR_GP(0, 0xF, Rd & 1));
+
+               /* "Prefetch flush" after modifying execution status in CPSR */
+               if (Rd == 16)
+                       cortex_a8_exec_opcode(target,
+                                       ARMV4_5_MCR(15, 0, 0, 7, 5, 4));
        }
 
        return retval;
@@ -517,7 +531,7 @@ static int cortex_a8_resume(struct target *target, int current,
                        armv4_5->core_mode, 15).valid = 1;
 
        cortex_a8_restore_context(target);
-//     arm7_9_restore_context(target); TODO Context is currently NOT Properly restored
+
 #if 0
        /* the front-end may request us not to handle breakpoints */
        if (handle_breakpoints)
@@ -836,30 +850,84 @@ static int cortex_a8_step(struct target *target, int current, uint32_t address,
 
 static int cortex_a8_restore_context(struct target *target)
 {
-       int i;
        uint32_t value;
        struct armv7a_common *armv7a = target_to_armv7a(target);
-       struct armv4_5_common_s *armv4_5 = &armv7a->armv4_5_common;
+       struct reg_cache *cache = armv7a->armv4_5_common.core_cache;
+       unsigned max = cache->num_regs;
+       struct reg *r;
+       bool flushed, flush_cpsr = false;
 
        LOG_DEBUG(" ");
 
        if (armv7a->pre_restore_context)
                armv7a->pre_restore_context(target);
 
-       for (i = 15; i >= 0; i--)
-       {
-               if (ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
-                                       armv4_5->core_mode, i).dirty)
-               {
-                       value = buf_get_u32(ARMV4_5_CORE_REG_MODE(
-                                               armv4_5->core_cache,
-                                               armv4_5->core_mode, i).value,
-                                       0, 32);
+       /* Flush all dirty registers from the cache, one mode at a time so
+        * that we write CPSR as little as possible.  Save CPSR and R0 for
+        * last; they're used to change modes and write other registers.
+        *
+        * REVISIT be smarter:  save eventual mode for last loop, don't
+        * need to write CPSR an extra time.
+        */
+       do {
+               enum armv4_5_mode mode = ARMV4_5_MODE_ANY;
+               unsigned i;
+
+               flushed = false;
+
+               /* write dirty non-{R0,CPSR} registers sharing the same mode */
+               for (i = max - 1, r = cache->reg_list + 1; i > 0; i--, r++) {
+                       struct armv4_5_core_reg *reg;
+
+                       if (!r->dirty || i == ARMV4_5_CPSR)
+                               continue;
+                       reg = r->arch_info;
+
                        /* TODO Check return values */
-                       cortex_a8_dap_write_coreregister_u32(target, value, i);
+
+                       /* Pick a mode and update CPSR; else ignore this
+                        * register if it's for a different mode than what
+                        * we're handling on this pass.
+                        *
+                        * REVISIT don't distinguish SYS and USR modes.
+                        *
+                        * FIXME if we restore from FIQ mode, R8..R12 will
+                        * get wrongly flushed onto FIQ shadows...
+                        */
+                       if (mode == ARMV4_5_MODE_ANY) {
+                               mode = reg->mode;
+                               if (mode != ARMV4_5_MODE_ANY) {
+                                       cortex_a8_dap_write_coreregister_u32(
+                                                       target, mode, 16);
+                                       flush_cpsr = true;
+                               }
+                       } else if (mode != reg->mode)
+                               continue;
+
+                       /* Write this register */
+                       value = buf_get_u32(r->value, 0, 32);
+                       cortex_a8_dap_write_coreregister_u32(target, value,
+                                       (reg->num == 16) ? 17 : reg->num);
+                       r->dirty = false;
+                       flushed = true;
                }
+
+       } while (flushed);
+
+       /* now flush CPSR if needed ... */
+       r = cache->reg_list + ARMV4_5_CPSR;
+       if (flush_cpsr || r->dirty) {
+               value = buf_get_u32(r->value, 0, 32);
+               cortex_a8_dap_write_coreregister_u32(target, value, 16);
+               r->dirty = false;
        }
 
+       /* ... and R0 always (it was dirtied when we saved context) */
+       r = cache->reg_list + 0;
+       value = buf_get_u32(r->value, 0, 32);
+       cortex_a8_dap_write_coreregister_u32(target, value, 0);
+       r->dirty = false;
+
        if (armv7a->post_restore_context)
                armv7a->post_restore_context(target);
 
@@ -950,28 +1018,64 @@ static int cortex_a8_store_core_reg_u32(struct target *target, int num,
 #endif
 
 
+static int cortex_a8_write_core_reg(struct target *target, int num,
+               enum armv4_5_mode mode, uint32_t value);
+
 static int cortex_a8_read_core_reg(struct target *target, int num,
                enum armv4_5_mode mode)
 {
        uint32_t value;
        int retval;
        struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
+       struct reg_cache *cache = armv4_5->core_cache;
+       uint32_t cpsr = 0;
+       unsigned cookie = num;
 
-       /* FIXME cortex may not be in "mode" ... */
-
-       cortex_a8_dap_read_coreregister_u32(target, &value, num);
+       /* avoid some needless mode changes
+        * FIXME move some of these to shared ARM code...
+        */
+       if (mode != armv4_5->core_mode) {
+               if ((armv4_5->core_mode == ARMV4_5_MODE_SYS)
+                               && (mode == ARMV4_5_MODE_USR))
+                       mode = ARMV4_5_MODE_ANY;
+               else if ((mode != ARMV4_5_MODE_FIQ) && (num <= 12))
+                       mode = ARMV4_5_MODE_ANY;
+
+               if (mode != ARMV4_5_MODE_ANY) {
+                       cpsr = buf_get_u32(cache ->reg_list[ARMV4_5_CPSR]
+                                       .value, 0, 32);
+                       cortex_a8_write_core_reg(target, 16,
+                                       ARMV4_5_MODE_ANY, mode);
+               }
+       }
 
-       if ((retval = jtag_execute_queue()) != ERROR_OK)
-       {
-               return retval;
+       if (num == 16) {
+               switch (mode) {
+               case ARMV4_5_MODE_USR:
+               case ARMV4_5_MODE_SYS:
+               case ARMV4_5_MODE_ANY:
+                       /* CPSR */
+                       break;
+               default:
+                       /* SPSR */
+                       cookie++;
+                       break;
+               }
        }
 
-       ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).valid = 1;
-       ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).dirty = 0;
-       buf_set_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
-                       mode, num).value, 0, 32, value);
+       cortex_a8_dap_read_coreregister_u32(target, &value, cookie);
+       retval = jtag_execute_queue();
+       if (retval == ERROR_OK) {
+               struct reg *r = &ARMV4_5_CORE_REG_MODE(cache, mode, num);
 
-       return ERROR_OK;
+               r->valid = 1;
+               r->dirty = 0;
+               buf_set_u32(r->value, 0, 32, value);
+       }
+
+       if (cpsr)
+               cortex_a8_write_core_reg(target, 16, ARMV4_5_MODE_ANY, cpsr);
+       return retval;
 }
 
 static int cortex_a8_write_core_reg(struct target *target, int num,
@@ -979,19 +1083,55 @@ static int cortex_a8_write_core_reg(struct target *target, int num,
 {
        int retval;
        struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
+       struct reg_cache *cache = armv4_5->core_cache;
+       uint32_t cpsr = 0;
+       unsigned cookie = num;
+
+       /* avoid some needless mode changes
+        * FIXME move some of these to shared ARM code...
+        */
+       if (mode != armv4_5->core_mode) {
+               if ((armv4_5->core_mode == ARMV4_5_MODE_SYS)
+                               && (mode == ARMV4_5_MODE_USR))
+                       mode = ARMV4_5_MODE_ANY;
+               else if ((mode != ARMV4_5_MODE_FIQ) && (num <= 12))
+                       mode = ARMV4_5_MODE_ANY;
+
+               if (mode != ARMV4_5_MODE_ANY) {
+                       cpsr = buf_get_u32(cache ->reg_list[ARMV4_5_CPSR]
+                                       .value, 0, 32);
+                       cortex_a8_write_core_reg(target, 16,
+                                       ARMV4_5_MODE_ANY, mode);
+               }
+       }
 
-       /* FIXME cortex may not be in "mode" ... */
 
-       cortex_a8_dap_write_coreregister_u32(target, value, num);
-       if ((retval = jtag_execute_queue()) != ERROR_OK)
-       {
-               return retval;
+       if (num == 16) {
+               switch (mode) {
+               case ARMV4_5_MODE_USR:
+               case ARMV4_5_MODE_SYS:
+               case ARMV4_5_MODE_ANY:
+                       /* CPSR */
+                       break;
+               default:
+                       /* SPSR */
+                       cookie++;
+                       break;
+               }
        }
 
-       ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).valid = 1;
-       ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).dirty = 0;
+       cortex_a8_dap_write_coreregister_u32(target, value, cookie);
+       if ((retval = jtag_execute_queue()) == ERROR_OK) {
+               struct reg *r = &ARMV4_5_CORE_REG_MODE(cache, mode, num);
 
-       return ERROR_OK;
+               buf_set_u32(r->value, 0, 32, value);
+               r->valid = 1;
+               r->dirty = 0;
+       }
+
+       if (cpsr)
+               cortex_a8_write_core_reg(target, 16, ARMV4_5_MODE_ANY, cpsr);
+       return retval;
 }
 
 

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