From e6dc927e972bb2d91131b0193b676c531377f318 Mon Sep 17 00:00:00 2001
From: David Brownell <dbrownell@users.sourceforge.net>
Date: Tue, 24 Nov 2009 00:13:58 -0800
Subject: ARM: new DPM interface
First version of interface for sharing code between ARMv6 and ARMv7a
debug modules ... now the architecture includes debug support. (Not
the same as for the trimmed-down v7m or v6m though!) This is a first
version of an interface that will let the ARM11 and Cortex-A8 support
share code, features, and bugfixes. Based on existing code from both
of those cores.
The ARM v7-AR architecture specification calls this commonality the
"Debug Programmer's Model (DPM)", which seemed to be an appropriate
acronym -- a TLA even! -- for use in our code. Made it so. :)
The initial scope of this just supports register access, and is geared
towards supporting top level "struct arm" mechanisms. Later, things
like breakpoint and watchpoint support should be included.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
src/target/Makefile.am | 2 +
src/target/arm_dpm.c | 529 +++++++++++++++++++++++++++++++++++++++++++++++++
src/target/arm_dpm.h | 87 ++++++++
src/target/armv4_5.c | 1 +
src/target/armv4_5.h | 6 +
5 files changed, 625 insertions(+)
create mode 100644 src/target/arm_dpm.c
create mode 100644 src/target/arm_dpm.h
diff --git a/src/target/Makefile.am b/src/target/Makefile.am
index 23aea82c..a367fd42 100644
--- a/src/target/Makefile.am
+++ b/src/target/Makefile.am
@@ -75,6 +75,7 @@ ARMV7_SRC = \
cortex_a8.c
ARM_DEBUG_SRC = \
+ arm_dpm.c \
arm_jtag.c \
arm_disassembler.c \
arm_simulator.c \
@@ -96,6 +97,7 @@ MIPS32_SRC = \
noinst_HEADERS = \
algorithm.h \
+ arm_dpm.h \
arm_jtag.h \
arm_adi_v5.h \
arm_disassembler.h \
diff --git a/src/target/arm_dpm.c b/src/target/arm_dpm.c
new file mode 100644
index 00000000..18a9dcc7
--- /dev/null
+++ b/src/target/arm_dpm.c
@@ -0,0 +1,529 @@
+/*
+ * Copyright (C) 2009 by David Brownell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "armv4_5.h" /* REVISIT to become arm.h */
+#include "arm_dpm.h"
+#include "jtag.h"
+#include "register.h"
+
+
+/**
+ * @file
+ * Implements various ARM DPM operations using architectural debug registers.
+ * These routines layer over core-specific communication methods to cope with
+ * implementation differences between cores like ARM1136 and Cortex-A8.
+ */
+
+/* Toggles between recorded core mode (USR, SVC, etc) and a temporary one.
+ * Routines *must* restore the original mode before returning!!
+ */
+static int dpm_modeswitch(struct arm_dpm *dpm, enum armv4_5_mode mode)
+{
+ int retval;
+ uint32_t cpsr;
+
+ /* restore previous mode */
+ if (mode == ARMV4_5_MODE_ANY)
+ cpsr = buf_get_u32(dpm->arm->cpsr->value, 0, 32);
+
+ /* else force to the specified mode */
+ else
+ cpsr = mode;
+
+ retval = dpm->instr_write_data_r0(dpm, ARMV4_5_MSR_GP(0, 0xf, 0), cpsr);
+
+ /* REVISIT on Cortex-A8, we need a Prefetch Flush operation too ...
+ cortex_a8_exec_opcode(target,
+ ARMV4_5_MCR(15, 0, 0, 7, 5, 4));
+ */
+
+ return retval;
+}
+
+/* just read the register -- rely on the core mode being right */
+static int dpm_read_reg(struct arm_dpm *dpm, struct reg *r, unsigned regnum)
+{
+ uint32_t value;
+ int retval;
+
+ switch (regnum) {
+ case 0 ... 14:
+ /* return via DCC: "MCR p14, 0, Rnum, c0, c5, 0" */
+ retval = dpm->instr_read_data_dcc(dpm,
+ ARMV4_5_MCR(14, 0, regnum, 0, 5, 0),
+ &value);
+ break;
+ case 15: /* PC */
+ /* "MOV r0, pc"; then return via DCC */
+ retval = dpm->instr_read_data_r0(dpm, 0xe1a0000f, &value);
+
+ /* NOTE: this seems like a slightly awkward place to update
+ * this value ... but if the PC gets written (the only way
+ * to change what we compute), the arch spec says subsequent
+ * reads return values which are "unpredictable". So this
+ * is always right except in those broken-by-intent cases.
+ */
+ switch (dpm->arm->core_state) {
+ case ARMV4_5_STATE_ARM:
+ value -= 8;
+ break;
+ case ARMV4_5_STATE_THUMB:
+ case ARM_STATE_THUMB_EE:
+ value -= 4;
+ break;
+ case ARMV4_5_STATE_JAZELLE:
+ /* core-specific ... ? */
+ LOG_WARNING("Jazelle PC adjustment unknown");
+ break;
+ }
+ break;
+ default:
+ /* 16: "MRS r0, CPSR"; then return via DCC
+ * 17: "MRS r0, SPSR"; then return via DCC
+ */
+ retval = dpm->instr_read_data_r0(dpm,
+ ARMV4_5_MRS(0, regnum & 1),
+ &value);
+ break;
+ }
+
+ if (retval == ERROR_OK) {
+ buf_set_u32(r->value, 0, 32, value);
+ r->valid = true;
+ r->dirty = false;
+ LOG_DEBUG("READ: %s, %8.8x", r->name, (unsigned) value);
+ }
+
+ return retval;
+}
+
+/* just write the register -- rely on the core mode being right */
+static int dpm_write_reg(struct arm_dpm *dpm, struct reg *r, unsigned regnum)
+{
+ int retval;
+ uint32_t value = buf_get_u32(r->value, 0, 32);
+
+ switch (regnum) {
+ case 0 ... 14:
+ /* load register from DCC: "MCR p14, 0, Rnum, c0, c5, 0" */
+ retval = dpm->instr_write_data_dcc(dpm,
+ ARMV4_5_MRC(14, 0, regnum, 0, 5, 0),
+ value);
+ break;
+ case 15: /* PC */
+ /* read r0 from DCC; then "MOV pc, r0" */
+ retval = dpm->instr_write_data_r0(dpm, 0xe1a0f000, value);
+ break;
+ default:
+ /* 16: read r0 from DCC, then "MSR r0, CPSR_cxsf"
+ * 17: read r0 from DCC, then "MSR r0, SPSR_cxsf"
+ */
+ retval = dpm->instr_write_data_r0(dpm,
+ ARMV4_5_MSR_GP(0, 0xf, regnum & 1),
+ value);
+
+ /* REVISIT on Cortex-A8, we need a Prefetch Flush operation
+ * after writing CPSR ...
+ cortex_a8_exec_opcode(target,
+ ARMV4_5_MCR(15, 0, 0, 7, 5, 4));
+ */
+
+ break;
+ }
+
+ if (retval == ERROR_OK) {
+ r->dirty = false;
+ LOG_DEBUG("WRITE: %s, %8.8x", r->name, (unsigned) value);
+ }
+
+ return retval;
+}
+
+/**
+ * Read basic registers of the the current context: R0 to R15, and CPSR;
+ * sets the core mode (such as USR or IRQ) and state (such as ARM or Thumb).
+ * In normal operation this is called on entry to halting debug state,
+ * possibly after some other operations supporting restore of debug state
+ * or making sure the CPU is fully idle (drain write buffer, etc).
+ */
+int arm_dpm_read_current_registers(struct arm_dpm *dpm)
+{
+ struct arm *arm = dpm->arm;
+ uint32_t cpsr;
+ int retval;
+ struct reg *r;
+
+ retval = dpm->prepare(dpm);
+ if (retval != ERROR_OK)
+ return retval;
+
+ /* read R0 first (it's used for scratch), then CPSR */
+ r = arm->core_cache->reg_list + 0;
+ if (!r->valid) {
+ retval = dpm_read_reg(dpm, r, 0);
+ if (retval != ERROR_OK)
+ goto fail;
+ }
+ r->dirty = true;
+
+ retval = dpm->instr_read_data_r0(dpm, ARMV4_5_MRS(0, 0), &cpsr);
+ if (retval != ERROR_OK)
+ goto fail;
+
+ /* update core mode and state, plus shadow mapping for R8..R14 */
+ arm_set_cpsr(arm, cpsr);
+
+ /* REVISIT we can probably avoid reading R1..R14, saving time... */
+ for (unsigned i = 1; i < 16; i++) {
+ r = arm_reg_current(arm, i);
+ if (r->valid)
+ continue;
+
+ retval = dpm_read_reg(dpm, r, i);
+ if (retval != ERROR_OK)
+ goto fail;
+ }
+
+ /* NOTE: SPSR ignored (if it's even relevant). */
+
+fail:
+ /* (void) */ dpm->finish(dpm);
+ return retval;
+}
+
+/**
+ * Writes all modified core registers for all processor modes. In normal
+ * operation this is called on exit from halting debug state.
+ */
+int arm_dpm_write_dirty_registers(struct arm_dpm *dpm)
+{
+ struct arm *arm = dpm->arm;
+ struct reg_cache *cache = arm->core_cache;
+ int retval;
+ bool did_write;
+
+ retval = dpm->prepare(dpm);
+ if (retval != ERROR_OK)
+ goto done;
+
+ /* Scan the registers until we find one that's both dirty and
+ * eligible for flushing. Flush that and everything else that
+ * shares the same core mode setting. Typically this won't
+ * actually find anything to do...
+ */
+ do {
+ enum armv4_5_mode mode = ARMV4_5_MODE_ANY;
+
+ did_write = false;
+
+ /* check everything except our scratch register R0 */
+ for (unsigned i = 1; i < cache->num_regs; i++) {
+ struct arm_reg *r;
+ unsigned regnum;
+
+ /* also skip PC, CPSR, and non-dirty */
+ if (i == 15)
+ continue;
+ if (arm->cpsr == cache->reg_list + i)
+ continue;
+ if (!cache->reg_list[i].dirty)
+ continue;
+
+ r = cache->reg_list[i].arch_info;
+ regnum = r->num;
+
+ /* may need to pick and set a mode */
+ if (!did_write) {
+ enum armv4_5_mode tmode;
+
+ did_write = true;
+ mode = tmode = r->mode;
+
+ /* cope with special cases */
+ switch (regnum) {
+ case 8 ... 12:
+ /* r8..r12 "anything but FIQ" case;
+ * we "know" core mode is accurate
+ * since we haven't changed it yet
+ */
+ if (arm->core_mode == ARMV4_5_MODE_FIQ
+ && ARMV4_5_MODE_ANY
+ != mode)
+ tmode = ARMV4_5_MODE_USR;
+ break;
+ case 16:
+ /* SPSR */
+ regnum++;
+ break;
+ }
+
+ /* REVISIT error checks */
+ if (tmode != ARMV4_5_MODE_ANY)
+ retval = dpm_modeswitch(dpm, tmode);
+ }
+ if (r->mode != mode)
+ continue;
+
+ retval = dpm_write_reg(dpm,
+ &cache->reg_list[i],
+ regnum);
+
+ }
+
+ } while (did_write);
+
+ /* Restore original CPSR ... assuming either that we changed it,
+ * or it's dirty. Must write PC to ensure the return address is
+ * defined, and must not write it before CPSR.
+ */
+ retval = dpm_modeswitch(dpm, ARMV4_5_MODE_ANY);
+ arm->cpsr->dirty = false;
+
+ retval = dpm_write_reg(dpm, &cache->reg_list[15], 15);
+ cache->reg_list[15].dirty = false;
+
+ /* flush R0 -- it's *very* dirty by now */
+ retval = dpm_write_reg(dpm, &cache->reg_list[0], 0);
+ cache->reg_list[0].dirty = false;
+
+ /* (void) */ dpm->finish(dpm);
+done:
+ return retval;
+}
+
+/* Returns ARMV4_5_MODE_ANY or temporary mode to use while reading the
+ * specified register ... works around flakiness from ARM core calls.
+ * Caller already filtered out SPSR access; mode is never MODE_SYS
+ * or MODE_ANY.
+ */
+static enum armv4_5_mode dpm_mapmode(struct arm *arm,
+ unsigned num, enum armv4_5_mode mode)
+{
+ enum armv4_5_mode amode = arm->core_mode;
+
+ /* don't switch if the mode is already correct */
+ if (amode == ARMV4_5_MODE_SYS)
+ amode = ARMV4_5_MODE_USR;
+ if (mode == amode)
+ return ARMV4_5_MODE_ANY;
+
+ switch (num) {
+ /* don't switch for non-shadowed registers (r0..r7, r15/pc, cpsr) */
+ case 0 ... 7:
+ case 15:
+ case 16:
+ break;
+ /* r8..r12 aren't shadowed for anything except FIQ */
+ case 8 ... 12:
+ if (mode == ARMV4_5_MODE_FIQ)
+ return mode;
+ break;
+ /* r13/sp, and r14/lr are always shadowed */
+ case 13:
+ case 14:
+ return mode;
+ default:
+ LOG_WARNING("invalid register #%u", num);
+ break;
+ }
+ return ARMV4_5_MODE_ANY;
+}
+
+static int arm_dpm_read_core_reg(struct target *target, struct reg *r,
+ int regnum, enum armv4_5_mode mode)
+{
+ struct arm_dpm *dpm = target_to_arm(target)->dpm;
+ int retval;
+
+ if (regnum < 0 || regnum > 16)
+ return ERROR_INVALID_ARGUMENTS;
+
+ if (regnum == 16) {
+ if (mode != ARMV4_5_MODE_ANY)
+ regnum = 17;
+ } else
+ mode = dpm_mapmode(dpm->arm, regnum, mode);
+
+ /* REVISIT what happens if we try to read SPSR in a core mode
+ * which has no such register?
+ */
+
+ retval = dpm->prepare(dpm);
+ if (retval != ERROR_OK)
+ return retval;
+
+ if (mode != ARMV4_5_MODE_ANY) {
+ retval = dpm_modeswitch(dpm, mode);
+ if (retval != ERROR_OK)
+ goto fail;
+ }
+
+ retval = dpm_read_reg(dpm, r, regnum);
+ /* always clean up, regardless of error */
+
+ if (mode != ARMV4_5_MODE_ANY)
+ /* (void) */ dpm_modeswitch(dpm, ARMV4_5_MODE_ANY);
+
+fail:
+ /* (void) */ dpm->finish(dpm);
+ return retval;
+}
+
+static int arm_dpm_write_core_reg(struct target *target, struct reg *r,
+ int regnum, enum armv4_5_mode mode, uint32_t value)
+{
+ struct arm_dpm *dpm = target_to_arm(target)->dpm;
+ int retval;
+
+
+ if (regnum < 0 || regnum > 16)
+ return ERROR_INVALID_ARGUMENTS;
+
+ if (regnum == 16) {
+ if (mode != ARMV4_5_MODE_ANY)
+ regnum = 17;
+ } else
+ mode = dpm_mapmode(dpm->arm, regnum, mode);
+
+ /* REVISIT what happens if we try to write SPSR in a core mode
+ * which has no such register?
+ */
+
+ retval = dpm->prepare(dpm);
+ if (retval != ERROR_OK)
+ return retval;
+
+ if (mode != ARMV4_5_MODE_ANY) {
+ retval = dpm_modeswitch(dpm, mode);
+ if (retval != ERROR_OK)
+ goto fail;
+ }
+
+ retval = dpm_write_reg(dpm, r, regnum);
+ /* always clean up, regardless of error */
+
+ if (mode != ARMV4_5_MODE_ANY)
+ /* (void) */ dpm_modeswitch(dpm, ARMV4_5_MODE_ANY);
+
+fail:
+ /* (void) */ dpm->finish(dpm);
+ return retval;
+}
+
+static int arm_dpm_full_context(struct target *target)
+{
+ struct arm *arm = target_to_arm(target);
+ struct arm_dpm *dpm = arm->dpm;
+ struct reg_cache *cache = arm->core_cache;
+ int retval;
+ bool did_read;
+
+ retval = dpm->prepare(dpm);
+ if (retval != ERROR_OK)
+ goto done;
+
+ do {
+ enum armv4_5_mode mode = ARMV4_5_MODE_ANY;
+
+ did_read = false;
+
+ /* We "know" arm_dpm_read_current_registers() was called so
+ * the unmapped registers (R0..R7, PC, AND CPSR) and some
+ * view of R8..R14 are current. We also "know" oddities of
+ * register mapping: special cases for R8..R12 and SPSR.
+ *
+ * Pick some mode with unread registers and read them all.
+ * Repeat until done.
+ */
+ for (unsigned i = 0; i < cache->num_regs; i++) {
+ struct arm_reg *r;
+
+ if (cache->reg_list[i].valid)
+ continue;
+ r = cache->reg_list[i].arch_info;
+
+ /* may need to pick a mode and set CPSR */
+ if (!did_read) {
+ did_read = true;
+ mode = r->mode;
+
+ /* For R8..R12 when we've entered debug
+ * state in FIQ mode... patch mode.
+ */
+ if (mode == ARMV4_5_MODE_ANY)
+ mode = ARMV4_5_MODE_USR;
+
+ /* REVISIT error checks */
+ retval = dpm_modeswitch(dpm, mode);
+ }
+ if (r->mode != mode)
+ continue;
+
+ /* CPSR was read, so "R16" must mean SPSR */
+ retval = dpm_read_reg(dpm,
+ &cache->reg_list[i],
+ (r->num == 16) ? 17 : r->num);
+
+ }
+
+ } while (did_read);
+
+ retval = dpm_modeswitch(dpm, ARMV4_5_MODE_ANY);
+ /* (void) */ dpm->finish(dpm);
+done:
+ return retval;
+}
+
+/**
+ * Hooks up this DPM to its associated target; call only once.
+ * Initially this only covers the register cache.
+ */
+int arm_dpm_setup(struct arm_dpm *dpm)
+{
+ struct arm *arm = dpm->arm;
+ struct target *target = arm->target;
+ struct reg_cache *cache;
+
+ arm->dpm = dpm;
+
+ arm->full_context = arm_dpm_full_context;
+ arm->read_core_reg = arm_dpm_read_core_reg;
+ arm->write_core_reg = arm_dpm_write_core_reg;
+
+ cache = armv4_5_build_reg_cache(target, arm);
+ if (!cache)
+ return ERROR_FAIL;
+
+ *register_get_last_cache_p(&target->reg_cache) = cache;
+ return ERROR_OK;
+}
+
+/**
+ * Reinitializes DPM state at the beginning of a new debug session
+ * or after a reset which may have affected the debug module.
+ */
+int arm_dpm_initialize(struct arm_dpm *dpm)
+{
+ /* FIXME -- nothing yet */
+ return ERROR_OK;
+}
diff --git a/src/target/arm_dpm.h b/src/target/arm_dpm.h
new file mode 100644
index 00000000..06b548ec
--- /dev/null
+++ b/src/target/arm_dpm.h
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2009 by David Brownell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __ARM_DPM_H
+#define __ARM_DPM_H
+
+/**
+ * @file
+ * This is the interface to the Debug Programmers Model for ARMv6 and
+ * ARMv7 processors. ARMv6 processors (such as ARM11xx implementations)
+ * introduced a model which became part of the ARMv7-AR architecture
+ * which is most familiar through the Cortex-A series parts. While
+ * specific details differ (like how to write the instruction register),
+ * the high level models easily support shared code because those
+ * registers are compatible.
+ */
+
+/**
+ * This wraps an implementation of DPM primitives. Each interface
+ * provider supplies a structure like this, which is the glue between
+ * upper level code and the lower level hardware access.
+ *
+ * It is a PRELIMINARY AND INCOMPLETE set of primitives, starting with
+ * support for CPU register access.
+ */
+struct arm_dpm {
+ struct arm *arm;
+
+ /** Cache of DIDR */
+ uint32_t didr;
+
+ /** Invoke before a series of instruction operations */
+ int (*prepare)(struct arm_dpm *);
+
+ /** Invoke after a series of instruction operations */
+ int (*finish)(struct arm_dpm *);
+
+ /* WRITE TO CPU */
+
+ /** Runs one instruction, writing data to DCC before execution. */
+ int (*instr_write_data_dcc)(struct arm_dpm *,
+ uint32_t opcode, uint32_t data);
+
+ /** Runs one instruction, writing data to R0 before execution. */
+ int (*instr_write_data_r0)(struct arm_dpm *,
+ uint32_t opcode, uint32_t data);
+
+ /* READ FROM CPU */
+
+ /** Runs one instruction, reading data from dcc after execution. */
+ int (*instr_read_data_dcc)(struct arm_dpm *,
+ uint32_t opcode, uint32_t *data);
+
+ /** Runs one instruction, reading data from r0 after execution. */
+ int (*instr_read_data_r0)(struct arm_dpm *,
+ uint32_t opcode, uint32_t *data);
+
+ // FIXME -- add breakpoint support
+
+ // FIXME -- add watchpoint support (including context-sensitive ones)
+
+ // FIXME -- read/write DCSR methods and symbols
+};
+
+int arm_dpm_setup(struct arm_dpm *dpm);
+int arm_dpm_reinitialize(struct arm_dpm *dpm);
+
+int arm_dpm_read_current_registers(struct arm_dpm *);
+int arm_dpm_write_dirty_registers(struct arm_dpm *);
+
+#endif /* __ARM_DPM_H */
diff --git a/src/target/armv4_5.c b/src/target/armv4_5.c
index 461d2061..da5c75a2 100644
--- a/src/target/armv4_5.c
+++ b/src/target/armv4_5.c
@@ -1233,6 +1233,7 @@ static int arm_full_context(struct target *target)
int armv4_5_init_arch_info(struct target *target, struct arm *armv4_5)
{
target->arch_info = armv4_5;
+ armv4_5->target = target;
armv4_5->common_magic = ARMV4_5_COMMON_MAGIC;
arm_set_cpsr(armv4_5, ARMV4_5_MODE_USR);
diff --git a/src/target/armv4_5.h b/src/target/armv4_5.h
index 49314554..7a6cb618 100644
--- a/src/target/armv4_5.h
+++ b/src/target/armv4_5.h
@@ -101,6 +101,12 @@ struct arm
/** Flag reporting unavailability of the BKPT instruction. */
bool is_armv4;
+ /** Backpointer to the target. */
+ struct target *target;
+
+ /** Handle for the debug module, if one is present. */
+ struct arm_dpm *dpm;
+
/** Handle for the Embedded Trace Module, if one is present. */
struct etm_context *etm;
--
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