[PATCH v4 2/4] AArch64: KGDB: Add Basic KGDB support
vijay.kilari at gmail.com
vijay.kilari at gmail.com
Tue Nov 5 03:45:44 EST 2013
From: Vijaya Kumar K <Vijaya.Kumar at caviumnetworks.com>
Add KGDB debug support for kernel debugging.
With this patch, basic KGDB debugging is possible.GDB register
layout is updated and GDB tool can establish connection with
target and can set/clear breakpoints.
Signed-off-by: Vijaya Kumar K <Vijaya.Kumar at caviumnetworks.com>
---
arch/arm64/include/asm/debug-monitors.h | 46 +++++
arch/arm64/include/asm/kgdb.h | 86 +++++++++
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/kgdb.c | 289 +++++++++++++++++++++++++++++++
4 files changed, 422 insertions(+)
diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h
index 6231479..d00c440 100644
--- a/arch/arm64/include/asm/debug-monitors.h
+++ b/arch/arm64/include/asm/debug-monitors.h
@@ -26,6 +26,52 @@
#define DBG_ESR_EVT_HWWP 0x2
#define DBG_ESR_EVT_BRK 0x6
+/*
+ * Break point instruction encoding
+ */
+#define BREAK_INSTR_SIZE 4
+
+/*
+ * ESR values expected for dynamic and compile time BRK instruction
+ */
+#define DBG_ESR_VAL_BRK(x) (0xf2000000 | ((x) & 0xfffff))
+
+/*
+ * #imm16 values used for BRK instruction generation
+ * 0: for dynamic BRK instruction
+ * 1: for compile time BRK instruction
+ */
+#define KGDB_DYN_DGB_BRK_IMM 0
+#define KDBG_COMPILED_DBG_BRK_IMM 1
+
+/*
+ * BRK instruction encoding
+ * The #imm16 value should be placed at bits[20:5] within BRK ins
+ */
+#define AARCH64_BREAK_MON 0xd4200000
+
+/*
+ * Extract byte from BRK instruction
+ */
+#define KGDB_DYN_DGB_BRK_INS_BYTE(x) \
+ ((((AARCH64_BREAK_MON) & 0xffe0001f) >> (x * 8)) & 0xff)
+
+/*
+ * Extract byte from BRK #imm16
+ */
+#define KGBD_DYN_DGB_BRK_IMM_BYTE(x) \
+ (((((KGDB_DYN_DGB_BRK_IMM) & 0xffff) << 5) >> (x * 8)) & 0xff)
+
+#define KGDB_DYN_DGB_BRK_BYTE(x) \
+ (KGDB_DYN_DGB_BRK_INS_BYTE(x) | KGBD_DYN_DGB_BRK_IMM_BYTE(x))
+
+#define KGDB_DYN_BRK_INS_BYTE0 KGDB_DYN_DGB_BRK_BYTE(0)
+#define KGDB_DYN_BRK_INS_BYTE1 KGDB_DYN_DGB_BRK_BYTE(1)
+#define KGDB_DYN_BRK_INS_BYTE2 KGDB_DYN_DGB_BRK_BYTE(2)
+#define KGDB_DYN_BRK_INS_BYTE3 KGDB_DYN_DGB_BRK_BYTE(3)
+
+#define CACHE_FLUSH_IS_SAFE 1
+
enum debug_el {
DBG_ACTIVE_EL0 = 0,
DBG_ACTIVE_EL1,
diff --git a/arch/arm64/include/asm/kgdb.h b/arch/arm64/include/asm/kgdb.h
new file mode 100644
index 0000000..5c9faa9
--- /dev/null
+++ b/arch/arm64/include/asm/kgdb.h
@@ -0,0 +1,86 @@
+/*
+ * AArch64 KGDB support
+ *
+ * Based on arch/arm/include/kgdb.h
+ *
+ * Copyright (C) 2013 Cavium Inc.
+ * Author: Vijaya Kumar K <vijaya.kumar at caviumnetworks.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ARM_KGDB_H__
+#define __ARM_KGDB_H__
+
+#include <linux/ptrace.h>
+#include <asm/debug-monitors.h>
+
+#ifndef __ASSEMBLY__
+
+static inline void arch_kgdb_breakpoint(void)
+{
+ asm ("brk %0" :: "I" (KDBG_COMPILED_DBG_BRK_IMM));
+}
+
+extern void kgdb_handle_bus_error(void);
+extern int kgdb_fault_expected;
+
+#endif /* !__ASSEMBLY__ */
+
+/*
+ * gdb is expecting the following registers layout.
+ *
+ * General purpose regs:
+ * r0-r30: 64 bit
+ * sp,pc : 64 bit
+ * pstate : 32 bit
+ * Total: 34
+ * FPU regs:
+ * f0-f31: 128 bit
+ * Total: 32
+ * Extra regs
+ * fpsr & fpcr: 32 bit
+ * Total: 2
+ *
+ */
+
+#define _GP_REGS 34
+#define _FP_REGS 32
+#define _EXTRA_REGS 2
+/*
+ * general purpose registers size in bytes.
+ * pstate is only 4 bytes. subtract 4 bytes
+ */
+#define GP_REG_BYTES ((_GP_REGS * 8) - 4)
+#define DBG_MAX_REG_NUM (_GP_REGS + _FP_REGS + _EXTRA_REGS)
+
+/*
+ * Size of I/O buffer for gdb packet.
+ * considering to hold all register contents, size is set to 1024
+ */
+
+#define BUFMAX 1024
+
+/*
+ * Number of bytes required for gdb_regs buffer.
+ * _GP_REGS: 8 bytes, _FP_REGS: 16 bytes and _EXTRA_REGS: 4 bytes each
+ * pstate reg is only 4 bytes. subtract 4 from size contributed
+ * by _GP_REGS.
+ * GDB fails to connect for size beyond this with error
+ * "'g' packet reply is too long"
+ */
+
+#define NUMREGBYTES (((_GP_REGS * 8) - 4) + (_FP_REGS * 16) + \
+ (_EXTRA_REGS * 4))
+
+#endif /* __ASM_KGDB_H__ */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 7b4b564..69613bb 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -18,6 +18,7 @@ arm64-obj-$(CONFIG_SMP) += smp.o smp_spin_table.o smp_psci.o
arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o
arm64-obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
+arm64-obj-$(CONFIG_KGDB) += kgdb.o
obj-y += $(arm64-obj-y) vdso/
obj-m += $(arm64-obj-m)
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
new file mode 100644
index 0000000..ec624bc
--- /dev/null
+++ b/arch/arm64/kernel/kgdb.c
@@ -0,0 +1,289 @@
+/*
+ * AArch64 KGDB support
+ *
+ * Based on arch/arm/kernel/kgdb.c
+ *
+ * Copyright (C) 2013 Cavium Inc.
+ * Author: Vijaya Kumar K <vijaya.kumar at caviumnetworks.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/irq.h>
+#include <linux/kdebug.h>
+#include <linux/kgdb.h>
+#include <asm/traps.h>
+
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
+ { "x0", 8, offsetof(struct pt_regs, regs[0])},
+ { "x1", 8, offsetof(struct pt_regs, regs[1])},
+ { "x2", 8, offsetof(struct pt_regs, regs[2])},
+ { "x3", 8, offsetof(struct pt_regs, regs[3])},
+ { "x4", 8, offsetof(struct pt_regs, regs[4])},
+ { "x5", 8, offsetof(struct pt_regs, regs[5])},
+ { "x6", 8, offsetof(struct pt_regs, regs[6])},
+ { "x7", 8, offsetof(struct pt_regs, regs[7])},
+ { "x8", 8, offsetof(struct pt_regs, regs[8])},
+ { "x9", 8, offsetof(struct pt_regs, regs[9])},
+ { "x10", 8, offsetof(struct pt_regs, regs[10])},
+ { "x11", 8, offsetof(struct pt_regs, regs[11])},
+ { "x12", 8, offsetof(struct pt_regs, regs[12])},
+ { "x13", 8, offsetof(struct pt_regs, regs[13])},
+ { "x14", 8, offsetof(struct pt_regs, regs[14])},
+ { "x15", 8, offsetof(struct pt_regs, regs[15])},
+ { "x16", 8, offsetof(struct pt_regs, regs[16])},
+ { "x17", 8, offsetof(struct pt_regs, regs[17])},
+ { "x18", 8, offsetof(struct pt_regs, regs[18])},
+ { "x19", 8, offsetof(struct pt_regs, regs[19])},
+ { "x20", 8, offsetof(struct pt_regs, regs[20])},
+ { "x21", 8, offsetof(struct pt_regs, regs[21])},
+ { "x22", 8, offsetof(struct pt_regs, regs[22])},
+ { "x23", 8, offsetof(struct pt_regs, regs[23])},
+ { "x24", 8, offsetof(struct pt_regs, regs[24])},
+ { "x25", 8, offsetof(struct pt_regs, regs[25])},
+ { "x26", 8, offsetof(struct pt_regs, regs[26])},
+ { "x27", 8, offsetof(struct pt_regs, regs[27])},
+ { "x28", 8, offsetof(struct pt_regs, regs[28])},
+ { "x29", 8, offsetof(struct pt_regs, regs[29])},
+ { "x30", 8, offsetof(struct pt_regs, regs[30])},
+ { "sp", 8, offsetof(struct pt_regs, sp)},
+ { "pc", 8, offsetof(struct pt_regs, pc)},
+ { "pstate", 4, offsetof(struct pt_regs, pstate)},
+ { "v0", 16, -1 },
+ { "v1", 16, -1 },
+ { "v2", 16, -1 },
+ { "v3", 16, -1 },
+ { "v4", 16, -1 },
+ { "v5", 16, -1 },
+ { "v6", 16, -1 },
+ { "v7", 16, -1 },
+ { "v8", 16, -1 },
+ { "v9", 16, -1 },
+ { "v10", 16, -1 },
+ { "v11", 16, -1 },
+ { "v12", 16, -1 },
+ { "v13", 16, -1 },
+ { "v14", 16, -1 },
+ { "v15", 16, -1 },
+ { "v16", 16, -1 },
+ { "v17", 16, -1 },
+ { "v18", 16, -1 },
+ { "v19", 16, -1 },
+ { "v20", 16, -1 },
+ { "v21", 16, -1 },
+ { "v22", 16, -1 },
+ { "v23", 16, -1 },
+ { "v24", 16, -1 },
+ { "v25", 16, -1 },
+ { "v26", 16, -1 },
+ { "v27", 16, -1 },
+ { "v28", 16, -1 },
+ { "v29", 16, -1 },
+ { "v30", 16, -1 },
+ { "v31", 16, -1 },
+ { "fpsr", 4, -1 },
+ { "fpcr", 4, -1 },
+};
+
+char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
+{
+ if (regno >= DBG_MAX_REG_NUM || regno < 0)
+ return NULL;
+
+ if (dbg_reg_def[regno].offset != -1)
+ memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
+ dbg_reg_def[regno].size);
+ else
+ memset(mem, 0, dbg_reg_def[regno].size);
+ return dbg_reg_def[regno].name;
+}
+
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
+{
+ if (regno >= DBG_MAX_REG_NUM || regno < 0)
+ return -EINVAL;
+
+ if (dbg_reg_def[regno].offset != -1)
+ memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
+ dbg_reg_def[regno].size);
+ return 0;
+}
+
+void
+sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
+{
+ struct pt_regs *thread_regs;
+
+ /* Initialize to zero */
+ memset((char *)gdb_regs, 0, NUMREGBYTES);
+ thread_regs = task_pt_regs(task);
+ memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
+}
+
+void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
+{
+ regs->pc = pc;
+}
+
+static int compiled_break;
+
+int kgdb_arch_handle_exception(int exception_vector, int signo,
+ int err_code, char *remcom_in_buffer,
+ char *remcom_out_buffer,
+ struct pt_regs *linux_regs)
+{
+ unsigned long addr;
+ char *ptr;
+ int err;
+
+ switch (remcom_in_buffer[0]) {
+ case 'D':
+ case 'k':
+ /*
+ * Packet D (Detach), k (kill). No special handling
+ * is required here
+ */
+ err = 0;
+ break;
+ case 'c':
+ /*
+ * Packet c (Continue) to continue executing.
+ * Set pc to required address.
+ * Try to read optional parameter and set pc.
+ * If this was a compiled breakpoint, we need to move
+ * to the next instruction else we will just breakpoint
+ * over and over again.
+ */
+ ptr = &remcom_in_buffer[1];
+ if (kgdb_hex2long(&ptr, &addr))
+ kgdb_arch_set_pc(linux_regs, addr);
+ else if (compiled_break == 1)
+ kgdb_arch_set_pc(linux_regs, linux_regs->pc + 4);
+
+ compiled_break = 0;
+
+ err = 0;
+ break;
+ default:
+ err = -1;
+ }
+ return err;
+}
+
+static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
+{
+ kgdb_handle_exception(1, SIGTRAP, 0, regs);
+ return 0;
+}
+
+static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
+{
+ compiled_break = 1;
+ kgdb_handle_exception(1, SIGTRAP, 0, regs);
+
+ return 0;
+}
+
+static struct break_hook kgdb_brkpt_hook = {
+ .esr_mask = 0xffffffff,
+ .esr_val = DBG_ESR_VAL_BRK(KGDB_DYN_DGB_BRK_IMM),
+ .fn = kgdb_brk_fn
+};
+
+static struct break_hook kgdb_compiled_brkpt_hook = {
+ .esr_mask = 0xffffffff,
+ .esr_val = DBG_ESR_VAL_BRK(KDBG_COMPILED_DBG_BRK_IMM),
+ .fn = kgdb_compiled_brk_fn
+};
+
+static void kgdb_call_nmi_hook(void *ignored)
+{
+ kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
+}
+
+void kgdb_roundup_cpus(unsigned long flags)
+{
+ local_irq_enable();
+ smp_call_function(kgdb_call_nmi_hook, NULL, 0);
+ local_irq_disable();
+}
+
+static int __kgdb_notify(struct die_args *args, unsigned long cmd)
+{
+ struct pt_regs *regs = args->regs;
+
+ if (kgdb_handle_exception(1, args->signr, cmd, regs))
+ return NOTIFY_DONE;
+ return NOTIFY_STOP;
+}
+
+static int
+kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
+{
+ unsigned long flags;
+ int ret;
+
+ local_irq_save(flags);
+ ret = __kgdb_notify(ptr, cmd);
+ local_irq_restore(flags);
+
+ return ret;
+}
+
+static struct notifier_block kgdb_notifier = {
+ .notifier_call = kgdb_notify,
+ .priority = -INT_MAX,
+};
+
+/*
+ * kgdb_arch_init - Perform any architecture specific initalization.
+ * This function will handle the initalization of any architecture
+ * specific callbacks.
+ */
+int kgdb_arch_init(void)
+{
+ int ret = register_die_notifier(&kgdb_notifier);
+
+ if (ret != 0)
+ return ret;
+
+ register_break_hook(&kgdb_brkpt_hook);
+ register_break_hook(&kgdb_compiled_brkpt_hook);
+
+ return 0;
+}
+
+/*
+ * kgdb_arch_exit - Perform any architecture specific uninitalization.
+ * This function will handle the uninitalization of any architecture
+ * specific callbacks, for dynamic registration and unregistration.
+ */
+void kgdb_arch_exit(void)
+{
+ unregister_break_hook(&kgdb_brkpt_hook);
+ unregister_break_hook(&kgdb_compiled_brkpt_hook);
+ unregister_die_notifier(&kgdb_notifier);
+}
+
+/*
+ * ARM instructions are always in LE.
+ * Break instruction is encoded in LE format
+ */
+struct kgdb_arch arch_kgdb_ops = {
+ .gdb_bpt_instr = {
+ KGDB_DYN_BRK_INS_BYTE0,
+ KGDB_DYN_BRK_INS_BYTE1,
+ KGDB_DYN_BRK_INS_BYTE2,
+ KGDB_DYN_BRK_INS_BYTE3,
+ }
+};
--
1.7.9.5
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