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Subject[RFC Patch v1 46/55] ARC: kgdb support
Date
From: Mischa Jonker <mjonker@synopsys.com>

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/Kconfig | 5 +-
arch/arc/include/asm/kgdb.h | 61 +++++++++++++
arch/arc/kernel/Makefile | 2 +
arch/arc/kernel/kgdb.c | 205 +++++++++++++++++++++++++++++++++++++++++++
arch/arc/kernel/traps.c | 6 ++
5 files changed, 277 insertions(+), 2 deletions(-)
create mode 100644 arch/arc/include/asm/kgdb.h
create mode 100644 arch/arc/kernel/kgdb.c

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 81d78fc..b878d3e 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -20,6 +20,7 @@ config ARC
select GENERIC_KERNEL_THREAD
select GENERIC_PENDING_IRQ if SMP
select GENERIC_SMP_IDLE_THREAD
+ select HAVE_ARCH_KGDB
select HAVE_ARCH_TRACEHOOK
select HAVE_GENERIC_HARDIRQS
select HAVE_KPROBES
@@ -383,12 +384,12 @@ config ARC_DW2_UNWIND

config ARC_DBG_TLB_PARANOIA
bool "Paranoia Checks in Low Level TLB Handlers"
- depends on ARC_DBG && !SMP
+ depends on ARC_DBG
default n

config ARC_DBG_EVENT_TIMELINE
bool "Low level event capture"
- depends on ARC_DBG
+ depends on ARC_DBG && !SMP
default n
help
Capture low level events: IRQ/Trap/Exception
diff --git a/arch/arc/include/asm/kgdb.h b/arch/arc/include/asm/kgdb.h
new file mode 100644
index 0000000..f3c4934
--- /dev/null
+++ b/arch/arc/include/asm/kgdb.h
@@ -0,0 +1,61 @@
+/*
+ * kgdb support for ARC
+ *
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.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.
+ */
+
+#ifndef __ARC_KGDB_H__
+#define __ARC_KGDB_H__
+
+#ifdef CONFIG_KGDB
+
+#include <asm/user.h>
+
+/* to ensure compatibility with Linux 2.6.35, we don't implement the get/set
+ * register API yet */
+#undef DBG_MAX_REG_NUM
+
+#define GDB_MAX_REGS 39
+
+#define BREAK_INSTR_SIZE 2
+#define CACHE_FLUSH_IS_SAFE 1
+#define NUMREGBYTES (GDB_MAX_REGS * 4)
+#define BUFMAX 2048
+
+static inline void arch_kgdb_breakpoint(void)
+{
+ __asm__ __volatile__ ("trap_s 0x4\n");
+}
+
+extern void kgdb_trap(struct pt_regs *regs, int param);
+
+enum arc700_linux_regnums {
+ _R0 = 0,
+ _R1, _R2, _R3, _R4, _R5, _R6, _R7, _R8, _R9, _R10, _R11, _R12, _R13,
+ _R14, _R15, _R16, _R17, _R18, _R19, _R20, _R21, _R22, _R23, _R24,
+ _R25, _R26,
+ _BTA = 27,
+ _LP_START = 28,
+ _LP_END = 29,
+ _LP_COUNT = 30,
+ _STATUS32 = 31,
+ _BLINK = 32,
+ _FP = 33,
+ __SP = 34,
+ _EFA = 35,
+ _RET = 36,
+ _ORIG_R8 = 37,
+ _STOP_PC = 38
+};
+
+#else
+static inline void kgdb_trap(struct pt_regs *regs, int param)
+{
+}
+#endif
+
+#endif /* __ARC_KGDB_H__ */
diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index 52ef6ce..a2b7493 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -17,6 +17,8 @@ obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_ARC_DW2_UNWIND) += unwind.o
obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_ARC_MISALIGN_ACCESS) += unaligned.o
+obj-$(CONFIG_KGDB) += kgdb.o
+
obj-$(CONFIG_ARC_FPU_SAVE_RESTORE) += fpu.o
CFLAGS_fpu.o += -mdpfp

diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c
new file mode 100644
index 0000000..2888ba5
--- /dev/null
+++ b/arch/arc/kernel/kgdb.c
@@ -0,0 +1,205 @@
+/*
+ * kgdb support for ARC
+ *
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.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.
+ */
+
+#include <linux/kgdb.h>
+#include <asm/disasm.h>
+#include <asm/cacheflush.h>
+
+static void to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs,
+ struct callee_regs *cregs)
+{
+ int regno;
+
+ for (regno = 0; regno <= 26; regno++)
+ gdb_regs[_R0 + regno] = get_reg(regno, kernel_regs, cregs);
+
+ for (regno = 27; regno < GDB_MAX_REGS; regno++)
+ gdb_regs[regno] = 0;
+
+ gdb_regs[_FP] = kernel_regs->fp;
+ gdb_regs[__SP] = kernel_regs->sp;
+ gdb_regs[_BLINK] = kernel_regs->blink;
+ gdb_regs[_RET] = kernel_regs->ret;
+ gdb_regs[_STATUS32] = kernel_regs->status32;
+ gdb_regs[_LP_COUNT] = kernel_regs->lp_count;
+ gdb_regs[_LP_END] = kernel_regs->lp_end;
+ gdb_regs[_LP_START] = kernel_regs->lp_start;
+ gdb_regs[_BTA] = kernel_regs->bta;
+ gdb_regs[_STOP_PC] = kernel_regs->ret;
+}
+
+static void from_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs,
+ struct callee_regs *cregs)
+{
+ int regno;
+
+ for (regno = 0; regno <= 26; regno++)
+ set_reg(regno, gdb_regs[regno + _R0], kernel_regs, cregs);
+
+ kernel_regs->fp = gdb_regs[_FP];
+ kernel_regs->sp = gdb_regs[__SP];
+ kernel_regs->blink = gdb_regs[_BLINK];
+ kernel_regs->ret = gdb_regs[_RET];
+ kernel_regs->status32 = gdb_regs[_STATUS32];
+ kernel_regs->lp_count = gdb_regs[_LP_COUNT];
+ kernel_regs->lp_end = gdb_regs[_LP_END];
+ kernel_regs->lp_start = gdb_regs[_LP_START];
+ kernel_regs->bta = gdb_regs[_BTA];
+}
+
+
+void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
+{
+ to_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *)
+ current->thread.callee_reg);
+}
+
+void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
+{
+ from_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *)
+ current->thread.callee_reg);
+}
+
+void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs,
+ struct task_struct *task)
+{
+ if (task)
+ to_gdb_regs(gdb_regs, task_pt_regs(task),
+ (struct callee_regs *) task->thread.callee_reg);
+}
+
+struct single_step_data_t {
+ uint16_t opcode[2];
+ unsigned long address[2];
+ int is_branch;
+ int armed;
+} single_step_data;
+
+static void undo_single_step(struct pt_regs *regs)
+{
+ if (single_step_data.armed) {
+ int i;
+
+ for (i = 0; i < (single_step_data.is_branch ? 2 : 1); i++) {
+ memcpy((void *) single_step_data.address[i],
+ &single_step_data.opcode[i],
+ BREAK_INSTR_SIZE);
+
+ flush_icache_range(single_step_data.address[i],
+ single_step_data.address[i] +
+ BREAK_INSTR_SIZE);
+ }
+ single_step_data.armed = 0;
+ }
+}
+
+static void place_trap(unsigned long address, void *save)
+{
+ memcpy(save, (void *) address, BREAK_INSTR_SIZE);
+ memcpy((void *) address, &arch_kgdb_ops.gdb_bpt_instr,
+ BREAK_INSTR_SIZE);
+ flush_icache_range(address, address + BREAK_INSTR_SIZE);
+}
+
+static void do_single_step(struct pt_regs *regs)
+{
+ single_step_data.is_branch = disasm_next_pc((unsigned long)
+ regs->ret, regs, (struct callee_regs *)
+ current->thread.callee_reg,
+ &single_step_data.address[0],
+ &single_step_data.address[1]);
+
+ place_trap(single_step_data.address[0], &single_step_data.opcode[0]);
+
+ if (single_step_data.is_branch) {
+ place_trap(single_step_data.address[1],
+ &single_step_data.opcode[1]);
+ }
+
+ single_step_data.armed++;
+}
+
+int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
+ char *remcomInBuffer, char *remcomOutBuffer,
+ struct pt_regs *regs)
+{
+ unsigned long addr;
+ char *ptr;
+
+ undo_single_step(regs);
+
+ switch (remcomInBuffer[0]) {
+ case 's':
+ case 'c':
+ ptr = &remcomInBuffer[1];
+ if (kgdb_hex2long(&ptr, &addr))
+ regs->ret = addr;
+
+ case 'D':
+ case 'k':
+ atomic_set(&kgdb_cpu_doing_single_step, -1);
+
+ if (remcomInBuffer[0] == 's') {
+ do_single_step(regs);
+ atomic_set(&kgdb_cpu_doing_single_step,
+ smp_processor_id());
+ }
+
+ return 0;
+ }
+ return -1;
+}
+
+unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+int kgdb_arch_init(void)
+{
+ single_step_data.armed = 0;
+ return 0;
+}
+
+void kgdb_trap(struct pt_regs *regs, int param)
+{
+ /* trap_s 3 is used for breakpoints that overwrite existing
+ * instructions, while trap_s 4 is used for compiled breakpoints.
+ *
+ * with trap_s 3 breakpoints the original instruction needs to be
+ * restored and continuation needs to start at the location of the
+ * breakpoint.
+ *
+ * with trap_s 4 (compiled) breakpoints, continuation needs to
+ * start after the breakpoint.
+ */
+ if (param == 3)
+ instruction_pointer(regs) -= BREAK_INSTR_SIZE;
+
+ kgdb_handle_exception(1, SIGTRAP, 0, regs);
+}
+
+void kgdb_arch_exit(void)
+{
+}
+
+void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+ instruction_pointer(regs) = ip;
+}
+
+struct kgdb_arch arch_kgdb_ops = {
+ /* breakpoint instruction: TRAP_S 0x3 */
+#ifdef CONFIG_CPU_BIG_ENDIAN
+ .gdb_bpt_instr = {0x78, 0x7e},
+#else
+ .gdb_bpt_instr = {0x7e, 0x78},
+#endif
+};
diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
index d2bc5bd..689c3fb 100644
--- a/arch/arc/kernel/traps.c
+++ b/arch/arc/kernel/traps.c
@@ -20,6 +20,7 @@
#include <asm/setup.h>
#include <asm/kprobes.h>
#include <asm/unaligned.h>
+#include <asm/kgdb.h>

void __init trap_init(void)
{
@@ -141,6 +142,11 @@ void do_non_swi_trap(unsigned long cause, unsigned long address,
trap_is_kprobe(param, address, regs);
break;

+ case 3:
+ case 4:
+ kgdb_trap(regs, param);
+ break;
+
default:
break;
}
--
1.7.4.1


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