7 files changed, 316 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c7ad324ddf2c..d048f6887d0b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -12,6 +12,7 @@ config ARM
         select RTC_LIB
         select SYS_SUPPORTS_APM_EMULATION
         select HAVE_OPROFILE
+        select HAVE_ARCH_KGDB
         select HAVE_KPROBES if (!XIP_KERNEL)
         select HAVE_KRETPROBES if (HAVE_KPROBES)
         select HAVE_FTRACE if (!XIP_KERNEL)
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index eb9092ca8008..1d296fc8494e 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_KPROBES)		+= kprobes.o kprobes-decode.o
 obj-$(CONFIG_ATAGS_PROC)        += atags.o
 obj-$(CONFIG_OABI_COMPAT)       += sys_oabi-compat.o
 obj-$(CONFIG_ARM_THUMBEE)       += thumbee.o
+obj-$(CONFIG_KGDB)              += kgdb.o
 
 obj-$(CONFIG_CRUNCH)            += crunch.o crunch-bits.o
 AFLAGS_crunch-bits.o            := -Wa,-mcpu=ep9312
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
new file mode 100644
index 000000000000..aaffaecffcd1
--- /dev/null
+++ b/arch/arm/kernel/kgdb.c
@@ -0,0 +1,201 @@
+/*
+ * arch/arm/kernel/kgdb.c
+ *
+ * ARM KGDB support
+ *
+ * Copyright (c) 2002-2004 MontaVista Software, Inc
+ * Copyright (c) 2008 Wind River Systems, Inc.
+ *
+ * Authors:  George Davis <davis_g@mvista.com>
+ *           Deepak Saxena <dsaxena@plexity.net>
+ */
+#include <linux/kgdb.h>
+#include <asm/traps.h>
+
+/* Make a local copy of the registers passed into the handler (bletch) */
+void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
+{
+        int regno;
+
+        /* Initialize all to zero. */
+        for (regno = 0; regno < GDB_MAX_REGS; regno++)
+                gdb_regs[regno] = 0;
+
+        gdb_regs[_R0]           = kernel_regs->ARM_r0;
+        gdb_regs[_R1]           = kernel_regs->ARM_r1;
+        gdb_regs[_R2]           = kernel_regs->ARM_r2;
+        gdb_regs[_R3]           = kernel_regs->ARM_r3;
+        gdb_regs[_R4]           = kernel_regs->ARM_r4;
+        gdb_regs[_R5]           = kernel_regs->ARM_r5;
+        gdb_regs[_R6]           = kernel_regs->ARM_r6;
+        gdb_regs[_R7]           = kernel_regs->ARM_r7;
+        gdb_regs[_R8]           = kernel_regs->ARM_r8;
+        gdb_regs[_R9]           = kernel_regs->ARM_r9;
+        gdb_regs[_R10]          = kernel_regs->ARM_r10;
+        gdb_regs[_FP]           = kernel_regs->ARM_fp;
+        gdb_regs[_IP]           = kernel_regs->ARM_ip;
+        gdb_regs[_SPT]          = kernel_regs->ARM_sp;
+        gdb_regs[_LR]           = kernel_regs->ARM_lr;
+        gdb_regs[_PC]           = kernel_regs->ARM_pc;
+        gdb_regs[_CPSR]         = kernel_regs->ARM_cpsr;
+}
+
+/* Copy local gdb registers back to kgdb regs, for later copy to kernel */
+void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
+{
+        kernel_regs->ARM_r0     = gdb_regs[_R0];
+        kernel_regs->ARM_r1     = gdb_regs[_R1];
+        kernel_regs->ARM_r2     = gdb_regs[_R2];
+        kernel_regs->ARM_r3     = gdb_regs[_R3];
+        kernel_regs->ARM_r4     = gdb_regs[_R4];
+        kernel_regs->ARM_r5     = gdb_regs[_R5];
+        kernel_regs->ARM_r6     = gdb_regs[_R6];
+        kernel_regs->ARM_r7     = gdb_regs[_R7];
+        kernel_regs->ARM_r8     = gdb_regs[_R8];
+        kernel_regs->ARM_r9     = gdb_regs[_R9];
+        kernel_regs->ARM_r10    = gdb_regs[_R10];
+        kernel_regs->ARM_fp     = gdb_regs[_FP];
+        kernel_regs->ARM_ip     = gdb_regs[_IP];
+        kernel_regs->ARM_sp     = gdb_regs[_SPT];
+        kernel_regs->ARM_lr     = gdb_regs[_LR];
+        kernel_regs->ARM_pc     = gdb_regs[_PC];
+        kernel_regs->ARM_cpsr   = gdb_regs[_CPSR];
+}
+
+void
+sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
+{
+        struct pt_regs *thread_regs;
+        int regno;
+
+        /* Just making sure... */
+        if (task == NULL)
+                return;
+
+        /* Initialize to zero */
+        for (regno = 0; regno < GDB_MAX_REGS; regno++)
+                gdb_regs[regno] = 0;
+
+        /* Otherwise, we have only some registers from switch_to() */
+        thread_regs             = task_pt_regs(task);
+        gdb_regs[_R0]           = thread_regs->ARM_r0;
+        gdb_regs[_R1]           = thread_regs->ARM_r1;
+        gdb_regs[_R2]           = thread_regs->ARM_r2;
+        gdb_regs[_R3]           = thread_regs->ARM_r3;
+        gdb_regs[_R4]           = thread_regs->ARM_r4;
+        gdb_regs[_R5]           = thread_regs->ARM_r5;
+        gdb_regs[_R6]           = thread_regs->ARM_r6;
+        gdb_regs[_R7]           = thread_regs->ARM_r7;
+        gdb_regs[_R8]           = thread_regs->ARM_r8;
+        gdb_regs[_R9]           = thread_regs->ARM_r9;
+        gdb_regs[_R10]          = thread_regs->ARM_r10;
+        gdb_regs[_FP]           = thread_regs->ARM_fp;
+        gdb_regs[_IP]           = thread_regs->ARM_ip;
+        gdb_regs[_SPT]          = thread_regs->ARM_sp;
+        gdb_regs[_LR]           = thread_regs->ARM_lr;
+        gdb_regs[_PC]           = thread_regs->ARM_pc;
+        gdb_regs[_CPSR]         = thread_regs->ARM_cpsr;
+}
+
+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;
+
+        switch (remcom_in_buffer[0]) {
+        case 'D':
+        case 'k':
+        case 'c':
+                kgdb_contthread = NULL;
+
+                /*
+                 * Try to read optional parameter, pc unchanged if no parm.
+                 * If this was a compiled breakpoint, we need to move
+                 * to the next instruction or we will just breakpoint
+                 * over and over again.
+                 */
+                ptr = &remcom_in_buffer[1];
+                if (kgdb_hex2long(&ptr, &addr))
+                        linux_regs->ARM_pc = addr;
+                else if (compiled_break == 1)
+                        linux_regs->ARM_pc += 4;
+
+                compiled_break = 0;
+
+                return 0;
+        }
+
+        return -1;
+}
+
+static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
+{
+        kgdb_handle_exception(1, SIGTRAP, 0, regs);
+
+        return 0;
+}
+
+static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
+{
+        compiled_break = 1;
+        kgdb_handle_exception(1, SIGTRAP, 0, regs);
+
+        return 0;
+}
+
+static struct undef_hook kgdb_brkpt_hook = {
+        .instr_mask             = 0xffffffff,
+        .instr_val              = KGDB_BREAKINST,
+        .fn                     = kgdb_brk_fn
+};
+
+static struct undef_hook kgdb_compiled_brkpt_hook = {
+        .instr_mask             = 0xffffffff,
+        .instr_val              = KGDB_COMPILED_BREAK,
+        .fn                     = kgdb_compiled_brk_fn
+};
+
+/**
+ *      kgdb_arch_init - Perform any architecture specific initalization.
+ *
+ *      This function will handle the initalization of any architecture
+ *      specific callbacks.
+ */
+int kgdb_arch_init(void)
+{
+        register_undef_hook(&kgdb_brkpt_hook);
+        register_undef_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_undef_hook(&kgdb_brkpt_hook);
+        unregister_undef_hook(&kgdb_compiled_brkpt_hook);
+}
+
+/*
+ * Register our undef instruction hooks with ARM undef core.
+ * We regsiter a hook specifically looking for the KGB break inst
+ * and we handle the normal undef case within the do_undefinstr
+ * handler.
+ */
+struct kgdb_arch arch_kgdb_ops = {
+#ifndef __ARMEB__
+        .gdb_bpt_instr          = {0xfe, 0xde, 0xff, 0xe7}
+#else /* ! __ARMEB__ */
+        .gdb_bpt_instr          = {0xe7, 0xff, 0xde, 0xfe}
+#endif
+};
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index b7b0720bc1bb..38f0e7940a13 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -36,6 +36,7 @@
 #include <asm/mach/arch.h>
 #include <asm/mach/irq.h>
 #include <asm/mach/time.h>
+#include <asm/traps.h>
 
 #include "compat.h"
 #include "atags.h"
@@ -853,6 +854,7 @@ void __init setup_arch(char **cmdline_p)
         conswitchp = &dummy_con;
 #endif
 #endif
+        early_trap_init();
 }
 
 
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 5595fdd75e82..7277aef83098 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -708,6 +708,11 @@ EXPORT_SYMBOL(abort);
 
 void __init trap_init(void)
 {
+        return;
+}
+
+void __init early_trap_init(void)
+{
         unsigned long vectors = CONFIG_VECTORS_BASE;
         extern char __stubs_start[], __stubs_end[];
         extern char __vectors_start[], __vectors_end[];
diff --git a/include/asm-arm/kgdb.h b/include/asm-arm/kgdb.h
new file mode 100644
index 000000000000..67af4b841984
--- /dev/null
+++ b/include/asm-arm/kgdb.h
@@ -0,0 +1,104 @@
+/*
+ * ARM KGDB support
+ *
+ * Author: Deepak Saxena <dsaxena@mvista.com>
+ *
+ * Copyright (C) 2002 MontaVista Software Inc.
+ *
+ */
+
+#ifndef __ARM_KGDB_H__
+#define __ARM_KGDB_H__
+
+#include <linux/ptrace.h>
+
+/*
+ * GDB assumes that we're a user process being debugged, so
+ * it will send us an SWI command to write into memory as the
+ * debug trap. When an SWI occurs, the next instruction addr is
+ * placed into R14_svc before jumping to the vector trap.
+ * This doesn't work for kernel debugging as we are already in SVC
+ * we would loose the kernel's LR, which is a bad thing. This
+ * is  bad thing.
+ *
+ * By doing this as an undefined instruction trap, we force a mode
+ * switch from SVC to UND mode, allowing us to save full kernel state.
+ *
+ * We also define a KGDB_COMPILED_BREAK which can be used to compile
+ * in breakpoints. This is important for things like sysrq-G and for
+ * the initial breakpoint from trap_init().
+ *
+ * Note to ARM HW designers: Add real trap support like SH && PPC to
+ * make our lives much much simpler. :)
+ */
+#define BREAK_INSTR_SIZE        4
+#define GDB_BREAKINST           0xef9f0001
+#define KGDB_BREAKINST          0xe7ffdefe
+#define KGDB_COMPILED_BREAK     0xe7ffdeff
+#define CACHE_FLUSH_IS_SAFE     1
+
+#ifndef __ASSEMBLY__
+
+static inline void arch_kgdb_breakpoint(void)
+{
+        asm(".word 0xe7ffdeff");
+}
+
+extern void kgdb_handle_bus_error(void);
+extern int kgdb_fault_expected;
+
+#endif /* !__ASSEMBLY__ */
+
+/*
+ * From Kevin Hilman:
+ *
+ * gdb is expecting the following registers layout.
+ *
+ * r0-r15: 1 long word each
+ * f0-f7:  unused, 3 long words each !!
+ * fps:    unused, 1 long word
+ * cpsr:   1 long word
+ *
+ * Even though f0-f7 and fps are not used, they need to be
+ * present in the registers sent for correct processing in
+ * the host-side gdb.
+ *
+ * In particular, it is crucial that CPSR is in the right place,
+ * otherwise gdb will not be able to correctly interpret stepping over
+ * conditional branches.
+ */
+#define _GP_REGS                16
+#define _FP_REGS                8
+#define _EXTRA_REGS             2
+#define GDB_MAX_REGS            (_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
+
+#define KGDB_MAX_NO_CPUS        1
+#define BUFMAX                  400
+#define NUMREGBYTES             (GDB_MAX_REGS << 2)
+#define NUMCRITREGBYTES         (32 << 2)
+
+#define _R0                     0
+#define _R1                     1
+#define _R2                     2
+#define _R3                     3
+#define _R4                     4
+#define _R5                     5
+#define _R6                     6
+#define _R7                     7
+#define _R8                     8
+#define _R9                     9
+#define _R10                    10
+#define _FP                     11
+#define _IP                     12
+#define _SPT                    13
+#define _LR                     14
+#define _PC                     15
+#define _CPSR                   (GDB_MAX_REGS - 1)
+
+/*
+ * So that we can denote the end of a frame for tracing,
+ * in the simple case:
+ */
+#define CFI_END_FRAME(func)     __CFI_END_FRAME(_PC, _SPT, func)
+
+#endif /* __ASM_KGDB_H__ */
diff --git a/include/asm-arm/traps.h b/include/asm-arm/traps.h
index f1541afcf85c..aa399aec568e 100644
--- a/include/asm-arm/traps.h
+++ b/include/asm-arm/traps.h
@@ -24,4 +24,6 @@ static inline int in_exception_text(unsigned long ptr)
                ptr < (unsigned long)&__exception_text_end;
 }
 
+extern void __init early_trap_init(void);
+
 #endif