]> pilppa.com Git - linux-2.6-omap-h63xx.git/commitdiff
kgdb: support for ARCH=arm
authorJason Wessel <jason.wessel@windriver.com>
Wed, 20 Feb 2008 19:33:40 +0000 (13:33 -0600)
committerJason Wessel <jason.wessel@windriver.com>
Wed, 23 Jul 2008 16:30:15 +0000 (11:30 -0500)
This patch adds the ARCH=arm specific a kgdb backend, originally
written by Deepak Saxena <dsaxena@plexity.net> and George Davis
<gdavis@mvista.com>.  Geoff Levand <geoffrey.levand@am.sony.com>,
Nicolas Pitre, Manish Lachwani, and Jason Wessel have contributed
various fixups here as well.

The KGDB patch makes one change to the core ARM architecture such that
the traps are initialized early for use with the debugger or other
subsystems.

[ mingo@elte.hu: small cleanups. ]
[ ben-linux@fluff.org: fixed early_trap_init ]

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Deepak Saxena <dsaxena@plexity.net>
arch/arm/Kconfig
arch/arm/kernel/Makefile
arch/arm/kernel/kgdb.c [new file with mode: 0644]
arch/arm/kernel/setup.c
arch/arm/kernel/traps.c
include/asm-arm/kgdb.h [new file with mode: 0644]
include/asm-arm/traps.h

index c7ad324ddf2cf407c89839f75487f8e27f9fa0cc..d048f6887d0b0aff8e882283923c9a3640a6a816 100644 (file)
@@ -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)
index eb9092ca80080cd4431951e46c6f2ce8daf70ab8..1d296fc8494e01f7f33a8cac97855506727f3e46 100644 (file)
@@ -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 (file)
index 0000000..aaffaec
--- /dev/null
@@ -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
+};
index b7b0720bc1bbe8295ea3ca7b2849e4a5ad875bf2..38f0e7940a132b1c9e0458bc10e9d1dc3f2401ee 100644 (file)
@@ -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();
 }
 
 
index 5595fdd75e8200ec0e8d5ea8a54c750ed0398e1f..7277aef8309836fb74b6e2368beabf050757af9d 100644 (file)
@@ -707,6 +707,11 @@ void abort(void)
 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[];
diff --git a/include/asm-arm/kgdb.h b/include/asm-arm/kgdb.h
new file mode 100644 (file)
index 0000000..67af4b8
--- /dev/null
@@ -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__ */
index f1541afcf85c200c457fb48fc93d5c88d250902d..aa399aec568ef02533c2d6694f192f91a8446ab5 100644 (file)
@@ -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