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Commit dcc78711 authored by Jason Wessel's avatar Jason Wessel
Browse files

kgdb: core changes to support kdb 



These are the minimum changes to the kgdb core in order to enable an
API to connect a new front end (kdb) to the debug core.

This patch introduces the dbg_kdb_mode variable controls where the
user level I/O is routed.  It will be routed to the gdbstub (kgdb) or
to the kdb front end which is a simple shell available over the kgdboc
connection.

You can switch back and forth between kdb or the gdb stub mode of
operation dynamically.  From gdb stub mode you can blindly type
"$3#33", or from the kdb mode you can enter "kgdb" to switch to the
gdb stub.

The logic in the debug core depends on kdb to look for the typical gdb
connection sequences and return immediately with KGDB_PASS_EVENT if a
gdb serial command sequence is detected.  That should allow a
reasonably seamless transition between kdb -> gdb without leaving the
kernel exception state.  The two gdb serial queries that kdb is
responsible for detecting are the "?" and "qSupported" packets.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
Acked-by: default avatarMartin Hicks <mort@sgi.com>
parent 67fc4e0c

arch/arm/kernel/kgdb.c

+5 −0
Original line number Diff line number Diff line
@@ -98,6 +98,11 @@ sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) 
	gdb_regs[_CPSR]		= thread_regs->ARM_cpsr;

}



void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)

{

	regs->ARM_pc = pc;

}



static int compiled_break;



int kgdb_arch_handle_exception(int exception_vector, int signo,

arch/mips/kernel/kgdb.c

+5 −0
Original line number Diff line number Diff line
@@ -180,6 +180,11 @@ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p) 
	*(ptr++) = regs->cp0_epc;

}



void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)

{

	regs->cp0_epc = pc;

}



/*

 * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,

 * then try to fall into the debugger

arch/powerpc/kernel/kgdb.c

+5 −0
Original line number Diff line number Diff line
@@ -309,6 +309,11 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs) 
	       (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));

}



void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)

{

	regs->nip = pc;

}



/*

 * This function does PowerPC specific procesing for interfacing to gdb.

 */

arch/x86/kernel/kgdb.c

+5 −0
Original line number Diff line number Diff line
@@ -690,6 +690,11 @@ unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) 
	return instruction_pointer(regs);

}



void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)

{

	regs->ip = ip;

}



struct kgdb_arch arch_kgdb_ops = {

	/* Breakpoint instruction: */

	.gdb_bpt_instr		= { 0xcc },

include/linux/kgdb.h

+9 −2
Original line number Diff line number Diff line
@@ -16,10 +16,12 @@ 
#include <linux/serial_8250.h>

#include <linux/linkage.h>

#include <linux/init.h>



#include <asm/atomic.h>

#ifdef CONFIG_HAVE_ARCH_KGDB

#include <asm/kgdb.h>

#endif



#ifdef CONFIG_KGDB

struct pt_regs;



/**
@@ -262,6 +264,7 @@ extern struct kgdb_arch arch_kgdb_ops; 


extern unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs);



extern void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc);

extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);

extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);

extern struct kgdb_io *dbg_io_ops;
@@ -279,5 +282,9 @@ extern int kgdb_nmicallback(int cpu, void *regs); 


extern int			kgdb_single_step;

extern atomic_t			kgdb_active;



#define in_dbg_master() \

	(raw_smp_processor_id() == atomic_read(&kgdb_active))

#else /* ! CONFIG_KGDB */

#define in_dbg_master() (0)

#endif /* ! CONFIG_KGDB */

#endif /* _KGDB_H_ */