2005-01-06 22:18:23 +00:00
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/*-
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1993-06-12 14:58:17 +00:00
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* Mach Operating System
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* Copyright (c) 1991,1990 Carnegie Mellon University
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* All Rights Reserved.
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1995-05-30 08:16:23 +00:00
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*
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1993-06-12 14:58:17 +00:00
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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1995-05-30 08:16:23 +00:00
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*
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1993-06-12 14:58:17 +00:00
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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1995-05-30 08:16:23 +00:00
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*
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1993-06-12 14:58:17 +00:00
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* Carnegie Mellon requests users of this software to return to
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1995-05-30 08:16:23 +00:00
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*
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1993-06-12 14:58:17 +00:00
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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1995-05-30 08:16:23 +00:00
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*
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1993-06-12 14:58:17 +00:00
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* any improvements or extensions that they make and grant Carnegie Mellon
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* the rights to redistribute these changes.
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*
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1999-08-28 01:08:13 +00:00
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* $FreeBSD$
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1993-06-12 14:58:17 +00:00
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*/
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1995-01-14 10:34:52 +00:00
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#ifndef _MACHINE_DB_MACHDEP_H_
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#define _MACHINE_DB_MACHDEP_H_
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1993-06-12 14:58:17 +00:00
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1995-12-03 10:40:16 +00:00
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#include <machine/frame.h>
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1999-10-04 13:55:35 +00:00
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#include <machine/trap.h>
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1993-06-12 14:58:17 +00:00
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typedef vm_offset_t db_addr_t; /* address - unsigned */
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typedef int db_expr_t; /* expression - signed */
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2016-08-14 16:51:25 +00:00
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#define PC_REGS() ((db_addr_t)(kdb_frame->tf_eflags & PSL_VM ? \
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(kdb_frame->tf_eip & 0xffff) + \
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((kdb_frame->tf_cs & 0xffff) << 4) : \
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kdb_frame->tf_eip))
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1993-06-12 14:58:17 +00:00
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#define BKPT_INST 0xcc /* breakpoint instruction */
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#define BKPT_SIZE (1) /* size of breakpoint inst */
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#define BKPT_SET(inst) (BKPT_INST)
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2004-09-15 23:26:49 +00:00
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#define BKPT_SKIP \
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do { \
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kdb_frame->tf_eip += 1; \
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kdb_thrctx->pcb_eip += 1; \
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} while(0)
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2001-09-15 11:06:07 +00:00
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2004-09-15 23:26:49 +00:00
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#define FIXUP_PC_AFTER_BREAK \
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do { \
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kdb_frame->tf_eip -= 1; \
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kdb_thrctx->pcb_eip -= 1; \
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} while(0);
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1993-06-12 14:58:17 +00:00
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2004-07-10 23:47:20 +00:00
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#define db_clear_single_step kdb_cpu_clear_singlestep
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#define db_set_single_step kdb_cpu_set_singlestep
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1993-06-12 14:58:17 +00:00
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1995-01-14 10:34:52 +00:00
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/*
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Abort single stepping in ddb if the trap is not for single-stepping.
This is not very easy to do, since ddb didn't know when traps are
for single-stepping. It more or less assumed that traps are either
breakpoints or single-step, but even for x86 this became inadequate
with the release of the i386 in ~1986, and FreeBSD passes it other
trap types for NMIs and panics.
On x86, teach ddb when a trap is for single stepping using the %dr6
register. Unknown traps are now treated almost the same as breakpoints
instead of as the same as single-steps. Previously, the classification
of breakpoints was almost correct and everything else was unknown so
had to be treated as a single-step. Now the classification of single-
steps is precise, the classification of breakpoints is almost correct
(as before) and everything else is unknown and treated like a
breakpoint.
This fixes:
- breakpoints not set by ddb, including the main one in kdb_enter(),
were treated as single-steps and not stopped on when stepping
(except for the usual, simple case of a step with residual count 1).
As special cases, kdb_enter() didn't stop for fatal traps or panics
- similarly for "hardware breakpoints".
Use a new MD macro IS_SSTEP_TRAP(type, code) to code to classify
single-steps. This is excessively complicated for bug-for-bug and
backwards compatibilty. Design errors apparently started in Mach
in ~1990 or perhaps in the FreeBSD interface in ~1993. Common trap
types like single steps should have a unique MI code (like the TRAP*
codes for user SIGTRAP) so that debuggers don't need macros like
IS_SSTEP_TRAP() to decode them. But 'type' is actually an ambiguous
MD trap number, and code was always 0 (now it is (int)%dr6 on x86).
So it was impossible to determine the trap type from the args.
Global variables had to be used.
There is already a classification macro db_pc_is_single_step(), but
this just gets in the way. It is only used to recover from bugs in
IS_BREAKPOINT_TRAP(). On some arches, IS_BREAKPOINT_TRAP() just
duplicates the ambiguity in 'type' and misclassifies single-steps as
breakpoints. It defaults to 'false', which is the opposite of what is
needed for bug-for-bug compatibility.
When this is cleaned up, MI classification bits should be passed in
'code'. This could be done now for positive-logic bits, since 'code'
was always 0, but some negative logic is needed for compatibility so
a simple MI classificition is not usable yet.
After reading %dr6, clear the single-step bit in it so that the type
of the next debugger trap can be decoded. This is a little
ddb-specific. ddb doesn't understand the need to clear this bit and
doing it before calling kdb is easiest. gdb would need to reverse
this to support hardware breakpoints, but it just doesn't support
them now since gdbstub doesn't support %dr*.
Fix a bug involving %dr6: when emulating a single-step trap for vm86,
set the bit for it in %dr6. Userland debuggers need this. ddb now
needs this for vm86 bios calls. The bit gets copied to 'code' then
cleared again.
Fix related style bugs:
- when clearing bits for hardware breakpoints in %dr6, spell the mask
as ~0xf on both amd64 and i386 to get the correct number of bits
using sign extension and not need a comment about using the wrong
mask on amd64 (amd64 traps for invalid results but clearing the
reserved top bits didn't trap since they are 0).
- rewrite my old wrong comments about using %dr6 for ddb watchpoints.
2016-09-15 17:24:23 +00:00
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* The debug exception type is copied from %dr6 to 'code' and used to
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* disambiguate single step traps. Watchpoints have no special support.
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* Our hardware breakpoints are not well integrated with ddb and are too
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* different from watchpoints. ddb treats them as unknown traps with
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* unknown addresses and doesn't turn them off while it is running.
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1995-01-14 10:34:52 +00:00
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*/
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Abort single stepping in ddb if the trap is not for single-stepping.
This is not very easy to do, since ddb didn't know when traps are
for single-stepping. It more or less assumed that traps are either
breakpoints or single-step, but even for x86 this became inadequate
with the release of the i386 in ~1986, and FreeBSD passes it other
trap types for NMIs and panics.
On x86, teach ddb when a trap is for single stepping using the %dr6
register. Unknown traps are now treated almost the same as breakpoints
instead of as the same as single-steps. Previously, the classification
of breakpoints was almost correct and everything else was unknown so
had to be treated as a single-step. Now the classification of single-
steps is precise, the classification of breakpoints is almost correct
(as before) and everything else is unknown and treated like a
breakpoint.
This fixes:
- breakpoints not set by ddb, including the main one in kdb_enter(),
were treated as single-steps and not stopped on when stepping
(except for the usual, simple case of a step with residual count 1).
As special cases, kdb_enter() didn't stop for fatal traps or panics
- similarly for "hardware breakpoints".
Use a new MD macro IS_SSTEP_TRAP(type, code) to code to classify
single-steps. This is excessively complicated for bug-for-bug and
backwards compatibilty. Design errors apparently started in Mach
in ~1990 or perhaps in the FreeBSD interface in ~1993. Common trap
types like single steps should have a unique MI code (like the TRAP*
codes for user SIGTRAP) so that debuggers don't need macros like
IS_SSTEP_TRAP() to decode them. But 'type' is actually an ambiguous
MD trap number, and code was always 0 (now it is (int)%dr6 on x86).
So it was impossible to determine the trap type from the args.
Global variables had to be used.
There is already a classification macro db_pc_is_single_step(), but
this just gets in the way. It is only used to recover from bugs in
IS_BREAKPOINT_TRAP(). On some arches, IS_BREAKPOINT_TRAP() just
duplicates the ambiguity in 'type' and misclassifies single-steps as
breakpoints. It defaults to 'false', which is the opposite of what is
needed for bug-for-bug compatibility.
When this is cleaned up, MI classification bits should be passed in
'code'. This could be done now for positive-logic bits, since 'code'
was always 0, but some negative logic is needed for compatibility so
a simple MI classificition is not usable yet.
After reading %dr6, clear the single-step bit in it so that the type
of the next debugger trap can be decoded. This is a little
ddb-specific. ddb doesn't understand the need to clear this bit and
doing it before calling kdb is easiest. gdb would need to reverse
this to support hardware breakpoints, but it just doesn't support
them now since gdbstub doesn't support %dr*.
Fix a bug involving %dr6: when emulating a single-step trap for vm86,
set the bit for it in %dr6. Userland debuggers need this. ddb now
needs this for vm86 bios calls. The bit gets copied to 'code' then
cleared again.
Fix related style bugs:
- when clearing bits for hardware breakpoints in %dr6, spell the mask
as ~0xf on both amd64 and i386 to get the correct number of bits
using sign extension and not need a comment about using the wrong
mask on amd64 (amd64 traps for invalid results but clearing the
reserved top bits didn't trap since they are 0).
- rewrite my old wrong comments about using %dr6 for ddb watchpoints.
2016-09-15 17:24:23 +00:00
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#define IS_BREAKPOINT_TRAP(type, code) ((type) == T_BPTFLT)
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#define IS_SSTEP_TRAP(type, code) ((type) == T_TRCTRAP && (code) & 0x4000)
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#define IS_WATCHPOINT_TRAP(type, code) 0
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1993-06-12 14:58:17 +00:00
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#define I_CALL 0xe8
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#define I_CALLI 0xff
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#define I_RET 0xc3
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#define I_IRET 0xcf
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#define inst_trap_return(ins) (((ins)&0xff) == I_IRET)
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#define inst_return(ins) (((ins)&0xff) == I_RET)
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#define inst_call(ins) (((ins)&0xff) == I_CALL || \
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(((ins)&0xff) == I_CALLI && \
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((ins)&0x3800) == 0x1000))
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#define inst_load(ins) 0
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#define inst_store(ins) 0
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2016-09-25 16:30:29 +00:00
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int db_segsize(struct trapframe *tfp);
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1995-01-14 10:34:52 +00:00
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#endif /* !_MACHINE_DB_MACHDEP_H_ */
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