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Fix the variables $esp, $ds, $es, $fs, $gs and $ss in vm86 mode.

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Fix PC_REGS() so that printing of instructions works in some useful
cases.  ddb only understands a single flat address space, but this
macro allows mapping $cs:$eip into vm86's flat address space well
enough for the MI parts of ddb.  This doesn't work for the MD parts
that do stack traces, and there are no similar macros for data addresses.

PC_REGS() has to use the trapframe pointer instead of the pcb for this.
For other CPUs, the trapframe pointer is not available except by tracing
back to it.  But tracing back through vm86 trapframes is broken even
starting with one.
This commit is contained in:
Bruce Evans 2016-08-14 16:51:25 +00:00
parent 99061149a3
commit 258b53d151
2 changed files with 40 additions and 6 deletions
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41
sys/i386/i386/db_trace.c
View File

@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
#include <sys/sysent.h>
#include <machine/cpu.h>
#include <machine/frame.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/reg.h>
@ -81,8 +82,8 @@ struct db_variable *db_eregs = db_regs + nitems(db_regs);
static __inline int
get_esp(struct trapframe *tf)
{
return ((ISPL(tf->tf_cs)) ? tf->tf_esp :
(db_expr_t)tf + (uintptr_t)DB_OFFSET(tf_esp));
return ((ISPL(tf->tf_cs) || kdb_frame->tf_eflags & PSL_VM) ?
tf->tf_esp : (intptr_t)&tf->tf_esp);
}
static int
@ -104,12 +105,32 @@ db_frame(struct db_variable *vp, db_expr_t *valuep, int op)
static int
db_frame_seg(struct db_variable *vp, db_expr_t *valuep, int op)
{
struct trapframe_vm86 *tfp;
int off;
uint16_t *reg;
if (kdb_frame == NULL)
return (0);
reg = (uint16_t *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep);
off = (intptr_t)vp->valuep;
if (kdb_frame->tf_eflags & PSL_VM) {
tfp = (void *)kdb_frame;
switch ((intptr_t)vp->valuep) {
case (intptr_t)DB_OFFSET(tf_cs):
reg = (uint16_t *)&tfp->tf_cs;
break;
case (intptr_t)DB_OFFSET(tf_ds):
reg = (uint16_t *)&tfp->tf_vm86_ds;
break;
case (intptr_t)DB_OFFSET(tf_es):
reg = (uint16_t *)&tfp->tf_vm86_es;
break;
case (intptr_t)DB_OFFSET(tf_fs):
reg = (uint16_t *)&tfp->tf_vm86_fs;
break;
}
} else
reg = (uint16_t *)((uintptr_t)kdb_frame + off);
if (op == DB_VAR_GET)
*valuep = *reg;
else
@ -134,7 +155,16 @@ db_esp(struct db_variable *vp, db_expr_t *valuep, int op)
static int
db_gs(struct db_variable *vp, db_expr_t *valuep, int op)
{
struct trapframe_vm86 *tfp;
if (kdb_frame != NULL && kdb_frame->tf_eflags & PSL_VM) {
tfp = (void *)kdb_frame;
if (op == DB_VAR_GET)
*valuep = tfp->tf_vm86_gs;
else
tfp->tf_vm86_gs = *valuep;
return (1);
}
if (op == DB_VAR_GET)
*valuep = rgs();
else
@ -150,8 +180,9 @@ db_ss(struct db_variable *vp, db_expr_t *valuep, int op)
return (0);
if (op == DB_VAR_GET)
*valuep = (ISPL(kdb_frame->tf_cs)) ? kdb_frame->tf_ss : rss();
else if (ISPL(kdb_frame->tf_cs))
*valuep = (ISPL(kdb_frame->tf_cs) ||
kdb_frame->tf_eflags & PSL_VM) ? kdb_frame->tf_ss : rss();
else if (ISPL(kdb_frame->tf_cs) || kdb_frame->tf_eflags & PSL_VM)
kdb_frame->tf_ss = *valuep;
return (1);
}

5
sys/i386/include/db_machdep.h
View File

@ -35,7 +35,10 @@
typedef vm_offset_t db_addr_t; /* address - unsigned */
typedef int db_expr_t; /* expression - signed */
#define PC_REGS() ((db_addr_t)kdb_thrctx->pcb_eip)
#define PC_REGS() ((db_addr_t)(kdb_frame->tf_eflags & PSL_VM ? \
(kdb_frame->tf_eip & 0xffff) + \
((kdb_frame->tf_cs & 0xffff) << 4) : \
kdb_frame->tf_eip))
#define BKPT_INST 0xcc /* breakpoint instruction */
#define BKPT_SIZE (1) /* size of breakpoint inst */