Author: bde
Date: Sun Aug 14 16:51:25 2016
New Revision: 304085
URL: https://svnweb.freebsd.org/changeset/base/304085
Log:
Fix the variables $esp, $ds, $es, $fs, $gs and $ss in vm86 mode.
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.
Modified:
head/sys/i386/i386/db_trace.c
head/sys/i386/include/db_machdep.h
Modified: head/sys/i386/i386/db_trace.c
==============================================================================
--- head/sys/i386/i386/db_trace.c Sun Aug 14 16:32:23 2016
(r304084)
+++ head/sys/i386/i386/db_trace.c Sun Aug 14 16:51:25 2016
(r304085)
@@ -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 +
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
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
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
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);
}
Modified: head/sys/i386/include/db_machdep.h
==============================================================================
--- head/sys/i386/include/db_machdep.h Sun Aug 14 16:32:23 2016
(r304084)
+++ head/sys/i386/include/db_machdep.h Sun Aug 14 16:51:25 2016
(r304085)
@@ -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 */
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