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qemu/target/i386/bpt_helper.c
Doug Evans c52ab08aee target-i386: Fix eflags.TF/#DB handling of syscall/sysret insns 
The syscall and sysret instructions behave a bit differently:
TF is checked after the instruction completes.
This allows the o/s to disable #DB at a syscall by adding TF to FMASK.
And then when the sysret is executed the #DB is taken "as if" the
syscall insn just completed.

Signed-off-by: Doug Evans <dje@google.com>
Message-Id: <94eb2c0bfa1c6a9fec0543057483@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-12-22 16:01:04 +01:00

336 lines
9.3 KiB
C
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/*
* i386 breakpoint helpers
*
* Copyright (c) 2003 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "exec/exec-all.h"
#include "exec/helper-proto.h"
#ifndef CONFIG_USER_ONLY
static inline bool hw_local_breakpoint_enabled(unsigned long dr7, int index)
{
return (dr7 >> (index * 2)) & 1;
}
static inline bool hw_global_breakpoint_enabled(unsigned long dr7, int index)
{
return (dr7 >> (index * 2)) & 2;
}
static inline bool hw_breakpoint_enabled(unsigned long dr7, int index)
{
return hw_global_breakpoint_enabled(dr7, index) ||
hw_local_breakpoint_enabled(dr7, index);
}
static inline int hw_breakpoint_type(unsigned long dr7, int index)
{
return (dr7 >> (DR7_TYPE_SHIFT + (index * 4))) & 3;
}
static inline int hw_breakpoint_len(unsigned long dr7, int index)
{
int len = ((dr7 >> (DR7_LEN_SHIFT + (index * 4))) & 3);
return (len == 2) ? 8 : len + 1;
}
static int hw_breakpoint_insert(CPUX86State *env, int index)
{
CPUState *cs = CPU(x86_env_get_cpu(env));
target_ulong dr7 = env->dr[7];
target_ulong drN = env->dr[index];
int err = 0;
switch (hw_breakpoint_type(dr7, index)) {
case DR7_TYPE_BP_INST:
if (hw_breakpoint_enabled(dr7, index)) {
err = cpu_breakpoint_insert(cs, drN, BP_CPU,
&env->cpu_breakpoint[index]);
}
break;
case DR7_TYPE_IO_RW:
/* Notice when we should enable calls to bpt_io. */
return hw_breakpoint_enabled(env->dr[7], index)
? HF_IOBPT_MASK : 0;
case DR7_TYPE_DATA_WR:
if (hw_breakpoint_enabled(dr7, index)) {
err = cpu_watchpoint_insert(cs, drN,
hw_breakpoint_len(dr7, index),
BP_CPU | BP_MEM_WRITE,
&env->cpu_watchpoint[index]);
}
break;
case DR7_TYPE_DATA_RW:
if (hw_breakpoint_enabled(dr7, index)) {
err = cpu_watchpoint_insert(cs, drN,
hw_breakpoint_len(dr7, index),
BP_CPU | BP_MEM_ACCESS,
&env->cpu_watchpoint[index]);
}
break;
}
if (err) {
env->cpu_breakpoint[index] = NULL;
}
return 0;
}
static void hw_breakpoint_remove(CPUX86State *env, int index)
{
CPUState *cs = CPU(x86_env_get_cpu(env));
switch (hw_breakpoint_type(env->dr[7], index)) {
case DR7_TYPE_BP_INST:
if (env->cpu_breakpoint[index]) {
cpu_breakpoint_remove_by_ref(cs, env->cpu_breakpoint[index]);
env->cpu_breakpoint[index] = NULL;
}
break;
case DR7_TYPE_DATA_WR:
case DR7_TYPE_DATA_RW:
if (env->cpu_breakpoint[index]) {
cpu_watchpoint_remove_by_ref(cs, env->cpu_watchpoint[index]);
env->cpu_breakpoint[index] = NULL;
}
break;
case DR7_TYPE_IO_RW:
/* HF_IOBPT_MASK cleared elsewhere. */
break;
}
}
void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
{
target_ulong old_dr7 = env->dr[7];
int iobpt = 0;
int i;
new_dr7 |= DR7_FIXED_1;
/* If nothing is changing except the global/local enable bits,
then we can make the change more efficient. */
if (((old_dr7 ^ new_dr7) & ~0xff) == 0) {
/* Fold the global and local enable bits together into the
global fields, then xor to show which registers have
changed collective enable state. */
int mod = ((old_dr7 | old_dr7 * 2) ^ (new_dr7 | new_dr7 * 2)) & 0xff;
for (i = 0; i < DR7_MAX_BP; i++) {
if ((mod & (2 << i * 2)) && !hw_breakpoint_enabled(new_dr7, i)) {
hw_breakpoint_remove(env, i);
}
}
env->dr[7] = new_dr7;
for (i = 0; i < DR7_MAX_BP; i++) {
if (mod & (2 << i * 2) && hw_breakpoint_enabled(new_dr7, i)) {
iobpt |= hw_breakpoint_insert(env, i);
} else if (hw_breakpoint_type(new_dr7, i) == DR7_TYPE_IO_RW
&& hw_breakpoint_enabled(new_dr7, i)) {
iobpt |= HF_IOBPT_MASK;
}
}
} else {
for (i = 0; i < DR7_MAX_BP; i++) {
hw_breakpoint_remove(env, i);
}
env->dr[7] = new_dr7;
for (i = 0; i < DR7_MAX_BP; i++) {
iobpt |= hw_breakpoint_insert(env, i);
}
}
env->hflags = (env->hflags & ~HF_IOBPT_MASK) | iobpt;
}
static bool check_hw_breakpoints(CPUX86State *env, bool force_dr6_update)
{
target_ulong dr6;
int reg;
bool hit_enabled = false;
dr6 = env->dr[6] & ~0xf;
for (reg = 0; reg < DR7_MAX_BP; reg++) {
bool bp_match = false;
bool wp_match = false;
switch (hw_breakpoint_type(env->dr[7], reg)) {
case DR7_TYPE_BP_INST:
if (env->dr[reg] == env->eip) {
bp_match = true;
}
break;
case DR7_TYPE_DATA_WR:
case DR7_TYPE_DATA_RW:
if (env->cpu_watchpoint[reg] &&
env->cpu_watchpoint[reg]->flags & BP_WATCHPOINT_HIT) {
wp_match = true;
}
break;
case DR7_TYPE_IO_RW:
break;
}
if (bp_match || wp_match) {
dr6 |= 1 << reg;
if (hw_breakpoint_enabled(env->dr[7], reg)) {
hit_enabled = true;
}
}
}
if (hit_enabled || force_dr6_update) {
env->dr[6] = dr6;
}
return hit_enabled;
}
void breakpoint_handler(CPUState *cs)
{
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
CPUBreakpoint *bp;
if (cs->watchpoint_hit) {
if (cs->watchpoint_hit->flags & BP_CPU) {
cs->watchpoint_hit = NULL;
if (check_hw_breakpoints(env, false)) {
raise_exception(env, EXCP01_DB);
} else {
cpu_loop_exit_noexc(cs);
}
}
} else {
QTAILQ_FOREACH(bp, &cs->breakpoints, entry) {
if (bp->pc == env->eip) {
if (bp->flags & BP_CPU) {
check_hw_breakpoints(env, true);
raise_exception(env, EXCP01_DB);
}
break;
}
}
}
}
#endif
void helper_single_step(CPUX86State *env)
{
#ifndef CONFIG_USER_ONLY
check_hw_breakpoints(env, true);
env->dr[6] |= DR6_BS;
#endif
raise_exception(env, EXCP01_DB);
}
void helper_rechecking_single_step(CPUX86State *env)
{
if ((env->eflags & TF_MASK) != 0) {
helper_single_step(env);
}
}
void helper_set_dr(CPUX86State *env, int reg, target_ulong t0)
{
#ifndef CONFIG_USER_ONLY
switch (reg) {
case 0: case 1: case 2: case 3:
if (hw_breakpoint_enabled(env->dr[7], reg)
&& hw_breakpoint_type(env->dr[7], reg) != DR7_TYPE_IO_RW) {
hw_breakpoint_remove(env, reg);
env->dr[reg] = t0;
hw_breakpoint_insert(env, reg);
} else {
env->dr[reg] = t0;
}
return;
case 4:
if (env->cr[4] & CR4_DE_MASK) {
break;
}
/* fallthru */
case 6:
env->dr[6] = t0 | DR6_FIXED_1;
return;
case 5:
if (env->cr[4] & CR4_DE_MASK) {
break;
}
/* fallthru */
case 7:
cpu_x86_update_dr7(env, t0);
return;
}
raise_exception_err_ra(env, EXCP06_ILLOP, 0, GETPC());
#endif
}
target_ulong helper_get_dr(CPUX86State *env, int reg)
{
switch (reg) {
case 0: case 1: case 2: case 3: case 6: case 7:
return env->dr[reg];
case 4:
if (env->cr[4] & CR4_DE_MASK) {
break;
} else {
return env->dr[6];
}
case 5:
if (env->cr[4] & CR4_DE_MASK) {
break;
} else {
return env->dr[7];
}
}
raise_exception_err_ra(env, EXCP06_ILLOP, 0, GETPC());
}
/* Check if Port I/O is trapped by a breakpoint. */
void helper_bpt_io(CPUX86State *env, uint32_t port,
uint32_t size, target_ulong next_eip)
{
#ifndef CONFIG_USER_ONLY
target_ulong dr7 = env->dr[7];
int i, hit = 0;
for (i = 0; i < DR7_MAX_BP; ++i) {
if (hw_breakpoint_type(dr7, i) == DR7_TYPE_IO_RW
&& hw_breakpoint_enabled(dr7, i)) {
int bpt_len = hw_breakpoint_len(dr7, i);
if (port + size - 1 >= env->dr[i]
&& port <= env->dr[i] + bpt_len - 1) {
hit |= 1 << i;
}
}
}
if (hit) {
env->dr[6] = (env->dr[6] & ~0xf) | hit;
env->eip = next_eip;
raise_exception(env, EXCP01_DB);
}
#endif
}
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