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5717f513696c4d926327df2af2ccdbfc80adbc29
xen/tools/debugger/kdd/kdd-xen.c
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Tim Deegan 5717f51369 "kdd" Windows debugger stub. 
kdd runs in dom0, attaches to a domain and speaks the Windows kd serial
protocol over a TCP connection (which should go to kd or windbg, e.g.
by having another VM with its virtual COM1 set up as a TCP listener).

It doesn't do breakpoints &c yet, and windbg can get quite confused
since the kernel debugger's not actually running, but it's good enough
to extract backtraces from wedged VMs.

Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
2010-10-26 11:56:31 +01:00

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/*
* kdd-xen.c -- xen-specific functions for the kdd debugging stub
*
* Tim Deegan <Tim.Deegan@citrix.com>
*
* Copyright (c) 2007-2010, Citrix Systems Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <inttypes.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <xenctrl.h>
#include <xen/xen.h>
#include <xen/hvm/save.h>
#include "kdd.h"
#define MAPSIZE 4093 /* Prime */
#define PAGE_SHIFT 12
#define PAGE_SIZE (1U << PAGE_SHIFT)
struct kdd_guest {
struct xentoollog_logger xc_log; /* Must be first for xc log callbacks */
xc_interface *xc_handle;
uint32_t domid;
char id[80];
FILE *log;
int verbosity;
void *hvm_buf;
uint32_t hvm_sz;
uint32_t pfns[MAPSIZE];
void * maps[MAPSIZE];
};
/* Flush any mappings we have of the guest memory: it's not polite
* top hold on to them while the guest is running */
static void flush_maps(kdd_guest *g)
{
int i;
for (i = 0; i < MAPSIZE; i++) {
if (g->maps[i] != NULL)
munmap(g->maps[i], PAGE_SIZE);
g->maps[i] = NULL;
}
}
/* Halt the guest so we can debug it */
void kdd_halt(kdd_guest *g)
{
uint32_t sz;
void *buf;
xc_domain_pause(g->xc_handle, g->domid);
/* How much space do we need for the HVM state? */
sz = xc_domain_hvm_getcontext(g->xc_handle, g->domid, 0, 0);
if (sz == (uint32_t) -1) {
KDD_LOG(g, "Can't get HVM state size for domid %"PRIu32": %s\n",
g->domid, strerror(errno));
return;
}
buf = realloc(g->hvm_buf, sz);
if (!buf) {
KDD_LOG(g, "Couldn't allocate %"PRIu32" for HVM buffer\n", sz);
return;
}
g->hvm_buf = buf;
g->hvm_sz = sz;
memset(buf, 0, sz);
/* Get the HVM state */
sz = xc_domain_hvm_getcontext(g->xc_handle, g->domid, buf, sz);
if (sz == (uint32_t) -1) {
KDD_LOG(g, "Can't get HVM state for domid %"PRIu32": %s\n",
g->domid, strerror(errno));
}
}
/* Check whether the guest has stopped. Returns 'interesting' vcpu or -1 */
/* TODO: open DEBUG_VIRQ if it's free and wait for events rather than
* always polling the guest state */
int kdd_poll_guest(kdd_guest *g)
{
/* TODO: finish plumbing through polling for breakpoints */
return 0;
}
/* Update the HVM state */
static void hvm_writeback(kdd_guest *g)
{
if (g->hvm_buf && xc_domain_hvm_setcontext(g->xc_handle, g->domid,
g->hvm_buf, g->hvm_sz))
KDD_LOG(g, "Can't set HVM state for domid %"PRIu32": %s\n",
g->domid, strerror(errno));
}
/* Start the guest running again */
void kdd_run(kdd_guest *g)
{
flush_maps(g);
hvm_writeback(g);
xc_domain_unpause(g->xc_handle, g->domid);
}
/* How many CPUs are there in this guest? */
int kdd_count_cpus(kdd_guest *g)
{
struct hvm_save_descriptor *desc;
int maxcpu = 0;
if (!g->hvm_buf)
return 0;
/* Scan the CPU save records. */
for (desc = g->hvm_buf;
(void *) desc >= g->hvm_buf && (void *) desc < g->hvm_buf + g->hvm_sz;
desc = ((void *)desc) + (sizeof *desc) + desc->length) {
if (desc->typecode == HVM_SAVE_CODE(CPU)) {
if (maxcpu < desc->instance)
maxcpu = desc->instance;
}
}
return maxcpu + 1;
}
/* Helper fn: get CPU state from cached HVM state */
static struct hvm_hw_cpu *get_cpu(kdd_guest *g, int cpuid)
{
struct hvm_save_descriptor *desc;
struct hvm_hw_cpu *cpu;
if (!g->hvm_buf)
return NULL;
/* Find the right CPU */
for (desc = g->hvm_buf;
(void *) desc >= g->hvm_buf && (void *) desc < g->hvm_buf + g->hvm_sz;
desc = ((void *)desc) + (sizeof *desc) + desc->length) {
if (desc->typecode == HVM_SAVE_CODE(CPU) && desc->instance == cpuid) {
cpu = ((void *)desc) + (sizeof *desc);
if ((void *) cpu + sizeof (*cpu) <= g->hvm_buf + g->hvm_sz)
return cpu;
}
}
KDD_LOG(g, "Dom %"PRIu32" has no CPU %i\n", g->domid, cpuid);
return NULL;
}
/* Helper fn: get APIC state from cached HVM state */
static struct hvm_hw_lapic_regs *get_lapic(kdd_guest *g, int cpuid)
{
struct hvm_save_descriptor *desc;
struct hvm_hw_lapic_regs *regs;
if (!g->hvm_buf)
return NULL;
/* Find the right CPU's LAPIC */
for (desc = g->hvm_buf;
(void *) desc >= g->hvm_buf && (void *) desc < g->hvm_buf + g->hvm_sz;
desc = ((void *)desc) + (sizeof *desc) + desc->length) {
if (desc->typecode == HVM_SAVE_CODE(LAPIC_REGS) && desc->instance == cpuid) {
regs = ((void *)desc) + (sizeof *desc);
if ((void *) regs + sizeof (*regs) <= g->hvm_buf + g->hvm_sz)
return regs;
}
}
KDD_LOG(g, "Dom %"PRIu32" has no LAPIC %i\n", g->domid, cpuid);
return NULL;
}
/* Accessors for guest user registers */
static void kdd_get_regs_x86_32(struct hvm_hw_cpu *cpu, kdd_regs_x86_32 *r)
{
r->gs = cpu->gs_sel;
r->fs = cpu->fs_sel;
r->es = cpu->es_sel;
r->ds = cpu->ds_sel;
r->edi = cpu->rdi;
r->esi = cpu->rsi;
r->ebx = cpu->rbx;
r->edx = cpu->rdx;
r->ecx = cpu->rcx;
r->eax = cpu->rax;
r->ebp = cpu->rbp;
r->eip = cpu->rip;
r->cs = cpu->cs_sel;
r->eflags = cpu->rflags;
r->esp = cpu->rsp;
r->ss = cpu->ss_sel;
memcpy(r->fp, cpu->fpu_regs, 112); // 108 save area + 4 of ???
}
static void kdd_set_regs_x86_32(struct hvm_hw_cpu *cpu, kdd_regs_x86_32 *r)
{
cpu->gs_sel = r->gs;
cpu->fs_sel = r->fs;
cpu->es_sel = r->es;
cpu->ds_sel = r->ds;
cpu->rdi = r->edi;
cpu->rsi = r->esi;
cpu->rbx = r->ebx;
cpu->rdx = r->edx;
cpu->rcx = r->ecx;
cpu->rax = r->eax;
cpu->rbp = r->ebp;
cpu->rip = r->eip;
cpu->cs_sel = r->cs;
cpu->rflags = r->eflags;
cpu->rsp = r->esp;
cpu->ss_sel = r->ss;
memcpy(cpu->fpu_regs, r->fp, 112); // 108 save area + 4 of ???
}
static void kdd_get_regs_x86_64(struct hvm_hw_cpu *cpu, kdd_regs_x86_64 *r)
{
// XXX debug pattern
uint16_t i;
for (i = 0 ; i < (sizeof *r / 2) ; i++)
((uint16_t *)r)[i] = i;
r->cs = cpu->cs_sel;
r->ds = cpu->ds_sel;
r->es = cpu->es_sel;
r->fs = cpu->fs_sel;
r->gs = cpu->gs_sel;
r->ss = cpu->ss_sel;
r->rflags = cpu->rflags;
r->dr0 = cpu->dr0;
r->dr1 = cpu->dr1;
r->dr2 = cpu->dr2;
r->dr3 = cpu->dr3;
r->dr6 = cpu->dr6;
r->dr7 = cpu->dr7;
r->rax = cpu->rax;
r->rcx = cpu->rcx;
r->rdx = cpu->rdx;
r->rbx = cpu->rbx;
r->rsp = cpu->rsp;
r->rbp = cpu->rbp;
r->rsi = cpu->rsi;
r->rdi = cpu->rdi;
r->r8 = cpu->r8;
r->r9 = cpu->r9;
r->r10 = cpu->r10;
r->r11 = cpu->r11;
r->r12 = cpu->r12;
r->r13 = cpu->r13;
r->r14 = cpu->r14;
r->r15 = cpu->r15;
r->rip = cpu->rip;
memcpy(r->fp, cpu->fpu_regs, 112); // Definitely not right
}
static void kdd_set_regs_x86_64(struct hvm_hw_cpu *cpu, kdd_regs_x86_64 *r)
{
cpu->cs_sel = r->cs;
cpu->ds_sel = r->ds;
cpu->es_sel = r->es;
cpu->fs_sel = r->fs;
cpu->gs_sel = r->gs;
cpu->ss_sel = r->ss;
cpu->rflags = r->rflags;
cpu->dr0 = r->dr0;
cpu->dr1 = r->dr1;
cpu->dr2 = r->dr2;
cpu->dr3 = r->dr3;
cpu->dr6 = r->dr6;
cpu->dr7 = r->dr7;
cpu->rax = r->rax;
cpu->rcx = r->rcx;
cpu->rdx = r->rdx;
cpu->rbx = r->rbx;
cpu->rsp = r->rsp;
cpu->rbp = r->rbp;
cpu->rsi = r->rsi;
cpu->rdi = r->rdi;
cpu->r8 = r->r8;
cpu->r9 = r->r9;
cpu->r10 = r->r10;
cpu->r11 = r->r11;
cpu->r12 = r->r12;
cpu->r13 = r->r13;
cpu->r14 = r->r14;
cpu->r15 = r->r15;
cpu->rip = r->rip;
memcpy(r->fp, cpu->fpu_regs, 112); // Definitely not right
}
int kdd_get_regs(kdd_guest *g, int cpuid, kdd_regs *r, int w64)
{
struct hvm_hw_cpu *cpu;
cpu = get_cpu(g, cpuid);
if (!cpu)
return -1;
memset(r, 0, sizeof(r));
if (w64)
kdd_get_regs_x86_64(cpu, &r->r64);
else
kdd_get_regs_x86_32(cpu, &r->r32);
return 0;
}
int kdd_set_regs(kdd_guest *g, int cpuid, kdd_regs *r, int w64)
{
struct hvm_hw_cpu *cpu;
cpu = get_cpu(g, cpuid);
if (!cpu)
return -1;
if (w64)
kdd_set_regs_x86_64(cpu, &r->r64);
else
kdd_set_regs_x86_32(cpu, &r->r32);
hvm_writeback(g);
return 0;
}
/* Accessors for guest control registers */
static void kdd_get_ctrl_x86_32(struct hvm_hw_cpu *cpu, kdd_ctrl_x86_32 *c)
{
c->cr0 = cpu->cr0;
c->cr2 = cpu->cr2;
c->cr3 = cpu->cr3;
c->cr4 = cpu->cr4;
c->dr0 = cpu->dr0;
c->dr1 = cpu->dr1;
c->dr2 = cpu->dr2;
c->dr3 = cpu->dr3;
c->dr6 = cpu->dr6;
c->dr7 = cpu->dr7;
c->gdt_base = cpu->gdtr_base;
c->gdt_limit = cpu->gdtr_limit;
c->idt_base = cpu->idtr_base;
c->idt_limit = cpu->idtr_limit;
c->tss_sel = cpu->tr_sel;
c->ldt_sel = cpu->ldtr_sel;
}
static void kdd_get_ctrl_x86_64(struct hvm_hw_cpu *cpu,
struct hvm_hw_lapic_regs *lapic,
kdd_ctrl_x86_64 *c)
{
c->cr0 = cpu->cr0;
c->cr2 = cpu->cr2;
c->cr3 = cpu->cr3;
c->cr4 = cpu->cr4;
c->dr0 = cpu->dr0;
c->dr1 = cpu->dr1;
c->dr2 = cpu->dr2;
c->dr3 = cpu->dr3;
c->dr6 = cpu->dr6;
c->dr7 = cpu->dr7;
c->gdt_base = cpu->gdtr_base;
c->gdt_limit = cpu->gdtr_limit;
c->idt_base = cpu->idtr_base;
c->idt_limit = cpu->idtr_limit;
c->tss_sel = cpu->tr_sel;
c->ldt_sel = cpu->ldtr_sel;
c->cr8 = lapic->data[0x80] >> 4; /* Top half of the low byte of the TPR */
}
int kdd_get_ctrl(kdd_guest *g, int cpuid, kdd_ctrl *ctrl, int w64)
{
struct hvm_hw_cpu *cpu;
struct hvm_hw_lapic_regs *lapic;
cpu = get_cpu(g, cpuid);
if (!cpu)
return -1;
if (w64) {
lapic = get_lapic(g, cpuid);
if (!lapic)
return -1;
kdd_get_ctrl_x86_64(cpu, lapic, &ctrl->c64);
} else {
kdd_get_ctrl_x86_32(cpu, &ctrl->c32);
}
return 0;
}
int kdd_wrmsr(kdd_guest *g, int cpuid, uint32_t msr, uint64_t value)
{
struct hvm_hw_cpu *cpu;
cpu = get_cpu(g, cpuid);
if (!cpu)
return -1;
switch (msr) {
case 0x00000174: cpu->sysenter_cs = value; break;
case 0x00000175: cpu->sysenter_esp = value; break;
case 0x00000176: cpu->sysenter_eip = value; break;
case 0xc0000080: cpu->msr_efer = value; break;
case 0xc0000081: cpu->msr_star = value; break;
case 0xc0000082: cpu->msr_lstar = value; break;
case 0xc0000083: cpu->msr_cstar = value; break;
case 0xc0000084: cpu->msr_syscall_mask = value; break;
case 0xc0000100: cpu->fs_base = value; break;
case 0xc0000101: cpu->gs_base = value; break;
case 0xc0000102: cpu->shadow_gs = value; break;
default:
return -1;
}
hvm_writeback(g);
return 0;
}
int kdd_rdmsr(kdd_guest *g, int cpuid, uint32_t msr, uint64_t *value)
{
struct hvm_hw_cpu *cpu;
cpu = get_cpu(g, cpuid);
if (!cpu)
return -1;
switch (msr) {
case 0x00000174: *value = cpu->sysenter_cs; break;
case 0x00000175: *value = cpu->sysenter_esp; break;
case 0x00000176: *value = cpu->sysenter_eip; break;
case 0xc0000080: *value = cpu->msr_efer; break;
case 0xc0000081: *value = cpu->msr_star; break;
case 0xc0000082: *value = cpu->msr_lstar; break;
case 0xc0000083: *value = cpu->msr_cstar; break;
case 0xc0000084: *value = cpu->msr_syscall_mask; break;
case 0xc0000100: *value = cpu->fs_base; break;
case 0xc0000101: *value = cpu->gs_base; break;
case 0xc0000102: *value = cpu->shadow_gs; break;
default:
return -1;
}
return 0;
}
/* Accessor for guest physical memory */
static uint32_t kdd_access_physical_page(kdd_guest *g, uint64_t addr,
uint32_t len, uint8_t *buf, int write)
{
uint32_t map_pfn, map_offset;
uint8_t *map;
map_pfn = (addr >> PAGE_SHIFT);
map_offset = addr & (PAGE_SIZE - 1);
/* Evict any mapping of the wrong frame from our slot */
if (g->pfns[map_pfn % MAPSIZE] != map_pfn
&& g->maps[map_pfn % MAPSIZE] != NULL) {
munmap(g->maps[map_pfn % MAPSIZE], PAGE_SIZE);
g->maps[map_pfn % MAPSIZE] = NULL;
}
g->pfns[map_pfn % MAPSIZE] = map_pfn;
/* Now map the frame if it's not already there */
if (g->maps[map_pfn % MAPSIZE] != NULL)
map = g->maps[map_pfn % MAPSIZE];
else {
map = xc_map_foreign_range(g->xc_handle,
g->domid,
PAGE_SIZE,
PROT_READ|PROT_WRITE,
map_pfn);
KDD_DEBUG(g, "map: %u, 0x%16.16"PRIx32": %p +0x%"PRIx32"\n",
write ? PROT_READ|PROT_WRITE : PROT_READ,
map_pfn, map, map_offset);
if (!map)
return 0;
g->maps[map_pfn % MAPSIZE] = map;
}
if (write)
memcpy(map + map_offset, buf, len);
else
memcpy(buf, map + map_offset, len);
return len;
}
uint32_t kdd_access_physical(kdd_guest *g, uint64_t addr,
uint32_t len, uint8_t *buf, int write)
{
uint32_t chunk, rv, done = 0;
while (len > 0) {
chunk = PAGE_SIZE - (addr & (PAGE_SIZE - 1));
if (chunk > len)
chunk = len;
rv = kdd_access_physical_page(g, addr, chunk, buf, write);
done += rv;
if (rv != chunk)
return done;
addr += chunk;
buf += chunk;
len -= chunk;
}
return done;
}
/* Plumb libxc log messages into our own logging */
static void kdd_xc_log(struct xentoollog_logger *logger,
xentoollog_level level,
int errnoval /* or -1 */,
const char *context /* eg "xc", "xl", may be 0 */,
const char *format /* without level, context, \n */,
va_list al)
{
kdd_guest *g = (kdd_guest *) logger;
/* Suppress most libxc levels unless we're logging at debug level */
if (g->verbosity < 1 || (level < XTL_WARN && g->verbosity < 3))
return;
fprintf(g->log, "libxc[%s:%i:%i]: ", context ? : "?", level, errnoval);
vfprintf(g->log, format, al);
fprintf(g->log, "\n");
(void) fflush(g->log);
}
/* Set up guest-specific state */
kdd_guest *kdd_guest_init(char *arg, FILE *log, int verbosity)
{
kdd_guest *g = NULL;
xc_interface *xch = NULL;
uint32_t domid;
xc_dominfo_t info;
g = calloc(1, sizeof (kdd_guest));
if (!g)
goto err;
g->log = log;
g->verbosity = verbosity;
g->xc_log.vmessage = kdd_xc_log;
xch = xc_interface_open(&g->xc_log, NULL, 0);
if (!xch)
goto err;
g->xc_handle = xch;
domid = strtoul(arg, NULL, 0);
if (domid == 0)
goto err;
g->domid = domid;
/* Check that the domain exists and is HVM */
if (xc_domain_getinfo(xch, domid, 1, &info) != 1 || !info.hvm)
goto err;
snprintf(g->id, (sizeof g->id) - 1,
"a xen guest with domain id %i", g->domid);
return g;
err:
free(g);
if (xch)
xc_interface_close(xch);
return NULL;
}
/* Say what kind of guest this is */
char *kdd_guest_identify(kdd_guest *g)
{
return g->id;
}
/* Tear down guest-specific state */
void kdd_guest_teardown(kdd_guest *g)
{
flush_maps(g);
xc_interface_close(g->xc_handle);
free(g->id);
free(g->hvm_buf);
free(g);
}
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