Author: jhb
Date: Fri May 24 00:34:13 2019
New Revision: 348212
URL: https://svnweb.freebsd.org/changeset/base/348212
Log:
Add support for writing to guest memory in the debug server.
- Add a write_mem counterpart to read_mem to handle writes to MMIO.
- Add support for the GDB 'M' packet to write bytes to the guest's
memory. For MMIO writes, attempt to batch writes up into words.
This is imprecise, but if you write a single 2 or 4-byte aligned
word, it should be treated as a single MMIO write operation.
- While here, tidy up the parsing of the 'm' command used for reading
memory to match 'M'.
Reviewed by: markj, Scott Phillips <d.scott.phill...@intel.com>
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20307
Modified:
head/usr.sbin/bhyve/gdb.c
head/usr.sbin/bhyve/mem.c
head/usr.sbin/bhyve/mem.h
Modified: head/usr.sbin/bhyve/gdb.c
==============================================================================
--- head/usr.sbin/bhyve/gdb.c Fri May 24 00:00:29 2019 (r348211)
+++ head/usr.sbin/bhyve/gdb.c Fri May 24 00:34:13 2019 (r348212)
@@ -767,15 +767,24 @@ gdb_read_mem(const uint8_t *data, size_t len)
bool started;
int error;
+ /* Skip 'm' */
+ data += 1;
+ len -= 1;
+
+ /* Parse and consume address. */
cp = memchr(data, ',', len);
- if (cp == NULL) {
+ if (cp == NULL || cp == data) {
send_error(EINVAL);
return;
}
- gva = parse_integer(data + 1, cp - (data + 1));
- resid = parse_integer(cp + 1, len - (cp + 1 - data));
- started = false;
+ gva = parse_integer(data, cp - data);
+ len -= (cp - data) + 1;
+ data += (cp - data) + 1;
+ /* Parse length. */
+ resid = parse_integer(data, len);
+
+ started = false;
while (resid > 0) {
error = guest_vaddr2paddr(cur_vcpu, gva, &gpa);
if (error == -1) {
@@ -861,6 +870,119 @@ gdb_read_mem(const uint8_t *data, size_t len)
finish_packet();
}
+static void
+gdb_write_mem(const uint8_t *data, size_t len)
+{
+ uint64_t gpa, gva, val;
+ uint8_t *cp;
+ size_t resid, todo, bytes;
+ int error;
+
+ /* Skip 'M' */
+ data += 1;
+ len -= 1;
+
+ /* Parse and consume address. */
+ cp = memchr(data, ',', len);
+ if (cp == NULL || cp == data) {
+ send_error(EINVAL);
+ return;
+ }
+ gva = parse_integer(data, cp - data);
+ len -= (cp - data) + 1;
+ data += (cp - data) + 1;
+
+ /* Parse and consume length. */
+ cp = memchr(data, ':', len);
+ if (cp == NULL || cp == data) {
+ send_error(EINVAL);
+ return;
+ }
+ resid = parse_integer(data, cp - data);
+ len -= (cp - data) + 1;
+ data += (cp - data) + 1;
+
+ /* Verify the available bytes match the length. */
+ if (len != resid * 2) {
+ send_error(EINVAL);
+ return;
+ }
+
+ while (resid > 0) {
+ error = guest_vaddr2paddr(cur_vcpu, gva, &gpa);
+ if (error == -1) {
+ send_error(errno);
+ return;
+ }
+ if (error == 0) {
+ send_error(EFAULT);
+ return;
+ }
+
+ /* Write bytes to current page. */
+ todo = getpagesize() - gpa % getpagesize();
+ if (todo > resid)
+ todo = resid;
+
+ cp = paddr_guest2host(ctx, gpa, todo);
+ if (cp != NULL) {
+ /*
+ * If this page is guest RAM, write it a byte
+ * at a time.
+ */
+ while (todo > 0) {
+ assert(len >= 2);
+ *cp = parse_byte(data);
+ data += 2;
+ len -= 2;
+ cp++;
+ gpa++;
+ gva++;
+ resid--;
+ todo--;
+ }
+ } else {
+ /*
+ * If this page isn't guest RAM, try to handle
+ * it via MMIO. For MMIO requests, use
+ * aligned writes of words when possible.
+ */
+ while (todo > 0) {
+ if (gpa & 1 || todo == 1) {
+ bytes = 1;
+ val = parse_byte(data);
+ } else if (gpa & 2 || todo == 2) {
+ bytes = 2;
+ val = parse_byte(data) |
+ (parse_byte(data + 2) << 8);
+ } else {
+ bytes = 4;
+ val = parse_byte(data) |
+ (parse_byte(data + 2) << 8) |
+ (parse_byte(data + 4) << 16) |
+ (parse_byte(data + 6) << 24);
+ }
+ error = write_mem(ctx, cur_vcpu, gpa, val,
+ bytes);
+ if (error == 0) {
+ gpa += bytes;
+ gva += bytes;
+ resid -= bytes;
+ todo -= bytes;
+ data += 2 * bytes;
+ len -= 2 * bytes;
+ } else {
+ send_error(EFAULT);
+ return;
+ }
+ }
+ }
+ assert(resid == 0 || gpa % getpagesize() == 0);
+ }
+ assert(len == 0);
+ send_ok();
+}
+
static bool
command_equals(const uint8_t *data, size_t len, const char *cmd)
{
@@ -1000,6 +1122,9 @@ handle_command(const uint8_t *data, size_t len)
case 'm':
gdb_read_mem(data, len);
break;
+ case 'M':
+ gdb_write_mem(data, len);
+ break;
case 'T': {
int tid;
@@ -1035,7 +1160,6 @@ handle_command(const uint8_t *data, size_t len)
finish_packet();
break;
case 'G': /* TODO */
- case 'M': /* TODO */
case 'v':
/* Handle 'vCont' */
/* 'vCtrlC' */
Modified: head/usr.sbin/bhyve/mem.c
==============================================================================
--- head/usr.sbin/bhyve/mem.c Fri May 24 00:00:29 2019 (r348211)
+++ head/usr.sbin/bhyve/mem.c Fri May 24 00:34:13 2019 (r348212)
@@ -251,30 +251,43 @@ emulate_mem(struct vmctx *ctx, int vcpu, uint64_t padd
return (access_memory(ctx, vcpu, paddr, emulate_mem_cb, &ema));
}
-struct read_mem_args {
- uint64_t *rval;
+struct rw_mem_args {
+ uint64_t *val;
int size;
+ int operation;
};
static int
-read_mem_cb(struct vmctx *ctx, int vcpu, uint64_t paddr, struct mem_range *mr,
+rw_mem_cb(struct vmctx *ctx, int vcpu, uint64_t paddr, struct mem_range *mr,
void *arg)
{
- struct read_mem_args *rma;
+ struct rw_mem_args *rma;
rma = arg;
- return (mr->handler(ctx, vcpu, MEM_F_READ, paddr, rma->size,
- rma->rval, mr->arg1, mr->arg2));
+ return (mr->handler(ctx, vcpu, rma->operation, paddr, rma->size,
+ rma->val, mr->arg1, mr->arg2));
}
int
read_mem(struct vmctx *ctx, int vcpu, uint64_t gpa, uint64_t *rval, int size)
{
- struct read_mem_args rma;
+ struct rw_mem_args rma;
- rma.rval = rval;
+ rma.val = rval;
rma.size = size;
- return (access_memory(ctx, vcpu, gpa, read_mem_cb, &rma));
+ rma.operation = MEM_F_READ;
+ return (access_memory(ctx, vcpu, gpa, rw_mem_cb, &rma));
+}
+
+int
+write_mem(struct vmctx *ctx, int vcpu, uint64_t gpa, uint64_t wval, int size)
+{
+ struct rw_mem_args rma;
+
+ rma.val = &wval;
+ rma.size = size;
+ rma.operation = MEM_F_WRITE;
+ return (access_memory(ctx, vcpu, gpa, rw_mem_cb, &rma));
}
static int
Modified: head/usr.sbin/bhyve/mem.h
==============================================================================
--- head/usr.sbin/bhyve/mem.h Fri May 24 00:00:29 2019 (r348211)
+++ head/usr.sbin/bhyve/mem.h Fri May 24 00:34:13 2019 (r348212)
@@ -61,5 +61,7 @@ int read_mem(struct vmctx *ctx, int vcpu, uint64_t gpa
int register_mem(struct mem_range *memp);
int register_mem_fallback(struct mem_range *memp);
int unregister_mem(struct mem_range *memp);
+int write_mem(struct vmctx *ctx, int vcpu, uint64_t gpa, uint64_t wval,
+ int size);
#endif /* _MEM_H_ */
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