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authorMeador Inge <meadori@codesourcery.com>2012-03-15 17:49:45 +0000
committerBlue Swirl <blauwirbel@gmail.com>2012-03-24 14:12:27 +0000
commitcdb432b2020d3a5b22a7c06278088ccc7d1b2843 (patch)
treeca3b412dd1afd124dfcfc9b9dcf98b466114c684
parent3179d694a8dcaa091131e3db644d445c0130713e (diff)
downloadqemu-arm-cdb432b2020d3a5b22a7c06278088ccc7d1b2843.tar.gz
gdbserver: Don't send a GDB syscall until the system CPU is stopped
Fix an issue where the GDB server implementation was sending GDB syscall requests while the system CPU was still running. Syscall requests must be sent while the CPU is stopped otherwise replies from the GDB client might get dropped and the GDB server might be incorrectly transitioned into a 'RUN_STATE_PAUSED' state. Signed-off-by: Meador Inge <meadori@codesourcery.com> [PMM: trivial rebase, reinstated comma after last item in RSState enum] Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Andreas Färber <afaerber@suse.de> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
-rw-r--r--gdbstub.c42
1 files changed, 27 insertions, 15 deletions
diff --git a/gdbstub.c b/gdbstub.c
index f4e97f7370..6a7e2c4934 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -284,7 +284,6 @@ enum RSState {
RS_GETLINE,
RS_CHKSUM1,
RS_CHKSUM2,
- RS_SYSCALL,
};
typedef struct GDBState {
CPUArchState *c_cpu; /* current CPU for step/continue ops */
@@ -304,6 +303,8 @@ typedef struct GDBState {
CharDriverState *chr;
CharDriverState *mon_chr;
#endif
+ char syscall_buf[256];
+ gdb_syscall_complete_cb current_syscall_cb;
} GDBState;
/* By default use no IRQs and no timers while single stepping so as to
@@ -346,8 +347,6 @@ static int get_char(GDBState *s)
}
#endif
-static gdb_syscall_complete_cb gdb_current_syscall_cb;
-
static enum {
GDB_SYS_UNKNOWN,
GDB_SYS_ENABLED,
@@ -2097,8 +2096,10 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
if (*p == ',')
p++;
type = *p;
- if (gdb_current_syscall_cb)
- gdb_current_syscall_cb(s->c_cpu, ret, err);
+ if (s->current_syscall_cb) {
+ s->current_syscall_cb(s->c_cpu, ret, err);
+ s->current_syscall_cb = NULL;
+ }
if (type == 'C') {
put_packet(s, "T02");
} else {
@@ -2398,7 +2399,12 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
const char *type;
int ret;
- if (running || s->state == RS_INACTIVE || s->state == RS_SYSCALL) {
+ if (running || s->state == RS_INACTIVE) {
+ return;
+ }
+ /* Is there a GDB syscall waiting to be sent? */
+ if (s->current_syscall_cb) {
+ put_packet(s, s->syscall_buf);
return;
}
switch (state) {
@@ -2468,8 +2474,8 @@ send_packet:
void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...)
{
va_list va;
- char buf[256];
char *p;
+ char *p_end;
target_ulong addr;
uint64_t i64;
GDBState *s;
@@ -2477,14 +2483,13 @@ void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...)
s = gdbserver_state;
if (!s)
return;
- gdb_current_syscall_cb = cb;
- s->state = RS_SYSCALL;
+ s->current_syscall_cb = cb;
#ifndef CONFIG_USER_ONLY
vm_stop(RUN_STATE_DEBUG);
#endif
- s->state = RS_IDLE;
va_start(va, fmt);
- p = buf;
+ p = s->syscall_buf;
+ p_end = &s->syscall_buf[sizeof(s->syscall_buf)];
*(p++) = 'F';
while (*fmt) {
if (*fmt == '%') {
@@ -2492,17 +2497,17 @@ void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...)
switch (*fmt++) {
case 'x':
addr = va_arg(va, target_ulong);
- p += snprintf(p, &buf[sizeof(buf)] - p, TARGET_FMT_lx, addr);
+ p += snprintf(p, p_end - p, TARGET_FMT_lx, addr);
break;
case 'l':
if (*(fmt++) != 'x')
goto bad_format;
i64 = va_arg(va, uint64_t);
- p += snprintf(p, &buf[sizeof(buf)] - p, "%" PRIx64, i64);
+ p += snprintf(p, p_end - p, "%" PRIx64, i64);
break;
case 's':
addr = va_arg(va, target_ulong);
- p += snprintf(p, &buf[sizeof(buf)] - p, TARGET_FMT_lx "/%x",
+ p += snprintf(p, p_end - p, TARGET_FMT_lx "/%x",
addr, va_arg(va, int));
break;
default:
@@ -2517,10 +2522,16 @@ void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...)
}
*p = 0;
va_end(va);
- put_packet(s, buf);
#ifdef CONFIG_USER_ONLY
+ put_packet(s, s->syscall_buf);
gdb_handlesig(s->c_cpu, 0);
#else
+ /* In this case wait to send the syscall packet until notification that
+ the CPU has stopped. This must be done because if the packet is sent
+ now the reply from the syscall request could be received while the CPU
+ is still in the running state, which can cause packets to be dropped
+ and state transition 'T' packets to be sent while the syscall is still
+ being processed. */
cpu_exit(s->c_cpu);
#endif
}
@@ -2919,6 +2930,7 @@ int gdbserver_start(const char *device)
s->chr = chr;
s->state = chr ? RS_IDLE : RS_INACTIVE;
s->mon_chr = mon_chr;
+ s->current_syscall_cb = NULL;
return 0;
}