bitkeeper revision 1.1163 (420b8f97P8m2OsC2o8di9OVsBppT2Q)

Arrange for it to work (some of the time) on modern Xen.

diff --git a/xen/arch/x86/cdb.c b/xen/arch/x86/cdb.c
index db0e9b0371d609aa70672cf9695f739b13caa04c..1bb50ab9de3b1d56de7c71d83c761b54661dfae8 100644 (file)
--- a/xen/arch/x86/cdb.c
+++ b/xen/arch/x86/cdb.c
@@ -10,10 +10,11 @@
 #include <asm/irq.h>
 #include <xen/spinlock.h>
 #include <asm/debugger.h>
+#include <asm/init.h>
 
 /* Printk isn't particularly safe just after we've trapped to the
    debugger. so avoid it. */
-#define dbg_printk(...)
+#define dbg_printk
 
 static unsigned char opt_cdb[30] = "none";
 string_param("cdb", opt_cdb);
@@ -24,6 +25,33 @@ struct xendbg_context {
        int currently_attached:1;
 };
 
+/* Like copy_from_user, but safe to call with interrupts disabled.
+
+   Trust me, and don't look behind the curtain. */
+static unsigned
+dbg_copy_from_user(void *dest, const void *src, unsigned len)
+{
+       int __d0, __d1, __d2;
+       ASSERT(!local_irq_is_enabled());
+       __asm__ __volatile__(
+               "1:     rep; movsb\n"
+               "2:\n"
+               ".section __pre_ex_table,\"a\"\n"
+               "       .align 4\n"
+               "       .long 1b,2b\n"
+               ".previous\n"
+               ".section __ex_table,\"a\"\n"
+               "       .align 4\n"
+               "       .long 1b,2b\n"
+               ".previous\n"
+               : "=c"(__d2), "=D" (__d0), "=S" (__d1)
+               : "0"(len), "1"(dest), "2"(src)
+               : "memory");
+       ASSERT(!local_irq_is_enabled());
+       printf("dbg_copy_from_user returning %d.\n", __d2);
+       return __d2;
+}
+
 static void
 xendbg_put_char(u8 data, struct xendbg_context *ctx)
 {
@@ -158,7 +186,7 @@ handle_memory_read_command(unsigned long addr, unsigned long length,
                   length);
        xendbg_start_reply(ctx);
        for (x = 0; x < length; x++) {
-               r = __copy_from_user(&val, (void *)(addr + x), 1);
+               r = dbg_copy_from_user(&val, (void *)(addr + x), 1);
                if (r != 0) {
                        dbg_printk("Error reading from %lx.\n", addr + x);
                        break;
@@ -221,6 +249,7 @@ process_command(char *received_packet, struct xen_regs *regs,
                switch (received_packet[0]) {
                case 'g': /* Read registers */
                        retry = handle_register_read_command(regs, ctx);
+                       ASSERT(!local_irq_is_enabled());
                        break;
                case 'm': /* Read memory */
                        addr = simple_strtoul(received_packet + 1, &ptr, 16);
@@ -238,6 +267,7 @@ process_command(char *received_packet, struct xen_regs *regs,
                                handle_memory_read_command(addr,
                                                           length,
                                                           ctx);
+                       ASSERT(!local_irq_is_enabled());
                        break;
                case 'G': /* Write registers */
                case 'M': /* Write memory */
@@ -318,6 +348,8 @@ __trap_to_cdb(struct xen_regs *regs)
                return;
        }
 
+       smp_send_stop();
+
        /* Shouldn't really do this, but otherwise we stop for no
           obvious reason, which is Bad */
        printk("Waiting for GDB to attach to XenDBG\n");
@@ -330,22 +362,27 @@ __trap_to_cdb(struct xen_regs *regs)
        }
 
        while (resume == 0) {
+               ASSERT(!local_irq_is_enabled());
                r = receive_command(recv_buf, &xdb_ctx);
+               ASSERT(!local_irq_is_enabled());
                if (r < 0) {
                        dbg_printk("GDB disappeared, trying to resume Xen...\n");
                        resume = 1;
-               } else
+               } else {
+                       ASSERT(!local_irq_is_enabled());
                        resume = process_command(recv_buf, regs, &xdb_ctx);
+                       ASSERT(!local_irq_is_enabled());
+               }
        }
        atomic_inc(&xendbg_running);
        local_irq_restore(flags);
 }
 
-void
+static int
 initialize_xendbg(void)
 {
        if (!strcmp(opt_cdb, "none"))
-               return;
+               return 0;
        xdb_ctx.serhnd = parse_serial_handle(opt_cdb);
        if (xdb_ctx.serhnd == -1)
                panic("Can't parse %s as CDB serial info.\n", opt_cdb);
@@ -354,4 +391,7 @@ initialize_xendbg(void)
        xendbg_put_char('+', &xdb_ctx);
 
        printk("Xendbg initialised.\n");
+       return 0;
 }
+
+__initcall(initialize_xendbg);