Commit aa96a3c6 authored Sep 05, 2013 by Rusty Russell

lguest: fix GPF in guest when using gdb.



Since the Guest is in ring 1, it can't read the debug registers: doing
so gives a number of nasty messages:

(gdb) run
Starting program: /bin/sleep
[   31.170230] general protection fault: 0000 [#1] SMP
[   31.170230] Modules linked in:
[   31.170230] CPU: 0 PID: 2678 Comm: sleep Not tainted 3.11.0+ #64
[   31.170230] task: cc5c09b0 ti: cc79c000 task.ti: cc79c000
[   31.170230] EIP: 0061:[<c01333d8>] EFLAGS: 00000097 CPU: 0
[   31.170230] EIP is at native_get_debugreg+0x58/0x70
[   31.170230] EAX: 00000006 EBX: cc79dfb4 ECX: b7fff918 EDX: 00000000
[   31.170230] ESI: cc5c09b0 EDI: 00000000 EBP: cc79df84 ESP: cc79df84
[   31.170230]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0069
[   31.170230] CR0: 00000008 CR2: 081ba69a CR3: 0e2f2000 CR4: 00000000

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

parent 98fb4e5e

arch/x86/lguest/boot.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -1056,6 +1056,12 @@ static void lguest_load_sp0(struct tss_struct *tss,
		}

		/* Let's just say, I wouldn't do debugging under a Guest. */
		static unsigned long lguest_get_debugreg(int regno)
		{
		/* FIXME: Implement */
		return 0;
		}

		static void lguest_set_debugreg(int regno, unsigned long value)
		{
		/* FIXME: Implement */
		@@ -1303,6 +1309,7 @@ __init void lguest_init(void)
		pv_cpu_ops.load_tr_desc = lguest_load_tr_desc;
		pv_cpu_ops.set_ldt = lguest_set_ldt;
		pv_cpu_ops.load_tls = lguest_load_tls;
		pv_cpu_ops.get_debugreg = lguest_get_debugreg;
		pv_cpu_ops.set_debugreg = lguest_set_debugreg;
		pv_cpu_ops.clts = lguest_clts;
		pv_cpu_ops.read_cr0 = lguest_read_cr0;

Admin message