[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] BUG: QEMU aborts when setting breakpoint in gdb (bisect
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] BUG: QEMU aborts when setting breakpoint in gdb (bisected) |
Date: |
Wed, 06 Nov 2013 18:39:42 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 |
Il 06/11/2013 17:22, Luiz Capitulino ha scritto:
> 1. Run qemu with gdb server support
>
> # qemu [...] -s -S
>
> 2. Connect gdb and try to set a breakpoint
>
> $ gdb /path/to/vmlinux
> (gdb) target remote:1234
> (gdb) b secondary_startup_64
(Note that this doesn't make much sense until the kernel has been loaded
into memory. You probably want hbreak instead).
> 3. On qemu terminal
>
> qemu-qmp:
> /home/lcapitulino/work/src/upstream/qmp-unstable/include/qemu/int128.h:22:
> int128_get64: Assertion `!a.hi' failed.
> Aborted (core dumped)
>
> According to bisect the culprit is:
>
> commit a53ae8e934cd54686875b5bcfc2f434244ee55d6
> Author: Marcel Apfelbaum <address@hidden>
> Date: Mon Sep 16 11:21:16 2013 +0300
>
> hw/pci: partially handle pci master abort
I couldn't get quite the same reproducer, mine was:
$ gdb
(gdb) set arch i386:x86-64
The target architecture is assumed to be i386:x86-64
(gdb) target remote localhost:1234
Remote debugging using localhost:1234
<bang>
The problem is that gdb attempts to read a few bytes from address
0xffffffffffffffe6 to 0xffffffffffffffff inclusive.
The region it gets is the (newly introduced) master abort region, which
is as big as the PCI address space (see pci_bus_init). Due to a typo
that's only 2^63-1, not 2^64. But we get it anyway because
phys_page_find ignores the upper bits of the physical address. In
address_space_translate_internal then
diff = int128_sub(section->mr->size, int128_make64(addr));
*plen = int128_get64(int128_min(diff, int128_make64(*plen)));
diff becomes negative, and int128_get64 booms.
Will send as a proper patch tomorrow... can you give your Tested-by?
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index b3d94bd..68901c3 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -114,7 +114,7 @@ static void pc_init1(QEMUMachineInitArgs *args,
if (pci_enabled) {
pci_memory = g_new(MemoryRegion, 1);
- memory_region_init(pci_memory, NULL, "pci", INT64_MAX);
+ memory_region_init(pci_memory, NULL, "pci", UINT64_MAX);
rom_memory = pci_memory;
} else {
pci_memory = NULL;
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 2e315f7..c9a03fc 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -101,7 +101,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
/* pci enabled */
if (pci_enabled) {
pci_memory = g_new(MemoryRegion, 1);
- memory_region_init(pci_memory, NULL, "pci", INT64_MAX);
+ memory_region_init(pci_memory, NULL, "pci", UINT64_MAX);
rom_memory = pci_memory;
} else {
pci_memory = NULL;
Re: [Qemu-devel] BUG: QEMU aborts when setting breakpoint in gdb (bisected), Luiz Capitulino, 2013/11/06