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Re: [Qemu-devel] BUG: QEMU aborts when setting breakpoint in gdb (bisect
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] BUG: QEMU aborts when setting breakpoint in gdb (bisected) |
Date: |
Wed, 6 Nov 2013 13:36:22 -0500 |
On Wed, 06 Nov 2013 18:39:42 +0100
Paolo Bonzini <address@hidden> wrote:
> 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).
hbreak didn't work either, gdb doesn't stop at the breakpoint. I tried to
test this with another random function and got a "Remote 'g' packet
reply is too long" (which seems to be yet another different problem).
> > 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?
Tested-by: Luiz Capitulino <address@hidden>
>
>
> 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), (continued)
Re: [Qemu-devel] BUG: QEMU aborts when setting breakpoint in gdb (bisected),
Luiz Capitulino <=