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Re: [Qemu-devel] [PATCH] memory: info mtree check mr range overflow
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH] memory: info mtree check mr range overflow |
Date: |
Wed, 15 Mar 2017 03:24:04 +0200 |
On Tue, Mar 14, 2017 at 08:56:27PM +0800, Peter Xu wrote:
> The address of memory regions might overflow when something wrong
> happened, like reported in:
>
> https://lists.gnu.org/archive/html/qemu-devel/2017-03/msg02043.html
>
> For easier debugging, let's try to detect it.
>
> Reported-by: Mark Cave-Ayland <address@hidden>
> Signed-off-by: Peter Xu <address@hidden>
After a chat with Paolo, I think the following is a more general fix
- fix info mtree to do 128 bit math and display more than
16 digits if necessary
- add info about region visibility
how much info is appropriate is arguable - after all we already have info
mtree -f
we probably should report if region is not visible at all,
how about partially occluded ones? listing all windows is probably not
needed - we have the -f flag for that.
> ---
> memory.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/memory.c b/memory.c
> index 284894b..64b0a60 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -2494,6 +2494,7 @@ static void mtree_print_mr(fprintf_function mon_printf,
> void *f,
> MemoryRegionListHead submr_print_queue;
> const MemoryRegion *submr;
> unsigned int i;
> + hwaddr cur_start, cur_end;
>
> if (!mr) {
> return;
> @@ -2503,6 +2504,18 @@ static void mtree_print_mr(fprintf_function
> mon_printf, void *f,
> mon_printf(f, MTREE_INDENT);
> }
>
> + cur_start = base + mr->addr;
> + cur_end = cur_start + MR_SIZE(mr->size);
> +
> + /*
> + * Try to detect overflow of memory region. This should never
> + * happen normally. When it happens, we dump something to warn the
> + * user who is observing this.
> + */
> + if (cur_start < base || cur_end < cur_start) {
> + mon_printf(f, "[DETECTED OVERFLOW!] ");
> + }
> +
> if (mr->alias) {
> MemoryRegionList *ml;
> bool found = false;
> @@ -2522,8 +2535,7 @@ static void mtree_print_mr(fprintf_function mon_printf,
> void *f,
> mon_printf(f, TARGET_FMT_plx "-" TARGET_FMT_plx
> " (prio %d, %s): alias %s @%s " TARGET_FMT_plx
> "-" TARGET_FMT_plx "%s\n",
> - base + mr->addr,
> - base + mr->addr + MR_SIZE(mr->size),
> + cur_start, cur_end,
> mr->priority,
> memory_region_type((MemoryRegion *)mr),
> memory_region_name(mr),
> @@ -2534,8 +2546,7 @@ static void mtree_print_mr(fprintf_function mon_printf,
> void *f,
> } else {
> mon_printf(f,
> TARGET_FMT_plx "-" TARGET_FMT_plx " (prio %d, %s):
> %s%s\n",
> - base + mr->addr,
> - base + mr->addr + MR_SIZE(mr->size),
> + cur_start, cur_end,
> mr->priority,
> memory_region_type((MemoryRegion *)mr),
> memory_region_name(mr),
> @@ -2562,7 +2573,7 @@ static void mtree_print_mr(fprintf_function mon_printf,
> void *f,
> }
>
> QTAILQ_FOREACH(ml, &submr_print_queue, queue) {
> - mtree_print_mr(mon_printf, f, ml->mr, level + 1, base + mr->addr,
> + mtree_print_mr(mon_printf, f, ml->mr, level + 1, cur_start,
> alias_print_queue);
> }
>
> --
> 2.7.4