On Fri, Jul 24, 2015 at 09:17:59PM -0700, enh wrote: > Android kernels have an extra prctl that lets us set a name for an > anonymous VMA, which is useful for debugging. at the moment strace > shows it like this: > > prctl(0x53564d41 /* PR_??? */, 0, 0x7f7ab0e000, 0x2000, 0x7f7aaf76d0) = 0 > prctl(0x53564d41 /* PR_??? */, 0, 0x7f7ab0d000, 0x1000, 0x7f7aaf76e8) = 0 > > with this patch: > > diff --git a/prctl.c b/prctl.c > index 4a6bd25..e43569c 100644 > --- a/prctl.c > +++ b/prctl.c > @@ -94,6 +94,22 @@ prctl_enter(struct tcb *tcp) > printstr(tcp, tcp->u_arg[1], TASK_COMM_LEN); > break; > > +#define PR_SET_VMA 0x53564d41 > +#define PR_SET_VMA_ANON_NAME 0
If there is a chance of these constants being defined in system headers
some day, please wrap these definitions in ifdefs.
> + case PR_SET_VMA:
> + if (tcp->u_arg[1] == PR_SET_VMA_ANON_NAME) {
> + tprintf(", %lu", tcp->u_arg[1]);
> + tprintf(", %#lx", tcp->u_arg[2]);
> + tprintf(", %lu, ", tcp->u_arg[3]);
> + printstr(tcp, tcp->u_arg[4], -1);
> + } else {
> + // There are no other sub-options now, but there
> + // might be in future...
> + for (i = 1; i < tcp->s_ent->nargs; i++)
> + tprintf(", %#lx", tcp->u_arg[i]);
Starting with commit v4.10-259-g3691562, this loop should be replaced with
print_prctl_args(tcp, 1);
> + }
> + break;
> +
> case PR_SET_MM:
> tprints(", ");
> printxval(pr_set_mm, tcp->u_arg[1], "PR_SET_MM_???");
>
> we get this instead:
>
> prctl(0x53564d41 /* PR_??? */, 0, 0x7f7ffe0000, 8192, "thread signal stack")
> = 0
> prctl(0x53564d41 /* PR_??? */, 0, 0x7f7ffdf000, 4096, "thread signal
> stack guard page") = 0
>
> obviously i could change the xlat prctl_options.in file to add
> PR_SET_VMA, but this isn't in upstream kernels so that seems wrong.
Agreed.
> i can easily keep the patch above and/or the one that touches the xlat
> file in our tree, but i thought i'd ask what -- if anything -- of this
> you'd be interested in having in upstream strace.
I think this change would be OK for upstream strace.
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