Date: Sat, 5 Jan 2019 15:22:00 -0800 From: Mark Millard <marklmi@yahoo.com> To: Kyle Evans <kevans@FreeBSD.org>, freebsd-emulation@freebsd.org, ports-list freebsd <freebsd-ports@freebsd.org> Cc: Sean Bruno <sbruno@freebsd.org> Subject: qemu-arm-static has target_sigframe missing sf_fvp field so target_sigframe is too small Message-ID: <693D6101-25B5-4D88-BD5F-1F8BD34AEA1D@yahoo.com>
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[The context here is FreeBSD head -r341836 based and ports head -r488859 =
based.]
Note: I assume that "struct target_sigframe" is meant to match the =
memory layout
of the target's native "struct sigframe". Otherwise the reported =
differences
below could be irrelevant.
For armv7 (and likely armv6) the following code:
printf("sizeof(struct sigframe) =3D %lu\n", (unsigned long) =
sizeof(struct sigframe));
// arm:
printf("sf_si %lu\n", (unsigned long) offsetof(struct sigframe, =
sf_si));
printf("sf_uc %lu\n", (unsigned long) offsetof(struct sigframe, =
sf_uc));
printf("sf_vfp %lu\n", (unsigned long) offsetof(struct sigframe, =
sf_vfp));
produces:
sizeof(struct sigframe) =3D 592
sf_si 0
sf_uc 64
sf_vfp 328
However gdb reports for qemu-arm-static (on amd64):
(gdb) p/d sizeof(struct target_sigframe)
$3 =3D 324
(gdb) p/d &((struct target_sigframe *)0)->sf_si
$4 =3D 0
(gdb) p/d &((struct target_sigframe *)0)->sf_uc
$5 =3D 64
(gdb) p/d &((struct target_sigframe *)0)->sf_vfp
There is no member named sf_vfp.
So the first two fields have matching offsets.
But note: sf_vfp is at 328, after the size of target_sigframe (324).
It looks like both contexts have 260 for the size of sf_uc so the
difference is padding before sf_vfp .
/usr/include/machine/frame.h has:
struct sigframe {
siginfo_t sf_si; /* actual saved siginfo */
ucontext_t sf_uc; /* actual saved ucontext */
mcontext_vfp_t sf_vfp; /* actual saved VFP context */
};
sf_vfp was added in -r315947 (2017-Mar-26) and is in 11.2 .
=
/wrkdirs/usr/ports/emulators/qemu-user-static/work/qemu-bsd-user-4ef7d07/b=
sd-user/arm/target_arch_signal.h
has:
struct target_sigframe {
target_siginfo_t sf_si; /* saved siginfo */
target_ucontext_t sf_uc; /* saved ucontext */
};
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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