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/*--------------------------------------------------------------------*/
/*--- Create/destroy signal delivery frames. ---*/
/*--- sigframe-x86-darwin.c ---*/
/*--------------------------------------------------------------------*/
/*
This file is part of Valgrind, a dynamic binary instrumentation
framework.
Copyright (C) 2006-2011 OpenWorks Ltd
info@open-works.co.uk
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307, USA.
The GNU General Public License is contained in the file COPYING.
*/
#if defined(VGP_x86_darwin)
#include "pub_core_basics.h"
#include "pub_core_vki.h"
#include "pub_core_vkiscnums.h"
#include "pub_core_libcsetjmp.h" // to keep _threadstate.h happy
#include "pub_core_threadstate.h"
#include "pub_core_aspacemgr.h"
#include "pub_core_libcbase.h"
#include "pub_core_libcassert.h"
#include "pub_core_libcprint.h"
#include "pub_core_machine.h"
#include "pub_core_options.h"
#include "pub_core_signals.h"
#include "pub_core_tooliface.h"
#include "pub_core_trampoline.h"
#include "pub_core_sigframe.h" /* self */
/* Cheap-ass hack copied from ppc32-aix5 code, just to get started.
Produce a frame with layout entirely of our own choosing. */
/* This module creates and removes signal frames for signal deliveries
on x86-darwin. Kludgey; the machine state ought to be saved in a
ucontext and retrieved from it later, so the handler can modify it
and return. However .. for now .. just stick the vex guest state
in the frame and snarf it again later.
Also, don't bother with creating siginfo and ucontext in the
handler, although do point them somewhere non-faulting.
Frame should have a 16-aligned size, just in case that turns out to
be important for Darwin. (be conservative)
*/
struct hacky_sigframe {
/* first four words look like a call to a 3-arg x86 function */
UInt returnAddr;
UInt a1_signo;
UInt a2_siginfo;
UInt a3_ucontext;
UChar lower_guardzone[512]; // put nothing here
VexGuestX86State gst;
VexGuestX86State gshadow1;
VexGuestX86State gshadow2;
vki_siginfo_t fake_siginfo;
struct vki_ucontext fake_ucontext;
UInt magicPI;
UInt sigNo_private;
vki_sigset_t mask; // saved sigmask; restore when hdlr returns
UInt __pad[1];
UChar upper_guardzone[512]; // put nothing here
// and don't zero it, since that might overwrite the client's
// stack redzone, at least on archs which have one
};
/* Extend the stack segment downwards if needed so as to ensure the
new signal frames are mapped to something. Return a Bool
indicating whether or not the operation was successful.
*/
static Bool extend ( ThreadState *tst, Addr addr, SizeT size )
{
ThreadId tid = tst->tid;
/* For tracking memory events, indicate the entire frame has been
allocated. Except, don't mess with the area which
overlaps the previous frame's redzone. */
/* XXX is the following call really right? compared with the
amd64-linux version, this doesn't appear to handle the redzone
in the same way. */
VG_TRACK( new_mem_stack_signal,
addr - VG_STACK_REDZONE_SZB, size, tid );
return True;
}
/* Create a signal frame for thread 'tid'. Make a 3-arg frame
regardless of whether the client originally requested a 1-arg
version (no SA_SIGINFO) or a 3-arg one (SA_SIGINFO) since in the
former case, the x86 calling conventions will simply cause the
extra 2 args to be ignored (inside the handler). */
void VG_(sigframe_create) ( ThreadId tid,
Addr sp_top_of_frame,
const vki_siginfo_t *siginfo,
const struct vki_ucontext *siguc,
void *handler,
UInt flags,
const vki_sigset_t *mask,
void *restorer )
{
ThreadState* tst;
Addr esp;
struct hacky_sigframe* frame;
Int sigNo = siginfo->si_signo;
vg_assert(VG_IS_16_ALIGNED(sizeof(struct hacky_sigframe)));
sp_top_of_frame &= ~0xf;
esp = sp_top_of_frame - sizeof(struct hacky_sigframe);
tst = VG_(get_ThreadState)(tid);
if (!extend(tst, esp, sp_top_of_frame - esp))
return;
vg_assert(VG_IS_16_ALIGNED(esp));
frame = (struct hacky_sigframe *) esp;
/* clear it (very conservatively) (why so conservatively??) */
VG_(memset)(&frame->lower_guardzone, 0, 512);
VG_(memset)(&frame->gst, 0, sizeof(VexGuestX86State));
VG_(memset)(&frame->gshadow1, 0, sizeof(VexGuestX86State));
VG_(memset)(&frame->gshadow2, 0, sizeof(VexGuestX86State));
VG_(memset)(&frame->fake_siginfo, 0, sizeof(frame->fake_siginfo));
VG_(memset)(&frame->fake_ucontext, 0, sizeof(frame->fake_ucontext));
/* save stuff in frame */
frame->gst = tst->arch.vex;
frame->gshadow1 = tst->arch.vex_shadow1;
frame->gshadow2 = tst->arch.vex_shadow2;
frame->sigNo_private = sigNo;
frame->mask = tst->sig_mask;
frame->magicPI = 0x31415927;
/* Minimally fill in the siginfo and ucontext. Note, utter
lameness prevails. Be underwhelmed, be very underwhelmed. */
frame->fake_siginfo.si_signo = sigNo;
frame->fake_siginfo.si_code = siginfo->si_code;
/* Set up stack pointer */
vg_assert(esp == (Addr)&frame->returnAddr);
VG_(set_SP)(tid, esp);
VG_TRACK( post_reg_write, Vg_CoreSignal, tid, VG_O_STACK_PTR, sizeof(UInt));
/* Set up program counter */
VG_(set_IP)(tid, (UInt)handler);
VG_TRACK( post_reg_write, Vg_CoreSignal, tid, VG_O_INSTR_PTR, sizeof(UInt));
/* Set up RA and args for the frame */
VG_TRACK( pre_mem_write, Vg_CoreSignal, tid, "signal handler frame",
(Addr)frame, 4*sizeof(UInt) );
frame->returnAddr = (UInt)&VG_(x86_darwin_SUBST_FOR_sigreturn);
frame->a1_signo = sigNo;
frame->a2_siginfo = (UInt)&frame->fake_siginfo; /* oh well */
frame->a3_ucontext = (UInt)&frame->fake_ucontext; /* oh well */
VG_TRACK( post_mem_write, Vg_CoreSignal, tid,
(Addr)frame, 4*sizeof(UInt) );
VG_TRACK( post_mem_write, Vg_CoreSignal, tid,
(Addr)&frame->fake_siginfo, sizeof(frame->fake_siginfo));
VG_TRACK( post_mem_write, Vg_CoreSignal, tid,
(Addr)&frame->fake_ucontext, sizeof(frame->fake_ucontext));
if (VG_(clo_trace_signals))
VG_(message)(Vg_DebugMsg,
"sigframe_create (thread %d): next EIP=%#lx, next ESP=%#lx",
tid, (Addr)handler, (Addr)frame );
}
/* Remove a signal frame from thread 'tid's stack, and restore the CPU
state from it. Note, isRT is irrelevant here. */
void VG_(sigframe_destroy)( ThreadId tid, Bool isRT )
{
ThreadState *tst;
Addr esp;
Int sigNo;
struct hacky_sigframe* frame;
vg_assert(VG_(is_valid_tid)(tid));
tst = VG_(get_ThreadState)(tid);
/* Check that the stack frame looks valid */
esp = VG_(get_SP)(tid);
/* why -4 ? because the signal handler's return will have popped
the return address of the stack; and the return address is the
lowest-addressed element of hacky_sigframe. */
frame = (struct hacky_sigframe*)(esp - 4);
vg_assert(frame->magicPI == 0x31415927);
vg_assert(VG_IS_16_ALIGNED(frame));
/* restore the entire guest state, and shadows, from the
frame. Note, as per comments above, this is a kludge - should
restore it from saved ucontext. Oh well. */
tst->arch.vex = frame->gst;
tst->arch.vex_shadow1 = frame->gshadow1;
tst->arch.vex_shadow2 = frame->gshadow2;
tst->sig_mask = frame->mask;
tst->tmp_sig_mask = frame->mask;
sigNo = frame->sigNo_private;
if (VG_(clo_trace_signals))
VG_(message)(Vg_DebugMsg,
"sigframe_destroy (thread %d): valid magic; next EIP=%#x",
tid, tst->arch.vex.guest_EIP);
VG_TRACK( die_mem_stack_signal,
(Addr)frame - VG_STACK_REDZONE_SZB,
sizeof(struct hacky_sigframe) );
/* tell the tools */
VG_TRACK( post_deliver_signal, tid, sigNo );
}
#endif // defined(VGP_x86_darwin)
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/
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