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/* signal-dispatch-lowlevel.c - ia32 specific signal handling functions.
Copyright (C) 2008 Free Software Foundation, Inc.
Written by Neal H. Walfield <neal@gnu.org>.
This file is part of the GNU Hurd.
The GNU Hurd is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License
as published by the Free Software Foundation; either version 3 of
the License, or (at your option) any later version.
The GNU Hurd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this program. If not, see
<http://www.gnu.org/licenses/>. */
#include <pt-internal.h>
#include <sig-internal.h>
#include <viengoos/thread.h>
#include <pthread.h>
#include <stdint.h>
#include <atomic.h>
extern char _signal_dispatch_entry;
/* - 0(%esp) a pointer to the thread's struct signal_state.
- 4(%esp) a pointer to a siginfo_t.
- 8(%esp) is a pointer to the ss_flags field (or NULL).
- 12(%esp)+4 is the value of the sp when the thread was interrupted (intr_sp)
- 0(intr_sp) is the value of the ip when the thread was interrupted.
- 16(%esp) - 16 byte register save area
*/
__asm__ ("\n\
.globl _signal_dispatch_entry\n\
_signal_dispatch_entry:\n\
/* Save caller saved registers (16 bytes). */\n\
mov %eax, 16(%esp)\n\
mov %ecx, 16+4(%esp)\n\
mov %edx, 16+8(%esp)\n\
pushf\n\
popl %eax\n\
mov %eax, 16+12(%esp)\n\
\n\
/* Reset EFLAGS. */\n\
cld\n\
call signal_dispatch\n\
\n\
/* Get the original stack and begin restoration. */\n\
mov 12(%esp), %edx\n\
\n\
/* Move the saved registers to the user stack. */\n\
sub $16, %edx\n\
/* eax. */\n\
mov 16+0(%esp), %ecx\n\
mov %ecx, 0(%edx)\n\
/* ecx. */\n\
mov 16+4(%esp), %ecx\n\
mov %ecx, 4(%edx)\n\
/* edx. */\n\
mov 16+8(%esp), %ecx\n\
mov %ecx, 8(%edx)\n\
/* eflags. */\n\
mov 16+12(%esp), %ecx\n\
mov %ecx, 12(%edx)\n\
\n\
/* Get the pointer to the sigaltstack flags. */\n\
mov 8(%esp), %ecx\n\
\n\
/* Restore the user stack. */\n\
mov %edx, %esp\n\
\n\
/* Clear the SA_ONSTACK flag. */\n\
and %ecx, %ecx\n\
jz after_clear\n\
lock; and $~1, 0(%ecx)\n\
after_clear:\n\
\n\
/* Restore eflags, the scratch regs and the original sp and ip. */\n\
popl %eax\n\
popl %ecx\n\
popl %edx\n\
popf\n\
ret\n");
extern char _signal_dispatch_entry_self;
/* - 0(%esp) is the return address (we ignore it)
- 4(%esp) is the sp to load
Since we are returning to signal_dispatch_lowlevel's caller, we
also need to restore its frame pointer. */
__asm__ ("\n\
.globl _signal_dispatch_entry_self\n\
_signal_dispatch_entry_self:\n\
mov 0(%ebp), %ebp\n\
mov 4(%esp), %esp\n\
jmp _signal_dispatch_entry\n");
void
signal_dispatch_lowlevel (struct signal_state *ss, pthread_t tid,
siginfo_t si)
{
assert (pthread_mutex_trylock (&ss->lock) == EBUSY);
struct __pthread *thread = __pthread_getid (tid);
bool self = tid == pthread_self ();
uintptr_t intr_sp;
if (self)
{
/* The return address is 4 bytes offset from the start of the
stack frame. */
intr_sp = (uintptr_t) __builtin_frame_address (0) + 4;
assert (* (void **) intr_sp == __builtin_return_address (0));
}
else
{
struct vg_thread_exregs_in in;
memset (&in, 0, sizeof (in));
struct vg_thread_exregs_out out;
error_t err;
err = vg_thread_exregs (VG_ADDR_VOID, thread->object,
VG_EXREGS_STOP | VG_EXREGS_ABORT_IPC
| VG_EXREGS_GET_REGS,
in, VG_ADDR_VOID, VG_ADDR_VOID, VG_ADDR_VOID, VG_ADDR_VOID,
&out, NULL, NULL, NULL, NULL);
if (err)
panic ("Failed to modify thread " VG_ADDR_FMT,
VG_ADDR_PRINTF (thread->object));
intr_sp = out.sp;
/* Push the ip on the user stack. */
intr_sp -= 4;
* (uintptr_t *) intr_sp = out.ip;
}
bool altstack = false;
uintptr_t sp;
if (! (ss->actions[si.si_signo - 1].sa_flags & SA_ONSTACK)
|| (ss->stack.ss_flags & SS_DISABLE)
|| (ss->stack.ss_flags & SS_ONSTACK))
{
assert (! self);
sp = intr_sp;
}
else
{
/* The stack grows down. */
sp = (uintptr_t) ss->stack.ss_sp + ss->stack.ss_size;
/* We know intimately that SS_ONSTACK is the least significant
bit. */
assert (SS_ONSTACK == 1);
atomic_bit_set (&ss->stack.ss_flags, 0);
altstack = true;
}
/* Set up the call frame for a call to signal_dispatch_entry. */
/* Allocate a siginfo structure on the stack. */
sp = sp - sizeof (siginfo_t);
siginfo_t *sip = (void *) sp;
/* Copy the user supplied values. */
*sip = si;
/* Add space for the 4 caller saved registers. */
sp -= 4 * sizeof (uintptr_t);
/* Save the interrupted sp. */
sp -= 4;
* (uintptr_t *) sp = intr_sp;
/* Address of the ss_flags. */
sp -= 4;
if (altstack)
* (uintptr_t *) sp = (uintptr_t) &ss->stack.ss_flags;
else
* (uintptr_t *) sp = 0;
/* Push the parameters to signal_dispatch. */
/* signal info structure. */
sp -= 4;
* (uintptr_t *) sp = (uintptr_t) sip;
/* The ss. */
sp -= 4;
* (uintptr_t *) sp = (uintptr_t) ss;
pthread_mutex_transfer_np (&ss->lock, tid);
if (self)
((void (*) (uintptr_t)) &_signal_dispatch_entry_self) ((uintptr_t) sp);
else
{
struct vg_thread_exregs_in in;
struct vg_thread_exregs_out out;
in.sp = sp;
in.ip = (uintptr_t) &_signal_dispatch_entry;
vg_thread_exregs (VG_ADDR_VOID, thread->object,
VG_EXREGS_SET_SP_IP
| VG_EXREGS_START | VG_EXREGS_ABORT_IPC,
in, VG_ADDR_VOID, VG_ADDR_VOID, VG_ADDR_VOID, VG_ADDR_VOID,
&out, NULL, NULL, NULL, NULL);
}
}
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