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/* Copyright (C) 2004-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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 2.1 of the License, or (at your option) any later version.
The GNU C Library 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 the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* The public __longjmp() implementation is limited to jumping within
the same stack. That is, in general it is not possible to use this
__longjmp() implementation to cross from one stack to another.
In contrast, the __sigstack_longjmp() implemented here allows
crossing from the alternate signal stack to the normal stack
as a special case. */
#include <assert.h>
#include <setjmp.h>
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <sysdep.h>
#include <sys/rse.h>
#define JB_SP 0
#define JB_BSP 17
struct rbs_flush_values
{
unsigned long bsp;
unsigned long rsc;
unsigned long rnat;
};
extern struct rbs_flush_values __ia64_flush_rbs (void);
extern void __ia64_longjmp (__jmp_buf buf, int val, long rnat, long rsc)
__attribute__ ((__noreturn__));
static void
copy_rbs (unsigned long *dst, unsigned long *dst_end, unsigned long dst_rnat,
unsigned long *src, unsigned long *src_end,
unsigned long current_rnat)
{
unsigned long dst_slot, src_rnat = 0, src_slot, *src_rnat_addr, nat_bit;
int first_time = 1;
while (dst < dst_end)
{
dst_slot = ia64_rse_slot_num (dst);
if (dst_slot == 63)
{
*dst++ = dst_rnat;
dst_rnat = 0;
}
else
{
/* read source value, including NaT bit: */
src_slot = ia64_rse_slot_num (src);
if (src_slot == 63)
{
/* skip src RNaT slot */
++src;
src_slot = 0;
}
if (first_time || src_slot == 0)
{
first_time = 0;
src_rnat_addr = ia64_rse_rnat_addr (src);
if (src_rnat_addr < src_end)
src_rnat = *src_rnat_addr;
else
src_rnat = current_rnat;
}
nat_bit = (src_rnat >> src_slot) & 1;
assert (src < src_end);
*dst++ = *src++;
if (nat_bit)
dst_rnat |= (1UL << dst_slot);
else
dst_rnat &= ~(1UL << dst_slot);
}
}
dst_slot = ia64_rse_slot_num (dst);
if (dst_slot > 0)
*ia64_rse_rnat_addr (dst) = dst_rnat;
}
void
__sigstack_longjmp (__jmp_buf buf, int val)
{
unsigned long *rbs_base, *bsp, *bspstore, *jb_bsp, jb_sp, ss_sp;
unsigned long ndirty, rnat, load_rnat, *jb_rnat_addr;
struct sigcontext *sc;
stack_t stk;
struct rbs_flush_values c;
/* put RSE into enforced-lazy mode and return current bsp/rsc/rnat: */
c = __ia64_flush_rbs ();
jb_sp = ((unsigned long *) buf)[JB_SP];
jb_bsp = ((unsigned long **) buf)[JB_BSP];
INTERNAL_SYSCALL_CALL (sigaltstack, NULL, &stk);
ss_sp = (unsigned long) stk.ss_sp;
jb_rnat_addr = ia64_rse_rnat_addr (jb_bsp);
if ((stk.ss_flags & SS_ONSTACK) == 0 || jb_sp - ss_sp < stk.ss_size)
/* Normal non-stack-crossing longjmp; if the RNaT slot for the bsp
saved in the jump-buffer is the same as the one for the current
BSP, use the current AR.RNAT value, otherwise, load it from the
jump-buffer's RNaT-slot. */
load_rnat = (ia64_rse_rnat_addr ((unsigned long *) c.bsp) != jb_rnat_addr);
else
{
/* If we are on the alternate signal-stack and the jump-buffer
lies outside the signal-stack, we may need to copy back the
dirty partition which was torn off and saved on the
signal-stack when the signal was delivered.
Caveat: we assume that the top of the alternate signal-stack
stores the sigcontext structure of the signal that
caused the switch to the signal-stack. This should
be a fairly safe assumption but the kernel _could_
do things differently.. */
sc = ((struct sigcontext *) ((ss_sp + stk.ss_size) & -16) - 1);
/* As a sanity-check, verify that the register-backing-store base
of the alternate signal-stack is where we expect it. */
rbs_base = (unsigned long *)
((ss_sp + sizeof (long) - 1) & -sizeof (long));
assert ((unsigned long) rbs_base == sc->sc_rbs_base);
ndirty = ia64_rse_num_regs (rbs_base, rbs_base + (sc->sc_loadrs >> 19));
bsp = (unsigned long *) sc->sc_ar_bsp;
bspstore = ia64_rse_skip_regs (bsp, -ndirty);
if (bspstore < jb_bsp)
/* AR.BSPSTORE at the time of the signal was below the value
of AR.BSP saved in the jump-buffer => copy the missing
portion from the torn off dirty partition which got saved
on the alternate signal-stack. */
copy_rbs (bspstore, jb_bsp, sc->sc_ar_rnat,
rbs_base, (unsigned long *) c.bsp, c.rnat);
load_rnat = 1;
}
if (load_rnat)
rnat = *jb_rnat_addr;
else
rnat = c.rnat;
__ia64_longjmp (buf, val, rnat, c.rsc);
}
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