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/* DWARF2 EH unwinding support for PA Linux.
Copyright (C) 2004-2017 Free Software Foundation, Inc.
This file is part of GCC.
GCC 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 3, or (at your option)
any later version.
GCC 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* Do code reading to identify a signal frame, and set the frame
state data appropriately. See unwind-dw2.c for the structs. */
/* Don't use this if inhibit_libc is set.
The build for this target will fail trying to include missing headers. */
#ifndef inhibit_libc
#include <signal.h>
#include <sys/ucontext.h>
/* Return TRUE if read access to *P is allowed. */
static inline long
pa32_read_access_ok (void *p)
{
long ret;
__asm__ ("proberi (%1),3,%0" : "=r" (ret) : "r" (p) :);
return ret;
}
/* Unfortunately, because of various bugs and changes to the kernel,
we have several cases to deal with.
In 2.4, the signal trampoline is 4 words, and (CONTEXT)->ra should
point directly at the beginning of the trampoline and struct rt_sigframe.
In <= 2.6.5-rc2-pa3, the signal trampoline is 9 words, and
(CONTEXT)->ra points at the 4th word in the trampoline structure. This
is wrong, it should point at the 5th word. This is fixed in 2.6.5-rc2-pa4.
To detect these cases, we first take (CONTEXT)->ra, align it to 64-bytes
to get the beginning of the signal frame, and then check offsets 0, 4
and 5 to see if we found the beginning of the trampoline. This will
tell us how to locate the sigcontext structure.
Note that with a 2.4 64-bit kernel, the signal context is not properly
passed back to userspace so the unwind will not work correctly.
There is also a bug in various glibc versions. The (CONTEXT)->ra
for the outermost frame is not marked as undefined, so we need to
check whether read access is allowed for all the accesses used in
searching for the signal trampoline. */
#define MD_FALLBACK_FRAME_STATE_FOR pa32_fallback_frame_state
static _Unwind_Reason_Code
pa32_fallback_frame_state (struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
unsigned long sp = (unsigned long)context->ra & ~63;
unsigned int *pc = (unsigned int *)sp;
unsigned long off;
_Unwind_Ptr new_cfa;
int i;
struct sigcontext *sc;
struct rt_sigframe {
siginfo_t info;
ucontext_t uc;
} *frame;
/* rt_sigreturn trampoline:
3419000x ldi 0, %r25 or ldi 1, %r25 (x = 0 or 2)
3414015a ldi __NR_rt_sigreturn, %r20
e4008200 be,l 0x100(%sr2, %r0), %sr0, %r31
08000240 nop */
if (pa32_read_access_ok (pc)
&& (pc[0] == 0x34190000 || pc[0] == 0x34190002))
off = 4*4;
else if (pa32_read_access_ok (&pc[4])
&& (pc[4] == 0x34190000 || pc[4] == 0x34190002))
{
pc += 4;
off = 10 * 4;
}
else if (pa32_read_access_ok (&pc[5])
&& (pc[5] == 0x34190000 || pc[5] == 0x34190002))
{
pc += 5;
off = 10 * 4;
}
else
{
/* We may have to unwind through an alternate signal stack.
We assume that the alignment of the alternate signal stack
is BIGGEST_ALIGNMENT (i.e., that it has been allocated using
malloc). As a result, we can't distinguish trampolines
used prior to 2.6.5-rc2-pa4. However after 2.6.5-rc2-pa4,
the return address of a signal trampoline will be on an odd
word boundary and we can then determine the frame offset. */
sp = (unsigned long)context->ra;
pc = (unsigned int *)sp;
if ((sp & 4)
&& pa32_read_access_ok (pc)
&& (pc[0] == 0x34190000 || pc[0] == 0x34190002))
off = 5 * 4;
else
return _URC_END_OF_STACK;
}
if (!pa32_read_access_ok (&pc[3])
|| pc[1] != 0x3414015a
|| pc[2] != 0xe4008200
|| pc[3] != 0x08000240)
return _URC_END_OF_STACK;
frame = (struct rt_sigframe *)(sp + off);
sc = &frame->uc.uc_mcontext;
new_cfa = sc->sc_gr[30];
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_reg = 30;
fs->regs.cfa_offset = new_cfa - (long) context->cfa;
for (i = 1; i <= 31; i++)
{
fs->regs.reg[i].how = REG_SAVED_OFFSET;
fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa;
}
for (i = 4; i <= 31; i++)
{
/* FP regs have left and right halves */
fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET;
fs->regs.reg[2*i+24].loc.offset
= (long)&sc->sc_fr[i] - new_cfa;
fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET;
fs->regs.reg[2*i+24+1].loc.offset
= (long)&sc->sc_fr[i] + 4 - new_cfa;
}
fs->regs.reg[88].how = REG_SAVED_OFFSET;
fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa;
fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how
= REG_SAVED_OFFSET;
fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset
= (long) &sc->sc_iaoq[0] - new_cfa;
fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
fs->signal_frame = 1;
return _URC_NO_REASON;
}
#endif /* inhibit_libc */
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