165 lines
5.5 KiB
C
165 lines
5.5 KiB
C
/* DWARF2 EH unwinding support for PA Linux.
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Copyright (C) 2004-2020 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/* Do code reading to identify a signal frame, and set the frame
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state data appropriately. See unwind-dw2.c for the structs. */
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/* Don't use this if inhibit_libc is set.
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The build for this target will fail trying to include missing headers. */
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#ifndef inhibit_libc
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#include <signal.h>
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#include <sys/ucontext.h>
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/* Return TRUE if read access to *P is allowed. */
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static inline long
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pa32_read_access_ok (void *p)
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{
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long ret;
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__asm__ ("proberi (%1),3,%0" : "=r" (ret) : "r" (p) :);
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return ret;
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}
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/* Unfortunately, because of various bugs and changes to the kernel,
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we have several cases to deal with.
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In 2.4, the signal trampoline is 4 words, and (CONTEXT)->ra should
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point directly at the beginning of the trampoline and struct rt_sigframe.
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In <= 2.6.5-rc2-pa3, the signal trampoline is 9 words, and
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(CONTEXT)->ra points at the 4th word in the trampoline structure. This
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is wrong, it should point at the 5th word. This is fixed in 2.6.5-rc2-pa4.
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To detect these cases, we first take (CONTEXT)->ra, align it to 64-bytes
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to get the beginning of the signal frame, and then check offsets 0, 4
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and 5 to see if we found the beginning of the trampoline. This will
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tell us how to locate the sigcontext structure.
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Note that with a 2.4 64-bit kernel, the signal context is not properly
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passed back to userspace so the unwind will not work correctly.
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There is also a bug in various glibc versions. The (CONTEXT)->ra
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for the outermost frame is not marked as undefined, so we need to
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check whether read access is allowed for all the accesses used in
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searching for the signal trampoline. */
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#define MD_FALLBACK_FRAME_STATE_FOR pa32_fallback_frame_state
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static _Unwind_Reason_Code
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pa32_fallback_frame_state (struct _Unwind_Context *context,
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_Unwind_FrameState *fs)
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{
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unsigned long sp = (unsigned long)context->ra & ~63;
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unsigned int *pc = (unsigned int *)sp;
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unsigned long off;
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_Unwind_Ptr new_cfa;
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int i;
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struct sigcontext *sc;
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struct rt_sigframe {
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siginfo_t info;
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ucontext_t uc;
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} *frame;
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/* rt_sigreturn trampoline:
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3419000x ldi 0, %r25 or ldi 1, %r25 (x = 0 or 2)
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3414015a ldi __NR_rt_sigreturn, %r20
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e4008200 be,l 0x100(%sr2, %r0), %sr0, %r31
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08000240 nop */
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if (pa32_read_access_ok (pc)
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&& (pc[0] == 0x34190000 || pc[0] == 0x34190002))
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off = 4*4;
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else if (pa32_read_access_ok (&pc[4])
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&& (pc[4] == 0x34190000 || pc[4] == 0x34190002))
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{
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pc += 4;
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off = 10 * 4;
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}
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else if (pa32_read_access_ok (&pc[5])
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&& (pc[5] == 0x34190000 || pc[5] == 0x34190002))
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{
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pc += 5;
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off = 10 * 4;
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}
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else
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{
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/* We may have to unwind through an alternate signal stack.
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We assume that the alignment of the alternate signal stack
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is BIGGEST_ALIGNMENT (i.e., that it has been allocated using
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malloc). As a result, we can't distinguish trampolines
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used prior to 2.6.5-rc2-pa4. However after 2.6.5-rc2-pa4,
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the return address of a signal trampoline will be on an odd
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word boundary and we can then determine the frame offset. */
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sp = (unsigned long)context->ra;
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pc = (unsigned int *)sp;
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if ((sp & 4)
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&& pa32_read_access_ok (pc)
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&& (pc[0] == 0x34190000 || pc[0] == 0x34190002))
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off = 5 * 4;
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else
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return _URC_END_OF_STACK;
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}
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if (!pa32_read_access_ok (&pc[3])
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|| pc[1] != 0x3414015a
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|| pc[2] != 0xe4008200
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|| pc[3] != 0x08000240)
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return _URC_END_OF_STACK;
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frame = (struct rt_sigframe *)(sp + off);
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sc = (struct sigcontext *)&frame->uc.uc_mcontext;
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new_cfa = sc->sc_gr[30];
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fs->regs.cfa_how = CFA_REG_OFFSET;
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fs->regs.cfa_reg = 30;
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fs->regs.cfa_offset = new_cfa - (long) context->cfa;
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for (i = 1; i <= 31; i++)
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{
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fs->regs.reg[i].how = REG_SAVED_OFFSET;
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fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa;
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}
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for (i = 4; i <= 31; i++)
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{
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/* FP regs have left and right halves */
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fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET;
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fs->regs.reg[2*i+24].loc.offset
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= (long)&sc->sc_fr[i] - new_cfa;
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fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET;
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fs->regs.reg[2*i+24+1].loc.offset
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= (long)&sc->sc_fr[i] + 4 - new_cfa;
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}
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fs->regs.reg[88].how = REG_SAVED_OFFSET;
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fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa;
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fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how
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= REG_SAVED_OFFSET;
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fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset
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= (long) &sc->sc_iaoq[0] - new_cfa;
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fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
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fs->signal_frame = 1;
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return _URC_NO_REASON;
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}
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#endif /* inhibit_libc */
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