Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder

This will be used to consolidate the libgcc_s access for backtrace
and pthread_cancel.

Unlike the existing backtrace implementations, it provides some
hardening based on pointer mangling.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 0 insertions, 67 deletions

diff --git a/sysdeps/unix/sysv/linux/mips/unwind-arch.h b/sysdeps/unix/sysv/linux/mips/unwind-arch.h
deleted file mode 100644
index 38bc60cde6..0000000000
--- a/sysdeps/unix/sysv/linux/mips/unwind-arch.h
+++ /dev/null
@@ -1,67 +0,0 @@
-/* Return backtrace of current program state.  Arch-specific bits.
-   Copyright (C) 2020-2021 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/>.  */
-
-#ifndef _UNWIND_ARCH_H
-#define _UNWIND_ARCH_H
-
-#include <stdint.h>
-
-/* MIPS fallback code handle a frame where its FDE can not be obtained
-   (for instance a signal frame) by reading the kernel allocated signal frame
-   and adding '2' to the value of 'sc_pc' [1].  The added value is used to
-   recognize an end of an EH region on mips16 [2].
-
-   The idea here is to adjust the obtained signal frame ADDR value and remove
-   the libgcc added value by checking if the previous frame is a signal frame
-   one.
-
-   [1] libgcc/config/mips/linux-unwind.h from gcc code.
-   [2] gcc/config/mips/mips.h from gcc code.  */
-
-static inline void *
-unwind_arch_adjustment (void *prev, void *addr)
-{
-  uint32_t *pc = (uint32_t *) prev;
-
-  if (pc == NULL)
-    return addr;
-
-  /* For MIPS16 or microMIPS frame libgcc makes no adjustment.  */
-  if ((uintptr_t) pc & 0x3)
-    return addr;
-
-  /* The vDSO containes either
-
-     24021061 li v0, 0x1061 (rt_sigreturn)
-     0000000c syscall
-	or
-     24021017 li v0, 0x1017 (sigreturn)
-     0000000c syscall  */
-  if (pc[1] != 0x0000000c)
-    return addr;
-#if _MIPS_SIM == _ABIO32
-  if (pc[0] == (0x24020000 | __NR_sigreturn))
-    return (void *) ((uintptr_t) addr - 2);
-#endif
-  if (pc[0] == (0x24020000 | __NR_rt_sigreturn))
-    return (void *) ((uintptr_t) addr - 2);
-
-  return addr;
-}
-
-#endif