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6e05978f0c
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 fix adjust the obtained signal frame value and remove the libgcc added value by checking if the previous frame is a signal frame one. Checked with backtrace and tst-sigcontext-get_pc tests on mips-linux-gnu and mips64-linux-gnu. [1] libgcc/config/mips/linux-unwind.h from gcc code. [2] gcc/config/mips/mips.h from gcc code. */
68 lines
2.1 KiB
C
68 lines
2.1 KiB
C
/* Return backtrace of current program state. Arch-specific bits.
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Copyright (C) 2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _UNWIND_ARCH_H
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#define _UNWIND_ARCH_H
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#include <stdint.h>
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/* MIPS fallback code handle a frame where its FDE can not be obtained
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(for instance a signal frame) by reading the kernel allocated signal frame
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and adding '2' to the value of 'sc_pc' [1]. The added value is used to
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recognize an end of an EH region on mips16 [2].
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The idea here is to adjust the obtained signal frame ADDR value and remove
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the libgcc added value by checking if the previous frame is a signal frame
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one.
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[1] libgcc/config/mips/linux-unwind.h from gcc code.
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[2] gcc/config/mips/mips.h from gcc code. */
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static inline void *
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unwind_arch_adjustment (void *prev, void *addr)
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{
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uint32_t *pc = (uint32_t *) prev;
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if (pc == NULL)
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return addr;
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/* For MIPS16 or microMIPS frame libgcc makes no adjustment. */
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if ((uintptr_t) pc & 0x3)
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return addr;
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/* The vDSO containes either
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24021061 li v0, 0x1061 (rt_sigreturn)
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0000000c syscall
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or
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24021017 li v0, 0x1017 (sigreturn)
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0000000c syscall */
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if (pc[1] != 0x0000000c)
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return addr;
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#if _MIPS_SIM == _ABIO32
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if (pc[0] == (0x24020000 | __NR_sigreturn))
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return (void *) ((uintptr_t) addr - 2);
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#endif
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if (pc[0] == (0x24020000 | __NR_rt_sigreturn))
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return (void *) ((uintptr_t) addr - 2);
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return addr;
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}
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#endif
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