mirror of git://sourceware.org/git/glibc.git
122 lines
4.2 KiB
C
122 lines
4.2 KiB
C
/* Copyright (C) 2006-2025 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 License as
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published by the Free Software Foundation; either version 2.1 of the
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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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#define JB_X19 0
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#define JB_X20 1
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#define JB_X21 2
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#define JB_X22 3
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#define JB_X23 4
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#define JB_X24 5
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#define JB_X25 6
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#define JB_X26 7
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#define JB_X27 8
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#define JB_X28 9
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#define JB_X29 10
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#define JB_LR 11
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#define JB_SP 13
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#define JB_D8 14
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#define JB_D9 15
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#define JB_D10 16
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#define JB_D11 17
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#define JB_D12 18
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#define JB_D13 19
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#define JB_D14 20
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#define JB_D15 21
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/* The target specific part of jmp_buf has no space for expansion but
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the public jmp_buf ABI type has. Unfortunately there is another type
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that is used with setjmp APIs and exposed by thread cancellation (in
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binaries built with -fno-exceptions) which complicates the situation.
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// Internal layout of the public jmp_buf type on AArch64.
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// This is passed to setjmp, longjmp, sigsetjmp, siglongjmp.
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struct
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{
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uint64_t jmpbuf[22]; // Target specific part.
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uint32_t mask_was_saved; // savemask bool used by sigsetjmp/siglongjmp.
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uint32_t pad;
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uint64_t saved_mask; // sigset_t bits used on linux.
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uint64_t unused[15]; // sigset_t bits not used on linux.
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};
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// Internal layout of the public __pthread_unwind_buf_t type.
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// This is passed to sigsetjmp with !savemask and to the internal
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// __libc_longjmp (currently alias of longjmp on AArch64).
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struct
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{
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uint64_t jmpbuf[22]; // Must match jmp_buf.
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uint32_t mask_was_saved; // Must match jmp_buf, always 0.
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uint32_t pad;
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void *prev; // List for unwinding.
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void *cleanup; // Cleanup handlers.
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uint32_t canceltype; // 1 bit cancellation type.
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uint32_t pad2;
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void *pad3;
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};
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Ideally only the target specific part of jmp_buf (A) is accessed by
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__setjmp and __longjmp. But that is always embedded into one of the
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two types above so the bits that are unused in those types (B) may be
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reused for target specific purposes. Setjmp can't distinguish between
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jmp_buf and __pthread_unwind_buf_t, but longjmp can: only an internal
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longjmp call uses the latter, so state that is not needed for cancel
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cleanups can go to fields (C). If generic code is refactored then the
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usage of additional fields can be optimized (D). And some fields are
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only accessible in the savedmask case (E). Reusability of jmp_buf
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fields on AArch64 for target purposes:
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struct
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{
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uint64_t A[22]; // 0 .. 176
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uint32_t D; // 176 .. 180
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uint32_t B; // 180 .. 184
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uint64_t D; // 184 .. 192
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uint64_t C; // 192 .. 200
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uint32_t C; // 200 .. 204
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uint32_t B; // 204 .. 208
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uint64_t B; // 208 .. 216
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uint64_t E[12]; // 216 .. 312
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}
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The B fields can be used with minimal glibc code changes. We need a
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64 bit field for the Guarded Control Stack pointer (GCSPR_EL0) which
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can use a C field too as cancellation cleanup does not execute RET
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for a previous BL of the cancelled thread, but that would require a
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custom __libc_longjmp. This layout can change in the future. */
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#define JB_GCSPR 208
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#ifndef __ASSEMBLER__
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#include <setjmp.h>
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#include <stdint.h>
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#include <sysdep.h>
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#include <pointer_guard.h>
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static inline uintptr_t __attribute__ ((unused))
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_jmpbuf_sp (__jmp_buf jmpbuf)
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{
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uintptr_t sp = jmpbuf[JB_SP];
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PTR_DEMANGLE (sp);
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return sp;
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}
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#endif
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/* Helper for generic ____longjmp_chk(). */
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#define JB_FRAME_ADDRESS(buf) \
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((void *) _jmpbuf_sp (buf))
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