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