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c92d40c0bc
There appears to be a discrepancy among the implementations of setcontext with regards to the function called once the last linked-to context has finished executing via setcontext. The POSIX standard says: ~~~ If the uc_link member of the ucontext_t structure pointed to by the ucp argument is equal to 0, then this context is the main context, and the thread will exit when this context returns. ~~~ It says "exit" not "exit immediately" nor "exit without running functions registered with atexit or on_exit." Therefore the AArch64, ARM, hppa and NIOS II implementations are wrong and no test detects it. It is questionable if this should even be fixed or just documented that the above 4 targets are wrong. The functions are deprecated and nobody should be using them, but at the same time it silly to have cross-target differences that make it hard to port old applications from say x86_64 to AArch64. Therefore I will ix the 4 arches, and checkin a regression test to prevent it from changing again. https://sourceware.org/ml/libc-alpha/2015-03/msg00720.html
130 lines
3.7 KiB
ArmAsm
130 lines
3.7 KiB
ArmAsm
/* Set current context.
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Copyright (C) 2009-2015 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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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include "ucontext_i.h"
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#include "ucontext-internal.h"
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/* int __setcontext (const ucontext_t *ucp)
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Restores the machine context in UCP and thereby resumes execution
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in that context.
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This implementation is intended to be used for *synchronous* context
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switches only. Therefore, it does not have to restore anything
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other than the PRESERVED state. */
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.text
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ENTRY (__setcontext)
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/* Save a copy of UCP. */
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mov x9, x0
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/* Set the signal mask with
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rt_sigprocmask (SIG_SETMASK, mask, NULL, _NSIG/8). */
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mov x0, #SIG_SETMASK
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add x1, x9, #UCONTEXT_SIGMASK
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mov x2, #0
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mov x3, #_NSIG8
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mov x8, SYS_ify (rt_sigprocmask)
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svc 0
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cbz x0, 1f
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b C_SYMBOL_NAME (__syscall_error)
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1:
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/* Restore the general purpose registers. */
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mov x0, x9
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cfi_def_cfa (x0, 0)
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cfi_offset (x18, oX0 + 18 * SZREG)
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cfi_offset (x19, oX0 + 19 * SZREG)
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cfi_offset (x20, oX0 + 20 * SZREG)
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cfi_offset (x21, oX0 + 21 * SZREG)
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cfi_offset (x22, oX0 + 22 * SZREG)
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cfi_offset (x23, oX0 + 23 * SZREG)
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cfi_offset (x24, oX0 + 24 * SZREG)
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cfi_offset (x25, oX0 + 25 * SZREG)
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cfi_offset (x26, oX0 + 26 * SZREG)
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cfi_offset (x27, oX0 + 27 * SZREG)
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cfi_offset (x28, oX0 + 28 * SZREG)
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cfi_offset (x29, oX0 + 29 * SZREG)
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cfi_offset (x30, oX0 + 30 * SZREG)
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cfi_offset ( d8, oV0 + 8 * SZVREG)
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cfi_offset ( d9, oV0 + 9 * SZVREG)
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cfi_offset (d10, oV0 + 10 * SZVREG)
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cfi_offset (d11, oV0 + 11 * SZVREG)
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cfi_offset (d12, oV0 + 12 * SZVREG)
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cfi_offset (d13, oV0 + 13 * SZVREG)
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cfi_offset (d14, oV0 + 14 * SZVREG)
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cfi_offset (d15, oV0 + 15 * SZVREG)
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ldp x18, x19, [x0, oX0 + 18 * SZREG]
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ldp x20, x21, [x0, oX0 + 20 * SZREG]
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ldp x22, x23, [x0, oX0 + 22 * SZREG]
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ldp x24, x25, [x0, oX0 + 24 * SZREG]
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ldp x26, x27, [x0, oX0 + 26 * SZREG]
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ldp x28, x29, [x0, oX0 + 28 * SZREG]
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ldr x30, [x0, oX0 + 30 * SZREG]
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ldr x2, [x0, oSP]
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mov sp, x2
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/* Check for FP SIMD context. We don't support restoring
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contexts created by the kernel, so this context must have
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been created by getcontext. Hence we can rely on the
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first extension block being the FP SIMD context. */
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add x2, x0, #oEXTENSION
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mov w3, #(FPSIMD_MAGIC & 0xffff)
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movk w3, #(FPSIMD_MAGIC >> 16), lsl #16
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ldr w1, [x2, #oHEAD + oMAGIC]
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cmp w1, w3
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b.ne 2f
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/* Restore the FP SIMD context. */
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add x3, x2, #oV0 + 8 * SZVREG
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ldp d8, d9, [x3], #2 * SZVREG
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ldp d10, d11, [x3], #2 * SZVREG
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ldp d12, d13, [x3], #2 * SZVREG
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ldp d14, d15, [x3], #2 * SZVREG
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add x3, x2, oFPSR
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ldr w4, [x3]
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msr fpsr, x4
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ldr w4, [x3, oFPCR - oFPSR]
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msr fpcr, x4
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2:
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ldr x16, [x0, oPC]
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/* Restore arg registers. */
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ldp x2, x3, [x0, oX0 + 2 * SZREG]
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ldp x4, x5, [x0, oX0 + 4 * SZREG]
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ldp x6, x7, [x0, oX0 + 6 * SZREG]
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ldp x0, x1, [x0, oX0 + 0 * SZREG]
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/* Jump to the new pc value. */
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br x16
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PSEUDO_END (__setcontext)
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weak_alias (__setcontext, setcontext)
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ENTRY (__startcontext)
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mov x0, x19
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cbnz x0, __setcontext
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1: b HIDDEN_JUMPTARGET (exit)
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END (__startcontext)
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