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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
105 lines
2.9 KiB
ArmAsm
105 lines
2.9 KiB
ArmAsm
/* Copyright (C) 2012-2015 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
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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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<http://www.gnu.org/licenses/>. */
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/* ??? Needs more rearrangement for the LDM to handle thumb mode. */
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#define NO_THUMB
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#include <sysdep.h>
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#include <rtld-global-offsets.h>
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#include "ucontext_i.h"
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.syntax unified
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.text
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/* int setcontext (const ucontext_t *ucp) */
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ENTRY(__setcontext)
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mov r4, r0
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add r0, r0, #UCONTEXT_REGSPACE
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/* Restore the VFP registers. Copied from arm/__longjmp.S. */
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#ifdef PIC
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ldr r2, 1f
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ldr r1, .Lrtld_global_ro
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0: add r2, pc, r2
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ldr r2, [r2, r1]
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ldr r2, [r2, #RTLD_GLOBAL_RO_DL_HWCAP_OFFSET]
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#else
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ldr r2, .Lhwcap
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ldr r2, [r2, #0]
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#endif
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#ifdef __SOFTFP__
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tst r2, #HWCAP_ARM_VFP
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beq .Lno_vfp_sc
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#endif
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/* Following instruction is vldmia r0!, {d8-d15}. */
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ldc p11, cr8, [r0], #64
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/* Restore the floating-point status register. */
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ldr r1, [r0], #4
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/* Following instruction is fmxr fpscr, r1. */
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mcr p10, 7, r1, cr1, cr0, 0
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.Lno_vfp_sc:
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tst r2, #HWCAP_ARM_IWMMXT
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beq .Lno_iwmmxt_sc
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/* Restore the call-preserved iWMMXt registers. */
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/* Following instructions are wldrd wr10, [r0], #8 (etc.) */
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ldcl p1, cr10, [r0], #8
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ldcl p1, cr11, [r0], #8
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ldcl p1, cr12, [r0], #8
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ldcl p1, cr13, [r0], #8
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ldcl p1, cr14, [r0], #8
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ldcl p1, cr15, [r0], #8
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.Lno_iwmmxt_sc:
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/* Now bring back the signal status. */
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mov r0, #SIG_SETMASK
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add r1, r4, #UCONTEXT_SIGMASK
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mov r2, #0
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bl PLTJMP(__sigprocmask)
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/* Loading r0-r3 makes makecontext easier. */
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add r14, r4, #MCONTEXT_ARM_R0
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ldmia r14, {r0-r12}
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ldr r13, [r14, #(MCONTEXT_ARM_SP - MCONTEXT_ARM_R0)]
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add r14, r14, #(MCONTEXT_ARM_LR - MCONTEXT_ARM_R0)
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ldmia r14, {r14, pc}
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END(setcontext)
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weak_alias(__setcontext, setcontext)
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/* Called when a makecontext() context returns. Start the
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context in R4 or fall through to exit(). */
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ENTRY(__startcontext)
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movs r0, r4
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bne PLTJMP(__setcontext)
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@ New context was 0 - exit
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b PLTJMP(HIDDEN_JUMPTARGET(exit))
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END(__startcontext)
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#ifdef PIC
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1: .long _GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
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.Lrtld_global_ro:
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.long C_SYMBOL_NAME(_rtld_global_ro)(GOT)
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#else
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.Lhwcap:
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.long C_SYMBOL_NAME(_dl_hwcap)
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#endif
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