@@ -106,3 +106,7 @@ ifeq ($(subdir),elf)
# callbacks whose parameters don't permit to get the context parameters.
check-execstack-xfail += ld.so libc.so libpthread.so
endif
+
+ifeq ($(subdir),stdlib)
+gen-as-const-headers += ucontext_i.sym
+endif
new file mode 100644
@@ -0,0 +1,74 @@
+/* Save current context.
+ Copyright (C) 2001-2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
+
+ 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/>. */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+
+ENTRY(__getcontext)
+ /* Load address of the context data structure. */
+ movl 4(%esp), %eax
+
+ /* Return value of getcontext. EAX is the only register whose
+ value is not preserved. */
+ movl $0, oEAX(%eax)
+
+ /* Save the 32-bit register values and the return address. */
+ movl %ecx, oECX(%eax)
+ movl %edx, oEDX(%eax)
+ movl %edi, oEDI(%eax)
+ movl %esi, oESI(%eax)
+ movl %ebp, oEBP(%eax)
+ movl (%esp), %ecx
+ movl %ecx, oEIP(%eax)
+ leal 4(%esp), %ecx /* Exclude the return address. */
+ movl %ecx, oESP(%eax)
+ movl %ebx, oEBX(%eax)
+
+ /* Save the FS segment register. We don't touch the GS register
+ since it is used for threads. */
+ xorl %edx, %edx
+ movw %fs, %dx
+ movl %edx, oFS(%eax)
+
+ leal oFPREGS(%eax), %ecx
+ /* Save the floating-point context. */
+ fnstenv (%ecx)
+ /* And load it right back since the processor changes the mask.
+ Intel thought this opcode to be used in interrupt handlers which
+ would block all exceptions. */
+ fldenv (%ecx)
+
+ /* Save the current signal mask. */
+ subl $12, %esp
+ cfi_adjust_cfa_offset (12)
+ leal oSIGMASK(%eax), %eax
+ movl %eax, 8(%esp)
+ movl $0, 4(%esp)
+ movl $SIG_BLOCK, (%esp)
+ call HIDDEN_JUMPTARGET (__sigprocmask)
+ addl $12, %esp
+ cfi_adjust_cfa_offset (-12)
+ /* Propagate %eax (and errno, in case). */
+
+ ret
+PSEUDO_END(__getcontext)
+
+weak_alias (__getcontext, getcontext)
new file mode 100644
@@ -0,0 +1,130 @@
+/* Create new context.
+ Copyright (C) 2001-2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
+
+ 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/>. */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+
+ENTRY(__makecontext)
+ movl 4(%esp), %eax
+
+ /* Load the address of the function we are supposed to run. */
+ movl 8(%esp), %ecx
+
+ /* Compute the address of the stack. The information comes from
+ to us_stack element. */
+ movl oSS_SP(%eax), %edx
+ movl %ecx, oEIP(%eax)
+ addl oSS_SIZE(%eax), %edx
+
+ /* Remember the number of parameters for the exit handler since
+ it has to remove them. We store the number in the EBX register
+ which the function we will call must preserve. */
+ movl 12(%esp), %ecx
+ movl %ecx, oEBX(%eax)
+
+ /* Make room on the new stack for the parameters.
+ Room for the arguments, return address (== L(exitcode)) and
+ oLINK pointer is needed. One of the pointer sizes is subtracted
+ after aligning the stack. */
+ negl %ecx
+ leal -4(%edx,%ecx,4), %edx
+ negl %ecx
+
+ /* Align the stack. */
+ andl $0xfffffff0, %edx
+ subl $4, %edx
+
+ /* Store the future stack pointer. */
+ movl %edx, oESP(%eax)
+
+ /* Put the next context on the new stack (from the uc_link
+ element). */
+ movl oLINK(%eax), %eax
+ movl %eax, 4(%edx,%ecx,4)
+
+ /* Copy all the parameters. */
+ jecxz 2f
+1: movl 12(%esp,%ecx,4), %eax
+ movl %eax, (%edx,%ecx,4)
+ decl %ecx
+ jnz 1b
+2:
+
+ /* If the function we call returns we must continue with the
+ context which is given in the uc_link element. To do this
+ set the return address for the function the user provides
+ to a little bit of helper code which does the magic (see
+ below). */
+#ifdef PIC
+ call 1f
+ cfi_adjust_cfa_offset (4)
+1: popl %ecx
+ cfi_adjust_cfa_offset (-4)
+ addl $L(exitcode)-1b, %ecx
+ movl %ecx, (%edx)
+#else
+ movl $L(exitcode), (%edx)
+#endif
+ /* We need to terminate the FDE here instead of after ret because
+ the unwinder looks at ra-1 for unwind information. */
+ cfi_endproc
+
+ /* 'makecontext' returns no value. */
+ ret
+
+ /* This is the helper code which gets called if a function which
+ is registered with 'makecontext' returns. In this case we
+ have to install the context listed in the uc_link element of
+ the context 'makecontext' manipulated at the time of the
+ 'makecontext' call. If the pointer is NULL the process must
+ terminate. */
+L(exitcode):
+ /* This removes the parameters passed to the function given to
+ 'makecontext' from the stack. EBX contains the number of
+ parameters (see above). */
+ leal (%esp,%ebx,4), %esp
+
+ cmpl $0, (%esp) /* Check the next context. */
+ je 2f /* If it is zero exit. */
+
+ call HIDDEN_JUMPTARGET(__setcontext)
+ /* If this returns (which can happen if the syscall fails) we'll
+ exit the program with the return error value (-1). */
+ jmp L(call_exit)
+
+2:
+ /* Exit with status 0. */
+ xorl %eax, %eax
+
+L(call_exit):
+ /* Align the stack and pass the exit code (from %eax). */
+ andl $0xfffffff0, %esp
+ subl $12, %esp
+ pushl %eax
+
+ call HIDDEN_JUMPTARGET(exit)
+ /* The 'exit' call should never return. In case it does cause
+ the process to terminate. */
+ hlt
+ cfi_startproc
+END(__makecontext)
+
+weak_alias (__makecontext, makecontext)
new file mode 100644
@@ -0,0 +1,93 @@
+/* Install given context.
+ Copyright (C) 2001-2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
+
+ 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/>. */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+
+ENTRY(__setcontext)
+ /* Load address of the context data structure. */
+ movl 4(%esp), %eax
+
+ /* Get the current signal mask. */
+ subl $12, %esp
+ cfi_adjust_cfa_offset (12)
+ movl $0, 8(%esp)
+ leal oSIGMASK(%eax), %eax
+ movl %eax, 4(%esp)
+ movl $SIG_SETMASK, (%esp)
+ call HIDDEN_JUMPTARGET (__sigprocmask)
+ addl $12, %esp
+ cfi_adjust_cfa_offset (-12)
+ testl %eax, %eax
+ jne L(pseudo_end)
+
+ /* EAX was modified, reload it. */
+ movl 4(%esp), %eax
+
+ /* Restore the floating-point context. Not the registers, only the
+ rest. */
+ leal oFPREGS(%eax), %ecx
+ fldenv (%ecx)
+
+ /* Restore the FS segment register. We don't touch the GS register
+ since it is used for threads. */
+ movl oFS(%eax), %ecx
+ movw %cx, %fs
+
+ /* Fetch the address to return to. */
+ movl oEIP(%eax), %ecx
+
+ /* Load the new stack pointer. */
+ cfi_def_cfa (eax, 0)
+ cfi_offset (edi, oEDI)
+ cfi_offset (esi, oESI)
+ cfi_offset (ebp, oEBP)
+ cfi_offset (ebx, oEBX)
+ cfi_offset (edx, oEDX)
+ cfi_offset (ecx, oECX)
+ movl oESP(%eax), %esp
+
+ /* Push the return address on the new stack so we can return there. */
+ pushl %ecx
+
+ /* Load the values of all the 32-bit registers (except ESP).
+ Since we are loading from EAX, it must be last. */
+ movl oEDI(%eax), %edi
+ movl oESI(%eax), %esi
+ movl oEBP(%eax), %ebp
+ movl oEBX(%eax), %ebx
+ movl oEDX(%eax), %edx
+ movl oECX(%eax), %ecx
+ movl oEAX(%eax), %eax
+
+ /* End FDE here, we fall into another context. */
+ cfi_endproc
+ cfi_startproc
+
+ /* The following 'ret' will pop the address of the code and jump
+ to it. */
+
+L(pseudo_end):
+ ret
+PSEUDO_END(__setcontext)
+libc_hidden_def (__setcontext)
+
+weak_alias (__setcontext, setcontext)
new file mode 100644
@@ -0,0 +1,110 @@
+/* Save current context and install the given one.
+ Copyright (C) 2001-2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
+
+ 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/>. */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+
+ENTRY(__swapcontext)
+ /* Load address of the context data structure we save in. */
+ movl 4(%esp), %eax
+
+ /* Return value of swapcontext. EAX is the only register whose
+ value is not preserved. */
+ movl $0, oEAX(%eax)
+
+ /* Save the 32-bit register values and the return address. */
+ movl %ecx, oECX(%eax)
+ movl %edx, oEDX(%eax)
+ movl %edi, oEDI(%eax)
+ movl %esi, oESI(%eax)
+ movl %ebp, oEBP(%eax)
+ movl (%esp), %ecx
+ movl %ecx, oEIP(%eax)
+ leal 4(%esp), %ecx
+ movl %ecx, oESP(%eax)
+ movl %ebx, oEBX(%eax)
+
+ /* Save the FS segment register. */
+ xorl %edx, %edx
+ movw %fs, %dx
+ movl %edx, oFS(%eax)
+
+ leal oFPREGS(%eax), %ecx
+ /* Save the floating-point context. */
+ fnstenv (%ecx)
+
+ /* Load address of the context data structure we have to load. */
+ movl 8(%esp), %ecx
+
+ /* Save the current signal mask and install the new one. */
+ subl $12, %esp
+ cfi_adjust_cfa_offset (12)
+ leal oSIGMASK(%eax), %eax
+ movl %eax, 8(%esp)
+ leal oSIGMASK(%ecx), %eax
+ movl %eax, 4(%esp)
+ movl $SIG_SETMASK, (%esp)
+ call HIDDEN_JUMPTARGET (__sigprocmask)
+ addl $12, %esp
+ cfi_adjust_cfa_offset (-12)
+ testl %eax, %eax
+ jne L(pseudo_end)
+
+ /* EAX was modified, reload it. */
+ movl 8(%esp), %eax
+
+ /* Restore the floating-point context. Not the registers, only the
+ rest. */
+ leal oFPREGS(%eax), %ecx
+ fldenv (%ecx)
+
+ /* Restore the FS segment register. We don't touch the GS register
+ since it is used for threads. */
+ movl oFS(%eax), %edx
+ movw %dx, %fs
+
+ /* Fetch the address to return to. */
+ movl oEIP(%eax), %ecx
+
+ /* Load the new stack pointer. */
+ movl oESP(%eax), %esp
+
+ /* Push the return address on the new stack so we can return there. */
+ pushl %ecx
+
+ /* Load the values of all the 32-bit registers (except ESP).
+ Since we are loading from EAX, it must be last. */
+ movl oEDI(%eax), %edi
+ movl oESI(%eax), %esi
+ movl oEBP(%eax), %ebp
+ movl oEBX(%eax), %ebx
+ movl oEDX(%eax), %edx
+ movl oECX(%eax), %ecx
+ movl oEAX(%eax), %eax
+
+ /* The following 'ret' will pop the address of the code and jump
+ to it. */
+
+L(pseudo_end):
+ ret
+PSEUDO_END(__swapcontext)
+
+weak_alias (__swapcontext, swapcontext)
new file mode 100644
@@ -0,0 +1,29 @@
+#include <stddef.h>
+#include <signal.h>
+#include <sys/ucontext.h>
+
+--
+
+SIG_BLOCK
+SIG_SETMASK
+
+#define ucontext(member) offsetof (ucontext_t, member)
+#define mcontext(member) ucontext (uc_mcontext.member)
+#define mreg(reg) mcontext (gregs[REG_##reg])
+
+oLINK ucontext (uc_link)
+oSS_SP ucontext (uc_stack.ss_sp)
+oSS_SIZE ucontext (uc_stack.ss_size)
+oGS mreg (GS)
+oFS mreg (FS)
+oEDI mreg (EDI)
+oESI mreg (ESI)
+oEBP mreg (EBP)
+oESP mreg (ESP)
+oEBX mreg (EBX)
+oEDX mreg (EDX)
+oECX mreg (ECX)
+oEAX mreg (EAX)
+oEIP mreg (EIP)
+oFPREGS mcontext (fpregs)
+oSIGMASK ucontext (uc_sigmask)
From: Thomas Schwinge <thomas@codesourcery.com> Adapted from the Linux x86 functions. Not thoroughly tested, but manual testing as well as glibc tests look fine, and manual -lpthread testing also looks fine (within the given bounds for a new stack to be used with makecontext). This has also been in use in Debian since 2013. --- sysdeps/mach/hurd/i386/Makefile | 4 + sysdeps/mach/hurd/i386/getcontext.S | 74 +++++++++++++++ sysdeps/mach/hurd/i386/makecontext.S | 130 ++++++++++++++++++++++++++ sysdeps/mach/hurd/i386/setcontext.S | 93 ++++++++++++++++++ sysdeps/mach/hurd/i386/swapcontext.S | 110 ++++++++++++++++++++++ sysdeps/mach/hurd/i386/ucontext_i.sym | 29 ++++++ 6 files changed, 440 insertions(+) create mode 100644 sysdeps/mach/hurd/i386/getcontext.S create mode 100644 sysdeps/mach/hurd/i386/makecontext.S create mode 100644 sysdeps/mach/hurd/i386/setcontext.S create mode 100644 sysdeps/mach/hurd/i386/swapcontext.S create mode 100644 sysdeps/mach/hurd/i386/ucontext_i.sym