[PATCH 6/9] libc: add support for {get,set,swap,make}context to i386
Florian Fainelli
florian at openwrt.org
Wed Jan 9 15:17:26 UTC 2013
This patch adds support for {get,set,swap,make}context to the i386
architecture. Files are imported from glibc.
Signed-off-by: Natanael Copa <ncopa at alpinelinux.org>
Signed-off-by: Florian Fainelli <florian at openwrt.org>
---
extra/Configs/Config.i386 | 1 +
libc/sysdeps/linux/i386/Makefile.arch | 5 ++
libc/sysdeps/linux/i386/getcontext.S | 84 ++++++++++++++++++++++
libc/sysdeps/linux/i386/makecontext.S | 123 ++++++++++++++++++++++++++++++++
libc/sysdeps/linux/i386/setcontext.S | 96 +++++++++++++++++++++++++
libc/sysdeps/linux/i386/swapcontext.S | 110 ++++++++++++++++++++++++++++
libc/sysdeps/linux/i386/ucontext_i.sym | 30 ++++++++
7 files changed, 449 insertions(+)
create mode 100644 libc/sysdeps/linux/i386/getcontext.S
create mode 100644 libc/sysdeps/linux/i386/makecontext.S
create mode 100644 libc/sysdeps/linux/i386/setcontext.S
create mode 100644 libc/sysdeps/linux/i386/swapcontext.S
create mode 100644 libc/sysdeps/linux/i386/ucontext_i.sym
diff --git a/extra/Configs/Config.i386 b/extra/Configs/Config.i386
index 288aa5e..92cee3b 100644
--- a/extra/Configs/Config.i386
+++ b/extra/Configs/Config.i386
@@ -12,6 +12,7 @@ config FORCE_OPTIONS_FOR_ARCH
default y
select ARCH_LITTLE_ENDIAN
select ARCH_HAS_MMU
+ select ARCH_HAS_UCONTEXT
choice
prompt "Target x86 Processor Family"
diff --git a/libc/sysdeps/linux/i386/Makefile.arch b/libc/sysdeps/linux/i386/Makefile.arch
index a3bf32f..186b83a 100644
--- a/libc/sysdeps/linux/i386/Makefile.arch
+++ b/libc/sysdeps/linux/i386/Makefile.arch
@@ -18,3 +18,8 @@ endif
ifneq ($(UCLIBC_HAS_THREADS_NATIVE),y)
SSRC += vfork.S clone.S
endif
+
+ifeq ($(UCLIBC_HAS_CONTEXT_FUNCS),y)
+SSRC += makecontext.S setcontext.S getcontext.S swapcontext.S
+endif
+
diff --git a/libc/sysdeps/linux/i386/getcontext.S b/libc/sysdeps/linux/i386/getcontext.S
new file mode 100644
index 0000000..3221b59
--- /dev/null
+++ b/libc/sysdeps/linux/i386/getcontext.S
@@ -0,0 +1,84 @@
+/* Save current context.
+ Copyright (C) 2001-2012 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper at 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
+ <http://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)
+
+ /* We have separate floating-point register content memory on the
+ stack. We use the __fpregs_mem block in the context. Set the
+ links up correctly. */
+ leal oFPREGSMEM(%eax), %ecx
+ movl %ecx, oFPREGS(%eax)
+ /* 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. */
+ pushl %ebx
+ cfi_adjust_cfa_offset (4)
+ cfi_rel_offset (ebx, 0)
+ leal oSIGMASK(%eax), %edx
+ xorl %ecx, %ecx
+ movl $SIG_BLOCK, %ebx
+ movl $__NR_sigprocmask, %eax
+ ENTER_KERNEL
+ popl %ebx
+ cfi_adjust_cfa_offset (-4)
+ cfi_restore (ebx)
+ cmpl $-4095, %eax /* Check %eax for error. */
+ jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */
+
+ /* All done, return 0 for success. */
+ xorl %eax, %eax
+L(pseudo_end):
+ ret
+PSEUDO_END(__getcontext)
+
+weak_alias (__getcontext, getcontext)
diff --git a/libc/sysdeps/linux/i386/makecontext.S b/libc/sysdeps/linux/i386/makecontext.S
new file mode 100644
index 0000000..d12799d
--- /dev/null
+++ b/libc/sysdeps/linux/i386/makecontext.S
@@ -0,0 +1,123 @@
+/* Create new context.
+ Copyright (C) 2001,2002,2005,2007,2008,2009 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper at 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
+ <http://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
+ /* 'makecontext' returns no value. */
+L(pseudo_end):
+ 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. */
+ cfi_endproc
+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
+
+#ifdef __PIC__
+ call 1f
+1: popl %ebx
+ addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ebx
+#endif
+ cmpl $0, (%esp) /* Check the next context. */
+ je 2f /* If it is zero exit. */
+
+ call JUMPTARGET(__setcontext)
+ /* If this returns (which can happen if the syscall fails) we'll
+ exit the program with the return error value (-1). */
+
+ movl %eax, (%esp)
+2: 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)
diff --git a/libc/sysdeps/linux/i386/setcontext.S b/libc/sysdeps/linux/i386/setcontext.S
new file mode 100644
index 0000000..ae953cc
--- /dev/null
+++ b/libc/sysdeps/linux/i386/setcontext.S
@@ -0,0 +1,96 @@
+/* Install given context.
+ Copyright (C) 2001-2012 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper at 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
+ <http://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. Note that we preserve EBX in case
+ the system call fails and we return from the function with an
+ error. */
+ pushl %ebx
+ cfi_adjust_cfa_offset (4)
+ xorl %edx, %edx
+ leal oSIGMASK(%eax), %ecx
+ movl $SIG_SETMASK, %ebx
+ cfi_rel_offset (ebx, 0)
+ movl $__NR_sigprocmask, %eax
+ ENTER_KERNEL
+ popl %ebx
+ cfi_adjust_cfa_offset (-4)
+ cfi_restore (ebx)
+ cmpl $-4095, %eax /* Check %eax for error. */
+ jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */
+
+ /* EAX was modified, reload it. */
+ movl 4(%esp), %eax
+
+ /* Restore the floating-point context. Not the registers, only the
+ rest. */
+ movl 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)
+
+weak_alias (__setcontext, setcontext)
diff --git a/libc/sysdeps/linux/i386/swapcontext.S b/libc/sysdeps/linux/i386/swapcontext.S
new file mode 100644
index 0000000..ee5d0e4
--- /dev/null
+++ b/libc/sysdeps/linux/i386/swapcontext.S
@@ -0,0 +1,110 @@
+/* Save current context and install the given one.
+ Copyright (C) 2001-2012 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper at 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
+ <http://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)
+
+ /* We have separate floating-point register content memory on the
+ stack. We use the __fpregs_mem block in the context. Set the
+ links up correctly. */
+ leal oFPREGSMEM(%eax), %ecx
+ movl %ecx, oFPREGS(%eax)
+ /* 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. */
+ pushl %ebx
+ leal oSIGMASK(%eax), %edx
+ leal oSIGMASK(%ecx), %ecx
+ movl $SIG_SETMASK, %ebx
+ movl $__NR_sigprocmask, %eax
+ ENTER_KERNEL
+ popl %ebx
+ cmpl $-4095, %eax /* Check %eax for error. */
+ jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */
+
+ /* EAX was modified, reload it. */
+ movl 8(%esp), %eax
+
+ /* Restore the floating-point context. Not the registers, only the
+ rest. */
+ movl 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)
diff --git a/libc/sysdeps/linux/i386/ucontext_i.sym b/libc/sysdeps/linux/i386/ucontext_i.sym
new file mode 100644
index 0000000..b11a550
--- /dev/null
+++ b/libc/sysdeps/linux/i386/ucontext_i.sym
@@ -0,0 +1,30 @@
+#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)
+oFPREGSMEM ucontext (__fpregs_mem)
--
1.7.10.4
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