freebsd-nq/lib/libc/i386/gen/getcontext.S
Daniel Eischen b66b8326e5 Add getcontext, setcontext, makecontext, and swapcontext. These
functions are defined in SUSv2 and the latest POSIX spec.

Thanks to Bernd Walter <ticso@cicely8.cicely.de> for helping debug my
alpha assembly.

Approved by:	-arch
2002-01-10 02:40:59 +00:00

169 lines
5.7 KiB
ArmAsm

/*
* Copyright (c) 2001 Daniel Eischen <deischen@freebsd.org>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Neither the name of the author nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY DANIEL EISCHEN AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* $FreeBSD$
*/
#include <machine/asm.h>
/*
* Where do we define these?
*/
#define UC_MC_VALID 0x0001 /* __UC_MC_VALID <machine/ucontext.h> */
#define UC_FP_VALID 0x0002 /* __UC_FP_VALID <machine/ucontext.h> */
#define MC_FP_VALID UC_MC_VALID | UC_FP_VALID
#define UC_MC_OFFSET 16 /* offset to mcontext from ucontext */
#define UC_FLAGS_OFFSET 208 /* offset to flags from ucontext */
#define MC_FLAGS_OFFSET 192 /* offset to flags from mcontext */
#define MC_FP_REGS_OFFSET 80 /* offset to FP regs from mcontext */
#define MC_FP_CW_OFFSET 80 /* offset to FP control word */
/*
* int setcontext(ucontext_t *ucp);
*
* calls sigprocmask(int how, sigset_t *set, sigset_t *oset);
*
* Returns 0 if there are no errors; -1 otherwise
*/
.weak CNAME(setcontext)
.set CNAME(setcontext),CNAME(__setcontext)
ENTRY(__setcontext)
movl 4(%esp), %eax /* get address of context and sigset */
cmpl $0, %eax /* check for null pointer */
jne 1f
movl $-1, %eax
jmp 5f
1: testl $UC_MC_VALID, UC_FLAGS_OFFSET(%eax) /* is context valid? */
jnz 2f
movl $-1, %eax /* bzzzt, invalid context */
jmp 5f
2: PIC_PROLOGUE
pushl $0 /* oset = NULL */
pushl %eax /* set = &ucp->uc_sigmask */
pushl $3 /* how = SIG_SETMASK */
call PIC_PLT(CNAME(_sigprocmask))
addl $12, %esp
PIC_EPILOGUE
testl %eax, %eax /* check for error */
jnz 5f
movl 4(%esp), %edx /* get address of context */
addl $UC_MC_OFFSET, %edx /* add offset to mcontext */
movl 4(%edx), %gs
movl 8(%edx), %fs
movl 12(%edx), %es
movl 16(%edx), %ds
movl 20(%edx), %edi
movl 24(%edx), %esi
movl 28(%edx), %ebp
movl 72(%edx), %esp /* switch to context defined stack */
subl $4, %esp /* leave space for the return address */
movl 60(%edx), %eax /* put return address at top of stack */
movl %eax, (%esp)
testl $UC_FP_VALID, MC_FLAGS_OFFSET(%edx) /* are FP regs valid? */
jz 3f
frstor MC_FP_REGS_OFFSET(%edx) /* restore FP regs */
jmp 4f
3: fninit
fldcw MC_FP_CW_OFFSET(%edx)
4: movl 68(%edx), %eax /* restore flags register */
sahf
movl 48(%edx), %eax /* restore ax, bx, cx, and dx last */
movl 36(%edx), %ebx
movl 44(%edx), %ecx
movl 40(%edx), %edx
5: ret
/*
* int getcontext(ucontext_t *ucp);
*
* calls sigprocmask(int how, sigset_t *set, sigset_t *oset);
*
* Returns 0 if there are no errors; -1 otherwise
*/
.weak CNAME(getcontext)
.set CNAME(getcontext),CNAME(__getcontext)
ENTRY(__getcontext)
movl 4(%esp), %eax /* get address of context */
cmpl $0, %eax /* check for null pointer */
jne 1f
movl $-1, %eax
jmp 2f
movl 4(%esp), %eax /* get address of context and sigset */
1: PIC_PROLOGUE
pushl %eax /* oset = &ucp->uc_sigmask */
pushl $0 /* set = NULL */
pushl $3 /* how = SIG_SETMASK */
call PIC_PLT(CNAME(_sigprocmask))
addl $12, %esp
PIC_EPILOGUE
testl %eax, %eax /* check for error */
jnz 2f
pushl %edx /* save value of edx */
movl 8(%esp), %edx /* get address of context */
addl $UC_MC_OFFSET, %edx /* add offset to mcontext */
movl %gs, 4(%edx)
movl %fs, 8(%edx)
movl %es, 12(%edx)
movl %ds, 16(%edx)
movl %edi, 20(%edx)
movl %esi, 24(%edx)
movl %ebp, 28(%edx)
movl %ebx, 36(%edx)
movl $0, 48(%edx) /* store successful return in eax */
popl %eax /* get saved value of edx */
movl %eax, 40(%edx) /* save edx */
movl %ecx, 44(%edx)
movl (%esp), %eax /* get return address */
movl %eax, 60(%edx) /* save return address */
/*
* XXX - Do we really need to save floating point registers?
*
* This is an explicit call to get the current context, so
* shouldn't the caller be done with the floating point registers?
* Contexts formed by involuntary switches, such as signal delivery,
* should have floating point registers saved by the kernel.
*
* As of this writing, the kernel doesn't yet save the FPU state
* on signal delivery, so a setcontext on the interrupted context
* may yield incorrect results regardless.
*/
#if 1
fnstcw MC_FP_CW_OFFSET(%edx)
movl $UC_MC_VALID, MC_FLAGS_OFFSET(%edx) /* mcontext valid, no FP */
#else
fnsave MC_FP_REGS_OFFSET(%edx) /* save FP regs */
movl $MC_FP_VALID, MC_FLAGS_OFFSET(%edx) /* mcontext and FP valid */
#endif
lahf /* get eflags */
movl %eax, 68(%edx) /* store eflags */
movl %esp, %eax /* setcontext pushes the return */
addl $4, %eax /* address onto the top of the */
movl %eax, 72(%edx) /* stack; account for this */
movl 40(%edx), %edx /* restore edx -- is this needed? */
xorl %eax, %eax /* return 0 */
2: ret