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/*=============================================================================
//
// context.S
//
// SPARC context switch code
//
//=============================================================================
// ####ECOSGPLCOPYRIGHTBEGIN####
// -------------------------------------------
// This file is part of eCos, the Embedded Configurable Operating System.
// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
//
// eCos is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 or (at your option) any later
// version.
//
// eCos 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 General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License
// along with eCos; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// As a special exception, if other files instantiate templates or use
// macros or inline functions from this file, or you compile this file
// and link it with other works to produce a work based on this file,
// this file does not by itself cause the resulting work to be covered by
// the GNU General Public License. However the source code for this file
// must still be made available in accordance with section (3) of the GNU
// General Public License v2.
//
// This exception does not invalidate any other reasons why a work based
// on this file might be covered by the GNU General Public License.
// -------------------------------------------
// ####ECOSGPLCOPYRIGHTEND####
//=============================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s): nickg, gthomas, hmt
// Contributors: nickg, gthomas, hmt
// Date: 1998-12-15
// Purpose: SPARC context switch code
// Description: This file contains implementations of the thread context
// switch routines. It also contains the longjmp() and setjmp()
// routines.
//
//####DESCRIPTIONEND####
//
//===========================================================================*/
#include <pkgconf/hal.h>
#include <cyg/hal/vectors.h>
#define DELAYS_AFTER_WRPSR_SAME_WINDOW
#define DELAYS_AFTER_WRWIM
.text
! ------------------------------------------------------------------------------
! hal_thread_switch_context
! Switch thread contexts
! %o0 = address of sp of next thread to execute
! %o1 = address of sp save location of current thread
.global hal_thread_switch_context
hal_thread_switch_context:
! First take the stack down to make room for the saved register
! state, including a window save area at the base. Leave the
! current window save area undisturbed. It is unused within the
! save but will become current again when we continue in this
! context. This lets us do this whole piece of work without
! diabling interrupts for too long, since, for example, we can
! lower the stack atomically with one instruction:
sub %sp, SAVE_REGS_SIZE, %sp
st %sp, [ %o1 ] ! return SP for this thread
std %l0, [%sp + 0 * 4] ! save L & I registers
std %l2, [%sp + 2 * 4]
std %l4, [%sp + 4 * 4]
std %l6, [%sp + 6 * 4]
std %i0, [%sp + 8 * 4]
std %i2, [%sp + 10 * 4]
std %i4, [%sp + 12 * 4]
std %i6, [%sp + 14 * 4]
#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
st %o7, [%sp + 31 * 4] ! save only the return address
! and no need to preserve %o0 even though it is restored
#else // save a maximal context
st %g1, [%sp + 17 * 4] ! save G & O registers
std %g2, [%sp + 18 * 4]
std %g4, [%sp + 20 * 4]
std %g6, [%sp + 22 * 4]
std %o0, [%sp + 24 * 4]
std %o2, [%sp + 26 * 4]
std %o4, [%sp + 28 * 4]
std %o6, [%sp + 30 * 4]
#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
! and save the CWP in %g0 save place
rd %psr, %g7
st %g7, [%sp + 16 * 4]
! Now load the destination thread by dropping through
! to hal_thread_load_context
! ------------------------------------------------------------------------------
! hal_thread_load_context
! Load thread context
! %o0 = address of sp of next thread to execute
! Note that this function is also the second half of hal_thread_switch_context
! and is simply dropped into from it.
.global hal_thread_load_context
hal_thread_load_context:
! Here, we are a leaf routine but with slightly odd properties.
! The stack is still the callers at this point but the register
! set is up for grabs. So we can use globals:
ld [ %o0 ], %g7 ! Get the next saved SP
! DISABLE INTERRUPTS *ONLY* NOT TRAPS
rd %psr, %g6
or %g6, 0xfe0, %g5 ! PIL up to 15 leave traps enabled
wr %g5, %psr
nop; nop; nop
! force out all our callers register sets onto the stack
! if necessary: the system will handily take care of this for
! us as follows:
save %sp, -16 * 4, %sp ! need all these to preserve
save %sp, -16 * 4, %sp ! the linked list property...
save %sp, -16 * 4, %sp
save %sp, -16 * 4, %sp
#if 6 < __WINSIZE
save %sp, -16 * 4, %sp
#if 7 < __WINSIZE
save %sp, -16 * 4, %sp
#endif
#endif
! Fewer saves if fewer register windows. For 8 register windows,
! six of these is correct; a seventh would force out the current
! set that was already saved manually above. Note that minimal
! space is allowed on stack for locals and ins in case this
! sequence itself gets interrupted and recurses too deep.
! now select the new window with traps disabled...
! get the new PSR and CWP that we will ultimately restore
! from the %g0 save place...
ld [%g7 + 16 * 4], %g6 ! %g7 holds the new stack pointer
andn %g6, 0x20, %g5 ! clear ET into %g5
and %g6, __WINBITS, %g4 ! CWP bits only in %g4
! calculate a new WIM...
add %g4, 1, %g3 ! required invalid window number
#if 8 == __WINSIZE
and %g3, __WINBITS, %g3 ! modulo 8
#else // expect 5 or 6 or 7 windows
cmp %g3, __WINSIZE
bge,a 567f ! taken: do delay slot, handle overflow
mov 0, %g3 ! only if .ge. above
567:
#endif
mov 1, %g2
sll %g2, %g3, %g2 ! converted to a mask for the WIM
! DISABLE INTERRUPTS (TRAPS)
wr %g5, %psr ! set CWP to new window, disable traps
wr %g2, %wim ! and WIM to new value
nop
nop
nop
! Must do this atomically so that the registers match the stack.
! After locals and ins are loaded, we are conformant to the PCS
! so can re-enable interrupts.
mov %g7, %sp ! target sp in situ (%sp = %o6)
ldd [%sp + 0 * 4], %l0 ! restore L & I registers
ldd [%sp + 2 * 4], %l2
ldd [%sp + 4 * 4], %l4
ldd [%sp + 6 * 4], %l6
ldd [%sp + 8 * 4], %i0
ldd [%sp + 10 * 4], %i2
ldd [%sp + 12 * 4], %i4
ldd [%sp + 14 * 4], %i6
! RESTORE INTERRUPTS to saved state
wr %g6, %psr ! set new CWP and old ET and PIL
nop
nop
nop
! now load the rest of the context; we can be interrupted here
! (if the saved context was a voluntary yield or threadstart)
! but that is OK, other state will be preserved in that case...
#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
ld [%sp + 24 * 4], %o0 ! must load the initial argument
#else // restore a maximal context
ld [%sp + 17 * 4], %g1
ldd [%sp + 18 * 4], %g2
ldd [%sp + 20 * 4], %g4
ldd [%sp + 22 * 4], %g6
ldd [%sp + 24 * 4], %o0
ldd [%sp + 26 * 4], %o2
ldd [%sp + 28 * 4], %o4
#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
! %o6 = %sp, already set up
ld [%sp + 31 * 4], %o7 ! "return" address
retl
add %sp, SAVE_REGS_SIZE, %sp ! and set the stack back
! to its entrant value
! ------------------------------------------------------------------------------
! HAL longjmp, setjmp implementations
!FUNC_START(hal_setjmp)
.global hal_setjmp
hal_setjmp:
! Treat this as a leaf routine, may as well.
! %o0 is the address of the buffer.
std %l0, [%o0 + 0 * 4] ! save L & I registers
std %l2, [%o0 + 2 * 4]
std %l4, [%o0 + 4 * 4]
std %l6, [%o0 + 6 * 4]
std %i0, [%o0 + 8 * 4]
std %i2, [%o0 + 10 * 4]
std %i4, [%o0 + 12 * 4]
std %i6, [%o0 + 14 * 4]
#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
std %o6, [%o0 + 30 * 4] ! just save %sp and return address
#else // save a maximal context
st %g1, [%o0 + 17 * 4] ! save G & O registers
std %g2, [%o0 + 18 * 4]
std %g4, [%o0 + 20 * 4]
std %g6, [%o0 + 22 * 4]
std %o0, [%o0 + 24 * 4]
std %o2, [%o0 + 26 * 4]
std %o4, [%o0 + 28 * 4]
std %o6, [%o0 + 30 * 4]
#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
! and save the CWP in %g0 save place
rd %psr, %g7
st %g7, [%o0 + 16 * 4]
! DISABLE INTERRUPTS *ONLY* NOT TRAPS
or %g7, 0xfe0, %g6 ! PIL up to 15 leave traps enabled
wr %g6, %psr
nop; nop; nop
! force out all our callers register sets onto the stack
! if necessary: the system will handily take care of this for
! us as follows:
save %sp, -16 * 4, %sp ! need all these to preserve
save %sp, -16 * 4, %sp ! the linked list property...
save %sp, -16 * 4, %sp
save %sp, -16 * 4, %sp
#if 6 < __WINSIZE
save %sp, -16 * 4, %sp
#if 7 < __WINSIZE
save %sp, -16 * 4, %sp
#endif
#endif
! Fewer saves if fewer register windows. For 8 register windows,
! six of these is correct; a seventh would force out the current
! set that was already saved manually above. Note that minimal
! space is allowed on stack for locals and ins in case this
! sequence itself gets interrupted and recurses too deep.
! (after all, we are about to call deeper not shallower, otherwise
! using setjmp is inappropriate)
! ENABLE INTERRUPTS
wr %g7, %psr ! set CWP back to as-was
nop
nop
nop
#ifndef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
ldd [%o0 + 22 * 4], %g6 ! preserve %g7 and %g6
#endif
retl ! ret and return zero to indicate
mov 0, %o0 ! not longjumped-to
! hal_longjmp loads state from arg0 and returns arg1
!FUNC_START(hal_longjmp)
.global hal_longjmp
hal_longjmp:
! This is kind of a leaf routine, it returns elsewhere
! %o0 is the address of the buffer.
! %o1 is the value to return in %o0 (since we are a leaf)
mov %o0, %g7 ! keep the pointer handy
mov %o1, %g1 ! and the return value
! now select the new window with traps disabled...
rd %psr, %g6
! preserve ET, clear CWP
andn %g6, __WINBITS_MAXIMAL, %g6
andn %g6, 0x20, %g5 ! clear ET also into %g5
! get new CWP from %g0 save place...
ld [%g7 + 16 * 4], %g4 ! %g7 holds the new stack pointer
and %g4, __WINBITS, %g4 ! preserve CWP bits
! calculate a new WIM...
add %g4, 1, %g3 ! required invalid window number
#if 8 == __WINSIZE
and %g3, __WINBITS, %g3 ! modulo 8
#else // expect 5 or 6 or 7 windows
cmp %g3, __WINSIZE
bge,a 567f ! taken: do delay slot, handle overflow
mov 0, %g3 ! only if .ge. above
567:
#endif
mov 1, %g2
sll %g2, %g3, %g2 ! converted to a mask for the WIM
! DISABLE INTERRUPTS
wr %g5, %g4, %psr ! set CWP to new window, disable traps
wr %g2, %wim ! and WIM to new value
nop
nop
nop
! Must do this atomically so that the registers match the stack.
! After locals and ins are loaded, we are conformant to the PCS
! so can re-enable interrupts.
ldd [%g7 + 0 * 4], %l0 ! restore L & I registers
ldd [%g7 + 2 * 4], %l2
ldd [%g7 + 4 * 4], %l4
ldd [%g7 + 6 * 4], %l6
ldd [%g7 + 8 * 4], %i0
ldd [%g7 + 10 * 4], %i2
ldd [%g7 + 12 * 4], %i4
ldd [%g7 + 14 * 4], %i6
ld [%g7 + 30 * 4], %sp ! %o6 = %sp, set up now so as to conform
! to PCS and so be interruptible
! ENABLE INTERRUPTS
wr %g6, %g4, %psr ! set new CWP and old ET
nop
nop
nop
! now load the rest of the context; we can be interrupted here, but
! that is OK, other state will be preserved in that case...
#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
! we are not preserving globals...
! %o6 = %sp, already set up
ld [%g7 + 31 * 4], %o7 ! "return" address
retl ! %g1 still holds the return value
mov %g1, %o0
#else // load a maximal context
mov %g7, %o0 ! original pointer was in %o0 anyway
ldd [%o0 + 18 * 4], %g2
ldd [%o0 + 20 * 4], %g4
ldd [%o0 + 22 * 4], %g6
ld [%o0 + 25 * 4], %o1 ! %o0 = original pointer
ldd [%o0 + 26 * 4], %o2
ldd [%o0 + 28 * 4], %o4
! %o6 = %sp, already set up
ld [%o0 + 31 * 4], %o7 ! "return" address
! %g1 still holds the return value; want to get this into %o0
! and restore %g1 from the saved state; %o0 is the state pointer:
! g1 = R, o0 = P
xor %o0, %g1, %g1 ! g1 = R^P, o0 = P
xor %o0, %g1, %o0 ! g1 = R^P, o0 = R
xor %o0, %g1, %g1 ! g1 = P, o0 = R all done
retl
ld [%g1 + 17 * 4], %g1 ! and finally restore %g1
#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
! ------------------------------------------------------------------------------
! end of context.S
|
