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/* IBM_PROLOG_BEGIN_TAG */
/* This is an automatically generated prolog. */
/* */
/* $Source: src/import/chips/p9/procedures/ppe/pk/kernel/pk_stack_init.c $ */
/* */
/* OpenPOWER sbe Project */
/* */
/* Contributors Listed Below - COPYRIGHT 2015,2016 */
/* [+] International Business Machines Corp. */
/* */
/* */
/* Licensed under the Apache License, Version 2.0 (the "License"); */
/* you may not use this file except in compliance with the License. */
/* You may obtain a copy of the License at */
/* */
/* http://www.apache.org/licenses/LICENSE-2.0 */
/* */
/* Unless required by applicable law or agreed to in writing, software */
/* distributed under the License is distributed on an "AS IS" BASIS, */
/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or */
/* implied. See the License for the specific language governing */
/* permissions and limitations under the License. */
/* */
/* IBM_PROLOG_END_TAG */
/// \file pk_stack_init.c
/// \brief PK stack initialization
///
/// The entry points in this file are initialization routines - they are never
/// needed after PK initialization and their code space could be reclaimed by
/// the application after initialization if required.
///
/// This code was split out from "pk_init.c" because it may be needed in a
/// thread configuration if threads are being created dynamically. in an
/// interrupt-only configuration it is not needed after \c pk_initialize().
#include "pk.h"
/// Initialize a stack area.
///
/// \param stack A pointer to the smallest legal address of the stack. The
/// stack address is modified as the stack is aligned and initialized.
///
/// \param size A pointer to the size of the stack (in bytes). The size is
/// modified as the stack is aligned and initialized. At exit this is the
/// final usable stack area size aligned to the size of the PK_STACK_TYPE.
///
/// PK makes no assumptions about size or alignment of the area provided as a
/// stack, and carefully aligns and initializes the stack. Regardless of how
/// the stack grows, the \a stack parameter is considered to be the lowest
/// legal address of the stack.
int
__pk_stack_init(PkAddress* stack,
size_t* size)
{
PkAddress mask;
size_t excess, i, count;
PK_STACK_TYPE* p;
if (PK_STACK_DIRECTION < 0)
{
// Stacks grow down. The initial stack pointer is set to just above
// the last allocated stack address. This is legal for pre-decrement
// stacks, otherwise the initial address is first brought into range
// before alignment. The stack is aligned downward, then the size is
// adjusted to a multiple of the stack type. Stacks are optionally
// prepatterned. Alignment is assumed to be a power of 2.
*stack += *size;
if (!PK_STACK_PRE_DECREMENT)
{
*stack -= sizeof(PK_STACK_TYPE);
*size -= sizeof(PK_STACK_TYPE);
}
mask = PK_STACK_ALIGNMENT - 1;
excess = *stack & mask;
*stack -= excess;
*size -= excess;
*size = (*size / sizeof(PK_STACK_TYPE)) * sizeof(PK_STACK_TYPE);
if (PK_STACK_CHECK)
{
p = (PK_STACK_TYPE*)(*stack);
count = *size / sizeof(PK_STACK_TYPE);
for (i = 0; i < count; i++)
{
if (PK_STACK_PRE_DECREMENT)
{
*(--p) = PK_STACK_PATTERN;
}
else
{
*(p--) = PK_STACK_PATTERN;
}
}
}
__pk_stack_create_initial_frame(stack, size);
}
else
{
PK_PANIC(PK_UNIMPLEMENTED);
}
return PK_OK;
}
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