208 lines
6.7 KiB
C
208 lines
6.7 KiB
C
/* Copyright (C) 2005 David Decotigny
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Copyright (C) 2000-2004, The KOS team
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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USA.
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*/
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#pragma once
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/**
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* @file cpu_context.h
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*
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* Low level API to manage kernel and user thread CPU contexts. Should
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* be some kind of architecture-independent.
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*/
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#include "types.h"
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#include "errno.h"
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/**
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* Opaque structure storing the CPU context of an inactive kernel or
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* user thread, as saved by the low level primitives below or by the
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* interrupt/exception handlers.
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*
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* @note This is an (architecture-independent) forward declaration:
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* see cpu_context.c and the *.S files for its
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* (architecture-dependent) definition.
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*/
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struct cpu_state;
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/**
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* The type of the functions passed as arguments to the Kernel thread
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* related functions.
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*/
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typedef void (cpu_kstate_function_arg1_t(void * arg1));
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/**
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* Function to create an initial context for a kernel thread starting
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* its execution at function start_func with the argument initial_arg,
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* and having the stack defined by stack_bottom/stack_size. When the
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* start_func function returns, the function exit_func is called with
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* argument exit_arg.
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*
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* @param kctxt The kernel thread CPU context to initialize. The
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* address of the newly-initialized struct cpu_state will be
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* stored in this variable. The contents of this struct cpu_state
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* are actually located /inside/ the stack.
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*
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* @param start_func The address of the first instruction that will be
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* executed when this context will be first transferred on
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* CPU. Practically speaking, this is the address of a function that
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* is assumed to take 1 argument.
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*
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* @param start_arg The value that will be passed as the argument to
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* start_func when the thread starts. The stack will be setup
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* accordingly to simulate a real call to the function and really
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* passing this arguement.
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*
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* @param stack_bottom The lowest address of the stack.
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*
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* @param stack_size The size of the stack.
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*
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* @param exit_func The address of the instruction executed after the
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* function start_func has returned. This function takes 1 parameter
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* as argument: exit_arg.
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*
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* @param exit_arg The argument passed to the function exit_func.
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*
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* @note the newly created context is INTERRUPTIBLE by default !
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*/
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int cpu_kstate_init(struct cpu_state **kctxt,
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cpu_kstate_function_arg1_t *start_func,
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uint32_t start_arg,
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vaddr_t stack_bottom,
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size_t stack_size,
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cpu_kstate_function_arg1_t *exit_func,
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uint32_t exit_arg);
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/**
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* Function that performs an immediate context-switch from one
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* kernel/user thread to another one. It stores the current executing
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* context in from_ctxt, and restores to_context on CPU.
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*
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* @param from_ctxt The address of the struct cpu_state will be
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* stored in this variable. Must NOT be NULL.
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*
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* @param to_ctxt The CPU will resume its execution with the struct
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* cpu_state located at this address. Must NOT be NULL.
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*/
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void cpu_context_switch(struct cpu_state **from_ctxt,
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struct cpu_state *to_ctxt);
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/*
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* Switch to the new given context (of a kernel/user thread) without
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* saving the old context (of another kernel/user thread), and call
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* the function reclaiming_func passing it the recalining_arg
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* argument. The reclaining function is called from within the stack
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* of the new context, so that it can (among other things) safely
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* destroy the stack of the former context.
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*
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* @param switch_to_ctxt The context that will be restored on the CPU
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*
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* @param reclaiming_func The address of the function that will be
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* called after having changed the stack, but before restoring the CPU
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* context to switch_to_ctxt.
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*/
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void
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cpu_context_exit_to(struct cpu_state *switch_to_ctxt,
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cpu_kstate_function_arg1_t *reclaiming_func,
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uint32_t reclaiming_arg) __attribute__((noreturn));
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/* =======================================================================
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* Public Accessor functions
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*/
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/**
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* Return Program Counter stored in the saved kernel/user context
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*/
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vaddr_t cpu_context_get_PC(const struct cpu_state *ctxt);
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/**
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* Return Stack Pointer stored in the saved kernel/user context
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*/
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vaddr_t cpu_context_get_SP(const struct cpu_state *ctxt);
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/**
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* Dump the contents of the CPU context (bochs + x86_videomem)
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*/
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void cpu_context_dump(const struct cpu_state *ctxt);
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/* =======================================================================
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* Public Accessor functions TO BE USED ONLY BY Exception handlers
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*/
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/**
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* Return the argument passed by the CPU upon exception, as stored in the
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* saved context
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*/
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uint32_t cpu_context_get_EX_info(const struct cpu_state *ctxt);
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/**
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* Return the faulting address of the exception
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*/
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vaddr_t
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cpu_context_get_EX_faulting_vaddr(const struct cpu_state *ctxt);
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/* =======================================================================
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* Macros controlling stack poisoning.
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* Stack poisoning can be used to detect:
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* - unitialized local variables
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* - when the thread might have gone too deep in the stack
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*/
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/** The signature of the poison */
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#define CPU_STATE_STACK_POISON 0xa5
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/**
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* When set, mean that the whole stack is poisoned to detect use of
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* unititialized variables
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*/
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#define CPU_STATE_DETECT_UNINIT_KERNEL_VARS
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/* #undef CPU_STATE_DETECT_UNINIT_KERNEL_VARS */
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/**
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* When set, mean that the bottom of the stack is poisoned to detect
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* probable stack overflow. Its value indicates the number of bytes
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* used for this detection.
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*/
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#define CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW 64
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/* #undef CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW */
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#if defined(CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW)
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void
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cpu_state_prepare_detect_kernel_stack_overflow(const struct cpu_state *ctxt,
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vaddr_t kernel_stack_bottom,
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size_t kernel_stack_size);
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void cpu_state_detect_kernel_stack_overflow(const struct cpu_state *ctxt,
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vaddr_t kernel_stack_bottom,
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size_t kernel_stack_size);
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#else
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# define cpu_state_prepare_detect_kernel_stack_overflow(ctxt,stkbottom,stksize) \
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({ /* nop */ })
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# define cpu_state_detect_kernel_stack_overflow(ctxt,stkbottom,stksize) \
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({ /* nop */ })
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#endif
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