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x86: Add support for (paging-based) protection domains

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This patch implements a simple, lightweight form of protection domains
using a pluggable framework.  Currently, the following plugin is
available:

 - Flat memory model with paging.

The overall goal of a protection domain implementation within this
framework is to define a set of resources that should be accessible to
each protection domain and to prevent that protection domain from
accessing other resources.  The details of each implementation of
protection domains may differ substantially, but they should all be
guided by the principle of least privilege.  However, that idealized
principle is balanced against the practical objectives of limiting the
number of relatively time-consuming context switches and minimizing
changes to existing code.

For additional information, please refer to cpu/x86/mm/README.md.

This patch also causes the C compiler to be used as the default linker
and assembler.
This commit is contained in:
Michael LeMay 2015-08-10 08:34:02 -07:00
parent b0de416682
commit 3908253038
48 changed files with 3558 additions and 295 deletions
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75
cpu/x86/init/common/cpu.c
View file

@ -28,11 +28,13 @@
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "cpu.h"
#include "gdt.h"
#include "helpers.h"
#include "idt.h"
#include "interrupt.h"
#include "irq.h"
#include "stacks.h"
static void
double_fault_handler(struct interrupt_context context)
@ -40,16 +42,79 @@ double_fault_handler(struct interrupt_context context)
halt();
}
/*---------------------------------------------------------------------------*/
void
cpu_init(void)
/* The OS has switched to its own segment descriptors. However, the protection
* domain support, if enabled, has not yet been fully activated.
*/
static void
boot_stage1(void)
{
gdt_init();
idt_init();
/* Set an interrupt handler for Double Fault exception. This way, we avoid
* the system to triple fault, leaving no trace about what happened.
*/
SET_INTERRUPT_HANDLER(8, 1, double_fault_handler);
SET_EXCEPTION_HANDLER(8, 1, double_fault_handler);
irq_init();
/* Initialize protection domain support, if enabled */
prot_domains_init();
prot_domains_leave_boot_stage1();
}
/*---------------------------------------------------------------------------*/
int main(void);
/* This routine runs with the initial, flat address space, even if protection
* domain support is enabled. The goal behind the design of this routine is to
* keep it as short as possible, since it is unable to directly reference data
* and invoke functions that are intended to be accessible later after the
* system has booted when a multi-segment protection domain model is in use.
*/
void
cpu_boot_stage0(void)
{
/* Reserve three stack slots for return addresses */
uintptr_t top_of_stack = STACKS_INIT_TOP;
#if X86_CONF_PROT_DOMAINS != X86_CONF_PROT_DOMAINS__NONE
uintptr_t *top_of_stack_ptr = (uintptr_t *)top_of_stack;
top_of_stack_ptr[0] = (uintptr_t)prot_domains_launch_kernel;
top_of_stack_ptr[1] = (uintptr_t)prot_domains_launch_app;
#endif
/* Perform common GDT initialization */
gdt_init();
/* Switch all data segment registers to the newly-initialized flat data
* descriptor.
*/
__asm__(
"mov %0, %%ds\n\t"
"mov %0, %%es\n\t"
"mov %0, %%fs\n\t"
"mov %0, %%gs\n\t"
:
: "r" (GDT_SEL_DATA_FLAT)
);
/**
* Perform specific GDT initialization tasks for the protection domain
* implementation that is enabled, if any.
*/
prot_domains_gdt_init();
/* Do not pass memory operands to the asm block below, since it is
* switching from the flat address space to a multi-segment address space
* model if such a model is used by the enabled protection domain
* implementation, if any.
*/
__asm__(
"mov %[_ss_], %%ss\n\t"
"mov %[_esp_], %%esp\n\t"
"ljmp %[_cs_], %[_stage1_]\n\t"
:
: [_ss_] "r" (GDT_SEL_STK_EXC),
[_esp_] "r" (top_of_stack),
[_cs_] "i" ((uint16_t)GDT_SEL_CODE_EXC),
[_stage1_] "i" (boot_stage1)
);
}