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https://github.com/Atmosphere-NX/Atmosphere.git
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145 lines
4 KiB
C
145 lines
4 KiB
C
/*
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* Copyright (c) 2018-2019 Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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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, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include <stddef.h>
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#include <string.h>
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#include "regs.h"
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#include "lib/printk.h"
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/**
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* Switches to EL1, and then calls main_el1.
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* Implemented in assembly in entry.S.
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*/
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void switch_to_el1();
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/**
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* C entry point for execution at EL1.
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*/
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void main_el1(void * fdt);
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/**
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* Reference to the EL2 vector table.
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* Note that the type here isn't reprsentative-- we just need the address of the label.
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*/
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extern uint64_t el2_vector_table;
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/**
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* Clear out the system's bss.
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*/
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void _clear_bss(void)
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{
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// These symbols don't actually have a meaningful type-- instead,
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// we care about the locations at which the linker /placed/ these
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// symbols, which happen to be at the start and end of the BSS.
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// We use chars here to make the math easy. :)
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extern char lds_bss_start, lds_bss_end;
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memset(&lds_bss_start, 0, &lds_bss_end - &lds_bss_start);
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}
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/**
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* Triggered on an unrecoverable condition; prints an error message
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* and terminates execution.
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*/
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void panic(const char * message)
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{
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printk("\n\n");
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printk("-----------------------------------------------------------------\n");
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printk("PANIC: %s\n", message);
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printk("-----------------------------------------------------------------\n");
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// TODO: This should probably induce a reboot,
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// rather than sticking here.
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while(1);
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}
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/**
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* Launch an executable kernel image. Should be the last thing called by
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* Discharge, as it does not return.
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*
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* @param kernel The kernel to be executed.
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* @param fdt The device tree to be passed to the given kernel.
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*/
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void launch_kernel(const void *kernel)
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{
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// Construct a function pointer to our kernel, which will allow us to
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// jump there immediately. Note that we don't care what this leaves on
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// the stack, as either our entire stack will be ignored, or it'll
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// be torn down by the target kernel anyways.
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void (*target_kernel)(void) = kernel;
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printk("Launching Horizon kernel...\n");
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target_kernel();
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}
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/**
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* Core section of the stub-- sets up the hypervisor from up in EL2.
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*/
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int main(int argc, void **argv)
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{
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// Read the currrent execution level...
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uint32_t el = get_current_el();
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/* Say hello. */
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printk("Welcome to Atmosph\xe8re Thermosph\xe8" "re!\n");
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printk("Running at EL%d.\n", el);
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// ... and ensure we're in EL2.
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if (el != 2) {
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panic("Thermosph\xe8" "re must be launched from EL2!");
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}
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// Set up the vector table for EL2, so that the HVC instruction can be used
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// from EL1. This allows us to return to EL2 after starting the EL1 guest.
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set_vbar_el2(&el2_vector_table);
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// TODO:
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// Insert any setup you want done in EL2, here. For now, EL2 is set up
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// to do almost nothing-- it doesn't take control of any hardware,
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// and it hasn't set up any trap-to-hypervisor features.
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printk("\nSwitching to EL1...\n");
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switch_to_el1();
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}
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/**
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* Secondary section of the stub, executed once we've surrendered
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* hypervisor privileges.
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*/
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void main_el1(void * fdt)
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{
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int rc;
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(void)rc;
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// Read the currrent execution level...
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uint32_t el = get_current_el();
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// Validate that we're in EL1.
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printk("Now executing from EL%d!\n", el);
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if(el != 1) {
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panic("Executing with more privilege than we expect!");
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}
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// If we've made it here, we failed to boot, and we can't recover.
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panic("We should launch Horizon here!");
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}
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