libsel4camkes/src/start.c

/*
 * Copyright 2019, Data61, CSIRO (ABN 41 687 119 230)
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <stddef.h>
#include <sel4runtime/start.h>
#include <stdint.h>
#include <camkes/init.h>

extern unsigned int _tdata_start[];
extern unsigned int _tdata_end[];
extern unsigned int _tbss_end[];
extern unsigned char bootinfo_frame[] __attribute__((weak));
long sel4_vsyscall(long sysnum, ...);

void camkes_start_control(int thread_id, void *ipc_buffer_ptr)
{
    uintptr_t tdata_start = (uintptr_t) &_tdata_start[0];
    uintptr_t tdata_end = (uintptr_t) &_tdata_end[0];
    uintptr_t tbss_end = (uintptr_t) &_tbss_end[0];

    Elf_Phdr tls_header = {
        .p_type   = PT_TLS,
        .p_offset = 0,
        .p_vaddr  = (Elf_Addr) tdata_start,
        .p_paddr  = 0,
        .p_filesz = tdata_end - tdata_start,
        .p_memsz  = tbss_end - tdata_start,
        .p_align = sizeof(long),
    };

    struct {
        char const *const argv[3];
        char const *const envp[2];
        auxv_t auxv[7];
    } info = {
        .argv = {
            "camkes",
            (char *)(uintptr_t) thread_id,
            NULL,
        },
        .envp = {
            "seL4=1",
            NULL,
        },
        .auxv = {
            {
                .a_type = AT_PHENT,
                .a_un.a_val = sizeof(Elf32_Phdr),
            }, {
                .a_type = AT_PHNUM,
                .a_un.a_val = 1,
            }, {
                .a_type = AT_PHDR,
                .a_un.a_ptr = &tls_header,
            }, {
                .a_type = AT_SYSINFO,
                .a_un.a_ptr = &sel4_vsyscall,
            }, {
                // NB: optionally filled in by rootserver, if not defined
                //   a_ptr will be null and dropped by parse_auxv
                .a_type = AT_SEL4_BOOT_INFO,
                .a_un.a_ptr = bootinfo_frame,
            }, {
                .a_type = AT_SEL4_IPC_BUFFER_PTR,
                .a_un.a_ptr = ipc_buffer_ptr,
            }, {
                // Null terminating entry
                .a_type = AT_NULL,
                .a_un.a_val = 0
            },
        },
    };

    __sel4runtime_start_main(main, ARRAY_LENGTH(info.argv) - 1, info.argv, info.envp, info.auxv);
}