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[kernel] Give threads initial arguments

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This commit changes the add_user_thunk to point to a new routine,
initialize_user_cpu, which sets all the registers that were previously
unset when starting a new user thread. The values for rdi and rsi are
popped off the initial stack values that add_user_thunk sets up, so that
user thread procs can take up to two arguments.

To suppor this, j6_thread_create gained two new arguments, which are
passed on to the thread.

This also let me finally get rid of the hack of passing an argument in
rsp when starting init.
This commit is contained in:
Justin C. Miller
2023-02-08 23:10:17 -08:00
parent 1cb8f1258d
commit 4125175870
10 changed files with 81 additions and 51 deletions
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2
src/user/srv.init/loader.cpp
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@@ -135,7 +135,7 @@ load_program(
}
j6_handle_t thread = j6_handle_invalid;
res = j6_thread_create(&thread, proc, stack_top - 6*sizeof(uint64_t), progelf.entrypoint());
res = j6_thread_create(&thread, proc, stack_top - 6*sizeof(uint64_t), progelf.entrypoint(), 0, 0);
if (res != j6_status_ok) {
sprintf(err_msg, " ** error loading program '%s': creating thread: %lx", name, res);
return false;

37
src/user/srv.init/start.s
View File

@@ -7,34 +7,29 @@ extern _arg_modules_phys
section .bss
align 0x100
init_stack_start:
resb 0x8000 ; 16KiB stack space
resb 0x8000 ; 16KiB stack space
init_stack_top:
section .text
global _start:function (_start.end - _start)
_start:
; No parent process exists to have created init's stack, so we create a
; stack in BSS and assign that to be init's first stack
mov [_arg_modules_phys], rdi
mov rsp, init_stack_top
push 0
push 0
; No parent process exists to have created init's stack, so we override
; _start to deal with that in two ways:
mov rbp, rsp
mov rdi, rsp
call __init_libj6
call __init_libc
; 1. We create a stack in BSS and assign that to be init's first stack
; 2. We take advantage of the fact that rsp is useless here as a way
; for the kernel to tell init where its initial modules page is.
mov [_arg_modules_phys], rsp
mov rsp, init_stack_top
push 0
push 0
pop rdi
mov rsi, rsp
call main
mov rbp, rsp
mov rdi, rsp
call __init_libj6
call __init_libc
pop rdi
mov rsi, rsp
call main
mov rdi, rax
call exit
mov rdi, rax
call exit
.end: