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Fix fork() for new task switching model

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This commit is contained in:
Justin C. Miller
2019-04-03 10:08:26 -07:00
parent 8375870af6
commit c605793a9d
13 changed files with 172 additions and 97 deletions
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50
src/kernel/process.cpp
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@@ -4,6 +4,8 @@
#include "process.h"
#include "scheduler.h"
extern "C" void task_fork_return_thunk();
void
process::exit(uint32_t code)
@@ -13,7 +15,7 @@ process::exit(uint32_t code)
}
pid_t
process::fork(cpu_state *regs)
process::fork()
{
auto &sched = scheduler::get();
auto *child = sched.create_process();
@@ -29,13 +31,31 @@ process::fork(cpu_state *regs)
child->pml4 = page_manager::get()->copy_table(pml4);
kassert(child->pml4, "process::fork() got null pml4");
log::debug(logs::task, "Copied process %d to %d, new PML4 %016lx.",
pid, child->pid, child->pml4);
log::debug(logs::task, " copied stack %016lx to %016lx, rsp %016lx.",
kernel_stack, child->kernel_stack, child->rsp);
child->rsp3 = bsp_cpu_data.rsp3;
child->setup_kernel_stack();
task_fork(child);
log::debug(logs::task, "Copied process %d to %d",
pid, child->pid);
log::debug(logs::task, " PML4 %016lx", child->pml4);
log::debug(logs::task, " RSP3 %016lx", child->rsp3);
log::debug(logs::task, " RSP0 %016lx", child->rsp0);
// Initialize a new empty stack with a fake saved state
// for returning out of syscall_handler_prelude
size_t ret_seg_size = sizeof(uintptr_t) * 8;
child->rsp -= ret_seg_size;
void *this_ret_seg =
reinterpret_cast<void*>(rsp0 - ret_seg_size);
void *child_ret_seg =
reinterpret_cast<void*>(child->rsp);
kutil::memcpy(child_ret_seg, this_ret_seg, ret_seg_size);
child->add_fake_task_return(
reinterpret_cast<uintptr_t>(task_fork_return_thunk));
log::debug(logs::task, " RSP %016lx", child->rsp);
return child->pid;
}
@@ -63,10 +83,26 @@ process::setup_kernel_stack()
kernel_stack_size = initial_stack_size;
kernel_stack = reinterpret_cast<uintptr_t>(stack_bottom);
rsp0 = reinterpret_cast<uintptr_t>(stack_top);
rsp = rsp0;
return stack_top;
}
void
process::add_fake_task_return(uintptr_t rip)
{
rsp -= sizeof(uintptr_t) * 7;
uintptr_t *stack = reinterpret_cast<uintptr_t*>(rsp);
stack[6] = rip; // return rip
stack[5] = rsp0; // rbp
stack[4] = 0xbbbbbbbb; // rbx
stack[3] = 0x12121212; // r12
stack[2] = 0x13131313; // r13
stack[1] = 0x14141414; // r14
stack[0] = 0x15151515; // r15
}
bool
process::wait_on_signal(uint64_t sigmask)
{