justin/jsix
1
1
Fork 0
mirror of https://github.com/justinian/jsix.git synced 2025-12-10 00:14:32 -08:00
Code Issues Packages Projects Releases Wiki Activity

Simplify task switches

Browse Source 
No longer using the rsp from the entry to the kernel, but instead
switching rsp at task-switching time in assembly.

This currently breaks fork()
This commit is contained in:
Justin C. Miller
2019-03-31 22:49:24 -07:00
parent 5cdbedd4d1
commit ca2362f858
21 changed files with 311 additions and 178 deletions
Download Patch File Download Diff File Expand all files Collapse all files

50
src/kernel/process.cpp
View File

@@ -1,4 +1,5 @@
#include "cpu.h"
#include "debug.h"
#include "log.h"
#include "process.h"
#include "scheduler.h"
@@ -12,7 +13,7 @@ process::exit(uint32_t code)
}
pid_t
process::fork(uintptr_t in_rsp)
process::fork(cpu_state *regs)
{
auto &sched = scheduler::get();
auto *child = sched.create_process();
@@ -25,40 +26,49 @@ process::fork(uintptr_t in_rsp)
sched.m_runlists[child->priority].push_back(child);
child->rsp = in_rsp;
child->pml4 = page_manager::get()->copy_table(pml4);
kassert(child->pml4, "process::fork() got null pml4");
child->setup_kernel_stack(kernel_stack_size, kernel_stack);
child->rsp = child->kernel_stack + (in_rsp - kernel_stack);
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 to %016lx.",
kernel_stack, child->kernel_stack, in_rsp, child->rsp);
log::debug(logs::task, " copied stack %016lx to %016lx, rsp %016lx.",
kernel_stack, child->kernel_stack, child->rsp);
// Add in the faked fork return value
cpu_state *regs = reinterpret_cast<cpu_state *>(child->rsp);
regs->rax = 0;
child->setup_kernel_stack();
task_fork(child); // Both parent and child will return from this
if (bsp_cpu_data.tcb->pid == child->pid) {
return 0;
}
return child->pid;
}
void *
process::setup_kernel_stack(size_t size, uintptr_t orig)
process::setup_kernel_stack()
{
void *stack0 = kutil::malloc(size);
constexpr unsigned null_frame_entries = 2;
constexpr size_t null_frame_size = null_frame_entries * sizeof(uint64_t);
if (orig)
kutil::memcpy(stack0, reinterpret_cast<void*>(orig), size);
else
kutil::memset(stack0, 0, size);
void *stack_bottom = kutil::malloc(initial_stack_size);
kutil::memset(stack_bottom, 0, initial_stack_size);
kernel_stack_size = size;
kernel_stack = reinterpret_cast<uintptr_t>(stack0);
log::debug(logs::memory, "Created kernel stack at %016lx size 0x%lx",
stack_bottom, initial_stack_size);
return stack0;
void *stack_top =
kutil::offset_pointer(stack_bottom,
initial_stack_size - null_frame_size);
uint64_t *null_frame = reinterpret_cast<uint64_t*>(stack_top);
for (unsigned i = 0; i < null_frame_entries; ++i)
null_frame[i] = 0;
kernel_stack_size = initial_stack_size;
kernel_stack = reinterpret_cast<uintptr_t>(stack_bottom);
rsp0 = reinterpret_cast<uintptr_t>(stack_top);
return stack_top;
}
bool