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[kernel] Pre-allocate cpu_data and pass to APs

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In order to avoid cyclic dependencies in the case of page faults while
bringing up an AP, pre-allocate the cpu_data structure and related CPU
control structures, and pass them to the AP startup code.

This also changes the following:
- cpu_early_init() was split out of cpu_early_init() to allow early
  usage of current_cpu() on the BSP before we're ready for the rest of
  cpu_init(). (These functions were also renamed to follow the preferred
  area_action naming style.)
- isr_handler now zeroes out the IST entry for its vector instead of
  trying to increment the IST stack pointer
- the IST stacks are allocated outside of cpu_init, to also help reduce
  stack pressue and chance of page faults before APs are ready
- share stack areas between AP idle threads so we only waste 1K per
  additional AP for the unused idle stack
This commit is contained in:
Justin C. Miller
2021-02-10 01:19:41 -08:00
parent 872f178d94
commit 2d4a65c654
9 changed files with 159 additions and 104 deletions
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67
src/kernel/cpu.cpp
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@@ -40,65 +40,26 @@ cpu_validate()
}
void
init_cpu(bool bsp)
cpu_early_init(cpu_data *cpu)
{
extern TSS &g_bsp_tss;
extern GDT &g_bsp_gdt;
extern vm_area_guarded &g_kernel_stacks;
uint8_t id = 0;
TSS *tss = nullptr;
GDT *gdt = nullptr;
cpu_data *cpu = nullptr;
if (bsp) {
gdt = &g_bsp_gdt;
tss = &g_bsp_tss;
cpu = &g_bsp_cpu_data;
} else {
g_idt.install();
tss = new TSS;
gdt = new GDT {tss};
cpu = new cpu_data;
gdt->install();
lapic &apic = device_manager::get().get_lapic();
id = apic.get_id();
}
kutil::memset(cpu, 0, sizeof(cpu_data));
cpu->self = cpu;
cpu->id = id;
cpu->gdt = gdt;
cpu->tss = tss;
IDT::get().install();
cpu->gdt->install();
// Install the GS base pointint to the cpu_data
wrmsr(msr::ia32_gs_base, reinterpret_cast<uintptr_t>(cpu));
}
using memory::frame_size;
using memory::kernel_stack_pages;
constexpr size_t stack_size = kernel_stack_pages * frame_size;
uint8_t ist_entries = g_idt.used_ist_entries();
// Set up the IST stacks
for (unsigned ist = 1; ist < 8; ++ist) {
if (!(ist_entries & (1 << ist)))
continue;
// Two zero entries at the top for the null frame
uintptr_t stack_bottom = g_kernel_stacks.get_section();
uintptr_t stack_top = stack_bottom + stack_size - 2 * sizeof(uintptr_t);
// Pre-realize these stacks, they're no good if they page fault
*reinterpret_cast<uint64_t*>(stack_top) = 0;
tss->ist_stack(ist) = stack_top;
void
cpu_init(cpu_data *cpu, bool bsp)
{
if (!bsp) {
// The BSP already called cpu_early_init
cpu_early_init(cpu);
}
lapic &apic = device_manager::get().get_lapic();
cpu->id = apic.get_id();
// Set up the syscall MSRs
syscall_enable();