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Kernel: Implement booting all CPU cores on x86_64
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The AP boot code was partially adapted to build on x86_64 but didn't
properly jump into 64 bit mode. Furthermore, the APIC code was still
using 32 bit pointers.

Fixes SerenityOS#12662
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@tomuta @awesomekling
tomuta authored and awesomekling committed Feb 21, 2022
1 parent b9dbe24 commit 6448964
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Showing 2 changed files with 81 additions and 46 deletions.
88 changes: 55 additions & 33 deletions Kernel/Arch/x86/x86_64/Boot/ap_setup.S
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,6 @@ gdt64ptr:
code64_sel:
.short 0

.extern init_ap
.type init_ap, @function

/*
The apic_ap_start function will be loaded to P0x00008000 where the APIC
will boot the AP from in real mode. This code also contains space for
Expand All @@ -31,6 +28,7 @@ code64_sel:
*/
.global apic_ap_start
.type apic_ap_start, @function
.align 8
apic_ap_start:
.code16
cli
Expand Down Expand Up @@ -68,15 +66,11 @@ apic_ap_start32:
lock; xaddl %eax, (ap_cpu_id - apic_ap_start)(%ebp) /* avoid relocation entries */
movl %eax, %esi

/* find our allocated stack based on the generated id */
movl (ap_cpu_init_stacks - apic_ap_start)(%ebp, %eax, 4), %esp

/* check if we support NX and enable it if we do */
movl $0x80000001, %eax
cpuid
testl $0x100000, %edx
// TODO: Uncomment this
//je (1f - apic_ap_start + 0x8000)
je (1f - apic_ap_start + 0x8000)
/* turn on IA32_EFER.NXE */
movl $0xc0000080, %ecx
rdmsr
Expand Down Expand Up @@ -105,15 +99,25 @@ apic_ap_start32:
movl %eax, %cr0

/* load the temporary 64-bit gdt from boot that points above 3GB */
// FIXME: uncomment this
//mov gdt64ptr, %eax
lgdt (%eax)
lgdt (ap_cpu_gdt64ptr - apic_ap_start + 0x8000)

/* jump above 3GB into our identity mapped area now */
// FIXME: this assumes that code64_sel is always 8
ljmpl $8, $(apic_ap_start64 - apic_ap_start + 0xc0008000)
/* Jump into our identity mapped area, stay in low memory for now.
We need to fully enable 64 bit mode before we can adjust rsp and rip
to values higher than 4GB */
ljmpl $(ap_cpu_gdt64code - ap_cpu_gdt64), $(apic_ap_start64 - apic_ap_start + 0x8000)
.code64
apic_ap_start64:
movq (ap_cpu_kernel_map_base - apic_ap_start)(%rbp), %rbp
addq $0x8000, %rbp

/* find our allocated stack based on the generated id */
movq (ap_cpu_init_stacks - apic_ap_start)(%rbp, %rsi, 8), %rsp

/* Now jump from our identity mapped area into high memory */
movq $(1f - apic_ap_start), %rax
addq %rbp, %rax
jmp *%rax
1:
mov $0, %ax
mov %ax, %ss
mov %ax, %ds
Expand All @@ -125,8 +129,6 @@ apic_ap_start64:
movq %cr3, %rax
movq %rax, %cr3

movl $0xc0008000, %ebp

/* now load the final gdt and idt from the identity mapped area */
movq (ap_cpu_gdtr - apic_ap_start)(%rbp), %rax
lgdt (%rax)
Expand All @@ -139,28 +141,25 @@ apic_ap_start64:
movq (ap_cpu_init_cr4 - apic_ap_start)(%rbp), %rax
movq %rax, %cr4

/* push the Processor pointer this CPU is going to use */
movq (ap_cpu_init_processor_info_array - apic_ap_start)(%ebp), %rax
leaq kernel_mapping_base(%rip), %r8
movq (%r8), %r8
addq %r8, %rax
movq 0(%rax, %rsi, 4), %rax
push %rax

/* push the cpu id, 0 representing the bsp and call into c++ */
incq %rsi
push %rsi
/* Save the cpu id into rdi (first argument), 0 representing the bsp */
movq %rsi, %rdi
incq %rdi

/* Save the Processor pointer this CPU is going to use into rsi (second argument) */
movq (ap_cpu_init_processor_info_array - apic_ap_start)(%rbp), %rax
movq 0(%rax, %rsi, 8), %rsi

/* Get the entry function */
movq (ap_cpu_kernel_entry_function - apic_ap_start)(%rbp), %r10

xor %ebp, %ebp
movq %rsp, %rbp
cld

/* We are in identity mapped P0x8000 and the BSP will unload this code
once all APs are initialized, so call init_ap but return to our
infinite loop */
leaq loop(%rip), %rax
pushq %rax
leaq init_ap(%rip), %rax
jmp *(%rax)
once all APs are initialized, so call the entry function and return to our
infinite loop if it ever were to return. */
call *%r10

loop:
hlt
Expand All @@ -186,6 +185,7 @@ ap_cpu_gdt_end:
ap_cpu_gdtr_initial:
.2byte ap_cpu_gdt_end - ap_cpu_gdt - 1
.4byte (ap_cpu_gdt - apic_ap_start) + 0x8000
.align 8
.global ap_cpu_gdtr
ap_cpu_gdtr:
.8byte 0x0 /* will be set at runtime */
Expand All @@ -201,6 +201,28 @@ ap_cpu_init_cr3:
.global ap_cpu_init_cr4
ap_cpu_init_cr4:
.8byte 0x0 /* will be set at runtime */
.global ap_cpu_gdt64
ap_cpu_gdt64:
.8byte 0x0
.global ap_cpu_gdt64code
ap_cpu_gdt64code:
.4byte 0xffff
.4byte 0xaf9a00
.global ap_cpu_gdt64data
ap_cpu_gdt64data:
.4byte 0xffff
.4byte 0xaf9200
.global ap_cpu_gdt64ptr
ap_cpu_gdt64ptr:
.2byte ap_cpu_gdt64ptr - ap_cpu_gdt64 - 1
.8byte (ap_cpu_gdt64 - apic_ap_start) + 0x8000
.align 8
.global ap_cpu_kernel_entry_function
ap_cpu_kernel_entry_function:
.8byte 0x0 /* will be set at runtime */
.global ap_cpu_kernel_map_base
ap_cpu_kernel_map_base:
.8byte 0x0 /* will be set at runtime */
.global ap_cpu_init_processor_info_array
ap_cpu_init_processor_info_array:
.8byte 0x0 /* will be set at runtime */
Expand Down
39 changes: 26 additions & 13 deletions Kernel/Interrupts/APIC.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -211,13 +211,19 @@ void APIC::write_icr(const ICRReg& icr)

extern "C" void apic_ap_start(void);
extern "C" u16 apic_ap_start_size;
extern "C" u32 ap_cpu_init_stacks;
extern "C" u32 ap_cpu_init_processor_info_array;
extern "C" FlatPtr ap_cpu_init_stacks;
extern "C" FlatPtr ap_cpu_init_processor_info_array;
extern "C" u32 ap_cpu_init_cr0;
extern "C" u32 ap_cpu_init_cr3;
extern "C" FlatPtr ap_cpu_init_cr3;
extern "C" u32 ap_cpu_init_cr4;
extern "C" u32 ap_cpu_gdtr;
extern "C" u32 ap_cpu_idtr;
extern "C" FlatPtr ap_cpu_gdtr;
extern "C" FlatPtr ap_cpu_idtr;
#if ARCH(X86_64)
extern "C" FlatPtr ap_cpu_kernel_map_base;
extern "C" FlatPtr ap_cpu_kernel_entry_function;
#endif

extern "C" [[noreturn]] void init_ap(FlatPtr, Processor*);

void APIC::eoi()
{
Expand Down Expand Up @@ -341,7 +347,8 @@ UNMAP_AFTER_INIT void APIC::setup_ap_boot_environment()
constexpr u64 apic_startup_region_base = 0x8000;
VERIFY(apic_startup_region_base + apic_ap_start_size < USER_RANGE_BASE);
auto apic_startup_region = create_identity_mapped_region(PhysicalAddress(apic_startup_region_base), Memory::page_round_up(apic_ap_start_size + (2 * aps_to_enable * sizeof(u32))).release_value_but_fixme_should_propagate_errors());
memcpy(apic_startup_region->vaddr().as_ptr(), reinterpret_cast<const void*>(apic_ap_start), apic_ap_start_size);
u8* apic_startup_region_ptr = apic_startup_region->vaddr().as_ptr();
memcpy(apic_startup_region_ptr, reinterpret_cast<const void*>(apic_ap_start), apic_ap_start_size);

// Allocate enough stacks for all APs
m_ap_temporary_boot_stacks.ensure_capacity(aps_to_enable);
Expand All @@ -357,7 +364,7 @@ UNMAP_AFTER_INIT void APIC::setup_ap_boot_environment()
}

// Store pointers to all stacks for the APs to use
auto* ap_stack_array = APIC_INIT_VAR_PTR(u32, apic_startup_region->vaddr().as_ptr(), ap_cpu_init_stacks);
auto* ap_stack_array = APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_init_stacks);
VERIFY(aps_to_enable == m_ap_temporary_boot_stacks.size());
for (size_t i = 0; i < aps_to_enable; i++) {
ap_stack_array[i] = m_ap_temporary_boot_stacks[i]->vaddr().get() + Thread::default_kernel_stack_size;
Expand All @@ -373,20 +380,26 @@ UNMAP_AFTER_INIT void APIC::setup_ap_boot_environment()
ap_processor_info_array[i] = FlatPtr(m_ap_processor_info[i].ptr());
dbgln_if(APIC_DEBUG, "APIC: CPU[{}] processor at {}", i + 1, VirtualAddress { ap_processor_info_array[i] });
}
*APIC_INIT_VAR_PTR(u32, apic_startup_region->vaddr().as_ptr(), ap_cpu_init_processor_info_array) = FlatPtr(&ap_processor_info_array[0]);
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_init_processor_info_array) = FlatPtr(&ap_processor_info_array[0]);

// Store the BSP's CR3 value for the APs to use
*APIC_INIT_VAR_PTR(u32, apic_startup_region->vaddr().as_ptr(), ap_cpu_init_cr3) = MM.kernel_page_directory().cr3();
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_init_cr3) = MM.kernel_page_directory().cr3();

// Store the BSP's GDT and IDT for the APs to use
const auto& gdtr = Processor::current().get_gdtr();
*APIC_INIT_VAR_PTR(u32, apic_startup_region->vaddr().as_ptr(), ap_cpu_gdtr) = FlatPtr(&gdtr);
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_gdtr) = FlatPtr(&gdtr);
const auto& idtr = get_idtr();
*APIC_INIT_VAR_PTR(u32, apic_startup_region->vaddr().as_ptr(), ap_cpu_idtr) = FlatPtr(&idtr);
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_idtr) = FlatPtr(&idtr);

#if ARCH(X86_64)
// TODO: Use these also in i686 builds
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_kernel_map_base) = FlatPtr(kernel_mapping_base);
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_kernel_entry_function) = FlatPtr(&init_ap);
#endif

// Store the BSP's CR0 and CR4 values for the APs to use
*APIC_INIT_VAR_PTR(u32, apic_startup_region->vaddr().as_ptr(), ap_cpu_init_cr0) = read_cr0();
*APIC_INIT_VAR_PTR(u32, apic_startup_region->vaddr().as_ptr(), ap_cpu_init_cr4) = read_cr4();
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_init_cr0) = read_cr0();
*APIC_INIT_VAR_PTR(FlatPtr, apic_startup_region_ptr, ap_cpu_init_cr4) = read_cr4();

m_ap_boot_environment = move(apic_startup_region);
}
Expand Down

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