Differential D31121 Diff 92277 sys/amd64/amd64/mpboot.S

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sys/amd64/amd64/mpboot.S

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mov $bootdata-gdt, %eax		mov $bootdata-gdt, %eax
mov %ax, %ds		mov %ax, %ds

/*		/*
* Turn on the PAE bit and optionally the LA57 bit for when paging		* Turn on the PAE bit and optionally the LA57 bit for when paging
* is later enabled.		* is later enabled.
*/		*/
mov %cr4, %eax		mov %cr4, %eax
orl $CR4_PAE, %eax		orl $(CR4_PAE \| CR4_PGE), %eax
		markjUnsubmitted Done Inline Actions Why does PGE now need to be set here? In particular, the load_cr4() in init_secondary_tail() which sets CR4_PGE no longer flushes the TLB, I believe. markj: Why does PGE now need to be set here? In particular, the load_cr4() in init_secondary_tail()…
		kibAuthorUnsubmitted Done Inline Actions Because I am switching to the kernel page table which in some configurations have PG_G bit set in PTEs. If not enabled there, CPU reacts with #gp when paging is enabled. I removed reload of %cr4 for PGE from the amd64-specific block in init_secondary_tail(). There is no need to flush TLB, we are already on the right page table. kib: Because I am switching to the kernel page table which in some configurations have PG_G bit set…
cmpb $0, mptramp_la57-mptramp_start(%ebx)		cmpb $0, mptramp_la57-mptramp_start(%ebx)
je 1f		je 1f
orl $CR4_LA57, %eax		orl $CR4_LA57, %eax
1: mov %eax, %cr4		1: mov %eax, %cr4

/*		/*
		* If the BSP reported NXE support, enable EFER.NXE for all APs
		* prior to loading %cr3. This avoids page faults if the AP
		* encounters memory marked with the NX bit prior to detecting and
		* enabling NXE support.
		*/
		cmpb $0,mptramp_nx-mptramp_start(%ebx)
		je 2f
		movl $MSR_EFER, %ecx
		rdmsr
		orl $EFER_NXE, %eax
		wrmsr
		2:
		/*
* Enable EFER.LME so that we get long mode when all the prereqs are		* Enable EFER.LME so that we get long mode when all the prereqs are
* in place. In this case, it turns on when CR0_PG is finally enabled.		* in place. In this case, it turns on when CR0_PG is finally enabled.
* Pick up a few other EFER bits that we'll use need we're here.		* Pick up a few other EFER bits that we'll use need we're here.
*/		*/
movl $MSR_EFER, %ecx		movl $MSR_EFER, %ecx
rdmsr		rdmsr
orl $EFER_LME \| EFER_SCE, %eax		orl $EFER_LME \| EFER_SCE, %eax
wrmsr		wrmsr

/*		/*
* Point to the embedded page tables for startup. Note that this		* Load kernel page table pointer into %cr3.
* only gets accessed after we're actually in 64 bit mode, however		* %ebx is still our relocation base.
* we can only set the bottom 32 bits of %cr3 in this state. This		*
* means we are required to use a temporary page table that is below		* Note that this only gets accessed after we're actually in 64 bit
* the 4GB limit. %ebx is still our relocation base. We could just		* mode, however we can only set the bottom 32 bits of %cr3 in this
* subtract 3 * PAGE_SIZE, but that would be too easy.		* state. This means we depend on the kernel page table being
		* allocated from the low 4G.
*/		*/
leal mptramp_pagetables-mptramp_start(%ebx),%eax		leal mptramp_pagetables-mptramp_start(%ebx),%eax
movl (%eax), %eax		movl (%eax), %eax
mov %eax, %cr3		mov %eax, %cr3

/*		/*
* Finally, switch to long bit mode by enabling paging. We have		* Finally, switch to long bit mode by enabling paging. We have
* to be very careful here because all the segmentation disappears		* to be very careful here because all the segmentation disappears
Show All 21 Lines
jmp_64:		jmp_64:
.byte 0xea /* opcode for far jump */		.byte 0xea /* opcode for far jump */
.long tramp_64-mptramp_start /* offset in segment */		.long tramp_64-mptramp_start /* offset in segment */
.word kernelcode-gdt /* index in gdt for 64 bit code */		.word kernelcode-gdt /* index in gdt for 64 bit code */

/*		/*
* Yeehar! We're running in 64 bit mode! We can mostly ignore our		* Yeehar! We're running in 64 bit mode! We can mostly ignore our
* segment registers, and get on with it.		* segment registers, and get on with it.
* Note that we are running at the correct virtual address, but with		* We are running at the correct virtual address space.
* a 1:1 1GB mirrored mapping over entire address space. We had better		* Note that the jmp is relative and that we've been relocated,
* switch to a real %cr3 promptly so that we can get to the direct map
* space. Remember that jmp is relative and that we've been relocated,
* so use an indirect jump.		* so use an indirect jump.
*/		*/
.code64		.code64
tramp_64:		tramp_64:
movabsq $entry_64,%rax /* 64 bit immediate load */		movabsq $entry_64,%rax /* 64 bit immediate load */
jmp *%rax		jmp *%rax

.p2align 4,0		.p2align 4,0
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mptramp_pagetables:		mptramp_pagetables:
.long 0		.long 0

/* 5-level paging ? */		/* 5-level paging ? */
.globl mptramp_la57		.globl mptramp_la57
mptramp_la57:		mptramp_la57:
.long 0		.long 0

		.globl mptramp_nx
		mptramp_nx:
		.long 0

/*		/*
* The pseudo descriptor for lgdt to use.		* The pseudo descriptor for lgdt to use.
*/		*/
lgdt_desc:		lgdt_desc:
.word gdtend-gdt /* Length */		.word gdtend-gdt /* Length */
.long gdt-mptramp_start /* Offset plus %ds << 4 */		.long gdt-mptramp_start /* Offset plus %ds << 4 */

mptramp_end:		mptramp_end:
/*		/*
* The size of the trampoline code that needs to be relocated		* The size of the trampoline code that needs to be relocated
* below the 1MiB boundary.		* below the 1MiB boundary.
*/		*/
.globl bootMP_size		.globl bootMP_size
bootMP_size:		bootMP_size:
.long mptramp_end - mptramp_start		.long mptramp_end - mptramp_start

/*		/*
* From here on down is executed in the kernel .text section.		* From here on down is executed in the kernel .text section.
*/		*/
.text		.text
.code64		.code64
.p2align 4,0		.p2align 4,0
entry_64:		entry_64:
/*
* If the BSP reported NXE support, enable EFER.NXE for all APs
* prior to loading %cr3. This avoids page faults if the AP
* encounters memory marked with the NX bit prior to detecting and
* enabling NXE support.
*/
movq pg_nx, %rbx
testq %rbx, %rbx
je 1f
movl $MSR_EFER, %ecx
rdmsr
orl $EFER_NXE, %eax
wrmsr

1:
/*
* Load a real %cr3 that has all the direct map stuff and switches
* off the 1GB replicated mirror. Load a stack pointer and jump
* into AP startup code in C.
*/
cmpl $0, la57
jne 2f
movq KPML4phys, %rax
jmp 3f
2: movq KPML5phys, %rax
3: movq %rax, %cr3
movq bootSTK, %rsp		movq bootSTK, %rsp
jmp init_secondary		jmp init_secondary