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linux_dsm_epyc7002/arch/x86/kernel/head_32.S
Thomas Gleixner f490e07c53 x86/pti/32: Size initial_page_table correctly 
Commit 945fd17ab6 ("x86/cpu_entry_area: Sync cpu_entry_area to
initial_page_table") introduced the sync for the initial page table for
32bit.

sync_initial_page_table() uses clone_pgd_range() which does the update for
the kernel page table. If PTI is enabled it also updates the user space
page table counterpart, which is assumed to be in the next page after the
target PGD.

At this point in time 32-bit did not have PTI support, so the user space
page table update was not taking place.

The support for PTI on 32-bit which was introduced later on, did not take
that into account and missed to add the user space counter part for the
initial page table.

As a consequence sync_initial_page_table() overwrites any data which is
located in the page behing initial_page_table causing random failures,
e.g. by corrupting doublefault_tss and wreckaging the doublefault handler
on 32bit.

Fix it by adding a "user" page table right after initial_page_table.

Fixes: 7757d607c6 ("x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Cc: stable@kernel.org
2019-11-21 19:37:43 +01:00

634 lines
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/* SPDX-License-Identifier: GPL-2.0 */
/*
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Enhanced CPU detection and feature setting code by Mike Jagdis
* and Martin Mares, November 1997.
*/
.text
#include <linux/threads.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page_types.h>
#include <asm/pgtable_types.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm/setup.h>
#include <asm/processor-flags.h>
#include <asm/msr-index.h>
#include <asm/cpufeatures.h>
#include <asm/percpu.h>
#include <asm/nops.h>
#include <asm/bootparam.h>
#include <asm/export.h>
#include <asm/pgtable_32.h>
/* Physical address */
#define pa(X) ((X) - __PAGE_OFFSET)
/*
* References to members of the new_cpu_data structure.
*/
#define X86 new_cpu_data+CPUINFO_x86
#define X86_VENDOR new_cpu_data+CPUINFO_x86_vendor
#define X86_MODEL new_cpu_data+CPUINFO_x86_model
#define X86_STEPPING new_cpu_data+CPUINFO_x86_stepping
#define X86_HARD_MATH new_cpu_data+CPUINFO_hard_math
#define X86_CPUID new_cpu_data+CPUINFO_cpuid_level
#define X86_CAPABILITY new_cpu_data+CPUINFO_x86_capability
#define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id
#define SIZEOF_PTREGS 17*4
/*
* Worst-case size of the kernel mapping we need to make:
* a relocatable kernel can live anywhere in lowmem, so we need to be able
* to map all of lowmem.
*/
KERNEL_PAGES = LOWMEM_PAGES
INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
RESERVE_BRK(pagetables, INIT_MAP_SIZE)
/*
* 32-bit kernel entrypoint; only used by the boot CPU. On entry,
* %esi points to the real-mode code as a 32-bit pointer.
* CS and DS must be 4 GB flat segments, but we don't depend on
* any particular GDT layout, because we load our own as soon as we
* can.
*/
__HEAD
ENTRY(startup_32)
movl pa(initial_stack),%ecx
/* test KEEP_SEGMENTS flag to see if the bootloader is asking
us to not reload segments */
testb $KEEP_SEGMENTS, BP_loadflags(%esi)
jnz 2f
/*
* Set segments to known values.
*/
lgdt pa(boot_gdt_descr)
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
movl %eax,%ss
2:
leal -__PAGE_OFFSET(%ecx),%esp
/*
* Clear BSS first so that there are no surprises...
*/
cld
xorl %eax,%eax
movl $pa(__bss_start),%edi
movl $pa(__bss_stop),%ecx
subl %edi,%ecx
shrl $2,%ecx
rep ; stosl
/*
* Copy bootup parameters out of the way.
* Note: %esi still has the pointer to the real-mode data.
* With the kexec as boot loader, parameter segment might be loaded beyond
* kernel image and might not even be addressable by early boot page tables.
* (kexec on panic case). Hence copy out the parameters before initializing
* page tables.
*/
movl $pa(boot_params),%edi
movl $(PARAM_SIZE/4),%ecx
cld
rep
movsl
movl pa(boot_params) + NEW_CL_POINTER,%esi
andl %esi,%esi
jz 1f # No command line
movl $pa(boot_command_line),%edi
movl $(COMMAND_LINE_SIZE/4),%ecx
rep
movsl
1:
#ifdef CONFIG_OLPC
/* save OFW's pgdir table for later use when calling into OFW */
movl %cr3, %eax
movl %eax, pa(olpc_ofw_pgd)
#endif
#ifdef CONFIG_MICROCODE
/* Early load ucode on BSP. */
call load_ucode_bsp
#endif
/* Create early pagetables. */
call mk_early_pgtbl_32
/* Do early initialization of the fixmap area */
movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
#ifdef CONFIG_X86_PAE
#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
#else
movl %eax,pa(initial_page_table+0xffc)
#endif
#ifdef CONFIG_PARAVIRT
/* This is can only trip for a broken bootloader... */
cmpw $0x207, pa(boot_params + BP_version)
jb .Ldefault_entry
/* Paravirt-compatible boot parameters. Look to see what architecture
we're booting under. */
movl pa(boot_params + BP_hardware_subarch), %eax
cmpl $num_subarch_entries, %eax
jae .Lbad_subarch
movl pa(subarch_entries)(,%eax,4), %eax
subl $__PAGE_OFFSET, %eax
jmp *%eax
.Lbad_subarch:
WEAK(xen_entry)
/* Unknown implementation; there's really
nothing we can do at this point. */
ud2a
__INITDATA
subarch_entries:
.long .Ldefault_entry /* normal x86/PC */
.long xen_entry /* Xen hypervisor */
.long .Ldefault_entry /* Moorestown MID */
num_subarch_entries = (. - subarch_entries) / 4
.previous
#else
jmp .Ldefault_entry
#endif /* CONFIG_PARAVIRT */
#ifdef CONFIG_HOTPLUG_CPU
/*
* Boot CPU0 entry point. It's called from play_dead(). Everything has been set
* up already except stack. We just set up stack here. Then call
* start_secondary().
*/
ENTRY(start_cpu0)
movl initial_stack, %ecx
movl %ecx, %esp
call *(initial_code)
1: jmp 1b
ENDPROC(start_cpu0)
#endif
/*
* Non-boot CPU entry point; entered from trampoline.S
* We can't lgdt here, because lgdt itself uses a data segment, but
* we know the trampoline has already loaded the boot_gdt for us.
*
* If cpu hotplug is not supported then this code can go in init section
* which will be freed later
*/
ENTRY(startup_32_smp)
cld
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
movl pa(initial_stack),%ecx
movl %eax,%ss
leal -__PAGE_OFFSET(%ecx),%esp
#ifdef CONFIG_MICROCODE
/* Early load ucode on AP. */
call load_ucode_ap
#endif
.Ldefault_entry:
movl $(CR0_STATE & ~X86_CR0_PG),%eax
movl %eax,%cr0
/*
* We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
* bits like NT set. This would confuse the debugger if this code is traced. So
* initialize them properly now before switching to protected mode. That means
* DF in particular (even though we have cleared it earlier after copying the
* command line) because GCC expects it.
*/
pushl $0
popfl
/*
* New page tables may be in 4Mbyte page mode and may be using the global pages.
*
* NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
* if and only if CPUID exists and has flags other than the FPU flag set.
*/
movl $-1,pa(X86_CPUID) # preset CPUID level
movl $X86_EFLAGS_ID,%ecx
pushl %ecx
popfl # set EFLAGS=ID
pushfl
popl %eax # get EFLAGS
testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set?
jz .Lenable_paging # hw disallowed setting of ID bit
# which means no CPUID and no CR4
xorl %eax,%eax
cpuid
movl %eax,pa(X86_CPUID) # save largest std CPUID function
movl $1,%eax
cpuid
andl $~1,%edx # Ignore CPUID.FPU
jz .Lenable_paging # No flags or only CPUID.FPU = no CR4
movl pa(mmu_cr4_features),%eax
movl %eax,%cr4
testb $X86_CR4_PAE, %al # check if PAE is enabled
jz .Lenable_paging
/* Check if extended functions are implemented */
movl $0x80000000, %eax
cpuid
/* Value must be in the range 0x80000001 to 0x8000ffff */
subl $0x80000001, %eax
cmpl $(0x8000ffff-0x80000001), %eax
ja .Lenable_paging
/* Clear bogus XD_DISABLE bits */
call verify_cpu
mov $0x80000001, %eax
cpuid
/* Execute Disable bit supported? */
btl $(X86_FEATURE_NX & 31), %edx
jnc .Lenable_paging
/* Setup EFER (Extended Feature Enable Register) */
movl $MSR_EFER, %ecx
rdmsr
btsl $_EFER_NX, %eax
/* Make changes effective */
wrmsr
.Lenable_paging:
/*
* Enable paging
*/
movl $pa(initial_page_table), %eax
movl %eax,%cr3 /* set the page table pointer.. */
movl $CR0_STATE,%eax
movl %eax,%cr0 /* ..and set paging (PG) bit */
ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */
1:
/* Shift the stack pointer to a virtual address */
addl $__PAGE_OFFSET, %esp
/*
* start system 32-bit setup. We need to re-do some of the things done
* in 16-bit mode for the "real" operations.
*/
movl setup_once_ref,%eax
andl %eax,%eax
jz 1f # Did we do this already?
call *%eax
1:
/*
* Check if it is 486
*/
movb $4,X86 # at least 486
cmpl $-1,X86_CPUID
je .Lis486
/* get vendor info */
xorl %eax,%eax # call CPUID with 0 -> return vendor ID
cpuid
movl %eax,X86_CPUID # save CPUID level
movl %ebx,X86_VENDOR_ID # lo 4 chars
movl %edx,X86_VENDOR_ID+4 # next 4 chars
movl %ecx,X86_VENDOR_ID+8 # last 4 chars
orl %eax,%eax # do we have processor info as well?
je .Lis486
movl $1,%eax # Use the CPUID instruction to get CPU type
cpuid
movb %al,%cl # save reg for future use
andb $0x0f,%ah # mask processor family
movb %ah,X86
andb $0xf0,%al # mask model
shrb $4,%al
movb %al,X86_MODEL
andb $0x0f,%cl # mask mask revision
movb %cl,X86_STEPPING
movl %edx,X86_CAPABILITY
.Lis486:
movl $0x50022,%ecx # set AM, WP, NE and MP
movl %cr0,%eax
andl $0x80000011,%eax # Save PG,PE,ET
orl %ecx,%eax
movl %eax,%cr0
lgdt early_gdt_descr
ljmp $(__KERNEL_CS),$1f
1: movl $(__KERNEL_DS),%eax # reload all the segment registers
movl %eax,%ss # after changing gdt.
movl $(__USER_DS),%eax # DS/ES contains default USER segment
movl %eax,%ds
movl %eax,%es
movl $(__KERNEL_PERCPU), %eax
movl %eax,%fs # set this cpu's percpu
movl $(__KERNEL_STACK_CANARY),%eax
movl %eax,%gs
xorl %eax,%eax # Clear LDT
lldt %ax
call *(initial_code)
1: jmp 1b
ENDPROC(startup_32_smp)
#include "verify_cpu.S"
/*
* setup_once
*
* The setup work we only want to run on the BSP.
*
* Warning: %esi is live across this function.
*/
__INIT
setup_once:
#ifdef CONFIG_STACKPROTECTOR
/*
* Configure the stack canary. The linker can't handle this by
* relocation. Manually set base address in stack canary
* segment descriptor.
*/
movl $gdt_page,%eax
movl $stack_canary,%ecx
movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
shrl $16, %ecx
movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
#endif
andl $0,setup_once_ref /* Once is enough, thanks */
ret
ENTRY(early_idt_handler_array)
# 36(%esp) %eflags
# 32(%esp) %cs
# 28(%esp) %eip
# 24(%rsp) error code
i = 0
.rept NUM_EXCEPTION_VECTORS
.if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
pushl $0 # Dummy error code, to make stack frame uniform
.endif
pushl $i # 20(%esp) Vector number
jmp early_idt_handler_common
i = i + 1
.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
.endr
ENDPROC(early_idt_handler_array)
early_idt_handler_common:
/*
* The stack is the hardware frame, an error code or zero, and the
* vector number.
*/
cld
incl %ss:early_recursion_flag
/* The vector number is in pt_regs->gs */
cld
pushl %fs /* pt_regs->fs (__fsh varies by model) */
pushl %es /* pt_regs->es (__esh varies by model) */
pushl %ds /* pt_regs->ds (__dsh varies by model) */
pushl %eax /* pt_regs->ax */
pushl %ebp /* pt_regs->bp */
pushl %edi /* pt_regs->di */
pushl %esi /* pt_regs->si */
pushl %edx /* pt_regs->dx */
pushl %ecx /* pt_regs->cx */
pushl %ebx /* pt_regs->bx */
/* Fix up DS and ES */
movl $(__KERNEL_DS), %ecx
movl %ecx, %ds
movl %ecx, %es
/* Load the vector number into EDX */
movl PT_GS(%esp), %edx
/* Load GS into pt_regs->gs (and maybe clobber __gsh) */
movw %gs, PT_GS(%esp)
movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */
call early_fixup_exception
popl %ebx /* pt_regs->bx */
popl %ecx /* pt_regs->cx */
popl %edx /* pt_regs->dx */
popl %esi /* pt_regs->si */
popl %edi /* pt_regs->di */
popl %ebp /* pt_regs->bp */
popl %eax /* pt_regs->ax */
popl %ds /* pt_regs->ds (always ignores __dsh) */
popl %es /* pt_regs->es (always ignores __esh) */
popl %fs /* pt_regs->fs (always ignores __fsh) */
popl %gs /* pt_regs->gs (always ignores __gsh) */
decl %ss:early_recursion_flag
addl $4, %esp /* pop pt_regs->orig_ax */
iret
ENDPROC(early_idt_handler_common)
/* This is the default interrupt "handler" :-) */
ENTRY(early_ignore_irq)
cld
#ifdef CONFIG_PRINTK
pushl %eax
pushl %ecx
pushl %edx
pushl %es
pushl %ds
movl $(__KERNEL_DS),%eax
movl %eax,%ds
movl %eax,%es
cmpl $2,early_recursion_flag
je hlt_loop
incl early_recursion_flag
pushl 16(%esp)
pushl 24(%esp)
pushl 32(%esp)
pushl 40(%esp)
pushl $int_msg
call printk
call dump_stack
addl $(5*4),%esp
popl %ds
popl %es
popl %edx
popl %ecx
popl %eax
#endif
iret
hlt_loop:
hlt
jmp hlt_loop
ENDPROC(early_ignore_irq)
__INITDATA
.align 4
GLOBAL(early_recursion_flag)
.long 0
__REFDATA
.align 4
ENTRY(initial_code)
.long i386_start_kernel
ENTRY(setup_once_ref)
.long setup_once
#ifdef CONFIG_PAGE_TABLE_ISOLATION
#define PGD_ALIGN (2 * PAGE_SIZE)
#define PTI_USER_PGD_FILL 1024
#else
#define PGD_ALIGN (PAGE_SIZE)
#define PTI_USER_PGD_FILL 0
#endif
/*
* BSS section
*/
__PAGE_ALIGNED_BSS
.align PGD_ALIGN
#ifdef CONFIG_X86_PAE
.globl initial_pg_pmd
initial_pg_pmd:
.fill 1024*KPMDS,4,0
#else
.globl initial_page_table
initial_page_table:
.fill 1024,4,0
#endif
.align PGD_ALIGN
initial_pg_fixmap:
.fill 1024,4,0
.globl swapper_pg_dir
.align PGD_ALIGN
swapper_pg_dir:
.fill 1024,4,0
.fill PTI_USER_PGD_FILL,4,0
.globl empty_zero_page
empty_zero_page:
.fill 4096,1,0
EXPORT_SYMBOL(empty_zero_page)
/*
* This starts the data section.
*/
#ifdef CONFIG_X86_PAE
__PAGE_ALIGNED_DATA
/* Page-aligned for the benefit of paravirt? */
.align PGD_ALIGN
ENTRY(initial_page_table)
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */
# if KPMDS == 3
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
# elif KPMDS == 2
.long 0,0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
# elif KPMDS == 1
.long 0,0
.long 0,0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
# else
# error "Kernel PMDs should be 1, 2 or 3"
# endif
.align PAGE_SIZE /* needs to be page-sized too */
#ifdef CONFIG_PAGE_TABLE_ISOLATION
/*
* PTI needs another page so sync_initial_pagetable() works correctly
* and does not scribble over the data which is placed behind the
* actual initial_page_table. See clone_pgd_range().
*/
.fill 1024, 4, 0
#endif
#endif
.data
.balign 4
ENTRY(initial_stack)
/*
* The SIZEOF_PTREGS gap is a convention which helps the in-kernel
* unwinder reliably detect the end of the stack.
*/
.long init_thread_union + THREAD_SIZE - SIZEOF_PTREGS - \
TOP_OF_KERNEL_STACK_PADDING;
__INITRODATA
int_msg:
.asciz "Unknown interrupt or fault at: %p %p %p\n"
#include "../../x86/xen/xen-head.S"
/*
* The IDT and GDT 'descriptors' are a strange 48-bit object
* only used by the lidt and lgdt instructions. They are not
* like usual segment descriptors - they consist of a 16-bit
* segment size, and 32-bit linear address value:
*/
.data
.globl boot_gdt_descr
ALIGN
# early boot GDT descriptor (must use 1:1 address mapping)
.word 0 # 32 bit align gdt_desc.address
boot_gdt_descr:
.word __BOOT_DS+7
.long boot_gdt - __PAGE_OFFSET
# boot GDT descriptor (later on used by CPU#0):
.word 0 # 32 bit align gdt_desc.address
ENTRY(early_gdt_descr)
.word GDT_ENTRIES*8-1
.long gdt_page /* Overwritten for secondary CPUs */
/*
* The boot_gdt must mirror the equivalent in setup.S and is
* used only for booting.
*/
.align L1_CACHE_BYTES
ENTRY(boot_gdt)
.fill GDT_ENTRY_BOOT_CS,8,0
.quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
.quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
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