82f76b056d
commit 7deecbda3026f5e2a8cc095d7ef7261a920efcf2 upstream. While booting on an AMD EPYC box the stack canary would detect stack overflows when using the current PVH early stack size (256). Switch to using the value defined by BOOT_STACK_SIZE, which prevents the stack overflow. Cc: <stable@vger.kernel.org> # 4.11 Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
188 lines
4.7 KiB
ArmAsm
188 lines
4.7 KiB
ArmAsm
/*
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* Copyright C 2016, Oracle and/or its affiliates. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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.code32
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.text
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#define _pa(x) ((x) - __START_KERNEL_map)
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#include <linux/elfnote.h>
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <asm/segment.h>
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#include <asm/asm.h>
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#include <asm/boot.h>
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#include <asm/processor-flags.h>
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#include <asm/msr.h>
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#include <xen/interface/elfnote.h>
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__HEAD
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/*
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* Entry point for PVH guests.
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*
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* Xen ABI specifies the following register state when we come here:
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*
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* - `ebx`: contains the physical memory address where the loader has placed
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* the boot start info structure.
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* - `cr0`: bit 0 (PE) must be set. All the other writeable bits are cleared.
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* - `cr4`: all bits are cleared.
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* - `cs `: must be a 32-bit read/execute code segment with a base of ‘0’
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* and a limit of ‘0xFFFFFFFF’. The selector value is unspecified.
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* - `ds`, `es`: must be a 32-bit read/write data segment with a base of
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* ‘0’ and a limit of ‘0xFFFFFFFF’. The selector values are all
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* unspecified.
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* - `tr`: must be a 32-bit TSS (active) with a base of '0' and a limit
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* of '0x67'.
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* - `eflags`: bit 17 (VM) must be cleared. Bit 9 (IF) must be cleared.
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* Bit 8 (TF) must be cleared. Other bits are all unspecified.
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*
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* All other processor registers and flag bits are unspecified. The OS is in
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* charge of setting up it's own stack, GDT and IDT.
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*/
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#define PVH_GDT_ENTRY_CS 1
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#define PVH_GDT_ENTRY_DS 2
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#define PVH_GDT_ENTRY_CANARY 3
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#define PVH_CS_SEL (PVH_GDT_ENTRY_CS * 8)
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#define PVH_DS_SEL (PVH_GDT_ENTRY_DS * 8)
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#define PVH_CANARY_SEL (PVH_GDT_ENTRY_CANARY * 8)
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ENTRY(pvh_start_xen)
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cld
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lgdt (_pa(gdt))
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mov $PVH_DS_SEL,%eax
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mov %eax,%ds
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mov %eax,%es
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mov %eax,%ss
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/* Stash hvm_start_info. */
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mov $_pa(pvh_start_info), %edi
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mov %ebx, %esi
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mov _pa(pvh_start_info_sz), %ecx
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shr $2,%ecx
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rep
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movsl
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mov $_pa(early_stack_end), %esp
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/* Enable PAE mode. */
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mov %cr4, %eax
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orl $X86_CR4_PAE, %eax
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mov %eax, %cr4
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#ifdef CONFIG_X86_64
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/* Enable Long mode. */
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mov $MSR_EFER, %ecx
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rdmsr
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btsl $_EFER_LME, %eax
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wrmsr
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/* Enable pre-constructed page tables. */
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mov $_pa(init_top_pgt), %eax
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mov %eax, %cr3
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mov $(X86_CR0_PG | X86_CR0_PE), %eax
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mov %eax, %cr0
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/* Jump to 64-bit mode. */
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ljmp $PVH_CS_SEL, $_pa(1f)
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/* 64-bit entry point. */
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.code64
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1:
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/* Set base address in stack canary descriptor. */
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mov $MSR_GS_BASE,%ecx
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mov $_pa(canary), %eax
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xor %edx, %edx
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wrmsr
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call xen_prepare_pvh
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/* startup_64 expects boot_params in %rsi. */
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mov $_pa(pvh_bootparams), %rsi
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mov $_pa(startup_64), %rax
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jmp *%rax
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#else /* CONFIG_X86_64 */
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/* Set base address in stack canary descriptor. */
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movl $_pa(gdt_start),%eax
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movl $_pa(canary),%ecx
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movw %cx, (PVH_GDT_ENTRY_CANARY * 8) + 2(%eax)
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shrl $16, %ecx
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movb %cl, (PVH_GDT_ENTRY_CANARY * 8) + 4(%eax)
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movb %ch, (PVH_GDT_ENTRY_CANARY * 8) + 7(%eax)
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mov $PVH_CANARY_SEL,%eax
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mov %eax,%gs
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call mk_early_pgtbl_32
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mov $_pa(initial_page_table), %eax
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mov %eax, %cr3
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mov %cr0, %eax
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or $(X86_CR0_PG | X86_CR0_PE), %eax
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mov %eax, %cr0
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ljmp $PVH_CS_SEL, $1f
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1:
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call xen_prepare_pvh
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mov $_pa(pvh_bootparams), %esi
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/* startup_32 doesn't expect paging and PAE to be on. */
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ljmp $PVH_CS_SEL, $_pa(2f)
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2:
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mov %cr0, %eax
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and $~X86_CR0_PG, %eax
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mov %eax, %cr0
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mov %cr4, %eax
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and $~X86_CR4_PAE, %eax
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mov %eax, %cr4
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ljmp $PVH_CS_SEL, $_pa(startup_32)
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#endif
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END(pvh_start_xen)
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.section ".init.data","aw"
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.balign 8
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gdt:
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.word gdt_end - gdt_start
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.long _pa(gdt_start)
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.word 0
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gdt_start:
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.quad 0x0000000000000000 /* NULL descriptor */
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#ifdef CONFIG_X86_64
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.quad GDT_ENTRY(0xa09a, 0, 0xfffff) /* PVH_CS_SEL */
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#else
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.quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* PVH_CS_SEL */
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#endif
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.quad GDT_ENTRY(0xc092, 0, 0xfffff) /* PVH_DS_SEL */
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.quad GDT_ENTRY(0x4090, 0, 0x18) /* PVH_CANARY_SEL */
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gdt_end:
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.balign 16
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canary:
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.fill 48, 1, 0
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early_stack:
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.fill BOOT_STACK_SIZE, 1, 0
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early_stack_end:
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ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY,
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_ASM_PTR (pvh_start_xen - __START_KERNEL_map))
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