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x86/boot/compressed/64: Setup IDT in startup_32 boot path 

This boot path needs exception handling when it is used with SEV-ES.
Setup an IDT and provide a helper function to write IDT entries for
use in 32-bit protected mode.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210312123824.306-5-joro@8bytes.org
This commit is contained in:
Joerg Roedel 2021-03-10 09:43:21 +01:00 committed by Borislav Petkov
parent 0c289ff81c
commit 79419e13e8
1 changed files with 72 additions and 0 deletions
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72
arch/x86/boot/compressed/head_64.S
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@ -116,6 +116,9 @@ SYM_FUNC_START(startup_32)
lretl
1:
/* Setup Exception handling for SEV-ES */
call startup32_load_idt
/* Make sure cpu supports long mode. */
call verify_cpu
testl %eax, %eax
@ -701,6 +704,19 @@ SYM_DATA_START(boot_idt)
.endr
SYM_DATA_END_LABEL(boot_idt, SYM_L_GLOBAL, boot_idt_end)
#ifdef CONFIG_AMD_MEM_ENCRYPT
SYM_DATA_START(boot32_idt_desc)
.word boot32_idt_end - boot32_idt - 1
.long 0
SYM_DATA_END(boot32_idt_desc)
.balign 8
SYM_DATA_START(boot32_idt)
.rept 32
.quad 0
.endr
SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)
#endif
#ifdef CONFIG_EFI_STUB
SYM_DATA(image_offset, .long 0)
#endif
@ -793,6 +809,62 @@ SYM_DATA_START_LOCAL(loaded_image_proto)
SYM_DATA_END(loaded_image_proto)
#endif
#ifdef CONFIG_AMD_MEM_ENCRYPT
__HEAD
.code32
/*
* Write an IDT entry into boot32_idt
*
* Parameters:
*
* %eax: Handler address
* %edx: Vector number
*
* Physical offset is expected in %ebp
*/
SYM_FUNC_START(startup32_set_idt_entry)
push %ebx
push %ecx
/* IDT entry address to %ebx */
leal rva(boot32_idt)(%ebp), %ebx
shl $3, %edx
addl %edx, %ebx
/* Build IDT entry, lower 4 bytes */
movl %eax, %edx
andl $0x0000ffff, %edx # Target code segment offset [15:0]
movl $__KERNEL32_CS, %ecx # Target code segment selector
shl $16, %ecx
orl %ecx, %edx
/* Store lower 4 bytes to IDT */
movl %edx, (%ebx)
/* Build IDT entry, upper 4 bytes */
movl %eax, %edx
andl $0xffff0000, %edx # Target code segment offset [31:16]
orl $0x00008e00, %edx # Present, Type 32-bit Interrupt Gate
/* Store upper 4 bytes to IDT */
movl %edx, 4(%ebx)
pop %ecx
pop %ebx
ret
SYM_FUNC_END(startup32_set_idt_entry)
#endif
SYM_FUNC_START(startup32_load_idt)
#ifdef CONFIG_AMD_MEM_ENCRYPT
/* Load IDT */
leal rva(boot32_idt)(%ebp), %eax
movl %eax, rva(boot32_idt_desc+2)(%ebp)
lidt rva(boot32_idt_desc)(%ebp)
#endif
ret
SYM_FUNC_END(startup32_load_idt)
/*
* Stack and heap for uncompression
*/