| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
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| 2 | /* |
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| 3 | * EFI call stub for IA32. |
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| 4 | * |
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| 5 | * This stub allows us to make EFI calls in physical mode with interrupts |
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| 6 | * turned off. |
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| 7 | */ |
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| 8 | |
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| 9 | #include <linux/linkage.h> |
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| 10 | #include <linux/init.h> |
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| 11 | #include <asm/asm-offsets.h> |
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| 12 | #include <asm/page_types.h> |
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| 13 | |
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| 14 | __INIT |
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| 15 | SYM_FUNC_START(efi_call_svam) |
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| 16 | push %ebp |
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| 17 | movl %esp, %ebp |
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| 18 | push %ebx |
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| 19 | |
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| 20 | push 16(%esp) |
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| 21 | push 16(%esp) |
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| 22 | push %ecx |
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| 23 | push %edx |
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| 24 | movl %eax, %ebx // &systab_phys->runtime |
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| 25 | |
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| 26 | /* |
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| 27 | * Switch to the flat mapped alias of this routine, by jumping to the |
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| 28 | * address of label '1' after subtracting PAGE_OFFSET from it. |
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| 29 | */ |
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| 30 | movl $1f, %edx |
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| 31 | subl $__PAGE_OFFSET, %edx |
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| 32 | jmp *%edx |
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| 33 | 1: |
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| 34 | |
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| 35 | /* disable paging */ |
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| 36 | movl %cr0, %edx |
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| 37 | andl $0x7fffffff, %edx |
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| 38 | movl %edx, %cr0 |
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| 39 | |
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| 40 | /* convert the stack pointer to a flat mapped address */ |
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| 41 | subl $__PAGE_OFFSET, %esp |
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| 42 | |
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| 43 | /* call the EFI routine */ |
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| 44 | movl (%eax), %eax |
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| 45 | call *EFI_svam(%eax) |
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| 46 | |
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| 47 | /* grab the virtually remapped EFI runtime services table pointer */ |
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| 48 | movl (%ebx), %ecx |
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| 49 | movl 36(%esp), %edx // &efi.runtime |
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| 50 | movl %ecx, (%edx) |
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| 51 | |
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| 52 | /* re-enable paging */ |
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| 53 | movl %cr0, %edx |
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| 54 | orl $0x80000000, %edx |
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| 55 | movl %edx, %cr0 |
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| 56 | |
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| 57 | movl 16(%esp), %ebx |
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| 58 | leave |
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| 59 | RET |
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| 60 | SYM_FUNC_END(efi_call_svam) |
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| 61 | |
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