74 lines
1.8 KiB
ArmAsm
74 lines
1.8 KiB
ArmAsm
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2013 Free Software Foundation, Inc.
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*
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* GRUB 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 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB 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
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <grub/offsets.h>
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#include <grub/symbol.h>
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#include <grub/machine/kernel.h>
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/*
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* uboot_syscall():
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* This function is effectively a veneer, so it cannot
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* modify the stack or corrupt any registers other than
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* r12 (ip). Furthermore it needs to restore r8 for
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* U-Boot (Global Data Pointer) and preserve it for Grub.
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*/
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FUNCTION(grub_uboot_syscall)
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str r8, transition_space
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str lr, transition_space + 4
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str r9, transition_space + 8
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ldr ip, saved_registers_ptr
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ldr r8, [ip, #4 * 8]
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ldr r9, [ip, #4 * 9]
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bl do_syscall
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ldr r8, transition_space
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ldr lr, transition_space + 4
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ldr r9, transition_space + 8
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bx lr
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do_syscall:
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ldr ip, grub_uboot_syscall_ptr
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bx ip
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FUNCTION(grub_uboot_return)
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ldr ip, saved_registers_ptr
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ldr sp, [ip, #4 * 4]
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pop {r4-r12, lr}
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mov sp, r12
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bx lr
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.align 3
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@ GRUB context stack space
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transition_space:
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.long 0 @ r8
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.long 0 @ lr
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.long 0 @ r9
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saved_registers_ptr:
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.long EXT_C(grub_arm_saved_registers)
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VARIABLE(grub_uboot_syscall_ptr)
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.long 0 @
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END
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