source: mainline/kernel/arch/amd64/src/asm_utils.S@ 86018c1

#
# Copyright (c) 2005 Ondrej Palkovsky
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

#define IREGISTER_SPACE 80

#define IOFFSET_RAX     0x0
#define IOFFSET_RCX     0x8
#define IOFFSET_RDX     0x10
#define IOFFSET_RSI     0x18
#define IOFFSET_RDI     0x20
#define IOFFSET_R8      0x28
#define IOFFSET_R9      0x30
#define IOFFSET_R10     0x38
#define IOFFSET_R11     0x40
#define IOFFSET_RBP     0x48

#  Mask for interrupts 0 - 31 (bits 0 - 31) where 0 means that int has no error word
# and 1 means interrupt with error word
#define ERROR_WORD_INTERRUPT_LIST 0x00027D00

#include <arch/pm.h>
#include <arch/mm/page.h>
        
.text
.global interrupt_handlers
.global syscall_entry
.global panic_printf

panic_printf:
        movq $halt, (%rsp)
        jmp printf

.global cpuid
.global has_cpuid
.global get_cycle
.global read_efer_flag
.global set_efer_flag
.global memsetb
.global memsetw
.global memcpy
.global memcpy_from_uspace
.global memcpy_to_uspace
.global memcpy_from_uspace_failover_address
.global memcpy_to_uspace_failover_address

# Wrapper for generic memsetb
memsetb:
        jmp _memsetb

# Wrapper for generic memsetw
memsetw:
        jmp _memsetw

#define MEMCPY_DST      %rdi
#define MEMCPY_SRC      %rsi
#define MEMCPY_SIZE     %rdx

/**
 * Copy memory from/to userspace.
 *
 * This is almost conventional memcpy().
 * The difference is that there is a failover part
 * to where control is returned from a page fault if
 * the page fault occurs during copy_from_uspace()
 * or copy_to_uspace().
 *
 * @param MEMCPY_DST    Destination address.
 * @param MEMCPY_SRC    Source address.
 * @param MEMCPY_SIZE   Number of bytes to copy.
 *
 * @retrun MEMCPY_DST on success, 0 on failure.
 */
memcpy:
memcpy_from_uspace:
memcpy_to_uspace:
        movq MEMCPY_DST, %rax

        movq MEMCPY_SIZE, %rcx
        shrq $3, %rcx                   /* size / 8 */
        
        rep movsq                       /* copy as much as possible word by word */

        movq MEMCPY_SIZE, %rcx
        andq $7, %rcx                   /* size % 8 */
        jz 0f
        
        rep movsb                       /* copy the rest byte by byte */
        
0:
        ret                             /* return MEMCPY_SRC, success */

memcpy_from_uspace_failover_address:
memcpy_to_uspace_failover_address:
        xorq %rax, %rax                 /* return 0, failure */
        ret

## Determine CPUID support
#
# Return 0 in EAX if CPUID is not support, 1 if supported.
#
has_cpuid:
        pushfq                  # store flags
        popq %rax               # read flags
        movq %rax,%rdx          # copy flags
        btcl $21,%edx           # swap the ID bit
        pushq %rdx
        popfq                   # propagate the change into flags
        pushfq
        popq %rdx               # read flags    
        andl $(1<<21),%eax      # interested only in ID bit
        andl $(1<<21),%edx
        xorl %edx,%eax          # 0 if not supported, 1 if supported
        ret

cpuid:
        movq %rbx, %r10  # we have to preserve rbx across function calls

        movl %edi,%eax  # load the command into %eax

        cpuid   
        movl %eax,0(%rsi)
        movl %ebx,4(%rsi)
        movl %ecx,8(%rsi)
        movl %edx,12(%rsi)

        movq %r10, %rbx
        ret

get_cycle:
        xorq %rax,%rax
        rdtsc
        ret

set_efer_flag:
        movq $0xc0000080, %rcx
        rdmsr
        btsl %edi, %eax
        wrmsr
        ret
        
read_efer_flag: 
        movq $0xc0000080, %rcx
        rdmsr
        ret             

# Push all volatile general purpose registers on stack
.macro save_all_gpr
        movq %rax, IOFFSET_RAX(%rsp)
        movq %rcx, IOFFSET_RCX(%rsp)
        movq %rdx, IOFFSET_RDX(%rsp)
        movq %rsi, IOFFSET_RSI(%rsp)
        movq %rdi, IOFFSET_RDI(%rsp)
        movq %r8, IOFFSET_R8(%rsp)
        movq %r9, IOFFSET_R9(%rsp)
        movq %r10, IOFFSET_R10(%rsp)
        movq %r11, IOFFSET_R11(%rsp)
        movq %rbp, IOFFSET_RBP(%rsp)
.endm

.macro restore_all_gpr
        movq IOFFSET_RAX(%rsp), %rax
        movq IOFFSET_RCX(%rsp), %rcx
        movq IOFFSET_RDX(%rsp), %rdx
        movq IOFFSET_RSI(%rsp), %rsi
        movq IOFFSET_RDI(%rsp), %rdi
        movq IOFFSET_R8(%rsp), %r8
        movq IOFFSET_R9(%rsp), %r9
        movq IOFFSET_R10(%rsp), %r10
        movq IOFFSET_R11(%rsp), %r11
        movq IOFFSET_RBP(%rsp), %rbp
.endm

#define INTERRUPT_ALIGN 128
        
## Declare interrupt handlers
#
# Declare interrupt handlers for n interrupt
# vectors starting at vector i.
#
# The handlers call exc_dispatch().
#
.macro handler i n

        /*
         * Choose between version with error code and version without error
         * code. Both versions have to be of the same size. amd64 assembly is,
         * however, a little bit tricky. For instance, subq $0x80, %rsp and
         * subq $0x78, %rsp can result in two instructions with different
         * op-code lengths.
         * Therefore we align the interrupt handlers.
         */

        .iflt \i-32
                .if (1 << \i) & ERROR_WORD_INTERRUPT_LIST
                        /*
                         * Version with error word.
                         */
                        subq $IREGISTER_SPACE, %rsp
                .else
                        /*
                         * Version without error word,
                         */
                        subq $(IREGISTER_SPACE+8), %rsp
                .endif
        .else
                /*
                 * Version without error word,
                 */
                subq $(IREGISTER_SPACE+8), %rsp
        .endif  

        save_all_gpr
        cld

        # Stop stack traces here
        xorq %rbp, %rbp

        movq $(\i), %rdi        # %rdi - first parameter
        movq %rsp, %rsi         # %rsi - pointer to istate
        call exc_dispatch       # exc_dispatch(i, istate)
        
        restore_all_gpr
        # $8 = Skip error word
        addq $(IREGISTER_SPACE+8), %rsp
        iretq

        .align INTERRUPT_ALIGN
        .if (\n-\i)-1
        handler "(\i+1)",\n
        .endif
.endm

.align INTERRUPT_ALIGN
interrupt_handlers:
h_start:
        handler 0 IDT_ITEMS
h_end:

## Low-level syscall handler
# 
# Registers on entry:
#
# @param rcx            Userspace return address.
# @param r11            Userspace RLFAGS.
#
# @param rax            Syscall number.
# @param rdi            1st syscall argument.
# @param rsi            2nd syscall argument.
# @param rdx            3rd syscall argument.
# @param r10            4th syscall argument. Used instead of RCX because the
#                       SYSCALL instruction clobbers it.
# @param r8             5th syscall argument.
# @param r9             6th syscall argument.
#
# @return               Return value is in rax.
#
syscall_entry:
        swapgs                  # Switch to hidden gs   
        # 
        # %gs:0                 Scratch space for this thread's user RSP
        # %gs:8                 Address to be used as this thread's kernel RSP
        #
        movq %rsp, %gs:0        # Save this thread's user RSP
        movq %gs:8, %rsp        # Set this thread's kernel RSP
        swapgs                  # Switch back to remain consistent
        sti
        
        pushq %rcx
        pushq %r11

        movq %r10, %rcx         # Copy the 4th argument where it is expected 
        pushq %rax
        call syscall_handler
        addq $8, %rsp
                
        popq %r11
        popq %rcx

        cli
        swapgs
        movq %gs:0, %rsp        # Restore the user RSP
        swapgs

        sysretq

.data
.global interrupt_handler_size

interrupt_handler_size: .quad (h_end-h_start)/IDT_ITEMS