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/*
* Copyright (C) 2024 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
/** @file
*
* Multiprocessor functions
*
*/
.section ".note.GNU-stack", "", @progbits
.text
/* Selectively assemble code for 32-bit/64-bit builds */
#if defined ( __x86_64__ ) && ! defined ( PLATFORM_pcbios )
#define codemp code64
#define DI rdi
#define SP rsp
#define if32 if 0
#define if64 if 1
#else
#define codemp code32
#define DI edi
#define SP esp
#define if32 if 1
#define if64 if 0
#endif
/* Standard features CPUID leaf */
#define CPUID_FEATURES 0x00000001
/* x2APIC is supported */
#define CPUID_FEATURES_ECX_X2APIC 0x00200000
/* Extended topology enumeration CPUID leaf */
#define CPUID_XT_ENUM 0x0000000b
/*
* Call multiprocessor function from C code
*
* Parameters:
* 4(%esp)/%rdi Multiprocessor function
* 8(%esp)/%rsi Opaque data pointer
*/
.section ".text.mp_call", "ax", @progbits
.codemp
.globl mp_call
mp_call:
.if64 /* Preserve registers, load incoming parameters into registers */
pushq %rax
pushq %rcx
pushq %rdx
pushq %rbx
pushq %rsp
pushq %rbp
pushq %rsi
pushq %rdi
pushq %r8
pushq %r9
pushq %r10
pushq %r11
pushq %r12
pushq %r13
pushq %r14
pushq %r15
.else
pushal
movl 36(%esp), %eax
movl 40(%esp), %edx
.endif
/* Call multiprocessor function */
call mp_jump
.if64 /* Restore registers and return */
popq %r15
popq %r14
popq %r13
popq %r12
popq %r11
popq %r10
popq %r9
popq %r8
popq %rdi
popq %rsi
popq %rbp
leaq 8(%rsp), %rsp /* discard */
popq %rbx
popq %rdx
popq %rcx
popq %rax
.else
popal
.endif
ret
.size mp_call, . - mp_call
/*
* Jump to multiprocessor function
*
* Parameters:
* %eax/%rdi Multiprocessor function
* %edx/%rsi Opaque data pointer
* %esp/%rsp Stack, or NULL to halt AP upon completion
*
* Obtain the CPU identifier (i.e. the APIC ID) and perform a tail
* call into the specified multiprocessor function.
*
* This code may run with no stack on an application processor.
*/
.section ".text.mp_jump", "ax", @progbits
.codemp
.globl mp_jump
mp_jump:
.if32 /* Move function parameters to available registers */
movl %eax, %edi
movl %edx, %esi
.endif
/* Get 8-bit APIC ID and x2APIC feature bit */
movl $CPUID_FEATURES, %eax
cpuid
shrl $24, %ebx
movl %ebx, %edx
/* Get 32-bit x2APIC ID if applicable */
testl $CPUID_FEATURES_ECX_X2APIC, %ecx
jz 1f
movl $CPUID_XT_ENUM, %eax
xorl %ecx, %ecx
cpuid
1:
.if64 /* Tail call to function */
movq %rdi, %rax
movq %rsi, %rdi
movl %edx, %esi
jmp *%rax
.else
movl %esi, %eax
jmp *%edi
.endif
.size mp_jump, . - mp_jump
/*
* Update maximum CPU identifier
*
* Parameters:
* %eax/%rdi Pointer to shared maximum APIC ID
* %edx/%rsi CPU identifier (APIC ID)
* %esp/%rsp Stack, or NULL to halt AP upon completion
*
* This code may run with no stack on an application processor.
*/
.section ".text.mp_update_max_cpuid", "ax", @progbits
.codemp
.globl mp_update_max_cpuid
mp_update_max_cpuid:
.if32 /* Move function parameters to available registers */
movl %eax, %edi
movl %edx, %esi
.endif
/* Update maximum APIC ID (atomically) */
movl (%DI), %eax
1: cmpl %esi, %eax
jae 2f
lock cmpxchgl %esi, (%DI)
jnz 1b
2:
/* Return to caller (if stack exists), or halt application processor */
test %SP, %SP
jz 3f
ret
3: cli
hlt
jmp 3b
.size mp_update_max_cpuid, . - mp_update_max_cpuid
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