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entry: implement syscall entry

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io-wait
Felix Kopp 3 years ago
parent 48c8961f07
commit 316b4c2c0c
No known key found for this signature in database
GPG Key ID: C478BA0A85F75728
11 changed files with 318 additions and 29 deletions
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4
arch/at91sam3x8e/Makefile
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@ -28,6 +28,7 @@ ARDIX_ARCH_PWD = $(PWD)/arch/at91sam3x8e
ARDIX_SOURCES += \
$(ARDIX_ARCH_PWD)/atom.c \
$(ARDIX_ARCH_PWD)/atomic.c \
$(ARDIX_ARCH_PWD)/entry.c \
$(ARDIX_ARCH_PWD)/interrupt.c \
$(ARDIX_ARCH_PWD)/sched.c \
$(ARDIX_ARCH_PWD)/serial.c \
@ -36,7 +37,8 @@ ARDIX_SOURCES += \
$(ARDIX_ARCH_PWD)/watchdog.c
ARDIX_ASM_SOURCES += \
$(ARDIX_ARCH_PWD)/irq_pend_sv.S
$(ARDIX_ARCH_PWD)/irq_pend_sv.S \
$(ARDIX_ARCH_PWD)/irq_svc.S
CFLAGS += \
-DARCH_AT91SAM3X8E

62
arch/at91sam3x8e/entry.c
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@ -0,0 +1,62 @@
/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
#include <arch/entry.h>
#include <arch/hardware.h>
#include <ardix/syscall.h>
#include <ardix/types.h>
#include <errno.h>
#include <stddef.h>
void arch_syscall(void *sp)
{
struct reg_snapshot *regs = sp;
enum syscall sc_num = arch_syscall_num(regs);
int (*handler)(sysarg_t arg1, sysarg_t arg2, sysarg_t arg3,
sysarg_t arg4, sysarg_t arg5, sysarg_t arg6);
int sc_ret;
if (sc_num > NSYSCALLS) {
arch_syscall_set_rval(regs, -EINVAL);
return;
}
handler = syscall_table[sc_num];
if (handler == NULL) {
arch_syscall_set_rval(regs, -EINVAL);
return;
}
/* TODO: not every syscall uses the max amount of parameters (duh) */
sc_ret = handler(arch_syscall_arg1(regs), arch_syscall_arg2(regs), arch_syscall_arg3(regs),
arch_syscall_arg4(regs), arch_syscall_arg5(regs), arch_syscall_arg6(regs));
arch_syscall_set_rval(regs, sc_ret);
}
/*
* Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the copyright holder nor the names of its contributors may be
* used to endorse or promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR
* CONTRIBUTORS 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.
*/

4
arch/at91sam3x8e/irq_pend_sv.S
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@ -26,8 +26,8 @@ irq_pend_sv:
* required because lr is overwritten when entering the irq).
* The stuff we push onto the stack manually looks about like this:
*
* >>> stack grow direction >>>
* r7 r6 r5 r4 lr r11 r10 r9 r8
* <<< stack grow direction (decreasing addresses) <<<
* r8 r9 r10 r11 lr r4 r5 r6 r7
*/
push {r4-r7} /* r4-r7 */

82
arch/at91sam3x8e/irq_svc.S
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@ -0,0 +1,82 @@
/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
.syntax unified
.thumb
.text
.extern arch_syscall
.thumb_func
.global irq_svc
.type irq_svc, %function
/* void irq_svc(void); */
irq_svc:
/*
* Syscalls on Cortex-M use the following parameter calling convention:
*
* arg1: r0
* arg2: r1
* arg3: r2
* arg4: r3
* rval: r0
*
* The syscall number is passed as part of the SVC instruction and read
* from the program counter in arch_syscall().
*/
/*
* like in irq_pend_sv, we save everything on the stack to make early
* process switching possible in case the syscall is blocking.
*/
push {r4-r7} /* r4-r7 */
mov r3, r8
mov r4, r9
mov r5, r10
mov r6, r11
mov r7, lr
push {r3-r7} /* r8-r11, lr */
mov r0, sp
bl arch_syscall /* arch_syscall(sp); */
pop {r3-r7} /* r8-r11, lr */
mov lr, r7
mov r11, r6
mov r10, r5
mov r9, r4
mov r8, r3
pop {r4-r7} /* r4-r7 */
bx lr
.size irq_svc, .-irq_svc
/*
* Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the copyright holder nor the names of its contributors may be
* used to endorse or promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR
* CONTRIBUTORS 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.
*/

4
arch/at91sam3x8e/sys.c
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@ -19,7 +19,7 @@
*/
uint32_t sys_core_clock = 84000000UL;
int sys_init(void)
void sys_init(void)
{
/*
* This method is basically an implementation of chapter 28.12 in the
@ -83,8 +83,6 @@ int sys_init(void)
REG_PMC_MCKR = REG_PMC_MCKR_PRES_VAL(1 /* = as fast as it gets */)
| REG_PMC_MCKR_CSS_VAL(2 /* = PLLA clock */);
mom_are_we_there_yet(REG_PMC_SR & REG_PMC_SR_MCKRDY_BIT);
return 0;
}
/*

42
include/arch/at91sam3x8e/hardware.h
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@ -3,7 +3,9 @@
#pragma once
#include <ardix/types.h>
#include <stdint.h>
typedef uint32_t word_t;
/** Current (volatile) system frequency in Hertz. */
extern uint32_t sys_core_clock;
@ -16,19 +18,19 @@ extern uint32_t sys_core_clock;
* hardware routines on IRQ entry. Required for scheduling / context switching.
*/
struct reg_sw_snapshot {
uint32_t r8;
uint32_t r9;
uint32_t r10;
uint32_t r11;
word_t r8;
word_t r9;
word_t r10;
word_t r11;
/*
* lr is saved by hardware, but we need to store it twice
* because the IRQ entry overwrites it
*/
void *lr; /* alias r14 */
uint32_t r4;
uint32_t r5;
uint32_t r6;
uint32_t r7;
word_t r4;
word_t r5;
word_t r6;
word_t r7;
};
/**
@ -36,14 +38,14 @@ struct reg_sw_snapshot {
* an IRQ, in the correct order.
*/
struct reg_hw_snapshot {
uint32_t r0;
uint32_t r1;
uint32_t r2;
uint32_t r3;
uint32_t r12;
word_t r0;
word_t r1;
word_t r2;
word_t r3;
word_t r12;
void *lr; /* alias r14 */
void *pc; /* alias r15 */
uint32_t psr;
word_t psr;
};
/** Combination of `struct reg_sw_snapshot` and `struct reg_hw_snapshot`. */
@ -52,6 +54,16 @@ struct reg_snapshot {
struct reg_hw_snapshot hw;
};
#define arch_syscall_num(reg_snap) ( ((uint8_t *)((reg_snap)->hw.lr))[1] )
#define arch_syscall_arg1(reg_snap) ((reg_snap)->hw.r0)
#define arch_syscall_arg2(reg_snap) ((reg_snap)->hw.r1)
#define arch_syscall_arg3(reg_snap) ((reg_snap)->hw.r2)
#define arch_syscall_arg4(reg_snap) ((reg_snap)->hw.r3)
#define arch_syscall_arg5(reg_snap) ((reg_snap)->sw.r8)
#define arch_syscall_arg6(reg_snap) ((reg_snap)->sw.r9)
#define arch_syscall_set_rval(reg_snap, val) ((reg_snap)->hw.r0 = (uint32_t)(val));
/*
* Real-time Timer (RTT)
*/

40
include/arch/entry.h
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@ -0,0 +1,40 @@
/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
#pragma once
/**
* Perform a syscall.
*
* This is the first and only method called by the irq handler for system calls.
* It is responsible for finishing the context switch, obtaining the syscall
* number and arguments, and invoking the respective system call.
*
* @param sp: The current stack pointer.
*/
void arch_syscall(void *sp);
/*
* Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the copyright holder nor the names of its contributors may be
* used to endorse or promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR
* CONTRIBUTORS 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.
*/

10
include/arch/hardware.h
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@ -26,14 +26,10 @@
* to know about it (especially the flash controller)
* - Enabling interrupts that are vital for stable operation
*
* If any of this fails, a nonzero value must be returned to indicate the error
* condition. An on-chip LED should be used to "morse" some kind of diagnostic
* message, if the system has one (kind of like BIOS beep codes).
*
* @returns `0` on success, a negative POSIX error code if applicable, or a
* positive (platform-dependant) number on hardware fault.
* If any of this fails, an on-chip LED should be used to "morse" some kind of
* diagnostic message, if the system has one (kind of like BIOS beep codes).
*/
int sys_init(void);
void sys_init(void);
#ifndef STACK_SIZE
/** stack size per process in bytes */

50
include/ardix/syscall.h
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@ -0,0 +1,50 @@
/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
#pragma once
#include <ardix/types.h>
#include <errno.h>
#include <toolchain.h>
enum syscall {
SYSCALL_READ = 0,
SYSCALL_WRITE = 1,
NSYSCALLS
};
/** The table of system call handlers, indexed by syscall number. */
extern const int (*syscall_table[NSYSCALLS])(sysarg_t arg1, sysarg_t arg2, sysarg_t arg3,
sysarg_t arg4, sysarg_t arg5, sysarg_t arg6);
/* catchall handler that returns -ENOSYS */
int sys_stub(void);
int sys_read(int fd, void *buf, size_t len, size_t off);
int sys_write(int fd, const void *buf, size_t len, size_t off);
/*
* Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the copyright holder nor the names of its contributors may be
* used to endorse or promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR
* CONTRIBUTORS 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.
*/

3
kernel/Makefile
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@ -32,4 +32,5 @@ ARDIX_SOURCES += \
$(ARDIX_KERNEL_PWD)/printk.c \
$(ARDIX_KERNEL_PWD)/ringbuf.c \
$(ARDIX_KERNEL_PWD)/sched.c \
$(ARDIX_KERNEL_PWD)/serial.c
$(ARDIX_KERNEL_PWD)/serial.c \
$(ARDIX_KERNEL_PWD)/syscall.c

46
kernel/syscall.c
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@ -0,0 +1,46 @@
/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
#include <ardix/syscall.h>
#include <toolchain.h>
#define syscall_entry(number, func) \
[number] (int (*)(sysarg_t, sysarg_t, sysarg_t, sysarg_t, sysarg_t, sysarg_t))(func)
__rodata
const int (*syscall_table[NSYSCALLS])(sysarg_t arg1, sysarg_t arg2, sysarg_t arg3,
sysarg_t arg4, sysarg_t arg5, sysarg_t arg6) = {
syscall_entry(SYSCALL_READ, &sys_stub),
syscall_entry(SYSCALL_WRITE, &sys_stub),
};
int sys_stub(void)
{
return -ENOSYS;
}
/*
* Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the copyright holder nor the names of its contributors may be
* used to endorse or promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR
* CONTRIBUTORS 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.
*/
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