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nuttx/arch/risc-v/include/syscall.h
Ville Juven e6973c764c riscv/syscall: Optimize user service call performance 
This patch changes how user service calls are executed:
Instead of using the common interrupt logic, execute the user service
call directly.

Why? When a user makes a service call request, all of the service call
parameters are already loaded into the correct registers, thus it makes
no sense to first clobber them and then reload them, which is what the
old logic does. It is much more effective to run the system call directly.

During a user system call the interrupts must be re-enabled, which the
new logic does as soon as we know the exception is a user service call
request.

This patch does NOT change the behavior of reserved system calls (like
switch_context), only the user service call request is affected.
2024-06-01 10:40:53 -03:00

362 lines
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/****************************************************************************
* arch/risc-v/include/syscall.h
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/* This file should never be included directly but, rather, only indirectly
* through include/syscall.h or include/sys/sycall.h
*/
#ifndef __ARCH_RISCV_INCLUDE_SYSCALL_H
#define __ARCH_RISCV_INCLUDE_SYSCALL_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifndef __ASSEMBLY__
# include <stdint.h>
#endif
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define SYS_syscall 0x00
/* Configuration ************************************************************/
/* This logic uses three system calls {0,1,2} for context switching and one
* for the syscall return. So a minimum of four syscall values must be
* reserved. If CONFIG_BUILD_FLAT isn't defined, then four more syscall
* values must be reserved.
*/
#ifndef CONFIG_BUILD_FLAT
# define CONFIG_SYS_RESERVED 8
#else
# define CONFIG_SYS_RESERVED 4
#endif
/* RV64GC system calls ******************************************************/
/* SYS call 1 and 2 are defined for internal use by the RISC-V port (see
* arch/risc-v/include/syscall.h). In addition, SYS call 3 is the
* return from a SYS call in kernel mode. The first four syscall values must,
* therefore, be reserved (0 is not used).
*/
/* SYS call 1:
*
* void riscv_fullcontextrestore(uintptr_t *restoreregs) noreturn_function;
*/
#define SYS_restore_context (1)
/* SYS call 2:
*
* void riscv_switchcontext(uintptr_t **saveregs, uintptr_t *restoreregs);
*/
#define SYS_switch_context (2)
#ifndef CONFIG_BUILD_FLAT
/* SYS call 4:
*
* void up_task_start(main_t taskentry, int argc, char *argv[])
* noreturn_function;
*/
#define SYS_task_start (4)
/* SYS call 5:
*
* void up_pthread_start(pthread_startroutine_t startup,
* pthread_startroutine_t entrypt, pthread_addr_t arg)
* noreturn_function
*/
#define SYS_pthread_start (5)
/* SYS call 6:
*
* void signal_handler(_sa_sigaction_t sighand, int signo,
* siginfo_t *info, void *ucontext);
*/
#define SYS_signal_handler (6)
/* SYS call 7:
*
* void signal_handler_return(void);
*/
#define SYS_signal_handler_return (7)
#endif /* !CONFIG_BUILD_FLAT */
/****************************************************************************
* Public Types
****************************************************************************/
/****************************************************************************
* Inline functions
****************************************************************************/
#ifndef __ASSEMBLY__
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
long smh_call(unsigned int nbr, void *parm);
#if defined(CONFIG_ARCH_USE_S_MODE) && defined(__KERNEL__)
uintptr_t sys_call0(unsigned int nbr);
uintptr_t sys_call1(unsigned int nbr, uintptr_t parm1);
uintptr_t sys_call2(unsigned int nbr, uintptr_t parm1, uintptr_t parm2);
uintptr_t sys_call3(unsigned int nbr, uintptr_t parm1, uintptr_t parm2,
uintptr_t parm3);
uintptr_t sys_call4(unsigned int nbr, uintptr_t parm1, uintptr_t parm2,
uintptr_t parm3, uintptr_t parm4);
uintptr_t sys_call5(unsigned int nbr, uintptr_t parm1, uintptr_t parm2,
uintptr_t parm3, uintptr_t parm4, uintptr_t parm5);
uintptr_t sys_call6(unsigned int nbr, uintptr_t parm1, uintptr_t parm2,
uintptr_t parm3, uintptr_t parm4, uintptr_t parm5,
uintptr_t parm6);
#else
/****************************************************************************
* Name: sys_call0
*
* Description:
* System call SYS_ argument and no additional parameters.
*
****************************************************************************/
static inline uintptr_t sys_call0(unsigned int nbr)
{
register long r0 asm("a0") = (long)(nbr);
asm volatile
(
"ecall"
:: "r"(r0)
: "memory"
);
asm volatile("nop" : "=r"(r0));
return r0;
}
/****************************************************************************
* Name: sys_call1
*
* Description:
* System call SYS_ argument and one additional parameter.
*
****************************************************************************/
static inline uintptr_t sys_call1(unsigned int nbr, uintptr_t parm1)
{
register long r0 asm("a0") = (long)(nbr);
register long r1 asm("a1") = (long)(parm1);
asm volatile
(
"ecall"
:: "r"(r0), "r"(r1)
: "memory"
);
asm volatile("nop" : "=r"(r0));
return r0;
}
/****************************************************************************
* Name: sys_call2
*
* Description:
* System call SYS_ argument and two additional parameters.
*
****************************************************************************/
static inline uintptr_t sys_call2(unsigned int nbr, uintptr_t parm1,
uintptr_t parm2)
{
register long r0 asm("a0") = (long)(nbr);
register long r1 asm("a1") = (long)(parm1);
register long r2 asm("a2") = (long)(parm2);
asm volatile
(
"ecall"
:: "r"(r0), "r"(r1), "r"(r2)
: "memory"
);
asm volatile("nop" : "=r"(r0));
return r0;
}
/****************************************************************************
* Name: sys_call3
*
* Description:
* System call SYS_ argument and three additional parameters.
*
****************************************************************************/
static inline uintptr_t sys_call3(unsigned int nbr, uintptr_t parm1,
uintptr_t parm2, uintptr_t parm3)
{
register long r0 asm("a0") = (long)(nbr);
register long r1 asm("a1") = (long)(parm1);
register long r2 asm("a2") = (long)(parm2);
register long r3 asm("a3") = (long)(parm3);
asm volatile
(
"ecall"
:: "r"(r0), "r"(r1), "r"(r2), "r"(r3)
: "memory"
);
asm volatile("nop" : "=r"(r0));
return r0;
}
/****************************************************************************
* Name: sys_call4
*
* Description:
* System call SYS_ argument and four additional parameters.
*
****************************************************************************/
static inline uintptr_t sys_call4(unsigned int nbr, uintptr_t parm1,
uintptr_t parm2, uintptr_t parm3,
uintptr_t parm4)
{
register long r0 asm("a0") = (long)(nbr);
register long r1 asm("a1") = (long)(parm1);
register long r2 asm("a2") = (long)(parm2);
register long r3 asm("a3") = (long)(parm3);
register long r4 asm("a4") = (long)(parm4);
asm volatile
(
"ecall"
:: "r"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4)
: "memory"
);
asm volatile("nop" : "=r"(r0));
return r0;
}
/****************************************************************************
* Name: sys_call5
*
* Description:
* System call SYS_ argument and five additional parameters.
*
****************************************************************************/
static inline uintptr_t sys_call5(unsigned int nbr, uintptr_t parm1,
uintptr_t parm2, uintptr_t parm3,
uintptr_t parm4, uintptr_t parm5)
{
register long r0 asm("a0") = (long)(nbr);
register long r1 asm("a1") = (long)(parm1);
register long r2 asm("a2") = (long)(parm2);
register long r3 asm("a3") = (long)(parm3);
register long r4 asm("a4") = (long)(parm4);
register long r5 asm("a5") = (long)(parm5);
asm volatile
(
"ecall"
:: "r"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4), "r"(r5)
: "memory"
);
asm volatile("nop" : "=r"(r0));
return r0;
}
/****************************************************************************
* Name: sys_call6
*
* Description:
* System call SYS_ argument and six additional parameters.
*
****************************************************************************/
static inline uintptr_t sys_call6(unsigned int nbr, uintptr_t parm1,
uintptr_t parm2, uintptr_t parm3,
uintptr_t parm4, uintptr_t parm5,
uintptr_t parm6)
{
register long r0 asm("a0") = (long)(nbr);
register long r1 asm("a1") = (long)(parm1);
register long r2 asm("a2") = (long)(parm2);
register long r3 asm("a3") = (long)(parm3);
register long r4 asm("a4") = (long)(parm4);
register long r5 asm("a5") = (long)(parm5);
register long r6 asm("a6") = (long)(parm6);
asm volatile
(
"ecall"
:: "r"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4), "r"(r5), "r"(r6)
: "memory"
);
asm volatile("nop" : "=r"(r0));
return r0;
}
#endif
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* __ASSEMBLY__ */
#endif /* __ARCH_RISCV_INCLUDE_SYSCALL_H */
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