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riscv: entry: Convert ret_from_fork() to C

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Move the main section of ret_from_fork() to C to allow inlining of
syscall_exit_to_user_mode().

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/all/20250320-riscv_optimize_entry-v6-1-63e187e26041@rivosinc.com
This commit is contained in:
Charlie Jenkins 2025-03-20 10:29:21 -07:00 committed by Thomas Gleixner
parent b4432656b3
commit f955aa8723
3 changed files with 19 additions and 11 deletions
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1
arch/riscv/include/asm/asm-prototypes.h
View File

@ -52,6 +52,7 @@ DECLARE_DO_ERROR_INFO(do_trap_ecall_s);
DECLARE_DO_ERROR_INFO(do_trap_ecall_m);
DECLARE_DO_ERROR_INFO(do_trap_break);
asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs);
asmlinkage void handle_bad_stack(struct pt_regs *regs);
asmlinkage void do_page_fault(struct pt_regs *regs);
asmlinkage void do_irq(struct pt_regs *regs);

15
arch/riscv/kernel/entry.S
View File

@ -319,17 +319,14 @@ SYM_CODE_END(handle_kernel_stack_overflow)
ASM_NOKPROBE(handle_kernel_stack_overflow)
#endif
SYM_CODE_START(ret_from_fork)
SYM_CODE_START(ret_from_fork_asm)
call schedule_tail
beqz s0, 1f /* not from kernel thread */
/* Call fn(arg) */
move a0, s1
jalr s0
1:
move a0, sp /* pt_regs */
call syscall_exit_to_user_mode
move a0, s1 /* fn_arg */
move a1, s0 /* fn */
move a2, sp /* pt_regs */
call ret_from_fork
j ret_from_exception
SYM_CODE_END(ret_from_fork)
SYM_CODE_END(ret_from_fork_asm)
#ifdef CONFIG_IRQ_STACKS
/*

14
arch/riscv/kernel/process.c
View File

@ -17,7 +17,9 @@
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <linux/personality.h>
#include <linux/entry-common.h>
#include <asm/asm-prototypes.h>
#include <asm/unistd.h>
#include <asm/processor.h>
#include <asm/csr.h>
@ -36,7 +38,7 @@ unsigned long __stack_chk_guard __read_mostly;
EXPORT_SYMBOL(__stack_chk_guard);
#endif
extern asmlinkage void ret_from_fork(void);
extern asmlinkage void ret_from_fork_asm(void);
void noinstr arch_cpu_idle(void)
{
@ -206,6 +208,14 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
return 0;
}
asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs)
{
if (unlikely(fn))
fn(fn_arg);
syscall_exit_to_user_mode(regs);
}
int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
@ -242,7 +252,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
p->thread.riscv_v_flags = 0;
if (has_vector() || has_xtheadvector())
riscv_v_thread_alloc(p);
p->thread.ra = (unsigned long)ret_from_fork;
p->thread.ra = (unsigned long)ret_from_fork_asm;
p->thread.sp = (unsigned long)childregs; /* kernel sp */
return 0;
}