arch/riscv/kernel/sys_riscv.c

Source file repositories/reference/linux-study-clean/arch/riscv/kernel/sys_riscv.c

File Facts

System
Linux kernel
Corpus path
arch/riscv/kernel/sys_riscv.c
Extension
.c
Size
2906 bytes
Lines
86
Domain
Architecture Layer
Bucket
arch/riscv
Inferred role
Architecture Layer: syscall or user/kernel boundary
Status
core implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
	unsigned long, prot, unsigned long, flags,
	unsigned long, fd, unsigned long, offset)
{
	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 0);
}
#endif

#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
	unsigned long, prot, unsigned long, flags,
	unsigned long, fd, unsigned long, offset)
{
	/*
	 * Note that the shift for mmap2 is constant (12),
	 * regardless of PAGE_SIZE
	 */
	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 12);
}
#endif

/*
 * Allows the instruction cache to be flushed from userspace.  Despite RISC-V
 * having a direct 'fence.i' instruction available to userspace (which we
 * can't trap!), that's not actually viable when running on Linux because the
 * kernel might schedule a process on another hart.  There is no way for
 * userspace to handle this without invoking the kernel (as it doesn't know the
 * thread->hart mappings), so we've defined a RISC-V specific system call to
 * flush the instruction cache.
 *
 * sys_riscv_flush_icache() is defined to flush the instruction cache over an
 * address range, with the flush applying to either all threads or just the
 * caller.  We don't currently do anything with the address range, that's just
 * in there for forwards compatibility.
 */
SYSCALL_DEFINE3(riscv_flush_icache, uintptr_t, start, uintptr_t, end,
	uintptr_t, flags)
{
	/* Check the reserved flags. */
	if (unlikely(flags & ~SYS_RISCV_FLUSH_ICACHE_ALL))
		return -EINVAL;

	flush_icache_mm(current->mm, flags & SYS_RISCV_FLUSH_ICACHE_LOCAL);

	return 0;
}

/* Not defined using SYSCALL_DEFINE0 to avoid error injection */
asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *__unused)
{
	return -ENOSYS;
}

Annotation

Implementation Notes