On Wed, 2021-01-20 at 11:27 +0900, Hajime Tazaki wrote:
>
> +++ b/arch/um/lkl/include/asm/atomic.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __UM_LIBMODE_ATOMIC_H
> +#define __UM_LIBMODE_ATOMIC_H
> +
> +#include <asm-generic/atomic.h>
> +
> +#ifndef CONFIG_GENERIC_ATOMIC64
> +#include "atomic64.h"
> +#endif /* !CONFIG_GENERIC_ATOMIC64 */
That's not actually configurable, is it? When is this on or off?
> +static inline void cpu_relax(void)
> +{
> + unsigned long flags;
> +
> + /* since this is usually called in a tight loop waiting for some
> + * external condition (e.g. jiffies) lets run interrupts now to allow
> + * the external condition to propagate
> + */
> + local_irq_save(flags);
> + local_irq_restore(flags);
Hmm?
If interrupts are enabled, then you'll get them anyway, and if not, then
this does nothing?
> +static inline void arch_copy_thread(struct arch_thread *from,
> + struct arch_thread *to)
> +{
> + panic("unimplemented %s: fork isn't supported yet", __func__);
> +}
"yet" seems kind of misleading - I mean, it really *won't* be, since
that's basically what UML is, no?
I mean, in principle, nothing actually stops you from building a
linux.so instead of linux binary, and having main() renamed to
linux_main() so the application can start up whenever it needs to, or
something like that?
> +#endif
> diff --git a/arch/um/lkl/include/asm/ptrace.h b/arch/um/lkl/include/asm/ptrace.h
> new file mode 100644
> index 000000000000..83f4e10fb677
> --- /dev/null
> +++ b/arch/um/lkl/include/asm/ptrace.h
> @@ -0,0 +1,21 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __UM_LIBMODE_PTRACE_H
> +#define __UM_LIBMODE_PTRACE_H
> +
> +#include <linux/errno.h>
> +
> +static int reg_dummy __attribute__((unused));
> +
> +#define PT_REGS_ORIG_SYSCALL(r) (reg_dummy)
> +#define PT_REGS_SYSCALL_RET(r) (reg_dummy)
> +#define PT_REGS_SET_SYSCALL_RETURN(r, res) (reg_dummy = (res))
> +#define REGS_SP(r) (reg_dummy)
> +
> +#define user_mode(regs) 0
> +#define kernel_mode(regs) 1
> +#define profile_pc(regs) 0
> +#define user_stack_pointer(regs) 0
> +
> +extern void new_thread_handler(void);
> +
> +#endif
> diff --git a/arch/um/lkl/include/asm/segment.h b/arch/um/lkl/include/asm/segment.h
> new file mode 100644
> index 000000000000..1f6746866b8b
> --- /dev/null
> +++ b/arch/um/lkl/include/asm/segment.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __UM_LIBMODE_SEGMENT_H
> +#define __UM_LIBMODE_SEGMENT_H
> +
> +typedef struct {
> + unsigned long seg;
> +} mm_segment_t;
> +
> +#endif /* _ASM_LKL_SEGMENT_H */
> diff --git a/arch/um/lkl/include/uapi/asm/bitsperlong.h b/arch/um/lkl/include/uapi/asm/bitsperlong.h
> new file mode 100644
> index 000000000000..f6657ba0ff9b
> --- /dev/null
> +++ b/arch/um/lkl/include/uapi/asm/bitsperlong.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __UM_LIBMODE_UAPI_BITSPERLONG_H
> +#define __UM_LIBMODE_UAPI_BITSPERLONG_H
> +
> +#ifdef CONFIG_64BIT
> +#define __BITS_PER_LONG 64
> +#else
> +#define __BITS_PER_LONG 32
> +#endif
> +
> +#include <asm-generic/bitsperlong.h>
First, that include does nothing. Second, the comment there says:
/*
* There seems to be no way of detecting this automatically from user
* space, so 64 bit architectures should override this in their
* bitsperlong.h. In particular, an architecture that supports
* both 32 and 64 bit user space must not rely on CONFIG_64BIT
* to decide it, but rather check a compiler provided macro.
*/
So you're doing exactly what it says *not* to?
In fact, that totally makes sense - I mean, this is *uapi* and
applications don't have access to CONFIG_ defines etc.
Do you expose that somehow to LKL users that makes this OK-ish? But it's
still very confusing, and you've not made sure the necessary header is
actually included. IIUC, lkl builds a (shared?) library, so it won't
really work this way?
> +++ b/arch/um/lkl/include/uapi/asm/byteorder.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __UM_LIBMODE_UAPI_BYTEORDER_H
> +#define __UM_LIBMODE_UAPI_BYTEORDER_H
> +
> +#if defined(CONFIG_BIG_ENDIAN)
> +#include <linux/byteorder/big_endian.h>
Same here.
> +++ b/arch/um/lkl/um/delay.c
> @@ -0,0 +1,31 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/jiffies.h>
> +#include <linux/delay.h>
> +#include <os.h>
> +
> +void __ndelay(unsigned long nsecs)
> +{
> + long long start = os_nsecs();
> +
> + while (os_nsecs() < start + nsecs)
> + ;
At least do something like cpu_relax()? Although ... you made that do
nothing, so you probably want an arch-specific thing here?
johannes
