Andy Chiu <andy.chiu@xxxxxxxxxx> writes:
> This patch add two riscv-specific prctls, to allow usespace control the
> use of vector unit:
>
> * PR_RISCV_V_SET_CONTROL: control the permission to use Vector at next,
> or all following execve for a thread. Turning off a thread's Vector
> live is not possible since libraries may have registered ifunc that
> may execute Vector instructions.
> * PR_RISCV_V_GET_CONTROL: get the same permission setting for the
> current thread, and the setting for following execve(s).
>
> Signed-off-by: Andy Chiu <andy.chiu@xxxxxxxxxx>
> Reviewed-by: Greentime Hu <greentime.hu@xxxxxxxxxx>
> Reviewed-by: Vincent Chen <vincent.chen@xxxxxxxxxx>
> ---
> Changelog v20:
> - address build issue when KVM is compile as a module (Heiko)
> - s/RISCV_V_DISABLE/RISCV_ISA_V_DEFAULT_ENABLE/ (Conor)
> - change function names to have better scoping
> - check has_vector() before accessing vstate_ctrl
> - use proper return type for prctl calls (long instead of uint)
> ---
> arch/riscv/include/asm/processor.h | 13 ++++
> arch/riscv/include/asm/vector.h | 4 +
> arch/riscv/kernel/process.c | 1 +
> arch/riscv/kernel/vector.c | 118 +++++++++++++++++++++++++++++
> arch/riscv/kvm/vcpu.c | 2 +
> include/uapi/linux/prctl.h | 11 +++
> kernel/sys.c | 12 +++
> 7 files changed, 161 insertions(+)
>
> diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> index 38ded8c5f207..17829c3003c8 100644
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -40,6 +40,7 @@ struct thread_struct {
> unsigned long s[12]; /* s[0]: frame pointer */
> struct __riscv_d_ext_state fstate;
> unsigned long bad_cause;
> + unsigned long vstate_ctrl;
> struct __riscv_v_ext_state vstate;
> };
>
> @@ -83,6 +84,18 @@ extern void riscv_fill_hwcap(void);
> extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
>
> extern unsigned long signal_minsigstksz __ro_after_init;
> +
> +#ifdef CONFIG_RISCV_ISA_V
> +/* Userspace interface for PR_RISCV_V_{SET,GET}_VS prctl()s: */
> +#define RISCV_V_SET_CONTROL(arg) riscv_v_vstate_ctrl_set_current(arg)
> +#define RISCV_V_GET_CONTROL() riscv_v_vstate_ctrl_get_current()
> +extern long riscv_v_vstate_ctrl_set_current(unsigned long arg);
> +extern long riscv_v_vstate_ctrl_get_current(void);
> +#else /* !CONFIG_RISCV_ISA_V */
> +#define RISCV_V_SET_CONTROL(arg) (-EINVAL)
> +#define RISCV_V_GET_CONTROL() (-EINVAL)
This version doesn't fix the issue I pointed out in [1]. Let me try to
be more explicit.
RISCV_V_GET_CONTROL and RISCV_V_SET_CONTROL are a function (if
CONFIG_RISCV_ISA_V is defined), otherwise (-EINVAL). However, they are
redefined below, so you can remove the whole #else to #endif...
[...]
> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
> index f23d9a16507f..3c36aeade991 100644
> --- a/include/uapi/linux/prctl.h
> +++ b/include/uapi/linux/prctl.h
> @@ -294,4 +294,15 @@ struct prctl_mm_map {
>
> #define PR_SET_MEMORY_MERGE 67
> #define PR_GET_MEMORY_MERGE 68
> +
> +#define PR_RISCV_V_SET_CONTROL 69
> +#define PR_RISCV_V_GET_CONTROL 70
> +# define PR_RISCV_V_VSTATE_CTRL_DEFAULT 0
> +# define PR_RISCV_V_VSTATE_CTRL_OFF 1
> +# define PR_RISCV_V_VSTATE_CTRL_ON 2
> +# define PR_RISCV_V_VSTATE_CTRL_INHERIT (1 << 4)
> +# define PR_RISCV_V_VSTATE_CTRL_CUR_MASK 0x3
> +# define PR_RISCV_V_VSTATE_CTRL_NEXT_MASK 0xc
> +# define PR_RISCV_V_VSTATE_CTRL_MASK 0x1f
> +
> #endif /* _LINUX_PRCTL_H */
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 339fee3eff6a..d0d3106698a1 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -140,6 +140,12 @@
> #ifndef GET_TAGGED_ADDR_CTRL
> # define GET_TAGGED_ADDR_CTRL() (-EINVAL)
> #endif
> +#ifndef PR_RISCV_V_SET_CONTROL
> +# define RISCV_V_SET_CONTROL(a) (-EINVAL)
> +#endif
> +#ifndef PR_RISCV_V_GET_CONTROL
> +# define RISCV_V_GET_CONTROL() (-EINVAL)
> +#endif
...because they are defined to EINVAL here. Or at least they are
supposed to. Now, the 2nd issue was that #ifndef PR_RISCV_V_SET_CONTROL
should be #ifndef RISCV_V_SET_CONTROL (and dito for GET).
PR_RISCV_V_SET_CONTROL is *always* defined in the uapi header above.
So, change to:
| #ifndef RISCV_V_SET_CONTROL
| # define RISCV_V_SET_CONTROL(a) (-EINVAL)
| #endif
| #ifndef RISCV_V_GET_CONTROL
| # define RISCV_V_GET_CONTROL() (-EINVAL)
| #endif
and remove the #else above.
>
> /*
> * this is where the system-wide overflow UID and GID are defined, for
> @@ -2708,6 +2714,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
> error = !!test_bit(MMF_VM_MERGE_ANY, &me->mm->flags);
> break;
> #endif
> + case PR_RISCV_V_SET_CONTROL:
> + error = RISCV_V_SET_CONTROL(arg2);
> + break;
> + case PR_RISCV_V_GET_CONTROL:
> + error = RISCV_V_GET_CONTROL();
PR_RISCV_V_{GET,SET}_CONTROL is always set!
Björn
[1] https://lore.kernel.org/linux-riscv/87ttwdhljn.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
