Re: [PATCH v3 21/23] arm64: hw_breakpoint: Allow EL2 breakpoints if running in HYP

Catalin Marinas
2016-02-08T16:52:20Z

On Mon, Feb 08, 2016 at 04:45:44PM +0000, Marc Zyngier wrote:
> I was being overzealous, and your solution is clearly better. I ended up with the following:
>
> diff --git a/arch/arm64/include/asm/hw_breakpoint.h b/arch/arm64/include/asm/hw_breakpoint.h
> index 9732908..c872b2f 100644
> --- a/arch/arm64/include/asm/hw_breakpoint.h
> +++ b/arch/arm64/include/asm/hw_breakpoint.h
[...]
> @@ -62,6 +45,7 @@ static inline void decode_ctrl_reg(u32 reg,
> #define AARCH64_ESR_ACCESS_MASK (1 << 6)
>
> /* Privilege Levels */
> +#define AARCH64_BREAKPOINT_EL2 0
> #define AARCH64_BREAKPOINT_EL1 1
> #define AARCH64_BREAKPOINT_EL0 2
>
> @@ -76,6 +60,35 @@ static inline void decode_ctrl_reg(u32 reg,
> #define ARM_KERNEL_STEP_ACTIVE 1
> #define ARM_KERNEL_STEP_SUSPEND 2
>
> +#define DBG_HMC_HYP (1 << 13)
> +#define DBG_SSC_HYP (3 << 14)
> +
> +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
> +{
> + u32 val = (ctrl.len << 5) | (ctrl.type << 3) | ctrl.enabled;
> +
> + if (is_kernel_in_hyp_mode() && ctrl.privilege == AARCH64_BREAKPOINT_EL1)
> + val |= DBG_HMC_HYP | DBG_SSC_HYP;

Nitpick, for completeness:

val |= DBG_HMC_HYP | DBG_SSC_HYP | (AARCH64_BREAKPOINT_EL2 << 1);

> + else
> + val |= ctrl.privilege << 1;
> +
> + return val;
> +}
> +
> +static inline void decode_ctrl_reg(u32 reg,
> + struct arch_hw_breakpoint_ctrl *ctrl)
> +{
> + ctrl->enabled = reg & 0x1;
> + reg >>= 1;
> + ctrl->privilege = reg & 0x3;
> + if (ctrl->privilege == AARCH64_BREAKPOINT_EL2)
> + ctrl->privilege = AARCH64_BREAKPOINT_EL1;
> + reg >>= 2;
> + ctrl->type = reg & 0x3;
> + reg >>= 2;
> + ctrl->len = reg & 0xff;
> +}
> +
> /*
> * Limits.
> * Changing these will require modifications to the register accessors.
>
> Was that what you had in mind?

Looks fine:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>