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SubjectRe: [PATCH v3 7/8] arm64: exception: handle asynchronous SError interrupt
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Hi XiuQi,

On 2017/3/30 18:31, Xie XiuQi wrote:
> Error Synchronization Barrier (ESB; part of the ARMv8.2 Extensions)
> is used to synchronize Unrecoverable errors. That is, containable errors
> architecturally consumed by the PE and not silently propagated.
>
> With ESB it is generally possible to isolate an unrecoverable error
> between two ESB instructions. So, it's possible to recovery from
> unrecoverable errors reported by asynchronous SError interrupt.
>
> If ARMv8.2 RAS Extension is not support, ESB is treated as a NOP.
>
> Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
> Signed-off-by: Wang Xiongfeng <wangxiongfengi2@huawei.com>
> ---
> arch/arm64/Kconfig | 16 ++++++++++
> arch/arm64/include/asm/esr.h | 14 +++++++++
> arch/arm64/kernel/entry.S | 70 ++++++++++++++++++++++++++++++++++++++++++--
> arch/arm64/kernel/traps.c | 54 ++++++++++++++++++++++++++++++++--
> 4 files changed, 150 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 859a90e..7402175 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -911,6 +911,22 @@ endmenu
>
> menu "ARMv8.2 architectural features"
>
> +config ARM64_ESB
> + bool "Enable support for Error Synchronization Barrier (ESB)"
> + default n
> + help
> + Error Synchronization Barrier (ESB; part of the ARMv8.2 Extensions)
> + is used to synchronize Unrecoverable errors. That is, containable errors
> + architecturally consumed by the PE and not silently propagated.
> +
> + Without ESB it is not generally possible to isolate an Unrecoverable
> + error because it is not known which instruction generated the error.
> +
> + Selecting this option allows inject esb instruction before the exception
> + change. If ARMv8.2 RAS Extension is not support, ESB is treated as a NOP.
> +
> + Note that ESB instruction can introduce slight overhead, so say N if unsure.
> +
> config ARM64_UAO
> bool "Enable support for User Access Override (UAO)"
> default y
> diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
> index f20c64a..22f9c90 100644
> --- a/arch/arm64/include/asm/esr.h
> +++ b/arch/arm64/include/asm/esr.h
> @@ -106,6 +106,20 @@
> #define ESR_ELx_AR (UL(1) << 14)
> #define ESR_ELx_CM (UL(1) << 8)
>
> +#define ESR_Elx_DFSC_SEI (0x11)
> +
> +#define ESR_ELx_AET_SHIFT (10)
> +#define ESR_ELx_AET_MAX (7)
> +#define ESR_ELx_AET_MASK (UL(7) << ESR_ELx_AET_SHIFT)
> +#define ESR_ELx_AET(esr) (((esr) & ESR_ELx_AET_MASK) >> ESR_ELx_AET_SHIFT)
> +
> +#define ESR_ELx_AET_UC (0)
> +#define ESR_ELx_AET_UEU (1)
> +#define ESR_ELx_AET_UEO (2)
> +#define ESR_ELx_AET_UER (3)
> +#define ESR_ELx_AET_CE (6)
> +
> +
> /* ISS field definitions for exceptions taken in to Hyp */
> #define ESR_ELx_CV (UL(1) << 24)
> #define ESR_ELx_COND_SHIFT (20)
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 43512d4..d8a7306 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -69,7 +69,14 @@
> #define BAD_FIQ 2
> #define BAD_ERROR 3
>
> + .arch_extension ras
> +
> .macro kernel_entry, el, regsize = 64
because we also want to take SEI exception in kernel space, we may need to unmask SEI in kernel_entry.
> +#ifdef CONFIG_ARM64_ESB
> + .if \el == 0
> + esb
> + .endif
> +#endif
> sub sp, sp, #S_FRAME_SIZE
> .if \regsize == 32
> mov w0, w0 // zero upper 32 bits of x0
> @@ -208,6 +215,7 @@ alternative_else_nop_endif
> #endif
>
> .if \el == 0
> + msr daifset, #0xF // Set flags
> ldr x23, [sp, #S_SP] // load return stack pointer
> msr sp_el0, x23
> #ifdef CONFIG_ARM64_ERRATUM_845719
> @@ -226,6 +234,15 @@ alternative_else_nop_endif
>
> msr elr_el1, x21 // set up the return data
> msr spsr_el1, x22
> +
> +#ifdef CONFIG_ARM64_ESB
> + .if \el == 0
> + esb // Error Synchronization Barrier
> + mrs x21, disr_el1 // Check for deferred error
> + tbnz x21, #31, el1_sei
> + .endif
> +#endif
> +
> ldp x0, x1, [sp, #16 * 0]
> ldp x2, x3, [sp, #16 * 1]
> ldp x4, x5, [sp, #16 * 2]
> @@ -318,7 +335,7 @@ ENTRY(vectors)
> ventry el1_sync_invalid // Synchronous EL1t
> ventry el1_irq_invalid // IRQ EL1t
> ventry el1_fiq_invalid // FIQ EL1t
> - ventry el1_error_invalid // Error EL1t
> + ventry el1_error // Error EL1t
>
> ventry el1_sync // Synchronous EL1h
> ventry el1_irq // IRQ EL1h
> @@ -328,7 +345,7 @@ ENTRY(vectors)
> ventry el0_sync // Synchronous 64-bit EL0
> ventry el0_irq // IRQ 64-bit EL0
> ventry el0_fiq_invalid // FIQ 64-bit EL0
> - ventry el0_error_invalid // Error 64-bit EL0
> + ventry el0_error // Error 64-bit EL0

for the situation 'Current EL with SPx', we also need to change the sError vector to el1_error.
>
> #ifdef CONFIG_COMPAT
> ventry el0_sync_compat // Synchronous 32-bit EL0
> @@ -508,12 +525,31 @@ el1_preempt:
> ret x24
> #endif
>
> + .align 6
> +el1_error:
> + kernel_entry 1
> +el1_sei:
> + /*
> + * asynchronous SError interrupt from kernel
> + */
> + mov x0, sp
> + mrs x1, esr_el1
> + mov x2, #1 // exception level of SEI generated
> + b do_sei
> +ENDPROC(el1_error)
> +
> +


Thanks,

Wang Xiongfeng


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