On Wed, Dec 30, 2015 at 10:56:41AM -0800, Tony Luck wrote:
> Make per-class functions for exception table fixup. Add #defines
> and general prettiness to make it clear how all the parts tie
> together.
>
> Add a new class that fills %rax with the fault number of the exception.
>
> Signed-off-by: Tony Luck <[email protected]>
> ---
> arch/x86/include/asm/asm.h | 24 ++++++++++-----
> arch/x86/include/asm/uaccess.h | 17 ++++++++---
> arch/x86/kernel/kprobes/core.c | 2 +-
> arch/x86/kernel/traps.c | 6 ++--
> arch/x86/mm/extable.c | 67
> +++++++++++++++++++++++++++---------------
> arch/x86/mm/fault.c | 2 +-
> 6 files changed, 79 insertions(+), 39 deletions(-)
>
> diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
> index b64121ffb2da..1888278d0559 100644
> --- a/arch/x86/include/asm/asm.h
> +++ b/arch/x86/include/asm/asm.h
> @@ -44,6 +44,7 @@
>
> /* Exception table entry */
>
> +#define _EXTABLE_BIAS 0x20000000
> /*
> * An exception table entry is 64 bits. The first 32 bits are the offset
> * from that entry to the potentially faulting instruction. sortextable
> @@ -54,26 +55,35 @@
> * address. All of these are generated by relocations, so we can only
> * rely on addition. We therefore emit:
> *
> - * (target - here) + (class) + 0x20000000
> + * (target - here) + (class) + _EXTABLE_BIAS
> *
> * This has the property that the two high bits are the class and the
> * rest is easy to decode.
> */
>
> -/* There are two bits of extable entry class, added to a signed offset. */
> -#define _EXTABLE_CLASS_DEFAULT 0 /* standard uaccess
> fixup */
> -#define _EXTABLE_CLASS_EX 0x80000000 /* uaccess + set uaccess_err */
> +/*
> + * There are two bits of extable entry class giving four classes
> + */
> +#define EXTABLE_CLASS_DEFAULT 0 /* standard uaccess fixup */
> +#define EXTABLE_CLASS_FAULT 1 /* provide fault number as well as
> fixup */
> +#define EXTABLE_CLASS_EX 2 /* uaccess + set uaccess_err */
> +#define EXTABLE_CLASS_UNUSED 3 /* available for something else */
>
> /*
> - * The biases are the class constants + 0x20000000, as signed integers.
> + * The biases are the class constants + _EXTABLE_BIAS, as signed integers.
> * This can't use ordinary arithmetic -- the assembler isn't that smart.
> */
> -#define _EXTABLE_BIAS_DEFAULT 0x20000000
> -#define _EXTABLE_BIAS_EX 0x20000000 - 0x80000000
> +#define _EXTABLE_BIAS_DEFAULT _EXTABLE_BIAS
> +#define _EXTABLE_BIAS_FAULT _EXTABLE_BIAS + 0x40000000
> +#define _EXTABLE_BIAS_EX _EXTABLE_BIAS - 0x80000000
> +#define _EXTABLE_BIAS_UNUSED _EXTABLE_BIAS - 0x40000000
>
> #define _ASM_EXTABLE(from,to)
> \
> _ASM_EXTABLE_CLASS(from, to, _EXTABLE_BIAS_DEFAULT)
>
> +#define _ASM_EXTABLE_FAULT(from,to) \
> + _ASM_EXTABLE_CLASS(from, to, _EXTABLE_BIAS_FAULT)
> +
> #define _ASM_EXTABLE_EX(from,to) \
> _ASM_EXTABLE_CLASS(from, to, _EXTABLE_BIAS_EX)
So you're touching those again in patch 2. Why not add those defines to
patch 1 directly and diminish the churn?
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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