On Tue, 2019-06-18 at 09:57 +0530, Ravi Bangoria wrote:
> Directly setting dawr and dawrx with 0 should be enough to
> disable watchpoint. No need to reset individual bits in
> variable and then set in hw.
This seems like a pointless optimisation to me.
I'm all for adding more code/complexity if it buys us some performance, but I
can't imagine this is a fast path (nor have you stated any performance
benefits).
Mikey
>
> Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com>
> ---
> arch/powerpc/include/asm/hw_breakpoint.h | 3 ++-
> arch/powerpc/kernel/process.c | 12 ++++++++++++
> 2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h
> b/arch/powerpc/include/asm/hw_breakpoint.h
> index 78202d5fb13a..8acbbdd4a2d5 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -19,6 +19,7 @@ struct arch_hw_breakpoint {
> /* Note: Don't change the the first 6 bits below as they are in the same
> order
> * as the dabr and dabrx.
> */
> +#define HW_BRK_TYPE_DISABLE 0x00
> #define HW_BRK_TYPE_READ 0x01
> #define HW_BRK_TYPE_WRITE 0x02
> #define HW_BRK_TYPE_TRANSLATE 0x04
> @@ -68,7 +69,7 @@ static inline void hw_breakpoint_disable(void)
> struct arch_hw_breakpoint brk;
>
> brk.address = 0;
> - brk.type = 0;
> + brk.type = HW_BRK_TYPE_DISABLE;
> brk.len = 0;
> if (ppc_breakpoint_available())
> __set_breakpoint(&brk);
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index f002d2ffff86..265fac9fb3a4 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -793,10 +793,22 @@ static inline int set_dabr(struct arch_hw_breakpoint
> *brk)
> return __set_dabr(dabr, dabrx);
> }
>
> +static int disable_dawr(void)
> +{
> + if (ppc_md.set_dawr)
> + return ppc_md.set_dawr(0, 0);
> +
> + mtspr(SPRN_DAWRX, 0);
> + return 0;
> +}
> +
> int set_dawr(struct arch_hw_breakpoint *brk)
> {
> unsigned long dawr, dawrx, mrd;
>
> + if (brk->type == HW_BRK_TYPE_DISABLE)
> + return disable_dawr();
> +
> dawr = brk->address;
>
> dawrx = (brk->type & HW_BRK_TYPE_RDWR) << (63 - 58);
