Re: [PATCH V3 2/3] perf/powerpc :add support for sampling intr machine state

[Michael Ellerman <mpe@ellerman.id.au>]

On Tue, 2015-11-03 at 11:40 +0530, Anju T wrote:

> The perf infrastructure uses a bit mask to find out
> valid registers to display. Define a register mask
> for supported registers defined in asm/perf_regs.h.
> The bit positions also correspond to register IDs
> which is used by perf infrastructure to fetch the register
> values.CONFIG_HAVE_PERF_REGS enables
> sampling of the interrupted machine state.

> diff --git a/arch/powerpc/perf/perf_regs.c b/arch/powerpc/perf/perf_regs.c
> new file mode 100644
> index 0000000..0520492
> --- /dev/null
> +++ b/arch/powerpc/perf/perf_regs.c
> @@ -0,0 +1,92 @@
> +#include <linux/errno.h>
> +#include <linux/kernel.h>
> +#include <linux/sched.h>
> +#include <linux/perf_event.h>
> +#include <linux/bug.h>
> +#include <linux/stddef.h>
> +#include <asm/ptrace.h>
> +#include <asm/perf_regs.h>
> +
> +#define PT_REGS_OFFSET(id, r) [id] = offsetof(struct pt_regs, r)
> +
> +#define REG_RESERVED (~((1ULL << PERF_REG_POWERPC_MAX) - 1))
> +
> +static unsigned int pt_regs_offset[PERF_REG_POWERPC_MAX] = {
> +	PT_REGS_OFFSET(PERF_REG_POWERPC_GPR0, gpr[0]),
> +	PT_REGS_OFFSET(PERF_REG_POWERPC_GPR1, gpr[1]),
> +	PT_REGS_OFFSET(PERF_REG_POWERPC_GPR2, gpr[2]),

<snip>

I realise you're following the example of other architectures, but we have
almost this exact same structure in ptrace.c, see regoffset_table.

It would be really nice if we could share them between ptrace and perf.

cheers