Re: [PATCH 02/23] perf: Unified API to record selective sets of arch registers

[Frederic Weisbecker <fweisbec@gmail.com>]

On Tue, Jun 19, 2012 at 05:47:53PM +0200, Jiri Olsa wrote:
> This brings a new API to help the selective dump of registers on
> event sampling, and its implementation for x86 arch.
> 
> Added HAVE_PERF_REGS config option to determine if the architecture
> provides perf registers ABI.
> 
> The information about desired registers will be passed in u64 mask.
> It's up to the architecture to map the registers into the mask bits.
> 
> For the x86 arch implementation, both 32 and 64 bit registers
> bits are defined within single enum to ensure 64 bit system can
> provide register dump for compat task if needed in the future.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> ---
>  arch/Kconfig                     |    6 +++
>  arch/x86/Kconfig                 |    1 +
>  arch/x86/include/asm/perf_regs.h |   34 ++++++++++++++
>  arch/x86/kernel/Makefile         |    2 +
>  arch/x86/kernel/perf_regs.c      |   90 ++++++++++++++++++++++++++++++++++++++
>  include/linux/perf_regs.h        |   19 ++++++++
>  6 files changed, 152 insertions(+), 0 deletions(-)
>  create mode 100644 arch/x86/include/asm/perf_regs.h
>  create mode 100644 arch/x86/kernel/perf_regs.c
>  create mode 100644 include/linux/perf_regs.h
> 
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 8c3d957..32f4873 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -222,6 +222,12 @@ config HAVE_PERF_EVENTS_NMI
>  	  subsystem.  Also has support for calculating CPU cycle events
>  	  to determine how many clock cycles in a given period.
>  
> +config HAVE_PERF_REGS
> +	bool
> +	help
> +	  Support selective register dumps for perf events. This includes
> +	  bit-mapping of each registers and a unique architecture id.
> +
>  config HAVE_ARCH_JUMP_LABEL
>  	bool
>  
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index d35438e..457d8d6 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -60,6 +60,7 @@ config X86
>  	select HAVE_MIXED_BREAKPOINTS_REGS
>  	select PERF_EVENTS
>  	select HAVE_PERF_EVENTS_NMI
> +	select HAVE_PERF_REGS
>  	select ANON_INODES
>  	select HAVE_ALIGNED_STRUCT_PAGE if SLUB && !M386
>  	select HAVE_CMPXCHG_LOCAL if !M386
> diff --git a/arch/x86/include/asm/perf_regs.h b/arch/x86/include/asm/perf_regs.h
> new file mode 100644
> index 0000000..0397bfc
> --- /dev/null
> +++ b/arch/x86/include/asm/perf_regs.h
> @@ -0,0 +1,34 @@
> +#ifndef _ASM_X86_PERF_REGS_H
> +#define _ASM_X86_PERF_REGS_H
> +
> +enum perf_event_x86_regs {
> +	PERF_REG_X86_AX,
> +	PERF_REG_X86_BX,
> +	PERF_REG_X86_CX,
> +	PERF_REG_X86_DX,
> +	PERF_REG_X86_SI,
> +	PERF_REG_X86_DI,
> +	PERF_REG_X86_BP,
> +	PERF_REG_X86_SP,
> +	PERF_REG_X86_IP,
> +	PERF_REG_X86_FLAGS,
> +	PERF_REG_X86_CS,
> +	PERF_REG_X86_DS,
> +	PERF_REG_X86_ES,
> +	PERF_REG_X86_FS,
> +	PERF_REG_X86_GS,
> +	PERF_REG_X86_R8,
> +	PERF_REG_X86_R9,
> +	PERF_REG_X86_R10,
> +	PERF_REG_X86_R11,
> +	PERF_REG_X86_R12,
> +	PERF_REG_X86_R13,
> +	PERF_REG_X86_R14,
> +	PERF_REG_X86_R15,
> +	PERF_REG_X86_SS,
> +
> +	/* non ABI */
> +	PERF_REG_X86_64_MAX = PERF_REG_X86_SS + 1,

SS also exist in 32 bits, right?
Although I guess userspace doesn't care much.