Re: [PATCH v6 1/7] perf/core: Define the common branch type classification

[Peter Zijlstra]

PPC folks, maddy, does this work for you guys?

On Thu, Apr 20, 2017 at 08:07:49PM +0800, Jin Yao wrote:
> It is often useful to know the branch types while analyzing branch
> data. For example, a call is very different from a conditional branch.
> 
> Currently we have to look it up in binary while the binary may later
> not be available and even the binary is available but user has to take
> some time. It is very useful for user to check it directly in perf
> report.
> 
> Perf already has support for disassembling the branch instruction
> to get the x86 branch type.
> 
> To keep consistent on kernel and userspace and make the classification
> more common, the patch adds the common branch type classification
> in perf_event.h.
> 
> PERF_BR_NONE      : unknown
> PERF_BR_JCC       : conditional jump
> PERF_BR_JMP       : jump
> PERF_BR_IND_JMP   : indirect jump
> PERF_BR_CALL      : call
> PERF_BR_IND_CALL  : indirect call
> PERF_BR_RET       : return
> PERF_BR_SYSCALL   : syscall
> PERF_BR_SYSRET    : syscall return
> PERF_BR_IRQ       : hw interrupt/trap/fault
> PERF_BR_INT       : sw interrupt
> PERF_BR_IRET      : return from interrupt
> PERF_BR_FAR_BRANCH: not generic far branch type
> 
> The patch also adds a new field type (4 bits) in perf_branch_entry
> to record the branch type.
> 
> Since the disassembling of branch instruction needs some overhead,
> a new PERF_SAMPLE_BRANCH_TYPE_SAVE is introduced to indicate if it
> needs to disassemble the branch instruction and record the branch
> type.
> 
> Change log
> ----------
> 
> v6: Not changed.
> 
> v5: Not changed. The v5 patch series just change the userspace.
> 
> v4: Comparing to previous version, the major changes are:
> 
> 1. Remove the PERF_BR_JCC_FWD/PERF_BR_JCC_BWD, they will be
>    computed later in userspace.
> 
> 2. Remove the "cross" field in perf_branch_entry. The cross page
>    computing will be done later in userspace.
> 
> Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
> ---
>  include/uapi/linux/perf_event.h       | 29 ++++++++++++++++++++++++++++-
>  tools/include/uapi/linux/perf_event.h | 29 ++++++++++++++++++++++++++++-
>  2 files changed, 56 insertions(+), 2 deletions(-)
> 
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index d09a9cd..69af012 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -174,6 +174,8 @@ enum perf_branch_sample_type_shift {
>  	PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT	= 14, /* no flags */
>  	PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT	= 15, /* no cycles */
>  
> +	PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT	= 16, /* save branch type */
> +
>  	PERF_SAMPLE_BRANCH_MAX_SHIFT		/* non-ABI */
>  };
>  
> @@ -198,9 +200,32 @@ enum perf_branch_sample_type {
>  	PERF_SAMPLE_BRANCH_NO_FLAGS	= 1U << PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT,
>  	PERF_SAMPLE_BRANCH_NO_CYCLES	= 1U << PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT,
>  
> +	PERF_SAMPLE_BRANCH_TYPE_SAVE	=
> +		1U << PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT,
> +
>  	PERF_SAMPLE_BRANCH_MAX		= 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
>  };
>  
> +/*
> + * Common flow change classification
> + */
> +enum {
> +	PERF_BR_NONE		= 0,	/* unknown */
> +	PERF_BR_JCC		= 1,	/* conditional jump */
> +	PERF_BR_JMP		= 2,	/* jump */
> +	PERF_BR_IND_JMP		= 3,	/* indirect jump */
> +	PERF_BR_CALL		= 4,	/* call */
> +	PERF_BR_IND_CALL	= 5,	/* indirect call */
> +	PERF_BR_RET		= 6,	/* return */
> +	PERF_BR_SYSCALL		= 7,	/* syscall */
> +	PERF_BR_SYSRET		= 8,	/* syscall return */
> +	PERF_BR_IRQ		= 9,	/* hw interrupt/trap/fault */
> +	PERF_BR_INT		= 10,	/* sw interrupt */
> +	PERF_BR_IRET		= 11,	/* return from interrupt */
> +	PERF_BR_FAR_BRANCH	= 12,	/* not generic far branch type */
> +	PERF_BR_MAX,
> +};
> +
>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
>  	(PERF_SAMPLE_BRANCH_USER|\
>  	 PERF_SAMPLE_BRANCH_KERNEL|\
> @@ -999,6 +1024,7 @@ union perf_mem_data_src {
>   *     in_tx: running in a hardware transaction
>   *     abort: aborting a hardware transaction
>   *    cycles: cycles from last branch (or 0 if not supported)
> + *      type: branch type
>   */
>  struct perf_branch_entry {
>  	__u64	from;
> @@ -1008,7 +1034,8 @@ struct perf_branch_entry {
>  		in_tx:1,    /* in transaction */
>  		abort:1,    /* transaction abort */
>  		cycles:16,  /* cycle count to last branch */
> -		reserved:44;
> +		type:4,     /* branch type */
> +		reserved:40;
>  };
>  
>  #endif /* _UAPI_LINUX_PERF_EVENT_H */
> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
> index d09a9cd..69af012 100644
> --- a/tools/include/uapi/linux/perf_event.h
> +++ b/tools/include/uapi/linux/perf_event.h
> @@ -174,6 +174,8 @@ enum perf_branch_sample_type_shift {
>  	PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT	= 14, /* no flags */
>  	PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT	= 15, /* no cycles */
>  
> +	PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT	= 16, /* save branch type */
> +
>  	PERF_SAMPLE_BRANCH_MAX_SHIFT		/* non-ABI */
>  };
>  
> @@ -198,9 +200,32 @@ enum perf_branch_sample_type {
>  	PERF_SAMPLE_BRANCH_NO_FLAGS	= 1U << PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT,
>  	PERF_SAMPLE_BRANCH_NO_CYCLES	= 1U << PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT,
>  
> +	PERF_SAMPLE_BRANCH_TYPE_SAVE	=
> +		1U << PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT,
> +
>  	PERF_SAMPLE_BRANCH_MAX		= 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
>  };
>  
> +/*
> + * Common flow change classification
> + */
> +enum {
> +	PERF_BR_NONE		= 0,	/* unknown */
> +	PERF_BR_JCC		= 1,	/* conditional jump */
> +	PERF_BR_JMP		= 2,	/* jump */
> +	PERF_BR_IND_JMP		= 3,	/* indirect jump */
> +	PERF_BR_CALL		= 4,	/* call */
> +	PERF_BR_IND_CALL	= 5,	/* indirect call */
> +	PERF_BR_RET		= 6,	/* return */
> +	PERF_BR_SYSCALL		= 7,	/* syscall */
> +	PERF_BR_SYSRET		= 8,	/* syscall return */
> +	PERF_BR_IRQ		= 9,	/* hw interrupt/trap/fault */
> +	PERF_BR_INT		= 10,	/* sw interrupt */
> +	PERF_BR_IRET		= 11,	/* return from interrupt */
> +	PERF_BR_FAR_BRANCH	= 12,	/* not generic far branch type */
> +	PERF_BR_MAX,
> +};
> +
>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
>  	(PERF_SAMPLE_BRANCH_USER|\
>  	 PERF_SAMPLE_BRANCH_KERNEL|\
> @@ -999,6 +1024,7 @@ union perf_mem_data_src {
>   *     in_tx: running in a hardware transaction
>   *     abort: aborting a hardware transaction
>   *    cycles: cycles from last branch (or 0 if not supported)
> + *      type: branch type
>   */
>  struct perf_branch_entry {
>  	__u64	from;
> @@ -1008,7 +1034,8 @@ struct perf_branch_entry {
>  		in_tx:1,    /* in transaction */
>  		abort:1,    /* transaction abort */
>  		cycles:16,  /* cycle count to last branch */
> -		reserved:44;
> +		type:4,     /* branch type */
> +		reserved:40;
>  };
>  
>  #endif /* _UAPI_LINUX_PERF_EVENT_H */
> -- 
> 2.7.4
>