linux-kernel - Re: [PATCH v2 3/3] perf/sdt/powerpc: Add argument support

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Date:   Tue, 28 Mar 2017 00:10:47 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Cc:     acme@...hat.com, alexis.berlemont@...il.com,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        naveen.n.rao@...ux.vnet.ibm.com, mpe@...erman.id.au,
        hemant@...ux.vnet.ibm.com
Subject: Re: [PATCH v2 3/3] perf/sdt/powerpc: Add argument support

On Mon, 27 Mar 2017 13:28:29 +0530
Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com> wrote:

> SDT marker argument is in N@OP format. Here OP is arch dependent
> component. Add powerpc logic to parse OP and convert it to uprobe
> compatible format.

Looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

BTW, using regex to parse this short string is a good idea!

Thanks,

> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
> ---
>  tools/perf/arch/powerpc/util/perf_regs.c | 111 +++++++++++++++++++++++++++++++
>  1 file changed, 111 insertions(+)
> 
> diff --git a/tools/perf/arch/powerpc/util/perf_regs.c b/tools/perf/arch/powerpc/util/perf_regs.c
> index a3c3e1c..4268f77 100644
> --- a/tools/perf/arch/powerpc/util/perf_regs.c
> +++ b/tools/perf/arch/powerpc/util/perf_regs.c
> @@ -1,5 +1,10 @@
> +#include <string.h>
> +#include <regex.h>
> +
>  #include "../../perf.h"
> +#include "../../util/util.h"
>  #include "../../util/perf_regs.h"
> +#include "../../util/debug.h"
>  
>  const struct sample_reg sample_reg_masks[] = {
>  	SMPL_REG(r0, PERF_REG_POWERPC_R0),
> @@ -47,3 +52,109 @@ const struct sample_reg sample_reg_masks[] = {
>  	SMPL_REG(dsisr, PERF_REG_POWERPC_DSISR),
>  	SMPL_REG_END
>  };
> +
> +/* REG or %rREG */
> +#define SDT_OP_REGEX1  "^(%r)?([1-2]?[0-9]|3[0-1])$"
> +
> +/* -NUM(REG) or NUM(REG) or -NUM(%rREG) or NUM(%rREG) */
> +#define SDT_OP_REGEX2  "^(\\-)?([0-9]+)\\((%r)?([1-2]?[0-9]|3[0-1])\\)$"
> +
> +static regex_t sdt_op_regex1, sdt_op_regex2;
> +
> +static int sdt_init_op_regex(void)
> +{
> +	static int initialized;
> +	int ret = 0;
> +
> +	if (initialized)
> +		return 0;
> +
> +	ret = regcomp(&sdt_op_regex1, SDT_OP_REGEX1, REG_EXTENDED);
> +	if (ret)
> +		goto error;
> +
> +	ret = regcomp(&sdt_op_regex2, SDT_OP_REGEX2, REG_EXTENDED);
> +	if (ret)
> +		goto free_regex1;
> +
> +	initialized = 1;
> +	return 0;
> +
> +free_regex1:
> +	regfree(&sdt_op_regex1);
> +error:
> +	pr_debug4("Regex compilation error.\n");
> +	return ret;
> +}
> +
> +/*
> + * Parse OP and convert it into uprobe format, which is, +/-NUM(%gprREG).
> + * Possible variants of OP are:
> + *	Format		Example
> + *	-------------------------
> + *	NUM(REG)	48(18)
> + *	-NUM(REG)	-48(18)
> + *	NUM(%rREG)	48(%r18)
> + *	-NUM(%rREG)	-48(%r18)
> + *	REG		18
> + *	%rREG		%r18
> + *	iNUM		i0
> + *	i-NUM		i-1
> + *
> + * SDT marker arguments on Powerpc uses %rREG form with -mregnames flag
> + * and REG form with -mno-regnames. Here REG is general purpose register,
> + * which is in 0 to 31 range.
> + */
> +int arch_sdt_arg_parse_op(char *old_op, char **new_op)
> +{
> +	int ret, new_len;
> +	regmatch_t rm[5];
> +	char prefix;
> +
> +	/* Constant argument. Uprobe does not support it */
> +	if (old_op[0] == 'i') {
> +		pr_debug4("Skipping unsupported SDT argument: %s\n", old_op);
> +		return SDT_ARG_SKIP;
> +	}
> +
> +	ret = sdt_init_op_regex();
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!regexec(&sdt_op_regex1, old_op, 3, rm, 0)) {
> +		/* REG or %rREG --> %gprREG */
> +
> +		new_len = 5;	/* % g p r NULL */
> +		new_len += (int)(rm[2].rm_eo - rm[2].rm_so);
> +
> +		*new_op = zalloc(new_len);
> +		if (!*new_op)
> +			return -ENOMEM;
> +
> +		scnprintf(*new_op, new_len, "%%gpr%.*s",
> +			(int)(rm[2].rm_eo - rm[2].rm_so), old_op + rm[2].rm_so);
> +	} else if (!regexec(&sdt_op_regex2, old_op, 5, rm, 0)) {
> +		/*
> +		 * -NUM(REG) or NUM(REG) or -NUM(%rREG) or NUM(%rREG) -->
> +		 *	+/-NUM(%gprREG)
> +		 */
> +		prefix = (rm[1].rm_so == -1) ? '+' : '-';
> +
> +		new_len = 8;	/* +/- ( % g p r ) NULL */
> +		new_len += (int)(rm[2].rm_eo - rm[2].rm_so);
> +		new_len += (int)(rm[4].rm_eo - rm[4].rm_so);
> +
> +		*new_op = zalloc(new_len);
> +		if (!*new_op)
> +			return -ENOMEM;
> +
> +		scnprintf(*new_op, new_len, "%c%.*s(%%gpr%.*s)", prefix,
> +			(int)(rm[2].rm_eo - rm[2].rm_so), old_op + rm[2].rm_so,
> +			(int)(rm[4].rm_eo - rm[4].rm_so), old_op + rm[4].rm_so);
> +	} else {
> +		pr_debug4("Skipping unsupported SDT argument: %s\n", old_op);
> +		return SDT_ARG_SKIP;
> +	}
> +
> +	return SDT_ARG_VALID;
> +}
> -- 
> 2.9.3
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>