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Commit 443e802b authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Martin Schwidefsky
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s390/cpum_sf: Detect KVM guest samples 



The host-program-parameter (hpp) value of basic sample-data-entries designates
a SIE control block that is set by the LPP instruction in sie64a().
Non-zero values indicate guest samples, a value of zero indicates a host sample.

For perf samples, host and guest samples are distinguished using particular
PERF_MISC_* flags.  The perf layer calls perf_misc_flags() to set the flags
based on the pt_regs content.  For each sample-data-entry, the cpum_sf PMU
creates a pt_regs structure with the sample-data information.  An additional
flag structure is added to easily distinguish between host and guest samples.

Signed-off-by: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 443d4beb

arch/s390/include/asm/perf_event.h

+6 −0
Original line number Diff line number Diff line
@@ -42,6 +42,12 @@ extern unsigned long perf_instruction_pointer(struct pt_regs *regs); 
extern unsigned long perf_misc_flags(struct pt_regs *regs);

#define perf_misc_flags(regs) perf_misc_flags(regs)



/* Perf pt_regs extension for sample-data-entry indicators */

struct perf_sf_sde_regs {

	unsigned char in_guest:1;	  /* guest sample */

	unsigned long reserved:63;	  /* reserved */

};



/* Perf PMU definitions for the counter facility */

#define PERF_CPUM_CF_MAX_CTR		256

arch/s390/kernel/perf_cpum_sf.c

+20 −0
Original line number Diff line number Diff line
@@ -840,6 +840,7 @@ static int perf_push_sample(struct perf_event *event, 
{

	int overflow;

	struct pt_regs regs;

	struct perf_sf_sde_regs *sde_regs;

	struct perf_sample_data data;



	/* Skip samples that are invalid or for which the instruction address
@@ -850,7 +851,16 @@ static int perf_push_sample(struct perf_event *event, 


	perf_sample_data_init(&data, 0, event->hw.last_period);



	/* Setup pt_regs to look like an CPU-measurement external interrupt

	 * using the Program Request Alert code.  The regs.int_parm_long

	 * field which is unused contains additional sample-data-entry related

	 * indicators.

	 */

	memset(&regs, 0, sizeof(regs));

	regs.int_code = 0x1407;

	regs.int_parm = CPU_MF_INT_SF_PRA;

	sde_regs = (struct perf_sf_sde_regs *) &regs.int_parm_long;



	regs.psw.addr = sample->ia;

	if (sample->T)

		regs.psw.mask |= PSW_MASK_DAT;
@@ -873,6 +883,16 @@ static int perf_push_sample(struct perf_event *event, 
		break;

	}



	/* The host-program-parameter (hpp) contains the sie control

	 * block that is set by sie64a() in entry64.S.	Check if hpp

	 * refers to a valid control block and set sde_regs flags

	 * accordingly.  This would allow to use hpp values for other

	 * purposes too.

	 * For now, simply use a non-zero value as guest indicator.

	 */

	if (sample->hpp)

		sde_regs->in_guest = 1;



	overflow = 0;

	if (perf_event_overflow(event, &data, &regs)) {

		overflow = 1;

arch/s390/kernel/perf_event.c

+24 −1
Original line number Diff line number Diff line 
/*

 * Performance event support for s390x

 *

 *  Copyright IBM Corp. 2012

 *  Copyright IBM Corp. 2012, 2013

 *  Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>

 *

 * This program is free software; you can redistribute it and/or modify
@@ -89,8 +89,31 @@ static unsigned long perf_misc_guest_flags(struct pt_regs *regs) 
					: PERF_RECORD_MISC_GUEST_KERNEL;

}



static unsigned long perf_misc_flags_sf(struct pt_regs *regs)

{

	struct perf_sf_sde_regs *sde_regs;

	unsigned long flags;



	sde_regs = (struct perf_sf_sde_regs *) &regs->int_parm_long;

	if (sde_regs->in_guest)

		flags = user_mode(regs) ? PERF_RECORD_MISC_GUEST_USER

					: PERF_RECORD_MISC_GUEST_KERNEL;

	else

		flags = user_mode(regs) ? PERF_RECORD_MISC_USER

					: PERF_RECORD_MISC_KERNEL;

	return flags;

}



unsigned long perf_misc_flags(struct pt_regs *regs)

{

	/* Check if the cpum_sf PMU has created the pt_regs structure.

	 * In this case, perf misc flags can be easily extracted.  Otherwise,

	 * do regular checks on the pt_regs content.

	 */

	if (regs->int_code == 0x1407 && regs->int_parm == CPU_MF_INT_SF_PRA)

		if (!regs->gprs[15])

			return perf_misc_flags_sf(regs);



	if (is_in_guest(regs))

		return perf_misc_guest_flags(regs);