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s390/cpum_sf: Detect KVM guest samples

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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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Hendrik Brueckner 2013-12-12 17:54:57 +01:00 committed by Martin Schwidefsky
parent 443d4beb82
commit 443e802bab
3 changed files with 50 additions and 1 deletions
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6
arch/s390/include/asm/perf_event.h
View file

@ -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

20
arch/s390/kernel/perf_cpum_sf.c
View file

@ -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;

25
arch/s390/kernel/perf_event.c
View file

@ -1,7 +1,7 @@
/*
* 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);