Commit 7a786832 authored by Michael Ellerman's avatar Michael Ellerman Committed by Benjamin Herrenschmidt
Browse files

powerpc/perf: Add an explict flag indicating presence of SLOT field

In perf_ip_adjust() we potentially use the MMCRA[SLOT] field to adjust
the reported IP of a sampled instruction.

Currently the logic is written so that if the backend does NOT have
the PPMU_ALT_SIPR flag set then we assume MMCRA[SLOT] exists.

However on power8 we do not want to set ALT_SIPR (it's in a third
location), and we also do not have MMCRA[SLOT].

So add a new flag which only indicates whether MMCRA[SLOT] exists.

Naively we'd set it on everything except power6/7, because they set
ALT_SIPR, and we've reversed the polarity of the flag. But it's more
complicated than that.

mpc7450 is 32-bit, and uses its own version of perf_ip_adjust()
which doesn't use MMCRA[SLOT], so it doesn't need the new flag set and
the behaviour is unchanged.

PPC970 (and I assume power4) don't have MMCRA[SLOT], so shouldn't have
the new flag set. This is a behaviour change on those cpus, though we
were probably getting lucky and the bits in question were 0.

power5 and power5+ set the new flag, behaviour unchanged.

power6 & power7 do not set the new flag, behaviour unchanged.

Signed-off-by: default avatarMichael Ellerman <>
Acked-by: default avatarPaul Mackerras <>
Signed-off-by: default avatarBenjamin Herrenschmidt <>
parent 240686c1
......@@ -52,6 +52,7 @@ struct power_pmu {
#define PPMU_NO_SIPR 0x00000004 /* no SIPR/HV in MMCRA at all */
#define PPMU_NO_CONT_SAMPLING 0x00000008 /* no continuous sampling */
#define PPMU_SIAR_VALID 0x00000010 /* Processor has SIAR Valid bit */
#define PPMU_HAS_SSLOT 0x00000020 /* Has sampled slot in MMCRA */
* Values for flags to get_alternatives()
......@@ -98,11 +98,12 @@ static inline unsigned long perf_ip_adjust(struct pt_regs *regs)
unsigned long mmcra = regs->dsisr;
if ((mmcra & MMCRA_SAMPLE_ENABLE) && !(ppmu->flags & PPMU_ALT_SIPR)) {
if ((ppmu->flags & PPMU_HAS_SSLOT) && (mmcra & MMCRA_SAMPLE_ENABLE)) {
unsigned long slot = (mmcra & MMCRA_SLOT) >> MMCRA_SLOT_SHIFT;
if (slot > 1)
return 4 * (slot - 1);
return 0;
......@@ -671,7 +671,7 @@ static struct power_pmu power5p_pmu = {
.get_alternatives = power5p_get_alternatives,
.disable_pmc = power5p_disable_pmc,
.limited_pmc_event = power5p_limited_pmc_event,
.flags = PPMU_LIMITED_PMC5_6,
.n_generic = ARRAY_SIZE(power5p_generic_events),
.generic_events = power5p_generic_events,
.cache_events = &power5p_cache_events,
......@@ -615,6 +615,7 @@ static struct power_pmu power5_pmu = {
.n_generic = ARRAY_SIZE(power5_generic_events),
.generic_events = power5_generic_events,
.cache_events = &power5_cache_events,
.flags = PPMU_HAS_SSLOT,
static int __init init_power5_pmu(void)
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