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tegrakernel/kernel/kernel-4.9/arch/x86/events/intel/lbr.c

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initial commit tegra kernel 32.6.1
2022-02-16 09:13:02 -06:00
#include <linux/perf_event.h>
#include <linux/types.h>
#include <asm/perf_event.h>
#include <asm/msr.h>
#include <asm/insn.h>
#include "../perf_event.h"
enum {
LBR_FORMAT_32 = 0x00,
LBR_FORMAT_LIP = 0x01,
LBR_FORMAT_EIP = 0x02,
LBR_FORMAT_EIP_FLAGS = 0x03,
LBR_FORMAT_EIP_FLAGS2 = 0x04,
LBR_FORMAT_INFO = 0x05,
LBR_FORMAT_TIME = 0x06,
LBR_FORMAT_MAX_KNOWN = LBR_FORMAT_TIME,
};
static enum {
LBR_EIP_FLAGS = 1,
LBR_TSX = 2,
} lbr_desc[LBR_FORMAT_MAX_KNOWN + 1] = {
[LBR_FORMAT_EIP_FLAGS] = LBR_EIP_FLAGS,
[LBR_FORMAT_EIP_FLAGS2] = LBR_EIP_FLAGS | LBR_TSX,
};
/*
* Intel LBR_SELECT bits
* Intel Vol3a, April 2011, Section 16.7 Table 16-10
*
* Hardware branch filter (not available on all CPUs)
*/
#define LBR_KERNEL_BIT 0 /* do not capture at ring0 */
#define LBR_USER_BIT 1 /* do not capture at ring > 0 */
#define LBR_JCC_BIT 2 /* do not capture conditional branches */
#define LBR_REL_CALL_BIT 3 /* do not capture relative calls */
#define LBR_IND_CALL_BIT 4 /* do not capture indirect calls */
#define LBR_RETURN_BIT 5 /* do not capture near returns */
#define LBR_IND_JMP_BIT 6 /* do not capture indirect jumps */
#define LBR_REL_JMP_BIT 7 /* do not capture relative jumps */
#define LBR_FAR_BIT 8 /* do not capture far branches */
#define LBR_CALL_STACK_BIT 9 /* enable call stack */
/*
* Following bit only exists in Linux; we mask it out before writing it to
* the actual MSR. But it helps the constraint perf code to understand
* that this is a separate configuration.
*/
#define LBR_NO_INFO_BIT 63 /* don't read LBR_INFO. */
#define LBR_KERNEL (1 << LBR_KERNEL_BIT)
#define LBR_USER (1 << LBR_USER_BIT)
#define LBR_JCC (1 << LBR_JCC_BIT)
#define LBR_REL_CALL (1 << LBR_REL_CALL_BIT)
#define LBR_IND_CALL (1 << LBR_IND_CALL_BIT)
#define LBR_RETURN (1 << LBR_RETURN_BIT)
#define LBR_REL_JMP (1 << LBR_REL_JMP_BIT)
#define LBR_IND_JMP (1 << LBR_IND_JMP_BIT)
#define LBR_FAR (1 << LBR_FAR_BIT)
#define LBR_CALL_STACK (1 << LBR_CALL_STACK_BIT)
#define LBR_NO_INFO (1ULL << LBR_NO_INFO_BIT)
#define LBR_PLM (LBR_KERNEL | LBR_USER)
#define LBR_SEL_MASK 0x3ff /* valid bits in LBR_SELECT */
#define LBR_NOT_SUPP -1 /* LBR filter not supported */
#define LBR_IGN 0 /* ignored */
#define LBR_ANY \
(LBR_JCC |\
LBR_REL_CALL |\
LBR_IND_CALL |\
LBR_RETURN |\
LBR_REL_JMP |\
LBR_IND_JMP |\
LBR_FAR)
#define LBR_FROM_FLAG_MISPRED BIT_ULL(63)
#define LBR_FROM_FLAG_IN_TX BIT_ULL(62)
#define LBR_FROM_FLAG_ABORT BIT_ULL(61)
#define LBR_FROM_SIGNEXT_2MSB (BIT_ULL(60) | BIT_ULL(59))
/*
* x86control flow change classification
* x86control flow changes include branches, interrupts, traps, faults
*/
enum {
X86_BR_NONE = 0, /* unknown */
X86_BR_USER = 1 << 0, /* branch target is user */
X86_BR_KERNEL = 1 << 1, /* branch target is kernel */
X86_BR_CALL = 1 << 2, /* call */
X86_BR_RET = 1 << 3, /* return */
X86_BR_SYSCALL = 1 << 4, /* syscall */
X86_BR_SYSRET = 1 << 5, /* syscall return */
X86_BR_INT = 1 << 6, /* sw interrupt */
X86_BR_IRET = 1 << 7, /* return from interrupt */
X86_BR_JCC = 1 << 8, /* conditional */
X86_BR_JMP = 1 << 9, /* jump */
X86_BR_IRQ = 1 << 10,/* hw interrupt or trap or fault */
X86_BR_IND_CALL = 1 << 11,/* indirect calls */
X86_BR_ABORT = 1 << 12,/* transaction abort */
X86_BR_IN_TX = 1 << 13,/* in transaction */
X86_BR_NO_TX = 1 << 14,/* not in transaction */
X86_BR_ZERO_CALL = 1 << 15,/* zero length call */
X86_BR_CALL_STACK = 1 << 16,/* call stack */
X86_BR_IND_JMP = 1 << 17,/* indirect jump */
};
#define X86_BR_PLM (X86_BR_USER | X86_BR_KERNEL)
#define X86_BR_ANYTX (X86_BR_NO_TX | X86_BR_IN_TX)
#define X86_BR_ANY \
(X86_BR_CALL |\
X86_BR_RET |\
X86_BR_SYSCALL |\
X86_BR_SYSRET |\
X86_BR_INT |\
X86_BR_IRET |\
X86_BR_JCC |\
X86_BR_JMP |\
X86_BR_IRQ |\
X86_BR_ABORT |\
X86_BR_IND_CALL |\
X86_BR_IND_JMP |\
X86_BR_ZERO_CALL)
#define X86_BR_ALL (X86_BR_PLM | X86_BR_ANY)
#define X86_BR_ANY_CALL \
(X86_BR_CALL |\
X86_BR_IND_CALL |\
X86_BR_ZERO_CALL |\
X86_BR_SYSCALL |\
X86_BR_IRQ |\
X86_BR_INT)
static void intel_pmu_lbr_filter(struct cpu_hw_events *cpuc);
/*
* We only support LBR implementations that have FREEZE_LBRS_ON_PMI
* otherwise it becomes near impossible to get a reliable stack.
*/
static void __intel_pmu_lbr_enable(bool pmi)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
u64 debugctl, lbr_select = 0, orig_debugctl;
/*
* No need to unfreeze manually, as v4 can do that as part
* of the GLOBAL_STATUS ack.
*/
if (pmi && x86_pmu.version >= 4)
return;
/*
* No need to reprogram LBR_SELECT in a PMI, as it
* did not change.
*/
if (cpuc->lbr_sel)
lbr_select = cpuc->lbr_sel->config & x86_pmu.lbr_sel_mask;
if (!pmi && cpuc->lbr_sel)
wrmsrl(MSR_LBR_SELECT, lbr_select);
rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
orig_debugctl = debugctl;
debugctl |= DEBUGCTLMSR_LBR;
/*
* LBR callstack does not work well with FREEZE_LBRS_ON_PMI.
* If FREEZE_LBRS_ON_PMI is set, PMI near call/return instructions
* may cause superfluous increase/decrease of LBR_TOS.
*/
if (!(lbr_select & LBR_CALL_STACK))
debugctl |= DEBUGCTLMSR_FREEZE_LBRS_ON_PMI;
if (orig_debugctl != debugctl)
wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
}
static void __intel_pmu_lbr_disable(void)
{
u64 debugctl;
rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
debugctl &= ~(DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI);
wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
}
static void intel_pmu_lbr_reset_32(void)
{
int i;
for (i = 0; i < x86_pmu.lbr_nr; i++)
wrmsrl(x86_pmu.lbr_from + i, 0);
}
static void intel_pmu_lbr_reset_64(void)
{
int i;
for (i = 0; i < x86_pmu.lbr_nr; i++) {
wrmsrl(x86_pmu.lbr_from + i, 0);
wrmsrl(x86_pmu.lbr_to + i, 0);
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
wrmsrl(MSR_LBR_INFO_0 + i, 0);
}
}
void intel_pmu_lbr_reset(void)
{
if (!x86_pmu.lbr_nr)
return;
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_32)
intel_pmu_lbr_reset_32();
else
intel_pmu_lbr_reset_64();
}
/*
* TOS = most recently recorded branch
*/
static inline u64 intel_pmu_lbr_tos(void)
{
u64 tos;
rdmsrl(x86_pmu.lbr_tos, tos);
return tos;
}
enum {
LBR_NONE,
LBR_VALID,
};
/*
* For formats with LBR_TSX flags (e.g. LBR_FORMAT_EIP_FLAGS2), bits 61:62 in
* MSR_LAST_BRANCH_FROM_x are the TSX flags when TSX is supported, but when
* TSX is not supported they have no consistent behavior:
*
* - For wrmsr(), bits 61:62 are considered part of the sign extension.
* - For HW updates (branch captures) bits 61:62 are always OFF and are not
* part of the sign extension.
*
* Therefore, if:
*
* 1) LBR has TSX format
* 2) CPU has no TSX support enabled
*
* ... then any value passed to wrmsr() must be sign extended to 63 bits and any
* value from rdmsr() must be converted to have a 61 bits sign extension,
* ignoring the TSX flags.
*/
static inline bool lbr_from_signext_quirk_needed(void)
{
int lbr_format = x86_pmu.intel_cap.lbr_format;
bool tsx_support = boot_cpu_has(X86_FEATURE_HLE) ||
boot_cpu_has(X86_FEATURE_RTM);
return !tsx_support && (lbr_desc[lbr_format] & LBR_TSX);
}
DEFINE_STATIC_KEY_FALSE(lbr_from_quirk_key);
/* If quirk is enabled, ensure sign extension is 63 bits: */
inline u64 lbr_from_signext_quirk_wr(u64 val)
{
if (static_branch_unlikely(&lbr_from_quirk_key)) {
/*
* Sign extend into bits 61:62 while preserving bit 63.
*
* Quirk is enabled when TSX is disabled. Therefore TSX bits
* in val are always OFF and must be changed to be sign
* extension bits. Since bits 59:60 are guaranteed to be
* part of the sign extension bits, we can just copy them
* to 61:62.
*/
val |= (LBR_FROM_SIGNEXT_2MSB & val) << 2;
}
return val;
}
/*
* If quirk is needed, ensure sign extension is 61 bits:
*/
u64 lbr_from_signext_quirk_rd(u64 val)
{
if (static_branch_unlikely(&lbr_from_quirk_key)) {
/*
* Quirk is on when TSX is not enabled. Therefore TSX
* flags must be read as OFF.
*/
val &= ~(LBR_FROM_FLAG_IN_TX | LBR_FROM_FLAG_ABORT);
}
return val;
}
static inline void wrlbr_from(unsigned int idx, u64 val)
{
val = lbr_from_signext_quirk_wr(val);
wrmsrl(x86_pmu.lbr_from + idx, val);
}
static inline void wrlbr_to(unsigned int idx, u64 val)
{
wrmsrl(x86_pmu.lbr_to + idx, val);
}
static inline u64 rdlbr_from(unsigned int idx)
{
u64 val;
rdmsrl(x86_pmu.lbr_from + idx, val);
return lbr_from_signext_quirk_rd(val);
}
static inline u64 rdlbr_to(unsigned int idx)
{
u64 val;
rdmsrl(x86_pmu.lbr_to + idx, val);
return val;
}
static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
{
int i;
unsigned lbr_idx, mask;
u64 tos;
if (task_ctx->lbr_callstack_users == 0 ||
task_ctx->lbr_stack_state == LBR_NONE) {
intel_pmu_lbr_reset();
return;
}
mask = x86_pmu.lbr_nr - 1;
tos = task_ctx->tos;
for (i = 0; i < task_ctx->valid_lbrs; i++) {
lbr_idx = (tos - i) & mask;
wrlbr_from(lbr_idx, task_ctx->lbr_from[i]);
wrlbr_to (lbr_idx, task_ctx->lbr_to[i]);
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
wrmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]);
}
for (; i < x86_pmu.lbr_nr; i++) {
lbr_idx = (tos - i) & mask;
wrlbr_from(lbr_idx, 0);
wrlbr_to(lbr_idx, 0);
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
wrmsrl(MSR_LBR_INFO_0 + lbr_idx, 0);
}
wrmsrl(x86_pmu.lbr_tos, tos);
task_ctx->lbr_stack_state = LBR_NONE;
}
static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
{
unsigned lbr_idx, mask;
u64 tos, from;
int i;
if (task_ctx->lbr_callstack_users == 0) {
task_ctx->lbr_stack_state = LBR_NONE;
return;
}
mask = x86_pmu.lbr_nr - 1;
tos = intel_pmu_lbr_tos();
for (i = 0; i < x86_pmu.lbr_nr; i++) {
lbr_idx = (tos - i) & mask;
from = rdlbr_from(lbr_idx);
if (!from)
break;
task_ctx->lbr_from[i] = from;
task_ctx->lbr_to[i] = rdlbr_to(lbr_idx);
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
rdmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]);
}
task_ctx->valid_lbrs = i;
task_ctx->tos = tos;
task_ctx->lbr_stack_state = LBR_VALID;
}
void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in)
{
struct x86_perf_task_context *task_ctx;
/*
* If LBR callstack feature is enabled and the stack was saved when
* the task was scheduled out, restore the stack. Otherwise flush
* the LBR stack.
*/
task_ctx = ctx ? ctx->task_ctx_data : NULL;
if (task_ctx) {
if (sched_in)
__intel_pmu_lbr_restore(task_ctx);
else
__intel_pmu_lbr_save(task_ctx);
return;
}
/*
* Since a context switch can flip the address space and LBR entries
* are not tagged with an identifier, we need to wipe the LBR, even for
* per-cpu events. You simply cannot resolve the branches from the old
* address space.
*/
if (sched_in)
intel_pmu_lbr_reset();
}
static inline bool branch_user_callstack(unsigned br_sel)
{
return (br_sel & X86_BR_USER) && (br_sel & X86_BR_CALL_STACK);
}
void intel_pmu_lbr_add(struct perf_event *event)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct x86_perf_task_context *task_ctx;
if (!x86_pmu.lbr_nr)
return;
cpuc->br_sel = event->hw.branch_reg.reg;
if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data) {
task_ctx = event->ctx->task_ctx_data;
task_ctx->lbr_callstack_users++;
}
/*
* Request pmu::sched_task() callback, which will fire inside the
* regular perf event scheduling, so that call will:
*
* - restore or wipe; when LBR-callstack,
* - wipe; otherwise,
*
* when this is from __perf_event_task_sched_in().
*
* However, if this is from perf_install_in_context(), no such callback
* will follow and we'll need to reset the LBR here if this is the
* first LBR event.
*
* The problem is, we cannot tell these cases apart... but we can
* exclude the biggest chunk of cases by looking at
* event->total_time_running. An event that has accrued runtime cannot
* be 'new'. Conversely, a new event can get installed through the
* context switch path for the first time.
*/
perf_sched_cb_inc(event->ctx->pmu);
if (!cpuc->lbr_users++ && !event->total_time_running)
intel_pmu_lbr_reset();
}
void intel_pmu_lbr_del(struct perf_event *event)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct x86_perf_task_context *task_ctx;
if (!x86_pmu.lbr_nr)
return;
if (branch_user_callstack(cpuc->br_sel) &&
event->ctx->task_ctx_data) {
task_ctx = event->ctx->task_ctx_data;
task_ctx->lbr_callstack_users--;
}
cpuc->lbr_users--;
WARN_ON_ONCE(cpuc->lbr_users < 0);
perf_sched_cb_dec(event->ctx->pmu);
}
void intel_pmu_lbr_enable_all(bool pmi)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
if (cpuc->lbr_users)
__intel_pmu_lbr_enable(pmi);
}
void intel_pmu_lbr_disable_all(void)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
if (cpuc->lbr_users)
__intel_pmu_lbr_disable();
}
static void intel_pmu_lbr_read_32(struct cpu_hw_events *cpuc)
{
unsigned long mask = x86_pmu.lbr_nr - 1;
u64 tos = intel_pmu_lbr_tos();
int i;
for (i = 0; i < x86_pmu.lbr_nr; i++) {
unsigned long lbr_idx = (tos - i) & mask;
union {
struct {
u32 from;
u32 to;
};
u64 lbr;
} msr_lastbranch;
rdmsrl(x86_pmu.lbr_from + lbr_idx, msr_lastbranch.lbr);
cpuc->lbr_entries[i].from = msr_lastbranch.from;
cpuc->lbr_entries[i].to = msr_lastbranch.to;
cpuc->lbr_entries[i].mispred = 0;
cpuc->lbr_entries[i].predicted = 0;
cpuc->lbr_entries[i].in_tx = 0;
cpuc->lbr_entries[i].abort = 0;
cpuc->lbr_entries[i].cycles = 0;
cpuc->lbr_entries[i].reserved = 0;
}
cpuc->lbr_stack.nr = i;
}
/*
* Due to lack of segmentation in Linux the effective address (offset)
* is the same as the linear address, allowing us to merge the LIP and EIP
* LBR formats.
*/
static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc)
{
bool need_info = false, call_stack = false;
unsigned long mask = x86_pmu.lbr_nr - 1;
int lbr_format = x86_pmu.intel_cap.lbr_format;
u64 tos = intel_pmu_lbr_tos();
int i;
int out = 0;
int num = x86_pmu.lbr_nr;
if (cpuc->lbr_sel) {
need_info = !(cpuc->lbr_sel->config & LBR_NO_INFO);
if (cpuc->lbr_sel->config & LBR_CALL_STACK)
call_stack = true;
}
for (i = 0; i < num; i++) {
unsigned long lbr_idx = (tos - i) & mask;
u64 from, to, mis = 0, pred = 0, in_tx = 0, abort = 0;
int skip = 0;
u16 cycles = 0;
int lbr_flags = lbr_desc[lbr_format];
from = rdlbr_from(lbr_idx);
to = rdlbr_to(lbr_idx);
/*
* Read LBR call stack entries
* until invalid entry (0s) is detected.
*/
if (call_stack && !from)
break;
if (lbr_format == LBR_FORMAT_INFO && need_info) {
u64 info;
rdmsrl(MSR_LBR_INFO_0 + lbr_idx, info);
mis = !!(info & LBR_INFO_MISPRED);
pred = !mis;
in_tx = !!(info & LBR_INFO_IN_TX);
abort = !!(info & LBR_INFO_ABORT);
cycles = (info & LBR_INFO_CYCLES);
}
if (lbr_format == LBR_FORMAT_TIME) {
mis = !!(from & LBR_FROM_FLAG_MISPRED);
pred = !mis;
skip = 1;
cycles = ((to >> 48) & LBR_INFO_CYCLES);
to = (u64)((((s64)to) << 16) >> 16);
}
if (lbr_flags & LBR_EIP_FLAGS) {
mis = !!(from & LBR_FROM_FLAG_MISPRED);
pred = !mis;
skip = 1;
}
if (lbr_flags & LBR_TSX) {
in_tx = !!(from & LBR_FROM_FLAG_IN_TX);
abort = !!(from & LBR_FROM_FLAG_ABORT);
skip = 3;
}
from = (u64)((((s64)from) << skip) >> skip);
/*
* Some CPUs report duplicated abort records,
* with the second entry not having an abort bit set.
* Skip them here. This loop runs backwards,
* so we need to undo the previous record.
* If the abort just happened outside the window
* the extra entry cannot be removed.
*/
if (abort && x86_pmu.lbr_double_abort && out > 0)
out--;
cpuc->lbr_entries[out].from = from;
cpuc->lbr_entries[out].to = to;
cpuc->lbr_entries[out].mispred = mis;
cpuc->lbr_entries[out].predicted = pred;
cpuc->lbr_entries[out].in_tx = in_tx;
cpuc->lbr_entries[out].abort = abort;
cpuc->lbr_entries[out].cycles = cycles;
cpuc->lbr_entries[out].reserved = 0;
out++;
}
cpuc->lbr_stack.nr = out;
}
void intel_pmu_lbr_read(void)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
if (!cpuc->lbr_users)
return;
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_32)
intel_pmu_lbr_read_32(cpuc);
else
intel_pmu_lbr_read_64(cpuc);
intel_pmu_lbr_filter(cpuc);
}
/*
* SW filter is used:
* - in case there is no HW filter
* - in case the HW filter has errata or limitations
*/
static int intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
{
u64 br_type = event->attr.branch_sample_type;
int mask = 0;
if (br_type & PERF_SAMPLE_BRANCH_USER)
mask |= X86_BR_USER;
if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
mask |= X86_BR_KERNEL;
/* we ignore BRANCH_HV here */
if (br_type & PERF_SAMPLE_BRANCH_ANY)
mask |= X86_BR_ANY;
if (br_type & PERF_SAMPLE_BRANCH_ANY_CALL)
mask |= X86_BR_ANY_CALL;
if (br_type & PERF_SAMPLE_BRANCH_ANY_RETURN)
mask |= X86_BR_RET | X86_BR_IRET | X86_BR_SYSRET;
if (br_type & PERF_SAMPLE_BRANCH_IND_CALL)
mask |= X86_BR_IND_CALL;
if (br_type & PERF_SAMPLE_BRANCH_ABORT_TX)
mask |= X86_BR_ABORT;
if (br_type & PERF_SAMPLE_BRANCH_IN_TX)
mask |= X86_BR_IN_TX;
if (br_type & PERF_SAMPLE_BRANCH_NO_TX)
mask |= X86_BR_NO_TX;
if (br_type & PERF_SAMPLE_BRANCH_COND)
mask |= X86_BR_JCC;
if (br_type & PERF_SAMPLE_BRANCH_CALL_STACK) {
if (!x86_pmu_has_lbr_callstack())
return -EOPNOTSUPP;
if (mask & ~(X86_BR_USER | X86_BR_KERNEL))
return -EINVAL;
mask |= X86_BR_CALL | X86_BR_IND_CALL | X86_BR_RET |
X86_BR_CALL_STACK;
}
if (br_type & PERF_SAMPLE_BRANCH_IND_JUMP)
mask |= X86_BR_IND_JMP;
if (br_type & PERF_SAMPLE_BRANCH_CALL)
mask |= X86_BR_CALL | X86_BR_ZERO_CALL;
/*
* stash actual user request into reg, it may
* be used by fixup code for some CPU
*/
event->hw.branch_reg.reg = mask;
return 0;
}
/*
* setup the HW LBR filter
* Used only when available, may not be enough to disambiguate
* all branches, may need the help of the SW filter
*/
static int intel_pmu_setup_hw_lbr_filter(struct perf_event *event)
{
struct hw_perf_event_extra *reg;
u64 br_type = event->attr.branch_sample_type;
u64 mask = 0, v;
int i;
for (i = 0; i < PERF_SAMPLE_BRANCH_MAX_SHIFT; i++) {
if (!(br_type & (1ULL << i)))
continue;
v = x86_pmu.lbr_sel_map[i];
if (v == LBR_NOT_SUPP)
return -EOPNOTSUPP;
if (v != LBR_IGN)
mask |= v;
}
reg = &event->hw.branch_reg;
reg->idx = EXTRA_REG_LBR;
/*
* The first 9 bits (LBR_SEL_MASK) in LBR_SELECT operate
* in suppress mode. So LBR_SELECT should be set to
* (~mask & LBR_SEL_MASK) | (mask & ~LBR_SEL_MASK)
* But the 10th bit LBR_CALL_STACK does not operate
* in suppress mode.
*/
reg->config = mask ^ (x86_pmu.lbr_sel_mask & ~LBR_CALL_STACK);
if ((br_type & PERF_SAMPLE_BRANCH_NO_CYCLES) &&
(br_type & PERF_SAMPLE_BRANCH_NO_FLAGS) &&
(x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO))
reg->config |= LBR_NO_INFO;
return 0;
}
int intel_pmu_setup_lbr_filter(struct perf_event *event)
{
int ret = 0;
/*
* no LBR on this PMU
*/
if (!x86_pmu.lbr_nr)
return -EOPNOTSUPP;
/*
* setup SW LBR filter
*/
ret = intel_pmu_setup_sw_lbr_filter(event);
if (ret)
return ret;
/*
* setup HW LBR filter, if any
*/
if (x86_pmu.lbr_sel_map)
ret = intel_pmu_setup_hw_lbr_filter(event);
return ret;
}
/*
* return the type of control flow change at address "from"
* instruction is not necessarily a branch (in case of interrupt).
*
* The branch type returned also includes the priv level of the
* target of the control flow change (X86_BR_USER, X86_BR_KERNEL).
*
* If a branch type is unknown OR the instruction cannot be
* decoded (e.g., text page not present), then X86_BR_NONE is
* returned.
*/
static int branch_type(unsigned long from, unsigned long to, int abort)
{
struct insn insn;
void *addr;
int bytes_read, bytes_left;
int ret = X86_BR_NONE;
int ext, to_plm, from_plm;
u8 buf[MAX_INSN_SIZE];
int is64 = 0;
to_plm = kernel_ip(to) ? X86_BR_KERNEL : X86_BR_USER;
from_plm = kernel_ip(from) ? X86_BR_KERNEL : X86_BR_USER;
/*
* maybe zero if lbr did not fill up after a reset by the time
* we get a PMU interrupt
*/
if (from == 0 || to == 0)
return X86_BR_NONE;
if (abort)
return X86_BR_ABORT | to_plm;
if (from_plm == X86_BR_USER) {
/*
* can happen if measuring at the user level only
* and we interrupt in a kernel thread, e.g., idle.
*/
if (!current->mm)
return X86_BR_NONE;
/* may fail if text not present */
bytes_left = copy_from_user_nmi(buf, (void __user *)from,
MAX_INSN_SIZE);
bytes_read = MAX_INSN_SIZE - bytes_left;
if (!bytes_read)
return X86_BR_NONE;
addr = buf;
} else {
/*
* The LBR logs any address in the IP, even if the IP just
* faulted. This means userspace can control the from address.
* Ensure we don't blindy read any address by validating it is
* a known text address.
*/
if (kernel_text_address(from)) {
addr = (void *)from;
/*
* Assume we can get the maximum possible size
* when grabbing kernel data. This is not
* _strictly_ true since we could possibly be
* executing up next to a memory hole, but
* it is very unlikely to be a problem.
*/
bytes_read = MAX_INSN_SIZE;
} else {
return X86_BR_NONE;
}
}
/*
* decoder needs to know the ABI especially
* on 64-bit systems running 32-bit apps
*/
#ifdef CONFIG_X86_64
is64 = kernel_ip((unsigned long)addr) || !test_thread_flag(TIF_IA32);
#endif
insn_init(&insn, addr, bytes_read, is64);
insn_get_opcode(&insn);
if (!insn.opcode.got)
return X86_BR_ABORT;
switch (insn.opcode.bytes[0]) {
case 0xf:
switch (insn.opcode.bytes[1]) {
case 0x05: /* syscall */
case 0x34: /* sysenter */
ret = X86_BR_SYSCALL;
break;
case 0x07: /* sysret */
case 0x35: /* sysexit */
ret = X86_BR_SYSRET;
break;
case 0x80 ... 0x8f: /* conditional */
ret = X86_BR_JCC;
break;
default:
ret = X86_BR_NONE;
}
break;
case 0x70 ... 0x7f: /* conditional */
ret = X86_BR_JCC;
break;
case 0xc2: /* near ret */
case 0xc3: /* near ret */
case 0xca: /* far ret */
case 0xcb: /* far ret */
ret = X86_BR_RET;
break;
case 0xcf: /* iret */
ret = X86_BR_IRET;
break;
case 0xcc ... 0xce: /* int */
ret = X86_BR_INT;
break;
case 0xe8: /* call near rel */
insn_get_immediate(&insn);
if (insn.immediate1.value == 0) {
/* zero length call */
ret = X86_BR_ZERO_CALL;
break;
}
case 0x9a: /* call far absolute */
ret = X86_BR_CALL;
break;
case 0xe0 ... 0xe3: /* loop jmp */
ret = X86_BR_JCC;
break;
case 0xe9 ... 0xeb: /* jmp */
ret = X86_BR_JMP;
break;
case 0xff: /* call near absolute, call far absolute ind */
insn_get_modrm(&insn);
ext = (insn.modrm.bytes[0] >> 3) & 0x7;
switch (ext) {
case 2: /* near ind call */
case 3: /* far ind call */
ret = X86_BR_IND_CALL;
break;
case 4:
case 5:
ret = X86_BR_IND_JMP;
break;
}
break;
default:
ret = X86_BR_NONE;
}
/*
* interrupts, traps, faults (and thus ring transition) may
* occur on any instructions. Thus, to classify them correctly,
* we need to first look at the from and to priv levels. If they
* are different and to is in the kernel, then it indicates
* a ring transition. If the from instruction is not a ring
* transition instr (syscall, systenter, int), then it means
* it was a irq, trap or fault.
*
* we have no way of detecting kernel to kernel faults.
*/
if (from_plm == X86_BR_USER && to_plm == X86_BR_KERNEL
&& ret != X86_BR_SYSCALL && ret != X86_BR_INT)
ret = X86_BR_IRQ;
/*
* branch priv level determined by target as
* is done by HW when LBR_SELECT is implemented
*/
if (ret != X86_BR_NONE)
ret |= to_plm;
return ret;
}
/*
* implement actual branch filter based on user demand.
* Hardware may not exactly satisfy that request, thus
* we need to inspect opcodes. Mismatched branches are
* discarded. Therefore, the number of branches returned
* in PERF_SAMPLE_BRANCH_STACK sample may vary.
*/
static void
intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
{
u64 from, to;
int br_sel = cpuc->br_sel;
int i, j, type;
bool compress = false;
/* if sampling all branches, then nothing to filter */
if ((br_sel & X86_BR_ALL) == X86_BR_ALL)
return;
for (i = 0; i < cpuc->lbr_stack.nr; i++) {
from = cpuc->lbr_entries[i].from;
to = cpuc->lbr_entries[i].to;
type = branch_type(from, to, cpuc->lbr_entries[i].abort);
if (type != X86_BR_NONE && (br_sel & X86_BR_ANYTX)) {
if (cpuc->lbr_entries[i].in_tx)
type |= X86_BR_IN_TX;
else
type |= X86_BR_NO_TX;
}
/* if type does not correspond, then discard */
if (type == X86_BR_NONE || (br_sel & type) != type) {
cpuc->lbr_entries[i].from = 0;
compress = true;
}
}
if (!compress)
return;
/* remove all entries with from=0 */
for (i = 0; i < cpuc->lbr_stack.nr; ) {
if (!cpuc->lbr_entries[i].from) {
j = i;
while (++j < cpuc->lbr_stack.nr)
cpuc->lbr_entries[j-1] = cpuc->lbr_entries[j];
cpuc->lbr_stack.nr--;
if (!cpuc->lbr_entries[i].from)
continue;
}
i++;
}
}
/*
* Map interface branch filters onto LBR filters
*/
static const int nhm_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX_SHIFT] = {
[PERF_SAMPLE_BRANCH_ANY_SHIFT] = LBR_ANY,
[PERF_SAMPLE_BRANCH_USER_SHIFT] = LBR_USER,
[PERF_SAMPLE_BRANCH_KERNEL_SHIFT] = LBR_KERNEL,
[PERF_SAMPLE_BRANCH_HV_SHIFT] = LBR_IGN,
[PERF_SAMPLE_BRANCH_ANY_RETURN_SHIFT] = LBR_RETURN | LBR_REL_JMP
| LBR_IND_JMP | LBR_FAR,
/*
* NHM/WSM erratum: must include REL_JMP+IND_JMP to get CALL branches
*/
[PERF_SAMPLE_BRANCH_ANY_CALL_SHIFT] =
LBR_REL_CALL | LBR_IND_CALL | LBR_REL_JMP | LBR_IND_JMP | LBR_FAR,
/*
* NHM/WSM erratum: must include IND_JMP to capture IND_CALL
*/
[PERF_SAMPLE_BRANCH_IND_CALL_SHIFT] = LBR_IND_CALL | LBR_IND_JMP,
[PERF_SAMPLE_BRANCH_COND_SHIFT] = LBR_JCC,
[PERF_SAMPLE_BRANCH_IND_JUMP_SHIFT] = LBR_IND_JMP,
};
static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX_SHIFT] = {
[PERF_SAMPLE_BRANCH_ANY_SHIFT] = LBR_ANY,
[PERF_SAMPLE_BRANCH_USER_SHIFT] = LBR_USER,
[PERF_SAMPLE_BRANCH_KERNEL_SHIFT] = LBR_KERNEL,
[PERF_SAMPLE_BRANCH_HV_SHIFT] = LBR_IGN,
[PERF_SAMPLE_BRANCH_ANY_RETURN_SHIFT] = LBR_RETURN | LBR_FAR,
[PERF_SAMPLE_BRANCH_ANY_CALL_SHIFT] = LBR_REL_CALL | LBR_IND_CALL
| LBR_FAR,
[PERF_SAMPLE_BRANCH_IND_CALL_SHIFT] = LBR_IND_CALL,
[PERF_SAMPLE_BRANCH_COND_SHIFT] = LBR_JCC,
[PERF_SAMPLE_BRANCH_IND_JUMP_SHIFT] = LBR_IND_JMP,
[PERF_SAMPLE_BRANCH_CALL_SHIFT] = LBR_REL_CALL,
};
static const int hsw_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX_SHIFT] = {
[PERF_SAMPLE_BRANCH_ANY_SHIFT] = LBR_ANY,
[PERF_SAMPLE_BRANCH_USER_SHIFT] = LBR_USER,
[PERF_SAMPLE_BRANCH_KERNEL_SHIFT] = LBR_KERNEL,
[PERF_SAMPLE_BRANCH_HV_SHIFT] = LBR_IGN,
[PERF_SAMPLE_BRANCH_ANY_RETURN_SHIFT] = LBR_RETURN | LBR_FAR,
[PERF_SAMPLE_BRANCH_ANY_CALL_SHIFT] = LBR_REL_CALL | LBR_IND_CALL
| LBR_FAR,
[PERF_SAMPLE_BRANCH_IND_CALL_SHIFT] = LBR_IND_CALL,
[PERF_SAMPLE_BRANCH_COND_SHIFT] = LBR_JCC,
[PERF_SAMPLE_BRANCH_CALL_STACK_SHIFT] = LBR_REL_CALL | LBR_IND_CALL
| LBR_RETURN | LBR_CALL_STACK,
[PERF_SAMPLE_BRANCH_IND_JUMP_SHIFT] = LBR_IND_JMP,
[PERF_SAMPLE_BRANCH_CALL_SHIFT] = LBR_REL_CALL,
};
/* core */
void __init intel_pmu_lbr_init_core(void)
{
x86_pmu.lbr_nr = 4;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_CORE_FROM;
x86_pmu.lbr_to = MSR_LBR_CORE_TO;
/*
* SW branch filter usage:
* - compensate for lack of HW filter
*/
}
/* nehalem/westmere */
void __init intel_pmu_lbr_init_nhm(void)
{
x86_pmu.lbr_nr = 16;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
x86_pmu.lbr_to = MSR_LBR_NHM_TO;
x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
x86_pmu.lbr_sel_map = nhm_lbr_sel_map;
/*
* SW branch filter usage:
* - workaround LBR_SEL errata (see above)
* - support syscall, sysret capture.
* That requires LBR_FAR but that means far
* jmp need to be filtered out
*/
}
/* sandy bridge */
void __init intel_pmu_lbr_init_snb(void)
{
x86_pmu.lbr_nr = 16;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
x86_pmu.lbr_to = MSR_LBR_NHM_TO;
x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
x86_pmu.lbr_sel_map = snb_lbr_sel_map;
/*
* SW branch filter usage:
* - support syscall, sysret capture.
* That requires LBR_FAR but that means far
* jmp need to be filtered out
*/
}
/* haswell */
void intel_pmu_lbr_init_hsw(void)
{
x86_pmu.lbr_nr = 16;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
x86_pmu.lbr_to = MSR_LBR_NHM_TO;
x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
x86_pmu.lbr_sel_map = hsw_lbr_sel_map;
if (lbr_from_signext_quirk_needed())
static_branch_enable(&lbr_from_quirk_key);
}
/* skylake */
__init void intel_pmu_lbr_init_skl(void)
{
x86_pmu.lbr_nr = 32;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
x86_pmu.lbr_to = MSR_LBR_NHM_TO;
x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
x86_pmu.lbr_sel_map = hsw_lbr_sel_map;
/*
* SW branch filter usage:
* - support syscall, sysret capture.
* That requires LBR_FAR but that means far
* jmp need to be filtered out
*/
}
/* atom */
void __init intel_pmu_lbr_init_atom(void)
{
/*
* only models starting at stepping 10 seems
* to have an operational LBR which can freeze
* on PMU interrupt
*/
if (boot_cpu_data.x86_model == 28
&& boot_cpu_data.x86_stepping < 10) {
pr_cont("LBR disabled due to erratum");
return;
}
x86_pmu.lbr_nr = 8;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_CORE_FROM;
x86_pmu.lbr_to = MSR_LBR_CORE_TO;
/*
* SW branch filter usage:
* - compensate for lack of HW filter
*/
}
/* slm */
void __init intel_pmu_lbr_init_slm(void)
{
x86_pmu.lbr_nr = 8;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_CORE_FROM;
x86_pmu.lbr_to = MSR_LBR_CORE_TO;
x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
x86_pmu.lbr_sel_map = nhm_lbr_sel_map;
/*
* SW branch filter usage:
* - compensate for lack of HW filter
*/
pr_cont("8-deep LBR, ");
}
/* Knights Landing */
void intel_pmu_lbr_init_knl(void)
{
x86_pmu.lbr_nr = 8;
x86_pmu.lbr_tos = MSR_LBR_TOS;
x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
x86_pmu.lbr_to = MSR_LBR_NHM_TO;
x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
x86_pmu.lbr_sel_map = snb_lbr_sel_map;
/* Knights Landing does have MISPREDICT bit */
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_LIP)
x86_pmu.intel_cap.lbr_format = LBR_FORMAT_EIP_FLAGS;
}