#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,
};
/*
* 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_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_PLM (LBR_KERNEL | LBR_USER)
#define LBR_SEL_MASK 0x1ff /* 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 (1ULL << 63)
#define for_each_branch_sample_type(x) \
for ((x) = PERF_SAMPLE_BRANCH_USER; \
(x) < PERF_SAMPLE_BRANCH_MAX; (x) <<= 1)
/*
* 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 */
};
#define X86_BR_PLM (X86_BR_USER | X86_BR_KERNEL)
#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_IND_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_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(void)
{
u64 debugctl;
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
if (cpuc->lbr_sel)
wrmsrl(MSR_LBR_SELECT, cpuc->lbr_sel->config);
rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
debugctl |= (DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI);
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);
}
}
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();
}
void intel_pmu_lbr_enable(struct perf_event *event)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
if (!x86_pmu.lbr_nr)
return;
/*
* Reset the LBR stack if we changed task context to
* avoid data leaks.
*/
if (event->ctx->task && cpuc->lbr_context != event->ctx) {
intel_pmu_lbr_reset();
cpuc->lbr_context = event->ctx;
}
cpuc->br_sel = event->hw.branch_reg.reg;
cpuc->lbr_users++;
}
void intel_pmu_lbr_disable(struct perf_event *event)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
if (!x86_pmu.lbr_nr)
return;
cpuc->lbr_users--;
WARN_ON_ONCE(cpuc->lbr_users < 0);
if (cpuc->enabled && !cpuc->lbr_users) {
__intel_pmu_lbr_disable();
/* avoid stale pointer */
cpuc->lbr_context = NULL;
}
}
void intel_pmu_lbr_enable_all(void)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
if (cpuc->lbr_users)
__intel_pmu_lbr_enable();
}
void intel_pmu_lbr_disable_all(void)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
if (cpuc->lbr_users)
__intel_pmu_lbr_disable();
}
/*
* TOS = most recently recorded branch
*/
static inline u64 intel_pmu_lbr_tos(void)
{
u64 tos;
rdmsrl(x86_pmu.lbr_tos, tos);
return tos;
}
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].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)
{
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;
for (i = 0; i < x86_pmu.lbr_nr; i++) {
unsigned long lbr_idx = (tos - i) & mask;
u64 from, to, mis = 0, pred = 0;
rdmsrl(x86_pmu.lbr_from + lbr_idx, from);
rdmsrl(x86_pmu.lbr_to + lbr_idx, to);
if (lbr_format == LBR_FORMAT_EIP_FLAGS) {
mis = !!(from & LBR_FROM_FLAG_MISPRED);
pred = !mis;
from = (u64)((((s64)from) << 1) >> 1);
}
cpuc->lbr_entries[i].from = from;
cpuc->lbr_entries[i].to = to;
cpuc->lbr_entries[i].mispred = mis;
cpuc->lbr_entries[i].predicted = pred;
cpuc->lbr_entries[i].reserved = 0;
}
cpuc->lbr_stack.nr = i;
}
void intel_pmu_lbr_read(void)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(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) {
if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
return -EACCES;
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;
/*
* 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, m;
u64 v;
for_each_branch_sample_type(m) {
if (!(br_type & m))
continue;
v = x86_pmu.lbr_sel_map[m];
if (v == LBR_NOT_SUPP)
return -EOPNOTSUPP;
if (v != LBR_IGN)
mask |= v;
}
reg = &event->hw.branch_reg;
reg->idx = EXTRA_REG_LBR;
/* LBR_SELECT operates in suppress mode so invert mask */
reg->config = ~mask & x86_pmu.lbr_sel_mask;
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"
* intruction 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)
{
struct insn insn;
void *addr;
int bytes, size = MAX_INSN_SIZE;
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 (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 = copy_from_user_nmi(buf, (void __user *)from, size);
if (bytes != size)
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;
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, is64);
insn_get_opcode(&insn);
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 */
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_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);
/* 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] = {
[PERF_SAMPLE_BRANCH_ANY] = LBR_ANY,
[PERF_SAMPLE_BRANCH_USER] = LBR_USER,
[PERF_SAMPLE_BRANCH_KERNEL] = LBR_KERNEL,
[PERF_SAMPLE_BRANCH_HV] = LBR_IGN,
[PERF_SAMPLE_BRANCH_ANY_RETURN] = 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] =
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] = LBR_IND_CALL | LBR_IND_JMP,
};
static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = {
[PERF_SAMPLE_BRANCH_ANY] = LBR_ANY,
[PERF_SAMPLE_BRANCH_USER] = LBR_USER,
[PERF_SAMPLE_BRANCH_KERNEL] = LBR_KERNEL,
[PERF_SAMPLE_BRANCH_HV] = LBR_IGN,
[PERF_SAMPLE_BRANCH_ANY_RETURN] = LBR_RETURN | LBR_FAR,
[PERF_SAMPLE_BRANCH_ANY_CALL] = LBR_REL_CALL | LBR_IND_CALL
| LBR_FAR,
[PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL,
};
/* core */
void 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
*/
pr_cont("4-deep LBR, ");
}
/* nehalem/westmere */
void 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
*/
pr_cont("16-deep LBR, ");
}
/* sandy bridge */
void 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
*/
pr_cont("16-deep LBR, ");
}
/* atom */
void 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_mask < 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
*/
pr_cont("8-deep LBR, ");
}
