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UPSTREAM: perf: Add wrappers for invoking guest callbacks

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Add helpers for the guest callbacks to prepare for burying the callbacks
behind a Kconfig (it's a lot easier to provide a few stubs than to #ifdef
piles of code), and also to prepare for converting the callbacks to
static_call().  perf_instruction_pointer() in particular will have subtle
semantics with static_call(), as the "no callbacks" case will return 0 if
the callbacks are unregistered between querying guest state and getting
the IP.  Implement the change now to avoid a functional change when adding
static_call() support, and because the new helper needs to return
_something_ in this case.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-8-seanjc@google.com
(cherry picked from commit 1c3430516b)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 233587962
Bug: 233588291
Change-Id: Iab2b8f21081e7e08514637da9da64a853dcf25d3
This commit is contained in:
Sean Christopherson
2021-11-11 02:07:28 +00:00
committed by Will Deacon
parent 637e737ad5
commit d97ef4912b
4 changed files with 35 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
arch/arm64/kernel/perf_callchain.c
View File

@@ -102,9 +102,7 @@ compat_user_backtrace(struct compat_frame_tail __user *tail,
void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
if (guest_cbs && guest_cbs->state()) {
if (perf_guest_state()) {
/* We don't support guest os callchain now */
return;
}
@@ -149,10 +147,9 @@ static bool callchain_trace(void *data, unsigned long pc)
void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
struct stackframe frame;
if (guest_cbs && guest_cbs->state()) {
if (perf_guest_state()) {
/* We don't support guest os callchain now */
return;
}
@@ -163,18 +160,15 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
unsigned long perf_instruction_pointer(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
if (guest_cbs && guest_cbs->state())
return guest_cbs->get_ip();
if (perf_guest_state())
return perf_guest_get_ip();
return instruction_pointer(regs);
}
unsigned long perf_misc_flags(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
unsigned int guest_state = perf_guest_state();
int misc = 0;
if (guest_state) {

15
arch/x86/events/core.c
View File

@@ -2762,11 +2762,10 @@ static bool perf_hw_regs(struct pt_regs *regs)
void
perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
struct unwind_state state;
unsigned long addr;
if (guest_cbs && guest_cbs->state()) {
if (perf_guest_state()) {
/* TODO: We don't support guest os callchain now */
return;
}
@@ -2866,11 +2865,10 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
void
perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
struct stack_frame frame;
const struct stack_frame __user *fp;
if (guest_cbs && guest_cbs->state()) {
if (perf_guest_state()) {
/* TODO: We don't support guest os callchain now */
return;
}
@@ -2947,18 +2945,15 @@ static unsigned long code_segment_base(struct pt_regs *regs)
unsigned long perf_instruction_pointer(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
if (guest_cbs && guest_cbs->state())
return guest_cbs->get_ip();
if (perf_guest_state())
return perf_guest_get_ip();
return regs->ip + code_segment_base(regs);
}
unsigned long perf_misc_flags(struct pt_regs *regs)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
unsigned int guest_state = perf_guest_state();
int misc = 0;
if (guest_state) {

5
arch/x86/events/intel/core.c
View File

@@ -2788,7 +2788,6 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
{
struct perf_sample_data data;
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct perf_guest_info_callbacks *guest_cbs;
int bit;
int handled = 0;
u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
@@ -2855,9 +2854,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
*/
if (__test_and_clear_bit(GLOBAL_STATUS_TRACE_TOPAPMI_BIT, (unsigned long *)&status)) {
handled++;
guest_cbs = perf_get_guest_cbs();
if (likely(!guest_cbs || !guest_cbs->handle_intel_pt_intr()))
if (!perf_guest_handle_intel_pt_intr())
intel_pt_interrupt();
}

24
include/linux/perf_event.h
View File

@@ -1244,6 +1244,30 @@ static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
*/
return rcu_dereference(perf_guest_cbs);
}
static inline unsigned int perf_guest_state(void)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
return guest_cbs ? guest_cbs->state() : 0;
}
static inline unsigned long perf_guest_get_ip(void)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
/*
* Arbitrarily return '0' in the unlikely scenario that the callbacks
* are unregistered between checking guest state and getting the IP.
*/
return guest_cbs ? guest_cbs->get_ip() : 0;
}
static inline unsigned int perf_guest_handle_intel_pt_intr(void)
{
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
if (guest_cbs && guest_cbs->handle_intel_pt_intr)
return guest_cbs->handle_intel_pt_intr();
return 0;
}
extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);