From 1c3430516b0732d923de9fd3bfb3e2e537eeb235 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 11 Nov 2021 02:07:28 +0000 Subject: [PATCH] perf: Add wrappers for invoking guest callbacks 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 Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Paolo Bonzini Link: https://lore.kernel.org/r/20211111020738.2512932-8-seanjc@google.com --- arch/arm64/kernel/perf_callchain.c | 16 +++++----------- arch/x86/events/core.c | 15 +++++---------- arch/x86/events/intel/core.c | 5 +---- include/linux/perf_event.h | 24 ++++++++++++++++++++++++ 4 files changed, 35 insertions(+), 25 deletions(-) diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c index 274dc3e11b6d..db04a55cee7e 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -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) { diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index e29312a1003a..620347398027 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2768,11 +2768,10 @@ 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; } @@ -2872,11 +2871,10 @@ 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; } @@ -2953,18 +2951,15 @@ 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) { diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 7ff24d1ecdb7..f7af8029664f 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2837,7 +2837,6 @@ 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); @@ -2904,9 +2903,7 @@ 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(); } diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 5e6b346d62a7..346d5aff5804 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1254,6 +1254,30 @@ 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);