[PATCH v2 05/13] perf: Force architectures to opt-in to guest callbacks

Sean Christopherson seanjc at google.com
Fri Aug 27 17:35:50 PDT 2021


Introduce HAVE_GUEST_PERF_EVENTS and require architectures to select it
to allow registering guest callbacks in perf.  Future patches will convert
the callbacks to static_call.  Rather than churn a bunch of arch code (that
was presumably copy+pasted from x86), remove it wholesale as it's useless
and at best wasting cycles.

Wrap even the stubs with an #ifdef to avoid an arch sneaking in a bogus
registration with CONFIG_PERF_EVENTS=n.

Signed-off-by: Sean Christopherson <seanjc at google.com>
---
 arch/arm/kernel/perf_callchain.c   | 33 ++++-------------------------
 arch/arm64/Kconfig                 |  1 +
 arch/csky/kernel/perf_callchain.c  | 12 -----------
 arch/nds32/kernel/perf_event_cpu.c | 34 ++++--------------------------
 arch/riscv/kernel/perf_callchain.c | 13 ------------
 arch/x86/Kconfig                   |  1 +
 include/linux/perf_event.h         |  4 ++++
 init/Kconfig                       |  3 +++
 kernel/events/core.c               |  2 ++
 9 files changed, 19 insertions(+), 84 deletions(-)

diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index 1626dfc6f6ce..bc6b246ab55e 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -62,14 +62,8 @@ user_backtrace(struct 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();
 	struct frame_tail __user *tail;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	perf_callchain_store(entry, regs->ARM_pc);
 
 	if (!current->mm)
@@ -99,44 +93,25 @@ callchain_trace(struct stackframe *fr,
 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 fr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	arm_get_current_stackframe(regs, &fr);
 	walk_stackframe(&fr, callchain_trace, 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->is_in_guest())
-		return guest_cbs->get_guest_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();
 	int misc = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
-			misc |= PERF_RECORD_MISC_GUEST_USER;
-		else
-			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-	} else {
-		if (user_mode(regs))
-			misc |= PERF_RECORD_MISC_USER;
-		else
-			misc |= PERF_RECORD_MISC_KERNEL;
-	}
+	if (user_mode(regs))
+		misc |= PERF_RECORD_MISC_USER;
+	else
+		misc |= PERF_RECORD_MISC_KERNEL;
 
 	return misc;
 }
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b5b13a932561..72a201a686c5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -190,6 +190,7 @@ config ARM64
 	select HAVE_NMI
 	select HAVE_PATA_PLATFORM
 	select HAVE_PERF_EVENTS
+	select HAVE_GUEST_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_REGS_AND_STACK_ACCESS_API
diff --git a/arch/csky/kernel/perf_callchain.c b/arch/csky/kernel/perf_callchain.c
index 35318a635a5f..92057de08f4f 100644
--- a/arch/csky/kernel/perf_callchain.c
+++ b/arch/csky/kernel/perf_callchain.c
@@ -86,13 +86,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 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();
 	unsigned long fp = 0;
 
-	/* C-SKY does not support virtualization. */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return;
-
 	fp = regs->regs[4];
 	perf_callchain_store(entry, regs->pc);
 
@@ -111,15 +106,8 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 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 fr;
 
-	/* C-SKY does not support virtualization. */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		pr_warn("C-SKY does not support perf in guest mode!");
-		return;
-	}
-
 	fr.fp = regs->regs[4];
 	fr.lr = regs->lr;
 	walk_stackframe(&fr, entry);
diff --git a/arch/nds32/kernel/perf_event_cpu.c b/arch/nds32/kernel/perf_event_cpu.c
index f38791960781..a78a879e7ef1 100644
--- a/arch/nds32/kernel/perf_event_cpu.c
+++ b/arch/nds32/kernel/perf_event_cpu.c
@@ -1363,7 +1363,6 @@ 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();
 	unsigned long fp = 0;
 	unsigned long gp = 0;
 	unsigned long lp = 0;
@@ -1372,11 +1371,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 
 	leaf_fp = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	perf_callchain_store(entry, regs->ipc);
 	fp = regs->fp;
 	gp = regs->gp;
@@ -1480,13 +1474,8 @@ 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 fr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
 	fr.fp = regs->fp;
 	fr.lp = regs->lp;
 	fr.sp = regs->sp;
@@ -1495,32 +1484,17 @@ 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();
-
-	/* However, NDS32 does not support virtualization */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_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();
 	int misc = 0;
 
-	/* However, NDS32 does not support virtualization */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
-			misc |= PERF_RECORD_MISC_GUEST_USER;
-		else
-			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-	} else {
-		if (user_mode(regs))
-			misc |= PERF_RECORD_MISC_USER;
-		else
-			misc |= PERF_RECORD_MISC_KERNEL;
-	}
+	if (user_mode(regs))
+		misc |= PERF_RECORD_MISC_USER;
+	else
+		misc |= PERF_RECORD_MISC_KERNEL;
 
 	return misc;
 }
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 8ecfc4c128bc..1fc075b8f764 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -56,13 +56,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 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();
 	unsigned long fp = 0;
 
-	/* RISC-V does not support perf in guest mode. */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return;
-
 	fp = regs->s0;
 	perf_callchain_store(entry, regs->epc);
 
@@ -79,13 +74,5 @@ static bool fill_callchain(void *entry, 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();
-
-	/* RISC-V does not support perf in guest mode. */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		pr_warn("RISC-V does not support perf in guest mode!");
-		return;
-	}
-
 	walk_stackframe(NULL, regs, fill_callchain, entry);
 }
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 49270655e827..a4de4aa7a3df 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -229,6 +229,7 @@ config X86
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_EVENTS_NMI
 	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
+	select HAVE_GUEST_PERF_EVENTS
 	select HAVE_PCI
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2b77e2154b61..e75971f85cc8 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1236,6 +1236,7 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
 				 enum perf_bpf_event_type type,
 				 u16 flags);
 
+#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
 extern struct perf_guest_info_callbacks *perf_guest_cbs;
 static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 {
@@ -1247,6 +1248,7 @@ static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 }
 extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
 extern void perf_unregister_guest_info_callbacks(void);
+#endif /* CONFIG_HAVE_GUEST_PERF_EVENTS */
 
 extern void perf_event_exec(void);
 extern void perf_event_comm(struct task_struct *tsk, bool exec);
@@ -1489,9 +1491,11 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)	{ }
 static inline void
 perf_bp_event(struct perf_event *event, void *data)			{ }
 
+#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
 static inline void perf_register_guest_info_callbacks
 (struct perf_guest_info_callbacks *callbacks)				{ }
 static inline void perf_unregister_guest_info_callbacks(void)		{ }
+#endif
 
 static inline void perf_event_mmap(struct vm_area_struct *vma)		{ }
 
diff --git a/init/Kconfig b/init/Kconfig
index 55f9f7738ebb..9ef51ae53977 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1776,6 +1776,9 @@ config HAVE_PERF_EVENTS
 	help
 	  See tools/perf/design.txt for details.
 
+config HAVE_GUEST_PERF_EVENTS
+	bool
+
 config PERF_USE_VMALLOC
 	bool
 	help
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1be95d9ace46..d7f606e06446 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6482,6 +6482,7 @@ static void perf_pending_event(struct irq_work *entry)
 		perf_swevent_put_recursion_context(rctx);
 }
 
+#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks *perf_guest_cbs;
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
@@ -6499,6 +6500,7 @@ void perf_unregister_guest_info_callbacks(void)
 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+#endif
 
 static void
 perf_output_sample_regs(struct perf_output_handle *handle,
-- 
2.33.0.259.gc128427fd7-goog




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