[PATCH v4 1/2] riscv: perf: add guest vs host distinction

[zhouquan at iscas.ac.cn]

From: Quan Zhou <zhouquan at iscas.ac.cn>

Introduce basic guest support in perf, enabling it to distinguish
between PMU interrupts in the host or guest, and collect
fundamental information.

Signed-off-by: Quan Zhou <zhouquan at iscas.ac.cn>
---
 arch/riscv/include/asm/perf_event.h |  6 +++++
 arch/riscv/kernel/perf_callchain.c  | 38 +++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/arch/riscv/include/asm/perf_event.h b/arch/riscv/include/asm/perf_event.h
index 665bbc9b2f84..38926b4a902d 100644
--- a/arch/riscv/include/asm/perf_event.h
+++ b/arch/riscv/include/asm/perf_event.h
@@ -8,7 +8,11 @@
 #ifndef _ASM_RISCV_PERF_EVENT_H
 #define _ASM_RISCV_PERF_EVENT_H
 
+#ifdef CONFIG_PERF_EVENTS
 #include <linux/perf_event.h>
+extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
+extern unsigned long perf_misc_flags(struct pt_regs *regs);
+#define perf_misc_flags(regs) perf_misc_flags(regs)
 #define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
 
 #define perf_arch_fetch_caller_regs(regs, __ip) { \
@@ -17,4 +21,6 @@
 	(regs)->sp = current_stack_pointer; \
 	(regs)->status = SR_PP; \
 }
+#endif
+
 #endif /* _ASM_RISCV_PERF_EVENT_H */
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index c7468af77c66..c2c81a80f816 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -28,11 +28,49 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
+	if (perf_guest_state()) {
+		/* TODO: We don't support guest os callchain now */
+		return;
+	}
+
 	arch_stack_walk_user(fill_callchain, entry, regs);
 }
 
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	if (perf_guest_state()) {
+		/* TODO: We don't support guest os callchain now */
+		return;
+	}
+
 	walk_stackframe(NULL, regs, fill_callchain, entry);
 }
+
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+	if (perf_guest_state())
+		return perf_guest_get_ip();
+
+	return instruction_pointer(regs);
+}
+
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+	unsigned int guest_state = perf_guest_state();
+	unsigned long misc = 0;
+
+	if (guest_state) {
+		if (guest_state & PERF_GUEST_USER)
+			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;
+	}
+
+	return misc;
+}
-- 
2.34.1