parisc: Add initial kernel-side perf_event support

Signed-off-by: Helge Deller <deller@gmx.de>

3 files changed, 89 insertions, 0 deletions

diff --git a/arch/parisc/kernel/Makefile b/arch/parisc/kernel/Makefile
index d5055ba33722..9157bc8bdf41 100644
--- a/arch/parisc/kernel/Makefile
+++ b/arch/parisc/kernel/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY)	+= topology.o
 obj-$(CONFIG_FUNCTION_TRACER)		+= ftrace.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o
 obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
+obj-$(CONFIG_PERF_EVENTS)		+= perf_event.o perf_regs.o
 obj-$(CONFIG_KGDB)			+= kgdb.o
 obj-$(CONFIG_KPROBES)			+= kprobes.o
 obj-$(CONFIG_KEXEC_CORE)		+= kexec.o relocate_kernel.o
diff --git a/arch/parisc/kernel/perf_event.c b/arch/parisc/kernel/perf_event.c
new file mode 100644
index 000000000000..f90b83886ab4
--- /dev/null
+++ b/arch/parisc/kernel/perf_event.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Performance event support for parisc
+ *
+ * Copyright (C) 2025 by Helge Deller <deller@gmx.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <asm/unwind.h>
+
+void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
+			   struct pt_regs *regs)
+{
+
+	struct unwind_frame_info info;
+
+	unwind_frame_init_task(&info, current, NULL);
+	while (1) {
+		if (unwind_once(&info) < 0 || info.ip == 0)
+			break;
+
+		if (!__kernel_text_address(info.ip) ||
+			perf_callchain_store(entry, info.ip))
+				return;
+	}
+}
diff --git a/arch/parisc/kernel/perf_regs.c b/arch/parisc/kernel/perf_regs.c
new file mode 100644
index 000000000000..68458e2f6197
--- /dev/null
+++ b/arch/parisc/kernel/perf_regs.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Copyright (C) 2025 by Helge Deller <deller@gmx.de> */
+
+#include <linux/perf_event.h>
+#include <linux/perf_regs.h>
+#include <asm/ptrace.h>
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+	switch (idx) {
+	case PERF_REG_PARISC_R0 ... PERF_REG_PARISC_R31:
+		return regs->gr[idx - PERF_REG_PARISC_R0];
+	case PERF_REG_PARISC_SR0 ... PERF_REG_PARISC_SR7:
+		return regs->sr[idx - PERF_REG_PARISC_SR0];
+	case PERF_REG_PARISC_IASQ0 ... PERF_REG_PARISC_IASQ1:
+		return regs->iasq[idx - PERF_REG_PARISC_IASQ0];
+	case PERF_REG_PARISC_IAOQ0 ... PERF_REG_PARISC_IAOQ1:
+		return regs->iasq[idx - PERF_REG_PARISC_IAOQ0];
+	case PERF_REG_PARISC_SAR:	/* CR11 */
+		return regs->sar;
+	case PERF_REG_PARISC_IIR:	/* CR19 */
+		return regs->iir;
+	case PERF_REG_PARISC_ISR:	/* CR20 */
+		return regs->isr;
+	case PERF_REG_PARISC_IOR:	/* CR21 */
+		return regs->ior;
+	case PERF_REG_PARISC_IPSW:	/* CR22 */
+		return regs->ipsw;
+	};
+	WARN_ON_ONCE((u32)idx >= PERF_REG_PARISC_MAX);
+	return 0;
+}
+
+#define REG_RESERVED (~((1ULL << PERF_REG_PARISC_MAX) - 1))
+
+int perf_reg_validate(u64 mask)
+{
+	if (!mask || mask & REG_RESERVED)
+		return -EINVAL;
+
+	return 0;
+}
+
+u64 perf_reg_abi(struct task_struct *task)
+{
+	if (!IS_ENABLED(CONFIG_64BIT))
+		return PERF_SAMPLE_REGS_ABI_32;
+
+	if (test_tsk_thread_flag(task, TIF_32BIT))
+		return PERF_SAMPLE_REGS_ABI_32;
+
+	return PERF_SAMPLE_REGS_ABI_64;
+}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+			struct pt_regs *regs)
+{
+	regs_user->regs = task_pt_regs(current);
+	regs_user->abi = perf_reg_abi(current);
+}